PDA

View Full Version : new build opinions required



george uk
03-09-2013, 07:47 PM
Hi

I will be finally getting round to building machine I have had in mind, over the next few weeks, and could d with some advise. I want to build a strong machine, and can get the frame built up. I really want 1200mm or better Y. 2.2 or 3.2, on X, as much depth and can get on Z.I want the Y and Z to be strong enough to handle a B/C type head if needed, but will mostly be used for cutting stone.

Opinions am looking for

Gantry

1. X configuration motor choices and design. Am Thinking Nema 42 single motor 2 ball-screws, or 2 nema 34s and 2 ball screws.

1.1 Nema 42 bolted to end of machine, timing and gears to drive 2 ballscrews ( what problems will I face ),
1.2 2*nema 34s, (driving direct or geared ? ) and slaved ( does this give accuracy problems )

Table build.

I can get steel at reasonable rates and ally if needed, and my brother makes gates and has workshop with tools and jigs, am thinking that for end accuracy and convenience, I am going to get it made in 5 bits at least ( unless advised otherwise, 2 sides, 2 ends and the bed ). and bolt it together and tack it on site. I know I am going to have to take a long time makings sure the frames level and accurate.

2.1 any advise on what profiles, thicknessís or design am thinking 125mm box section, 2 oblongs about 1.2mtr high by 3.2mtr long, and 2 squares 1.2mtr
2.2 am making the bed in three sections, very sturdy, ( 1 4th axis, plasma/laser, printing area ). any advice ?

I will ask the other questions when I have finalised the design, am currently reading through the threads to get tips ) . Your opinions will not not be wasted, I have the funds to build this and I want to get the frame built next week, and the motors and heads ordered this Friday or Monday. Am thinking about 1200 for motors and electronics , 800 for the metal for the table ( cost price ), 600 or more for rails and screws. ( leaving 400 unbaked but can be increased ) .

cheers

george uk
04-09-2013, 11:53 AM
found this thread, it answers nearly everything i was looking for

http://www.mycncuk.com/forums/router-build-logs/6484-sufficiently-strong-machine.html

george uk
10-12-2013, 10:48 PM
finally getting on with this.

Going for a rig thats 2000mm double x 1200mm y 300mm z

ordered this lot

supported linear rails SBR20-300/1200/2000mm rails(6 supported rails+12 SBR20UU bearing blocks)
4pcs of ballscrews RM1605-350/1200/2000/2000mm overall length-C7(4screws+4ballnuts+4end-machinings)
4 SETS OF BK/BF12(with locknuts and cir-cplis)
4pcs of flexible couplings 6.35mm*8mm

am building a base similar to the above mentioned thread, with a few modds for rigid bed

am going for duel x motors, so heres my first question.

There now seems to be nema23 and nema24 motors, with the latter having more power eg
4 Axis Nema24 Stepper Motor 567oz-in CNC Controller Kit With Display And Keypad | eBay (http://www.ebay.co.uk/itm/350927581033?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)

so, is it worth the extra for the nema 24s, or is there something am not seeing ?

I want the Y gantry to be heave duty so i can maybe strap a B/C head on,

question 2 would a nema24 be overkill for a y axis at 1200mm travel, would i be better of with nema23

Question 3, i want to build a heavy duty rotary table on part of the bed, for stone carving. would nema 34 cause me any problems with lighter weight things like wood or foam and what gearing would you recommend.

i sort of need to order the motors over the next 2 days

EddyCurrent
10-12-2013, 11:04 PM
Sorry I can't advise on most of your questions but these motors are 4Nm (same as those in your link) but nema23, I got some and they run very smoothly albeit just on my bench at the moment.

Nema23 4Nm (http://www.cnc4you.co.uk/index.php?route=product/category&path=20_27)

JAZZCNC
11-12-2013, 12:54 AM
am going for duel x motors, so heres my first question.

There now seems to be nema23 and nema24 motors, with the latter having more power eg
4 Axis Nema24 Stepper Motor 567oz-in CNC Controller Kit With Display And Keypad | eBay (http://www.ebay.co.uk/itm/350927581033?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)

so, is it worth the extra for the nema 24s, or is there something am not seeing ?

YES your not seeing plenty.?

First the only difference between Nema 23 & 24 is physical outer Dim 23=57mm 24=60mm both have the same Bolt centres so both can be used on same mount.

The Difference you'll be seeing between them is Holding torque, Probably 3.1Nm and 4Nm.
Now the thing you don't realise is that what's important is the Inductance rating and often the larger 4Nm motors have much higher inductance than the lower 3.1Nm and this means they don't perform has good.
Now the Motors Eddy linked to seem quite Low inductance for 4Nm if that is indeed true.?? But most of the 4nm Chinese motors I've encountered have been quite High and IME the slightly lower 3.1Nm motors perform much better.

Now it seems to me your Rushing and not really knowing what your buying or what Mass you have to move.? This is a recipe for disaster and you will end up buying the wrong stuff if your not careful.!

The Kit you linked to is a prime example, it's Rubbish and completely wrong for your needs. The Drives are Rubbish junk, The PSU is way to Low voltage at 36V for those motors you'll end up with a very low performing machine. Thou this won't be too much of a problem thou has the drives will probably have died in short time so it won't be going anywhere.!!

Honestly I'm not just being Negative or pulling down but please take a Step back put a foot on the brakes and assess what you need better otherwise you'll regret it and waste shit load of money.

I'll PM you my number if you want to ring me and I'll try to help.

irving2008
11-12-2013, 01:02 AM
The Nema24 motors are 4mH/phase and ideally need 60v but are shipping with a 36v supply and 42v drives . The Nema23s are 3mH/phase and ideally need 55v and ship with 38v supply and 50v drives.

The Nema23 are the better option.

Boyan Silyavski
11-12-2013, 10:01 PM
Call Dean/JAZZCNC/ and cancel or put a hold on your order!

Most sellers stock everything or can source it, so stop the order until its not too late. Later you can just order from them the correct things. And add some money to the bill :-)

alboy
12-12-2013, 12:20 AM
Best advice I can give is talk to Jazz. Could save you a whole lot of expense and agro. Have spoken and emailed jazz a fair bit and he certainly knows about cnc machines.I would grab his offer for help as it is a rare thing nowadays for someone to offer to pass on their hard earned knowledge.
Jazz is extremely helpful and has a refreshingly no Bullsh*t approach. If you do take him up on his offer of help, please remember that Jazz and other knowledgeable members of this board impart their considerable knowledge and help at the expense of their own time so please respect that.

Alan

george uk
13-12-2013, 02:59 PM
Hi

Thanks all, exactly the info i needed, i was not thinking about these


The Nema24 motors are 4mH/phase and ideally need 60v but are shipping with a 36v supply and 42v drives . The Nema23s are 3mH/phase and ideally need 55v and ship with 38v supply and 50v drives.


and


Now the thing you don't realise is that what's important is the Inductance rating and often the larger 4Nm motors have much higher inductance than the lower 3.1Nm and this means they don't perform has good.

are both important bits of info, dont you just love proper hobbyist forums:courage:


Honestly I'm not just being Negative or pulling down

I like direct answers like that, and am listening and reading.


Now it seems to me your Rushing and not really knowing what your buying or what Mass you have to move.

AM not rushing, but am eager, i have the funds in the bank.

The gantry i have planned will be below 40kg, fully loaded, probably closer to 35kg, I know how i will do the gantry, but have not finalised the design, as i need to think about what i might need to strap on to it.

I want to incorporate a turret on the end of the table, and a rotary table or b/c head on the table. and a geared 4th axis


I'll PM you my number if you want to ring me and I'll try to help..

I will write up fully on here what am doing and mp you, thanks.

Thanks to all of you for your replies, :thumsup:

Boyan Silyavski
13-12-2013, 09:42 PM
AM not rushing, but am eager, i have the funds in the bank.

Me also from a month/at last/, but as i have still not finished the detailed drawing i am not eager to spend hard earned cash.




The gantry i have planned will be below 40kg, fully loaded, probably closer to 35kg, I know how i will do the gantry, but have not finalised the design, as i need to think about what i might need to strap on to it.

George,
i wonder how that really will be with the specifications /size/ you stated in the beginning? Are you sure you did not forget something? What type of gantry will that be?

george uk
14-12-2013, 10:39 AM
hi


i wonder how that really will be with the specifications /size/ you stated in the beginning? Are you sure you did not forget something? What type of gantry will that be?

I can afford to increase weight if needed, I have gone for 20mm supported rails and can beefed up if needed. I want the machine to be able to surface and etch stone, maybe even v-carve it. Accuracy is more important that speed,

The bed is going to be deep, but have fixing on it to bring parts up to Z, and troughs to allow water for laser or plasma cutting. When using stone, the surface if the stone will be close to the Z top ( least angle ), but enough drop in the bed to allow me to get a wide bit of foam on the 4th axis.

My initial gantry design,2* 100mm or 150mm by 40mm steel with drops, Y rails on the top, bit of engineering to get close to an A frame for the z plates. So pivot point is very close to the z bottom ( basically, z bottom minus the bit length )

Boyan Silyavski
14-12-2013, 01:45 PM
Working stone will need an extremely rigid gantry and Z+ square supported rails and long bearing blocks, even better-roller type ones. Did you have some other example build/working machine/ in mind when started buying, or its your design?

JAZZCNC
15-12-2013, 07:21 PM
The gantry i have planned will be below 40kg, fully loaded, probably closer to 35kg, I know how i will do the gantry, but have not finalised the design, as i need to think about what i might need to strap on to it.

I want to incorporate a turret on the end of the table, and a rotary table or b/c head on the table. and a geared 4th axis

Think you'll find your miles away with weight and to be affective and sturdy enough for cutting stone you'll be least in the 60-70's.
Like you say Speed isn't important but rigidity is massively important for cutting stone or any hard material with accuracy. To surface and cut stone effectively you'll need a slow spinning spindle with high torque, this alone will mean heavy spindle motor which will require a substantial Z axis to attach it too which will be heavy enough.
Mass greatly helps with surface finish so don't be chasing weight.!! . .. Better to be Chubby and Slow than Slim and weak.!

I wasn't going to mention this has seems you'd already ordered them but seen has Silva has already commented I will Confirm what he's saying. The cheap round rails will not take the Water and fine Grit that comes from stone dust, Add to this the weight and high vibrations that cutting hard materials will put thru the frame and they will die in short order.!!

My advise is cancel the order and Buy Proper Liner bearing other wise your wasting your time if your wanting accuracy and to cut hard materials. If you can't Cancel then sell them before using so still new and buy the correct components for the Job.

george uk
16-12-2013, 10:58 PM
i haven't order it yet, and i can change if needed, i want to build a multi purpose machine, and i will build a second, task purpose machine, when i have done the first, all in all, i have between 5k - 8k but can up that if i think its worth it.

I will have a number of spindles/heads, and am looking at 600 to 2000rpm options at the mo, i want XYZ basic, solid and strong enough for any material up to approx 200mm, with the top bed having 2 cross bars, splitting it into 3 lower areas with up to an extra 150mm depth, the lowwer areas holding setups for plastics, B/C head, 4th axis, plasma/arc, rotational table .

And i also want nearly a full length of x 4th axis, indexable for carving foam.

I know i will make many mistakes making this macheen, but stripping back and rebuilding replacing, is not a problem, trying out different electronics, is not a problem ( as long as am not waist-full ) . I quite good at pulling projects together, free time permitting.

Boyan Silyavski
16-12-2013, 11:09 PM
Hi George,
drawing your ideas and perfecting the design will save you a lot of cash and headaches. There are many small details in a build, which if overlooked will lead to big waste of effort and money.
The parts for a solid topnotch 1000x2000x200 machine will cost approximately 2500-3000.

So, don't do that mistakes you are intending to do, read the builds here, take the best stuff and draw it. Sleep on it and then buy the parts.

george uk
17-12-2013, 11:56 PM
something i can not understand, a why not, in relation to y stability from x axis

why not have rails or fix round bar, on both the top and bottom of the x axis, IE, 2* 125mm box, 2200mm long, why put rails jujst on the top and rely on waight and engineering to get a stable point for Z to fix to.

It would seem an obvoius solution but i see its not used, that means these something am clearly not accounting for. am prity sure i could get them level to each other easly, so what am i not thinking of ?

mekanik
18-12-2013, 12:49 AM
Hi George
I am a noobe to this as well & had the same thought but after you have done some reading by the guys that know what there doing it is very difficult to get the two faces parallel especially after welding up a frame, there is apparently considerable clearance on the round rail/bearing setup but the profile rail i believe is manufactured to a tighter tolerance and is a lot more ridgid, if you have a good mooch through the build logs it will all become clear,and someone will probably provide a better insight than i can.
Regards
Mike

Boyan Silyavski
18-12-2013, 10:09 AM
Because that's not the problem. The problem is overhang. Z to Y rigidity+Y twist and bend.

george uk
18-12-2013, 10:18 AM
Hi, i considered that, but then thought to get round that, i would m,achine the underside and fit the second rail, after the machine is part built, fit the Y/Z axis and use that to machine the underside of the x Bar. It would be perfectly level to the top.

or
First make a level on the floor, then, Make a level the top of the x, with epoxy, spin the full machine over, level the bottom with epoxy.

Although, i would be more confident in option 1. because as long as your top surface is accurate, so will your bottom rail.

If i can do it this way, i can design a substantially better Y/Z Lighter and stronger. I know i will fubar bearings faster, but it would be an asceptable costs

With long braces on the guides, you would be able to minimise any undulation anyhow, there has got to be something else wrong, just can not see what at the moment.

Any suggestions anyone ?

EddyCurrent
18-12-2013, 10:22 AM
George, if you don't have something like Sketchup then download it and let us see some drawings, it's far easier than trying to explain it.

george uk
18-12-2013, 11:17 AM
*** sorry double posty ***

george uk
18-12-2013, 11:30 AM
i will whip up the gantry and x in scetch up and post it later. i prefer to do initial engineerings and calcs in pencil and paper, Think of it as 2 C clamps per x rail, spaced at maybe 200mm

Boyan Silyavski
18-12-2013, 01:33 PM
reading this (http://www.cncroutersource.com/do-it-yourself-CNC-router.html)will answer your questions about the forces in play. what you suggest will not work , as you have to decrease moment B and the best way to do it is to increase distance D4.

11037

george uk
18-12-2013, 02:15 PM
Hi

Wont be a problem as it will have equaL up forces from the guide underneath

in that drawing, my x would be were moment A is, and were the two yellow arrows are ( d3 ) would be the top and bottom connection to the X Rails.

The Y gantry, will be between the 2 x rails ( above and below ) , putting its COG were moment/force A is. I think i will only need the tool going below the gantry, not the spindle, the aim was always to get the bottom point of the spindle finnishing at the y gantry and bringing any material up to it

EddyCurrent
18-12-2013, 02:23 PM
At the bottom of that drawing is Force D and Force C, these are are right angles to the rails.
With your proposal these forces would be along the rails, parallel to them and pointing in opposite directions

george uk
18-12-2013, 03:34 PM
Eddy - yes exactly, and if i increase the distance of the gap on the bottom rail bearings, that should change the force angle a bit. ( cutting force ).

Also, the rails can run on the top of x, and the side of x, if its to hard to get the bottom level to the top. The intention being, the second rail would absorb some of the stress, and the ammount of extra stress relief should be proportional to the allowable gantry weight reduction.

If it will work this way, i can loose loads of weight from the gantry but maintain its rigidity. I still think there must be something am not seeing,

Boyan Silyavski
18-12-2013, 03:54 PM
Yes, yes, they will change direction/the forces. But... on a typical router the bearings that move the gantry are spaced 260-300mm/including, if rectangular supported/. On a heavy duty, like my current build for example, they will be spaced 400mm and above. So you have to space them obviously. What you are not taking into account is the overall height of that and the gantry and what i am speaking of is RESONANCE. It will resonate like crazy cause the forces of the tool and the assembly will be in paralel lines. Something like this resonator , where one fork will be the tool and its plate and the other the gantry assembly
11038

there are some other forces which you don't take into effect- inertia and gravitation. Which are not problem in normal L shape gantry.

Just imagine a tank speeding on its noze vertically, when it has to stop. Tanks are low and long. Thats what best sturdy gantry design is.

While gravity and long L take care of the balance spreading it over the bearing blocks, the non achievable balance will f^^^ck what you propose. Vertical tank on its nose, it doesn't matter that it will be supported in the middle. if not that, then the resonance.

I am music instrument maker and here what will tell you. to lower resonance, you divide a long force arm into short ones and put each of them in different plane, so they will not help each other

george uk
18-12-2013, 04:42 PM
I will put it in sketchup, as my current build of typhoo boxes and cartons and kitchen items, looks a bit to heath robinson ( I can write the Math on them, makes it easier to visualise stresses )

Of all the point you mention above, i think resonance is the one i can not design around, but, If the rails art fixed hard, the bearings will take out some. And although my design may increase the occurrence of resonances, it also reduces the requirement of weight of the gantry, therefor, having less effect ( less mass to carry the force of the resonance beyond the barings ), and also lowering the inertia problem

My works table is within the box of the frame ( half way ), the Y ganrty will be the top of the frame, not above. To keep forces and resonance down, my Z does not extend beyond the gantry frame. only the tool.

My z, will be between the two Y walls of the ganrty, fixed to both walls, the gantry, is a box itself, ( 100/150mm deep - 40mm wall width ), giving me the gap in the center to fit the Z gubbins

EddyCurrent
18-12-2013, 05:23 PM
Unfortunately George I was meaning it was a bad thing that the forces were parallel along the rails unless you have 2 bearings on the top and 2 on the bottom but that would be overkill.
Unless your drawing, when you post it, makes it clearer.

george uk
18-12-2013, 07:24 PM
hi eddy, yes i am going for 2 bearings per rail, 4 bearings per X side, and when i ment spacing them out, earlier, its the gap between the bearings per rail, not the rails themselves ( top bottom ) .

I think that overdoing it on the bearings and rails, will allow me to make the gantry lighter, and a stable box, If i can get the gantry lighter, i dont have to worry about inertia , am also thinking that, in might want to be able temporarily add weight to the Gantry for some jobs, like surfacing stone,

I did go down the heavy road at first, and gantry weight, can cause as many problems as it solves, every time i work on the calculations with heavy gantry, am hitting performance limits on bearings, then bar, way before the machine design going to hit any problems. Then when you look at the costs of baeringfs an rails that will perform ok with the weight, ooooaaaarrr , then, when your bearings and rail can take it, your machine may need supporting. chicken and egg game.

whereas, the more rigid the Y, the less weight it needs to be stable

Boyan Silyavski
18-12-2013, 07:52 PM
George,
To avoid chicken egg problem, why not start from the Z. Usually the weakest spot on any machine. THEN this will command the gantry design. Or you have it clear there?

EddyCurrent
18-12-2013, 10:22 PM
George, I forgot you were cutting stone so maybe 4 bearings per side is not overkill, my mind is currently filled with routers for wood :hopelessness: Will wait for drawing.

george uk
19-12-2013, 02:25 AM
Hi



To avoid chicken egg problem, why not start from the Z. Usually the weakest spot on any machine. THEN this will command the gantry design. Or you have it clear there?


i started with the plan that the z should be able to handle different spindles+additions, without differing what forces it can handle in both +-xy. most of the moving gantry designs, like the one you linked to, favour one direction down X, and rely on weight of the garntry to offset the stability looses you get by having to mount the spindle forword of the Y, on the drawing you link to, every mm forword the z mech is away from Y, the force you can apply at the bit tip drops substantialy, and would be different X+ than X-.

so, the problem/limit for z, when considering deflections , is all in the Y, when you factor in a 4th axis, again the differing forces between X+ and X-, start loosing accuracy , the longer the jobs running, the worse it gets, the bigger the job is down the x axis, the faster this will happen. .

but, if you have 2 of them Y axis you linked to, facing each other, and the Z in the center, Zs force is equal on X+- and Y+-. the forces Y can take, could be ajusted by spacing th 2 bearings per rail further apart

then, Z drop, is the next place you start looking at, will try and get it in sckechup tomorrow, failing that, i will take a photo of my drawings and post that:moon:

george uk
03-01-2014, 10:59 AM
Hi

am trying to nail down the interface card i will use, has anyone used any of the following, ( listed in preference )

6 axis 250KHz USB CNC card, MACH3 plugin, auto zero, auto tool setting, API | eBay (http://www.ebay.co.uk/itm/6-axis-250KHz-USB-CNC-card-MACH3-plugin-auto-zero-auto-tool-setting-API/111235807945?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%2 6asc%3D286%26meid%3D3852804033738567098%26pid%3D10 0005%26prg%3D1048%26rk%3D1%26rkt%3D2%26sd%3D111225 500995%26)

Martzis USB HID Interface (MUHI) Card Board For Linux EMC and Mach 3 PC Via BUS | eBay (http://www.ebay.co.uk/itm/221232671152?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)

5Axis Upgraded CNC Breakout Board Interface Set +Keypad +Display, Manual Control | eBay (http://www.ebay.co.uk/itm/190978619459?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)

Boyan Silyavski
03-01-2014, 02:16 PM
Hi

am trying to nail down the interface card i will use, has anyone used any of the following, ( listed in preference )

6 axis 250KHz USB CNC card, MACH3 plugin, auto zero, auto tool setting, API | eBay (http://www.ebay.co.uk/itm/6-axis-250KHz-USB-CNC-card-MACH3-plugin-auto-zero-auto-tool-setting-API/111235807945?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%2 6asc%3D286%26meid%3D3852804033738567098%26pid%3D10 0005%26prg%3D1048%26rk%3D1%26rkt%3D2%26sd%3D111225 500995%26)

Martzis USB HID Interface (MUHI) Card Board For Linux EMC and Mach 3 PC Via BUS | eBay (http://www.ebay.co.uk/itm/221232671152?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)

5Axis Upgraded CNC Breakout Board Interface Set +Keypad +Display, Manual Control | eBay (http://www.ebay.co.uk/itm/190978619459?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)

Hi George,
i don't know from where you dig out that boards, as i am also at this point but see them for first time.

The first one has its outputs 3v, so you have to check out if compatible with the drivers you intend to use
The second one seems I/0 board only, unable to generate train pulse for motors if i am not mistaken
The third one...no, seems some problematic chinese board

It seems money is an issue, then take a look at :
-http://www.planet-cnc.com (http://www.planet-cnc.com/) usb boards with proprietary software instead Mach3, if you still don't own it
-if you want to go Linux, look at the Mesa FPGA boards, search the Linux forum
-CNCdrive - motion controls (http://cncdrive.com/UC300.html)

Of course depends how many axis you will like to drive,

Then comes the Ethernet smooth stepper + BOB / PMDX126/ or a CSMIO 4 axis board/ or the expensive 6 axis, which in fact has all that one should look for in a board altogether/

Another possible solution i am looking at now is the KFLOP, which for the moment seems to be my choice, money wise for what it offers

Pokeys is also a good money wise .

george uk
03-01-2014, 04:50 PM
Hi

Moneys not a problem, but am bulding 2, test one first, then production one, so its ok if i make the odd mistake. If i find a board that does everything i want, and someone else has used it, i will buy it.

am looking at the solutions you pointed to, and this looks good
http://www.planet-cnc.com/img/controllerMk2_800.jpg

More axis the better, if possible, i would like to stick to Mach3/4 and Linuxcnc, just becuase of the learning curve and macros. I will read up on that one this weekend.

and as you guessed, i didnt read option 2 before i posted,

Boyan Silyavski
05-01-2014, 12:14 AM
Another option i am considering which looks very promising is the Centipede KSI Labs, LLC (http://www.ksilabs.com/centipede.php) .

JAZZCNC
05-01-2014, 01:21 AM
Another option i am considering which looks very promising is the Centipede KSI Labs, LLC (http://www.ksilabs.com/centipede.php) .

It's a very nice bit of kit but be careful because I think the developer has thrown the teddy out the pram with Artsoft because he doesn't like the direction they are taking with Mach4.?

Regards the Kflop and Galia etc then unless your intending on using Servo's with high count encoders then your wasting your money has other than quality they offer no more advantage than the ESS or other Sub £200 cards for steppers.
If your using steppers and don't need slaved Axis then the Csmio-IP-M is by far the best I've ever used and use's industry standard 24V differential signals. there's No Bob's needed and very high quality units in a neat package.

If I needed higher pulse rates for servo's then I wouldn't hesitate to buy the higher priced Csmio-Ip-S which will give many of the other much more expensive high end motion controllers a good run for there money.

The Kflop is a nice bit of kit but it's still using USB and Ethernet is so much better and noise immune compared to USB. I've never been a fan of USB for Bob's etc and while I didn't have too much trouble with using the USB version of the SS I did get some troubles. With Ethernet I've not had any issues with noise at all other than a Dodgy card and can run machine from in the house with a laptop sat on my knee if I like using the network.!! . . . . I don't but I could.!!

george uk
06-01-2014, 12:06 AM
i need 5 or 6 axis minimum , am fairly sure i will need to slave a 2nd x at least, I need to stick to bobs that can run mach3/4 and or emc, just because of the support you can get if you get stuck. I need at least spindle control and 2* encoder reading capability's from the electronics. As well as spindle on the y ganrty, i want to build in a turret into the machine frame, and have a sepotate 4th axis, and seporate b/c head. i could do it all with 5 axis, just mean swapping the leads around when i want to set the machine up different,

i had guessed through reading the other threads, that a smooth stepper is a good idea, and you have just confirmed that, am looking at the other cards mentioned on here, am going with steppers not servoes

Am up for any recomendations, ?


and can run machine from in the house with a laptop sat on my knee if I like using the network.!! . . . . I don't but I could.!!

Ha ha, not without a really really long estop cable.

Tell you what though, you have just got me thinking, i wander how secure the cards are on a network and how they would react to being probed,

Boyan Silyavski
06-01-2014, 12:59 AM
Sorry, don't want to hijack the thread, but here is what i think.

I agree with all that Dean said. But the reason i am still digging for BOBs is axis count and money i would pay for what i would get. Similar to you i will start with 4 motors. Then i want a minimum 1 axis for rotary table, possibly 2. So -6 axis until now. Later i am thinking of separate axis maybe for plasma and may be one more for a device, that pushes MDF sheet while routing and lifts / i saw this somewhwre on internet.
I agree that all can be done with 6 axis and some thinking it out. But also i am living in rented house and in foreign country, so may be one day if i have to change country will be best to sell the machine, so axis count could be better

OK. After continuous digging and analyzing if multi axis tralalala is desired , here are my personal conclusions:

1. No usb boards. They will be obsolete in an year or two. PCI-maybe. Ethernet-best.


2. only 3 boards/ combinations/ for me are worth the money, which support 6 or more axis:

-ESS +PMDX126+PMDX-107 - quite cheaper than the CSMIO, 500Mhz step frequency, mach3, 180$+40$ shipping + 174$ +$57.00 +~40$ shipping = ~410 euro +eventual tax
-CSMIO- 5-24v differential I/O, 6 axis, mach3, 549eur+23% vat= 675 euro +??shipping= ~700euro , so, very nice but quite expensive in fact

-Mesa 7i80+7i76 or 5i25+7i76 . More and more seems Linux is the way. First combo is 119$+150$ +~ 40$ shipping=~250euro , second combo is 200$+~40$shipping =~180 euro.
Basically the first combo is similar to the CSMIO with ethernet, 5v-32V, differential I/0, etc + the added benefit of aditional 5 axis for only 100$ more+ this baby has 4 slots, so 20 axis or aditional things can be put there
The second combo is PCI and again axis can be added later.
And not to speak of the drives and other boards that Mesa have and can be seamlessly integrated for cheap.

The other boards from the previous posts i ignored , due to USB, due to limited support, price per what they offer, lack of differential 24v I/O

I wonder why nobody wrote a serious plugin for the Mesas and Mach3. This is f+==g crazy. Furthermore they have a new board still not supported in Linux -7i76E which is Ethernet 5 axis for 199$ that can be further expanded.

What i will do is start to play with Linux to see if i am up to the task and save some money.

PS. If i knew just before a week what i know now, i would have bought the Galil 4080 for 540eur at ebay just on 31. December. But somebody knew this so he bought all 3 of them. Bloody ignorance of mine.

Clive S
06-01-2014, 03:05 PM
-Mesa 7i80+7i76 or 5i25+7i76 . More and more seems Linux is the way. First combo is 119$+150$ +~ 40$ shipping=~250euro , second combo is 200$+~40$shipping =~180 euro.

Silyavski If you are thinking of Linuxcnc and need to slave motor on one axis there is a problem with homing that has not been ironed out yet. See here LinuxCNC Support Forum :: Topic: Homing and limits with X axis 2 joints (1/2) (http://www.linuxcnc.org/index.php/english/forum/49-basic-configuration/27067-homing-and-limits-with-x-axis-2-joints) and here LinuxCNC Support Forum :: Topic: Configurate Slave Axis (1/4) (http://www.linuxcnc.org/index.php/english/forum/38-general-linuxcnc-questions/24458-configurate-slave-axis) This might be being fixed in the next release. ..Clive

george uk
07-01-2014, 09:42 AM
again, a few very important bits of info between you lot there.

I see the sence in the more expensive cards, i will pick one of them. and its seems that there on it with linuxcnc and homing double axis, and there are some work arounds, I like mach3, but hate windows, although i have to use it sometimes, but it is worth using a windows machine just for mach3/4.

I found a local company that can supply me the b-screws and rails and barings ect. and there are a few high precision engineering company's near me as well, so am looking at some alternative mounts for the Y gantry to the x axis. I have been reading with interest on here the posts for R&P over ballscrews. I will put the designs in sketchup in the next day or so.

2 rails per x axis side, one above, one below, 2 barings per rail, seems to make the most sense on an equal loading/force approach. Maybe its not a bad idea to have the barings as the week point, Because they are cheeper to replace in time and money, compared to unbending a machine gantry. If, from the design stage, you consider the barings as consumables ( not to short a life time though ). it free's up some design options.

R&P suits a heavy gantry, and i can see why most heavy machines use it, but, when your building your 80k to 100k + to sell to a customer, the customers not going to acsept thaty every n100 hours of running, they will have to replace the barings, and every n1000 hours , the ballscrews, so you design a machine thats heavy enough to absorb the forces, to give your barings and ballscrews some help. but the extra weight requires bigger motor or servoes, and causes other problems, or pushes you design in certan directions.

wereas, if you specificaly design your machine for the barings to be the week point, you can make you Y gantry a box, that contains a Z Axis, thats a box iteslf with rails on both insides of the Y gantry. The hole Y ganty, clamped by rails and barings on the top and bottom of the X axis, with the ballscrew in the gap between them (between the edge of the Table frame/X axis and the Y ganrty box ).

Done this way, every axis forces are contained within the box frames, and takes out any levers if you get what i mean, all the above gantry designs are big leavers that you have to compensate for. Whereas, if the only leaver is the projection of the bit from the Z bottom, and that is within the X frame box. What this gives you is equal forces/loading in X and Y both directions, and a very strong Z Boxwith heavy down force capability, but, very heavy loading X and Y, if the Z is retracted and only the tip of the bit is projecting, Like for surfacing a large piece of stone.

Also, a box within a box makes sence because you can bolt certan cruital parts inplace ( Y gantry ), on the machine, make sure there all square and level, before you weild, and you can use the bolt points to strengthen up the metal near the weilds, to help ofset any twisting/pulling your frames wants to do while its weilded.

My main reason for designing like this, apart from equal forces in all directions, is machine down time if a mistake is made, This is through experiance of owning/running a Gocarting track 97-2001. Go carts have lots of expencive barings in them, and after 2 years of large parts bills, we redesigned and refitted the frames, to eas of on the barings, What a mistake, we spent a lot less on barings that season but down time per cart frame due to bending was horrendus, each frame had to be stripped and bolted in the jig for 2 days, heated and coolded, then brazzed, then rebuilt, That job went from once after the end of each season, to frames queing up to be placed in the jig.
My point being, make a mistake and bend your machine, your down time is a lot more (maybe days ), and you dont know what the cost of repair might be, whereas, if you pop your barings, its costly, but you know how long it will take and how much it will cost before your machine is running.

I will try get it in sketchup later

Boyan Silyavski
07-01-2014, 12:34 PM
Silyavski If you are thinking of Linuxcnc and need to slave motor on one axis there is a problem with homing that has not been ironed out yet. See here LinuxCNC Support Forum :: Topic: Homing and limits with X axis 2 joints (1/2) (http://www.linuxcnc.org/index.php/english/forum/49-basic-configuration/27067-homing-and-limits-with-x-axis-2-joints) and here LinuxCNC Support Forum :: Topic: Configurate Slave Axis (1/4) (http://www.linuxcnc.org/index.php/english/forum/38-general-linuxcnc-questions/24458-configurate-slave-axis) This might be being fixed in the next release. ..Clive

Thanks for the info. Though here is what i think of it in my case, may be concerning this build also:
-if the machine is rigid like mine and like this will be , may be it shouldn't be a problem. With Hiwin 20 HA bearing spacement at the gantry sides of 40cm/ or even 30/ i don't see how it would go out of true, its not a flimsy machine we are talking about here.
-i would use servos, they will simply stop due to error


again, a few very important bits of info between you lot there.


2 rails per x axis side, one above, one below, 2 barings per rail, seems to make the most sense on an equal loading/force approach. Maybe its not a bad idea to have the barings as the week point, Because they are cheeper to replace in time and money, compared to unbending a machine gantry. If, from the design stage, you consider the barings as consumables ( not to short a life time though ). it free's up some design options.



I still don't like that design of yours, but that shouldn't discourage you :-)



R&P suits a heavy gantry, and i can see why most heavy machines use it, but, when your building your 80k to 100k + to sell to a customer, the customers not going to acsept thaty every n100 hours of running, they will have to replace the barings, and every n1000 hours , the ballscrews, so you design a machine thats heavy enough to absorb the forces, to give your barings and ballscrews some help. but the extra weight requires bigger motor or servoes, and causes other problems, or pushes you design in certan directions.




I don't know if i am understanding you wrong. But:
RP is far more wear prone than ball screw. Ball screw is far more better and smooth. for 6m long table, yes RP, but for anything under 3m-ballscrew.



wereas, if you specificaly design your machine for the barings to be the week point, you can make you Y gantry a box, that contains a Z Axis, thats a box iteslf with rails on both insides of the Y gantry. The hole Y ganty, clamped by rails and barings on the top and bottom of the X axis, with the ballscrew in the gap between them (between the edge of the Table frame/X axis and the Y ganrty box ).



IMHO the weakest points in order of a DIY machine FYI:
1. Router bit - deflection
2. Z overhang-plate twist
3. Gantry twist and bend ,
4. Gantry sides
5. bearings/assuming you use square
6.Spindle power
7. Balscrew support bearings, spindle bearings
8...etc



My main reason for designing like this, apart from equal forces in all directions, is machine down time if a mistake is made, This is through experiance of owning/running a Gocarting track 97-2001. Go carts have lots of expencive barings in them, and after 2 years of large parts bills, we redesigned and refitted the frames, to eas of on the barings, What a mistake, we spent a lot less on barings that season but down time per cart frame due to bending was horrendus, each frame had to be stripped and bolted in the jig for 2 days, heated and coolded, then brazzed, then rebuilt, That job went from once after the end of each season, to frames queing up to be placed in the jig.
My point being, make a mistake and bend your machine, your down time is a lot more (maybe days ), and you dont know what the cost of repair might be, whereas, if you pop your barings, its costly, but you know how long it will take and how much it will cost before your machine is running.


You can not bend with steppers a properly constructed machine. They will simply stall. Remember this. Nor you can wear Hiwin bearings if properly mounted. When you have them in your hands you will see why. They will be probably that last element in a machine to fail.

Back to the BOBs

I have another questions in mind concerning the BOBs. Please some one more knowledgeable clear it for me:

-With steppers: If Mach 3 outputs as max 100kHz pulse/ even less normally/, then a normal reliable board that supports 100khz should be ok, yes?

-With servos: If Mach 3 outputs as max 100kHz pulse/ even less normally/, then why should i care to buy a board like the CSMIO or other? I know, apart from the reliability and connections, i mean. Every modern servo drive can upscale by gearing the frequency and generate the proper signal , so why waste money on expensive cards that will do exactly the same thing in fact? I start to believe that the driver generating the pulses will be quite better and reliable..
It seems that mach3 is the limiting factor, not the board?

george uk
07-01-2014, 03:02 PM
Hi


Though here is what i think of it in my case, may be concerning this build also:

i agree with what your saying here, am thinking i may cog and belt the 2 ballscrews together, to stop any small chance of them going out of alignment. Or, go back to using one motor to drive both ballscrews.


I still don't like that design of yours, but that shouldn't discourage you :-)

Dont worry me, i prefare people to be direct and to the point. and getting something wrong is not failing, its a leaning step on the way to success.


I don't know if i am understanding you wrong. But:RP is far more wear prone than ball screw.

I was thinking aloud, i am going with ballscrew,


You can not bend with steppers a properly constructed machine. .

I have seen this happen, Nema23 on z, Z bocx mounted forward like you pictured. Z down gave it enough leaver, that when his limit switch failed, put a slight bend in a very well constructed Y gantry, both the mounting rails and ballscrew had a noticable movment when passing the point were it had bent.

He was very ham fisted with his limit switches, hence it failed, but it did bend it, i will have a go at doing the math tonight again,


IMHO the weakest points in order of a DIY machine FYI:
1. Router bit - deflection
2. Z overhang-plate twist
3. Gantry twist and bend ,
4. Gantry sides
5. bearings/assuming you use square
6.Spindle power
7. Balscrew support bearings, spindle bearings
8...etc


Wen i consider the list of week points, i think of it more the order i would want it to break if it does go wrong. I need to put my design is sketchup so you can see it,

am thinking ( but will acsept that am wrong, ), is that No 1 should be the baring mount screws or the baring, I think you will understand when you see my X design.

Boyan Silyavski
07-01-2014, 03:34 PM
Hi



.

I have seen this happen, Nema23 on z, Z bocx mounted forward like you pictured. Z down gave it enough leaver, that when his limit switch failed, put a slight bend in a very well constructed Y gantry, both the mounting rails and ballscrew had a noticable movment when passing the point were it had bent.

He was very ham fisted with his limit switches, hence it failed, but it did bend it, i will have a go at doing the math tonight again,



Thats why i insist that only 2 possible models of homing and limit switches should exist, no other variation trade-offs, like the ones popularized by Mach3 in fact:

1. Small hobby machines with weak motors and more or less rigid / like mine current one/ - no limit switches, instead software limits . Mistake, axis go to end , motor stalls and nothing happens. Probably limits only on Z, as there could be a problem with flimsier ones/ like mine :-)/ Its typical situation where the BOB has limited I/O.

2.BOB with a lot of I/O and homing and limit on for each axis on SEPARATE I/O, so a limit switch is a limit switch, nothing else. Thats what i intend to do and advice you for your build, this with my limited knowledge. And if servos, the limit switches directly to the servos, not the BOB, i don't see a reason why the servo should wait for the BOB to tell him to stop. Cause with servo, a lot could happen in a very short time if geared and running fast. It seems most of the servos i looked at support it, so they stop and later they tell the BOB that they are not moving .

JAZZCNC
07-01-2014, 06:26 PM
-With servos: If Mach 3 outputs as max 100kHz pulse/ even less normally/, then why should i care to buy a board like the CSMIO or other? I know, apart from the reliability and connections, i mean. Every modern servo drive can upscale by gearing the frequency and generate the proper signal , so why waste money on expensive cards that will do exactly the same thing in fact? I start to believe that the driver generating the pulses will be quite better and reliable..
It seems that mach3 is the limiting factor, not the board?

Mach3 is only the limiting factor when using the parallel port and even then it's Not really Mach3 it's the Parallel port and it's driver.
When you use an external motion control card all these restrictions are taken away and infact Mach3 does very little other than watch I/O's and this is why low spec PC and Laptops can be used.

Now with servo's the freqency rate becomes important because the encoders and depending on the encoder count will depend on if you need higher than 100Khz. Which for most servos you will with out using the electronic gearing feature built into the drives.
Most who are using servos avoid electronic gearing because it lowers resolution and often the whole point of servo's and encoders is to give high resolution.

Now lets say you are using typical servo's with quadrature encoders having 2500cpr this means you need 10,000 pulses per rev so divideing the controler Pulse rate (IE: KHZ) by this amount gives Pulses per sec then times x 60 will determine the maximum speed you'll get from the Servo's. . .IE: 100Khz / 10,000ppr=10pps x 60s=600RPM

So has you can see 100Khz won't be much good if have 3000rpm servos has the fastest speed you'll get is 600rpm.!!

Now if the drives have electronic gearing multiplier then you can use this at the expense of resolution. So when 4x multiplier is applied then for every 1 pulse Mach3 controller sends out the drive will see it has 4 so 100Khz becomes 400Khz but the resolution is divided by 4.!!
400khz/10,000x60=2400Rpm better but still not enough so you'll need to use the nearest or above to give the 500Khz you'll need for 3000rpm with 2500CPR encoders.!!
Electronic gearing can be ok for some machines because the resolution will be very high to start with.!!

The next problem comes from the BOBs if used and it's Max pulse rate causing a bottle neck and yep most typical BOB's don't go that high so you'll need a very fast BOB and high quality BOB if your using servos with high pulse counts.
This is also why lots of High end motion control cards don't use BOB's so to speak (IE Csmio) and connect direct to any devices attached or thru dedicated daughter boards which don't cause a bottle neck.!

So be warned to all those dreaming of using servo's just be aware they take you to another all new level of head scratching and expense.!! . . . . . So I honestly suggest you ask your self do you Really Really Really need Servo's.??? . . . . . . . Oh and just be aware they are still not closed Loop with Mach3.!! . . . . . The best they can do is Fault if they see a following error.

For 99.9% of DIY machines and even relatively slower Light industrial machines steppers if spec'd and setup correctly are far far far less hassle and plenty accurate enough.

Boyan Silyavski
07-01-2014, 09:02 PM
Dean,

thanks for the great input, cleared some clouds :-) , but still my question stands:

Mach3 outputs normally 25khz pulse. On a perfect PC it could output stable 100kHz /or even up to 300kHz before it locks, on a top computer, according to its creators/ .

Now, how these 100kz become 1Mhz or 4Mhz on CSMIO, Galil or whatsoever when mach3 outputs only pulses, not trajectory information. They generate them, the same way a geared servo drive generates them, so in fact - no real resolution benefit at all with expensive boards for the $$$, coupled with servos, steppers and Mach3. Apart from the reliability , ethernet or usb connection and I/O. It seems to me that these Mhz they are offering are a hype. No body can prove to me that a generated signal from a BOB is better from the same signal generated from a Panasonic servo drive electronically geared, for example.

Dont ask me who put this in my head :-) but now i have it clear after that digging, it took me a week to wake up from the hype- until Mach3 or 4 or.. closes the loop at the PC and transmits trajectory signal to the motion control, i wouldn't care for the Mhz of the boards. It wouldnt happen on windows, except on some kind of dedicated hardware pc probably.

That investigation answered the other questions of mine, why the good DSP motion control cards have + encoder inputs, / not only for Analog servo drives i mean/ . And why a separate dedicated motion control solution for a machine is so darn expensive.

Now seems Linux a kind of do that what we are speaking of. Wow, i am starting to defend Linux :hysterical:

JAZZCNC
07-01-2014, 10:26 PM
No you miss understand. Mach is only limited and prone to crashing when using the Parallel port at high Khz ratings.
The Parallel port and it's driver are the problem when using high Khz and struggle above 60Khz.

Motion control cards free Mach of these problems and it's Now the job of the Hardware on the Motion control card to generate the pulses NOT Mach3.
Mach3 just passes the trajectory Data to the Motion control which Buffers it in memory then generates the pulses needed, which it can do at very high pulse rates.

The main differance between Mach3 and Linux Cnc is that Mach3 and it's Motion control cards have to buffer information and Linux works in real time.
Can't speak for Linux has I don't use it but I can for MAch3 and it's motion control cards and trust me it's not hype. They do exactly what they say and generate very clean high quality pulses very fast.!!. . . . . If they didn't there would be lots of very very unhappy people who are now daily running industrial machines for there living which have been converted to Mach and using high count Servo's with encoders.!!

Also not sure what your on about regards Bob and Servo drives.? . . . . Bob does nothing more than distribute signals and servo drive does nothing but receive signals. Again I think you confused here.??

Boyan Silyavski
07-01-2014, 11:05 PM
Ok,
May be i am mistaken in my limited understanding. Will stop here. Still not knowledgeable enough. Will have to investigate further. It still though is quite mystery to me how Mach3 passes trajectory data if it sends only pulses, meaning the card doesn't know whats next or what to expect. May be it has to do something with the drivers/plugins for each card and mach3.

No problems with the BOBs :-) , just want to make sure they do all what they claim to do and don't mislead us in some subtle way. Want to be a wise buyer and make sure where my $ could do a better job.

JAZZCNC
07-01-2014, 11:52 PM
Mach doesn't send Pulses it sends "DATA". . .Has in Trajectory DATA to the Motion control Card which use's this DATA and does some Complex Maths with it to then create "PULSES" which it outputs to the drives at very high speed and with nice clear crisp signal. Whether that be Stepper or Servo drives or any device that expects Pulse signals.

Now if you want Closed Loop with Mach3 then you can have it.? . . . . But Mach can't do it internally, the Motion control card has to do it and there are very few that do and these come at a cost.

Electronic gearing in Servo drives are just Multipliers, they can only multiply what comes in and essentialy this comes from the encoder. So to give an overly simplified example say the lowest resolution your encoder can read equals 1mm and you have 4:1 gearing in the Drive then your lowest count or best resolution encoder can read now = 4mm. . . . So your speed increases but your resolution drops.!! . . . . . . Just has in life Everything that's free cost's something.!!

george uk
08-01-2014, 03:16 AM
Again, very usfull stuff in there.

Am using motors as i can easly get the resloution i need and if i make a mistake i can change them reletivly cheeply,


Nor you can wear Hiwin bearings if properly mounted. When you have them in your hands you will see why. They will be probably that last element in a machine to fail.


You not considering the difference in wear when using stone, Its not just the heavy use on the machine parts, your basicaly air-rating grinding paste. allthough the powder feels fine and soft, on a particulate level, its rock hard and sharpe. vacuums and covers can pre-long bearing wear, but, you are going to wear rails and bearings when cutting or surfacing stone. Then think that large beds are hardly every fully utilised, everybody's got there own favourite sweet spot on there machine were most of the smaller jobs get done, so you get uneaven wear.

If you then want to surface a large bit of stone, 1500mm by 800mm, you would see the wear patterns in the surfacing as the rails and screws go between the commonly used area and the less used area.

There are other considerations as to why it might be a good idea to have the bearings as the failure points. Re=straightening a frame, or gantry, is quite a long and complex job, that involves building a jig, usualy into a thick concrete floor, and gooing through a heating,cooling and tighnening routines, then when its in shape, heat it and cool it to even the stresses.

8/10 times, it would be cheaper to just remake the gantry, and salvage the unbent parts.

whereas, if you specifically design your frame for the bearing to be the week point, servicing is easier, serviced periods are calculable and variable depending on machine use. and as long as your bearings will fail, beyond the maximum cutting forces your machine will exert, then you could consider it a safety feature.

JAZZCNC
08-01-2014, 09:47 AM
whereas, if you specifically design your frame for the bearing to be the week point, servicing is easier, serviced periods are calculable and variable depending on machine use. and as long as your bearings will fail, beyond the maximum cutting forces your machine will exert, then you could consider it a safety feature.

Your correct about stone being grinding paste but don't agree that you will be designing in the rails to be a fail point.?. . . . They will naturaly be a fail point because they are moving components, has will the be ballscrews and nut.
So instead of designing in what will happen anyway put all your design efforts into the best way to limit or avoid this.

Best why I know off is to cover and conseal so get them either up high out the way or under neith and under cover.!! . . . . Now Remember you'll be using Mass's of water which tends to run down hill, also gravity brings droplets down eventually so personally I'd be looking to get the rails higher rather than lower and still under cover has much possible.

Then you have the Ballscrew or R&P debate.? At 3mtr length then the Only way I'd use ballscrews is if they used rotating ballnuts. Which would actually help with reducing the number of rotating parts and be much easier to cover and conseal.
To use rotating ballscrews at 3mtr length would require at least 25mm Dia screws which then takes you into large Stepper motors/ drives etc added to this the fact your gantry will be heavy anyway means even larger motors or going with servo motors and all that comes with them.!
This is why ballscrews and long machines don't match perfectly well and if you find any long machine that use's Ballscrews you'll see they often have large diameter screws with a Large pitch thats geared with ratio to keep the rotation speed down and whip from happening. They also have servos on the ends because steppers can't handle the torque required to Accel and Slow from traveling a heavy gantry with large rotating mass.!

R&P is there foreoften used when accurecy isn't the prime concern because it's less expensive and has less rotating Mass. Down side is it's less efficeint and more exposed and prone to interference from debris getting into the workings so again needs careful placement and consealment.!!

Which I'd use would depend on machine design and my budget.? Probably Ballscrew because I prefer them but 100% it would be a rotating nut and up high out the way along with the rails. This is where all my design efforts would be concentrated and even if it cost extra money to put up high and under cover because of building in the extra strength required I would do it to save on the down time which would come from replacing worn components.

Machine setup can take many hours or days and even weeks at DIY level if your after close tolerances so anything to reduce this or limit having to disturb the finely setup machine would be my prime concern along with strength and accuracy.

Now I'm going to honest and blunt here George.!! . . . . I think you are going to waste an awful lot of time and money plus dissapointed with results because what your wanting to have is Large machine that is all things to all materials but haven't got a clue to just how hard that is to achive or make happen.
When you go large even with machine designed just for one main purpose the design and build process takes you to new levels, expensive levels well above the average DIY build. SO to try and build a machine to be ALL THINGS to ALL MATERAILS with advanced features like 4th & 5th axis etc is a BIG BIG BIG under taking that would make even the most experienced DIY builder like Jonathan or Me sit down and think very very very carefully.? . . . . . To take a project like this on with NO experience is a recipey for wasting money and time .!
My advice is don't do it and build smaller or focus at one machine designed for that main task, which at this size will still be a very very big challenge for some new.!!

george uk
08-01-2014, 02:43 PM
Hi

I have reduced the length of the macheen to give me just under 2000mm cutting in X. I have really took a lot in that has been discussed on here,


SO to try and build a machine to be ALL THINGS to ALL MATERAILS with advanced features like 4th & 5th axis etc is a BIG BIG BIG under taking that would make even the most experienced DIY builder like Jonathan or Me sit down and think very very very carefully.? . . . . . To take a project like this on with NO experience is a recipey for wasting money and time .!.

Its not beyond my current skill set, althoug i have not built a CNC router before, i have had experience in pulling some quite complex tasks together, and i live in an area, full of engineering works, anything beyond of my level of accuracy, can be done by them. I do understand that it will cost a lot, perhaps around the 5k mark, without software. and i have a few month to do it, with the funds currently sat in the bank,

I will try hard to put it in sketchup tonight


Now I'm going to honest and blunt here George.!! , your not blunt, your straight to the point, and sharing your considerable experience.


I think you are going to waste an awful lot of time and money plus dissapointed with results because what your wanting to have is Large machine that is all things to all materials but haven't got a clue to just how hard that is to achive or make happen.

I do understand the difficulty involved, and the design complexitys, am not expecting to get thinks perfect first time, and i have budgeted some funds for mistakes.


it would be a rotating nut and up high out the way along with the rails. This is where all my design efforts would be concentrated and even if it cost extra money to put up high and under cover

agreed, my x-rails and screw, are the top of the frame/x Box, The Y/Z is underneath that. I would cover X with accordian or brushes for dust.

george uk
09-01-2014, 10:36 AM
Hi

Can anyone see any problems or design issues with this described below.

Standard re-enforced rectangle box frame made out of 80mm 80mm by 4 mill ( or 100omm ) 2200mm

On top of that, down the X, Two bits of 160mm by 80mm, fixed, bolted to frame. I beleive i can get these true and level, ( with machineing and epox ). I then want to bolt rails ( round or square ) to the top and underneath of the overhang, both sides. Apart from the difficulty of getting the rails level to each other and true

What other problems can anyone envisage. ?

It would seem a very obvious design to give you close to equal forces in most directions but i can not see any machines designed the same way. The problems i have envisiaged

Trueing and leveling for the Rails. ------- think i have that covered
Deflection forces on overhang ------ Theses exceed the possible forces applied by the Z, so not a problem
Nobody else usese this design -------- This is my biggest problem , there are a lot of clever people on here, noboby seems to do it this way -- why.

Fire way with opinions , Am especially interested in anyone that has previously considered and discounted this.

Boyan Silyavski
11-01-2014, 12:21 AM
Hi

Nobody else uses this design -------- This is my biggest problem , there are a lot of clever people on here, noboby seems to do it this way -- why.



There is a reason skydivers pack 2 parachutes :whistle:

Just joking, couldnt help . Lets see the design when you draw it

ramsbury
11-01-2014, 01:38 PM
Hello George well intrested as You are building a machine for similar reasons,,
I Spent a couple of years building sound rooms for recording studios (in my spare time)You tend to find out what dampens vibration, Which is Dry sand filled tubes and walling .if the sand gets wet then it doesn't help at all.
Guts on masonry always under the table with a Drip check and should be dry when you look under when the machine is in full spray.

the overhead type even when the Gantry is 600 higher than the workpiece still gets covered in Abrasive dust and the rails wear quite quickly.
Ive seen at least 3 machines fail because of rails being on top or the side.
Humphries Masonry in Hungerford their machine right before xmas rails scored by a pieces of stone about the size of grass seed and all the carriages and rails needed replaced. Blooming expensive 3 metre Kolb machine

I had a look at a machine which uses 120x60x3mm 2400 on x and 1200mm on Y
this machine also had Hexagonal rails and v rollers on the X with 45degree 45mm v rollers on the Y and Z. I cant find Hex rails on the net it all seems to be profile which Jazz suggest.

george uk
11-01-2014, 02:40 PM
Hi Ramsbury


Guts on masonry always under the table with a Drip check and should be dry when you look under when the machine is in full spray.

I noticed that on the ones i looked at, am trying to avoid it, becuse of the rebuild time required if they do fail, Knowing that the rails and baering will fail, i want them accssesable without heavy lifting.

I think the V barings and design styles on stone machines are to do with the machine weight, and i think , with the right design, you can reduce the required weight substantialy, making everything else easyer to make.

With top mounted V Baerings, you need a considerable weight gantry, just to hold it on the rack. and there starts you chicken and egg game with motor sizes and rails.

Wereas, i am considering, bolting on a lenght of 160*50 by 3mm , down the X, and mounting rails both on the top and underneith, using the shearing/form strengh of the baerings and rails to act like a counter weight when the Z is pushing down. Allowing the gantry to be considerably lighter, and easy to design.

Am going a lillte under 2200mm on the X, becuase i think i need to maintain a relationship between the size of X, and the gap between to baerings on the Y width per side, to small a gap will allow to much resonence down the rails, With the Y Lenght at 1200mm, i think i need the Y width someware between 300mm and 400mm, That meens if i want a X cutting area of 2000mm i need an overhang of 200mm on each end of the X ( making the X approx 2500mm in lenght. Am working on the principal that the Y width needs to be at least 1/8th of the X lenght to counter resonance down the X Rails,

I think ( scratching my head ) that the math works out, to give the Gantry enough force to not deflect under the chip loading of the cutter, pushing through stone.

Do you get what i mean ?

I was also thinking of fixing accordion cover to the X and Y if possible, to help counter dust

ramsbury
11-01-2014, 03:32 PM
All the machines I have for cutting stone have hex bar and rollers. which are on top rails and of course have easy access But the table is also on large V rails to load the stone one of them is worn so I don't get the Accuracy I need to Make stone profiles But its still great for straight cuts and 90 degrees . it only takes 15 mins to change the rails except on the Bottom as the rolling table weighs a ton.
all the Hex rail machines with rails underneath do have difficulty changing and the gantry must be Supported when they are lifted off. But my attitude is if it needs changed Its done its work about 4 hours per rail to change only because they are bolted with Sunken heads. even mild steel rails last a lot of cuts and justifys the rail change

george uk
11-01-2014, 03:41 PM
Hi again ramsbury.

This is stone machine specific,

am thinking of adding rollers just beyond the start and end of the bed ( X ) and supports, to keep the machine size down. and allow me to do very big pieces.

A column for example, or the upright part of a norman church door, or a church window upright

If i have rollers at the end, and a support trolly, i can machine 2000mm per time, then just move the piece up the table and machine the remainder. If i can design this part correctly, i may even reduce the lenght of the bed. You can use a probe routine to make sure the piece is positioned carfully

Also, am trying to decide between building rollers into the bed, that are jackable, or, an air table, to allow me to position heavy pieces of stone and move it around.

ramsbury
11-01-2014, 05:24 PM
I prefer an Overhead jib or gantry crane they are very easy to make
and move.
the Machine I wish to make has only its Gantry above its working table making things easier to put on and More important Taking off without damaging using either clamps or Vacuum lift regarding heavy objects , straight onto a waiting vehicle or storage area.
I don't do granite worktops and all the gravestones I do are Hand cut and hand finished.
Raised side rails prohibit the full use of the table, as most lifting equipment needs its own space usually 100mm margin area.

george uk
24-01-2014, 01:28 PM
another question.

Bolting a frame together, prior to weilding or bolting instead of wielding

Am thinking that i could probably make a JIG for the bolt holes, and am confident that i could make the machine straight and true with bolts. and then just tac it were required, once nearly assembled.

I have been mainly thinking this because my X will have an overhang, were the rails will be placed. and am thinking that, at least that bit, will be easyer to get exactly level, by bolting and shimming first.

Again, nobody seem to do this, and it seams a no brainer as an easy way to ensure a straight and level machine, but, its probably me not engaging my brain, am open to any opinions on this,

EddyCurrent
24-01-2014, 02:05 PM
People do use that method, such as my build here;
http://www.mycncuk.com/forums/gantry-router-build-logs/6565-ready-steady-eddy-3.html#post50664

which actually turned out like this;
http://www.mycncuk.com/forums/gantry-router-build-logs/6565-ready-steady-eddy-10.html#post52425

Jazzcnc also uploaded some photos once showing a part bolted, part welded frame. I would think that if it's a large and heavy machine it's a good idea to make sides and ends then bolt these sub frames together.
Regarding shimming, there are two lines of thought. The first as you say, and the method I'll be using, is to bolt the top beam that supports the rails, this way it can be shimmed level. Also within this method are two ideas that I've seen mentioned, one is to use standard metal shims, the other Jazzcnc method is to use epoxy putty where the rails are bolted down until level thus squeezing the putty until it sets. A piece of cling film or similar is stretched over one component to prevent the putty sticking it all together.
The other way is to fully weld the frame and use the 'epoxy method' to level the top prior to fixing the rails, you can search the forum for that.
My own take on it is this; if accuracy is your main concern and as such you will likely be cutting metal to high tolerance, then the epoxy method is best. If you are cutting mainly wood and your tolerances are not so high then the shimming method would most likely work, after all the wood will shrink and expand probably beyond a fine tolerance.

JAZZCNC
24-01-2014, 11:41 PM
Eddy is quite correct and most of the larger machines I've built have been welded and bolted. It just makes good sense when you think about.!!
Also I've said this many many times.!! . . The more adjustabilty you build into a DIY machine the easier it will be to set it up. Bolting makes for another area where you can tweak a machine into alignment etc.

I also mostly Agree with Eddy's take on it except that full epoxy is better for high tolerances than Shimming because it's not really, it's just easier(Quicker). I'd actually go has far to say it's potentially less accurate because your soley relying on the epoxy with no room for error or improvement where has with shimming you can tweak out any error it just takes a lot of time. Personaly I'd do a mixture of both on a large or long machine that requires higher accuracy.!!

ramsbury
25-01-2014, 10:04 AM
I believe there must be available movement to Get the Highest precision as possible. especially on the rails. so have a preference to Shims.

EddyCurrent
26-01-2014, 11:41 PM
Shim steel is more expensive that I thought, do people just cut up food/drink cans or is there somewhere to buy an assortment cheap ?

george uk
27-01-2014, 12:59 AM
both have advantages and disadvantages.

Epoxy makes sence if your floor is level and machine is square=ish, to take out imperfections,

Shims give you a very high level of presision, but take time to get right

but , then i start thinking back to the days i had a go-cart circuit, and the jigs we built for straightening the frames, we could easly achive very high levels of precision, at complex angles, much more than you would need for rails.

So am thinking why not build a simple jig, into the top of the frame, both sides down the X ( 80mm or 100mm box ). a simple bolt pattern jig, Fix a bit of say 80-160-4, on that just leaving enough overhang to fit rails to, use the jig to get the 80-160 perfect, with a laser level and a few mirriors, you could get a very long X, very accurate, and make sure the opposite x was perfectly alligned.

I do get that this would be a waste for any machine with less then 1600mm X, but, you could be close to unlimited on X length andd get very accurate, with just a very basic tool kit.

My proposed build plan goes like this.

wield

Build 2 ends in Jig ( Y ) 1400mm
Build 2 sides in jig, ( X ) 2500mm , with Jig/bolt patterns

Assmeble square, by bolting together

Fit the 80-160 to the X, by adjusting down on the bolt/jig, to get it perfect as possible, using simple laser.

Then, bolt a bed, on, using you X to ensure your fitting the bed as close to perfectrly level with the x.

george uk
27-01-2014, 01:58 AM
further reasons for the above build plan.

1. can be manufactured and assembled at differnt places
2. Easier to get into workshop/transport
3. Final truing is simple, a few spanners, a few cups of tea, and a bit of time.
4. it can be moved, if required, and is simple to true up again
5. It can be built very accurately with simple tools ( pillar drill, cutters and grinders and weilder ),
6. it will be a lot easyer to get a large but solid bed level to the x/y, possibly even have a replacable bed for different configurations,

Cons

1, it uses a lot more steel, but if you want you bed to hold a lot of weight, its not a loss
2. It takes time to make sure all your cut pieces are exactly teh right size, and to get your bolt patters accurate, but, accurate pattens could be printed from a standerd desktop printer, and overlaid,

i can not think of many more cons,

you will notice that i have not mentioned the gantry yet, its because am working on a very differnt type of design, but i need the frame built, to make the final tweeks, my Y is going to be more like a cartridge than a carriage. giving me much better force resitance in all dirrections. Again, for standard XYZ, this may seem overkill, but, if i want to build a turret on one of the Y sides, or strap a B/C head to the Z, then it makes sense, .

any opinions welcome

Jonathan
27-01-2014, 02:12 AM
I'd actually go has far to say it's potentially less accurate because your soley relying on the epoxy with no room for error or improvement where has with shimming you can tweak out any error it just takes a lot of time.

The problem with shimming is you can't compensate for rail twist with it. I discussed it at length in the recent build log (http://www.mycncuk.com/forums/gantry-router-build-logs/6484-sufficiently-strong-machine.html). I didn't include the readings from the shimmed rail in that post, however if you want I can dig out the graphs obtained when the rail was shimmed and you'll see the error was still far worse than the final result obtained using self-levelling epoxy. I'll quote myself, from the build log:


At this stage it is interesting to note that the bearings slide smoothly on the rails, so although compensating for the height error with shims or a machined profile is sufficient for the bearings to run smoothly, this does not by any means assure accuracy since neither method compensates for the angular error.

It all depends on how accurate you want the machine to be and its intended use. The error at the tool introduced due to rail twist will be exceptionally small, so you'd need a very strong machine to notice it. The additional wear on the bearings caused by the rail twist will depend on the stiffness and accuracy of the structure they're mounted to, so it's hard to judge, but in a DIY CNC situation is unlikely to be too significant. I'd still choose epoxy though as it's so much quicker and easier than messing about with shims and enables one to get very good accuracy with less measuring equipment.

george uk
27-01-2014, 02:52 AM
hi


I'd still choose epoxy though as it's so much quicker and easier than messing about with shims ,

yes i am doing, i think you did post the readings from your shims then your epoxy, iether that or it was the bare metal and the epoxy.

I was thinking, epoxy on top to take out surface imperfections, ( although a real lot of that would be taken out by the bolt jig ). Am also haveing quite a wide ( down the X ) gantry ( sacrificing cutting area ), so alot of minor imperfections will taken out becasue of the space between the Y barings to the X

JAZZCNC
27-01-2014, 04:38 PM
Shim steel is more expensive that I thought, do people just cut up food/drink cans or is there somewhere to buy an assortment cheap ?

Often I use tin foil has it's thin cheap and won't rust.!! If I need more than 2 layers I'm upset.!!


The problem with shimming is you can't compensate for rail twist with it. I discussed it at length in the recent build log (http://www.mycncuk.com/forums/gantry-router-build-logs/6484-sufficiently-strong-machine.html). I didn't include the readings from the shimmed rail in that post, however if you want I can dig out the graphs obtained when the rail was shimmed and you'll see the error was still far worse than the final result obtained using self-levelling epoxy. I'll quote myself, from the build log:

Why not.? Shimming is all about where you place the shims.! I agree it's not easy in comparison to epoxy but it can be done, I've done it many times.

Your experiences with epoxy are on a short machine but on a longer machine then things are slightly more exagerated and just relying on one method that is fixed or not very flexible is not so clever IMO. That's why I say for a Long machine(requiring higher precision), longer than 4ft I use both methods.!

Why make life hard for the sake of some plates and bolts, which if Epoxy hits the mark first time you don't need to touch, if it doesn't then fine it can still be tweaked if needed. Adjustabilty is Key and the more of it you have without compromising the machines strength the better at DIY level.!!

george uk
28-01-2014, 11:28 PM
have had another think, about if i can use the same principals used in making a jig for the top, in the overall machine design and i have had an interesting thought and wander what you think. ?

am using 100mm by 5 at 1200mm high, for 4 main legs at the machine corners. with very accurate bolting patterns pre cut. and patterns drilled for threaded bar. For the lengths (x,y), i was looking 2 lenghs per side of oblong profiles, like 80,160,4mm, cut at 2500mm and 1500mm.

And hers is were the idea come when considering plans for getting the frame as dimentinaly perfect as possible with simple tools. and an easy to build jig/vice.

I can build a simple jig for the bolt patterns, small, and very accurate, Lay out the lengths of 80,160. Accuratly place/fix/drill the jig at set intervals don the X and Y lengths. Doiong it like this, i can initialy ignor any twists in the metal, becuase i only need the 200mm long section were the Jig is to be accurate, so the angle of the bolt holes are perfect ( 5 pattern ). Do this for all the cut lenths and supports, accuratly mesureing were you place the jig..

Lay out the first 2 X sides, on top of 2 lenghts of 100mm/4m at 1200, with the accurate bolt patterns in, Put one bolt in each far corner to get your first square-ish, If any of the other bolt patterns line up perfect, fabulas, but not expected at this stage, Take one of you central struts, put a bolt in the top right, and if you can, bottom left, slight movement of the frame should allow this, Then, use the cheep threaded bar, to do you frame adjustments, dropping bolts in as you work outwards, at this stage, most but not all bolt points will fit.

Do this to both X and Y sides, Dont force ANY of the bolts in, only the ones that fit.

Assmble the sides and cross struts with the same principal, each accurate bolt fitted will pull the hole frame into shape, useing simple threaded bar and nuts to ajust. i should be able to get the frame very close to perfect within reason.

I would be relying on accurate mesurments over small areas, not long lenghts.

I also think there are some other good reasons for this,

1. your using shorter lengths of metal, its easer to pick out or cut reletivly straight lengths, and you still only relying on the small areas of 200mm long being dimentonly accurate, any you could probably pick them out by eye and simple tools.
2. You use the smaller lengths to pull/push the longer lengths into perfect shape, adjusting with threaded bar and nuts.
3. It would make the assembly process at lot easer that wielding, and take out any chance of the wield putting a twist in
4. could be done with pillar drill, £ 40 micro-measure from maplins, basic desk top printer.
all the bolts will only fit when it is,

It will cost a bit in bolts, but, can not see many other problems but can see lots of benefits, like stronger machine, more bolt points, simple

george uk
30-01-2014, 02:29 PM
am on with this at the mo.

i think am going with 120 x 60mm 3.6mm with 100mm box for the legs ( 10kg per meter )

anyone suggest a good suppler of bolts,

ramsbury
30-01-2014, 06:20 PM
am on with this at the mo.

i think am going with 120 x 60mm 3.6mm with 100mm box for the legs ( 10kg per meter )

anyone suggest a good suppler of bolts,

My frame legs are 120x60x5 mm got from parker steel they have an online price guide they also do Nuts bolts and tools.
and Devizes steel for odds and sods also do nuts and Bolts.

Special sizes and threads, Nuts and bolts i make myself using my lathe but many times i reckon its easlier Buying them.

george uk
04-02-2014, 06:51 PM
Well, all parts cut to length out of 120*60*3.6, will spend some time overt the next few days trying to accurately cut the bolt patterns, prior to assembly

Lee Roberts
04-02-2014, 07:45 PM
Well, all parts cut to length out of 120*60*3.6, will spend some time overt the next few days trying to accurately cut the bolt patterns, prior to assembly

Sounds like a plan George, have/are you going to start a new build log thread for us to follow or continue here?

.Me

george uk
04-02-2014, 10:11 PM
depends on how successful the first attempt works out. i will post the successful result as a individual build log, but

I have a different type of frame assembly planned, hopefully making it easier to assemble a heavy duty frame, relatively accurately. but if it goes wrong, i can disassemble and get it wielded. The idea being make an accurate bolting jig, about 200mm long. a 5 star pattern and a 3 bolt straight line. Start at the center of each length for the first bolt pattern. then accurately measured outwards for the next ones. the advantages being ;
1. your only relying on each 200mm section to be square for you bolt patterns.
2. Your not relying on your cut lengths to be totally square at the end ( perfectly )
3. As you assemble the frame, you will pull out most of the surface twists in the metal, ( as long as you have a proper assembly plan ).

then things am still trying to work out,

1. optimum bolt width/distance between bolt patterns. ( material is approx 10kg pmtr, 120x60x3.6 )
2. No of positions to plan for threaded bar/nuts to assist in initial lining up

Once initially assembled, i can then decide what parts need welding or maybe brazing, and if i have made enough places for triangles in the corners. If done correctly, the final bits bolted on should meen the frame is very close to am accurate box, and very strong. But, if am not accurate enough with the bolt patterns, it will be all over the place.

I will post any mistakes i make on this one, as i go along ( and ask for help ). then post a seporate one for the completed sucsesfull build.
Am currently considering building\buying\converting a mil to get the accurate bolt patterns. as i will need this for the head designs i have in mind. But, ther are a few companys near me that can mill metal to the accuracys i need. So i need to get proper prices first from them.

Boyan Silyavski
04-02-2014, 10:46 PM
Dont forget to drill a pin hole near the bolts, at the end i mean. Once assembled and centered and shimmed, you drill and hammer a single pin there at each assembly. That will help eventual disassembly and assembly in the future.