Adil / andy / dean got to say cheers to you fellas! started drawing up a gantry based on this L layout and intuition is saying this is soooo much better.
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Adil / andy / dean got to say cheers to you fellas! started drawing up a gantry based on this L layout and intuition is saying this is soooo much better.
You're welcome buddy, I'm also at a stage where I'm very pleased with my design, finally stopped stressing over it and started to get it built.
One more question if I may - what profile brand are you planning on using?
I'll be buying from KJN KJN - Suppliers or Aluminium Profile and Accessories since they do a 45x90 profile unlike Value Frame whose closest is 40x80 profile. I went with bigger is better, also from reviews I've seen on here about their good service and accurate cuts, I'm sold.
Don't for get to order all the extra connecting elements like T nuts and screws when you place the order with your chosen supplier. Also if you go with profile rails rather than supported rails you need to check the maximum socket head screw that will fit in the rail pocket, as you will have to get appropriate T nuts. For the profile rails I have, I found an M6 thread will fit but its head is fractionally too big, so had to use M5. For connecting ali extrusion profile with other I'll be using M6 Screws and nuts.
Hope it helps, Adil
A couple of quick queries please Adil...
Does the fit of the T-Nuts in the Slots allow for a wee bit of sideways adjustment, or can you achieve this by using the M5 socket-screws in your rails?
I'm wondering whether it's best to go for high-tensile screws/bolts or whether A2 stainless is good enough....
Also where peeps have found a good place to source socket-head-screws? Did you just get them off eBay?
Screw fix is always a good place to start?Quote:
Originally Posted by WandrinAndy
I use the local fasteners shop (Charnwood Fasteners). Perhaps search for places that sell fasteners nearby as they should be much cheaper than eBay or Screw-fix.
Adil, how's the build going??
Hi Joe, thanks bumping for my build thread. I've been quite busy with other things and haven't really had time to work on it. I can see my life getting less hectic in a few weeks and that's when you'll see a big jump in progress. I'm getting all the ali plate for the whole z axis, gantry ends and all motor mounts machined. I've seen some teasing pictures, but I'll post when I get them in my hands, and I can't wait.
I got some new tools to play with off ebay to help when I start building. There's a band saw, metal chop saw, stick welder and drill press. I got an eye open on a bargain metal lathe and engineers straight edge. Suppose you can say I'm getting my home workshop ready not just to build the router, but for all the projects to follow.
Some of the recent threads about dual motor X axis vs single motor and long belts, then another about 10mm pitch screws have got me thinking again. Suppose these are thing which can be upgraded easily if I'm not happy. So might just use 1 motor with long belts on my 1605 screws, as that's what I have prepared for, then go from there.
Adil
Glad things are still ticking along in the background, I too now have a stick welder to play with and seem to be making reasonable progress?!
I saw the 10mm pitch threads too but now I have the 1605 I'm sticking to my guns. The results dean gets from 1605 are plenty good enough for me and if I can get to anywhere close I'll be a happy man!
Look forward to seeing those ali bits and pieces when there done.... Cheers joe
The thing is, it's not just a question of does the machine work well enough with 1605. If 1610 is used where appropriate, then you will get better acceleration and probably higher feedrates with the same motors. The maths to prove that is simple - moment of inertia (J) of 1610 and 1605 is pretty much identical, but to get the same acceleration 1605 needs to spin twice as fast. Torque is moment of inertia multiplied by angular acceleration (Newton's 2nd law), so since we require double the acceleration the torque is twice as great.Quote:
Originally Posted by JoeHarris
Now you may say that you don't need these benefits, since the 1605s are 'good enough', but the point is if you leave it at the same speed and acceleration as you get with 1605 and use 1610 the required torque from the motors is lower. That means you're running further from the limit, so are less likely to have problems since the system isn't being 'stressed' so much. That's not to say you should immediately sell the 1605 screws, since it's no loss to try it and see.
That's exactly what I plan on doing, stick them on and try. If 1605 doesn't work well for me, a pair of 1610 at 1300mm will cost an extra £100 + p&p so its not too bad. What I'd like to clarify, is resolution regards pitch, and micro stepping, and pulley reduction. here's the situations:Quote:
Originally Posted by Jonathan
1. stick to my 1605 and gear 1:2 to get effective 10mm pitch but, will my nema23 have the torque needed for this gearing? I got the option to gear 1:1 when I need resolution,
2. buy 1610 and gear down 2:1 for high resolution, and stick to my nema23
3. buy 1610 and use micro stepping when high resolution is needed.
Thanks
Microstepping helps with resolution, but not as much as it initially appears to. The datasheets for many stepper motors specify that the tolerance on the angular position for each step is 5%, for a 200step/rev motor. That means you can say with some confidence that if stopping on a full step, the motor will be accurate to 1/(5/100%)=1/20th of a step. That implies that down to around 1/20th microstepping you'll gain resolution, however when stopping on microsteps the tolerance is worse since the relationship between the reluctance of the rotor, and angular position, is not ideal. It's hard to say exactly how much resolution you can gain. My micro lathe has 4mm pitch ballscrews, geared 2.5:1, so the effective pitch is 1.6mm and with 1600step/rev (1600 is good number to use in general) that's 1um per microstep. If I put an indicator on it and try and measure this, the axes do appear to move about 1um per step, which is promising but bear in mind that's in a static situation. Whilst the motor is spinning continuously it will be less accurate. Arguably the main bonus from microstepping is it means the motors are exciting the system at a higher frequency, so problems with resonance are attenuated.
I can think of very few parts that would benefit from the 2* resolution gain got from using 5mm effective pitch instead of 10mm. There's only one part I've made where I decided to swap my pulleys round to get higher resolution, and that wasn't the Mayan calender. However there are numerous other reasons to use pulleys, so it's still a good idea to plan for the ability to swap them to get the higher resolution. If you stick with the 1605 screws then option 1 (1:2 to get 10mm effective pitch) will work substantially better than 1:1.
Unless you'
You can't say that without knowing what's being done with machine.? 1610 doesn't work better it just allows higher speeds and if those speeds aren't needed then there's no point.! . . . Infact it's wasted resolution/torque.Quote:
Originally Posted by Jonathan
That said I didn't realise Adil bought 5mm pitch screws for all axis and believe he mainly wants to cut wood in which case 10mm pitch would have been better suited. But as we know it's not the end of the world and with belt gearing easy sorted.
Regards Micros stepping then Really you shouldn't consider micro stepping for resolution it's biggest help is with smoother operation of the motors at lower speeds and like Jon says it helps with resonance. Just remember the higher you set the resolution the harder the Parallel port has to work putting out more pulses's for the same movement so you'll need a good PP port other wise you could easily lose steps. More than 2000(10x) micros steps is pointless really has most of the Cheaper motors can't resolve to higher than that.
Jazz, I bought my 1605 screws 2-3 years ago, don't think 1610 would've been available then, maybe, can't remember.
You are correct, I will be mainly cutting wood and MDF, next perspex, and dabble in ali. So I do hope my design will cope with the stress of cutting ali now and again.
Am I right in thinking for wood/MDF and plastic, 10mm screws are ideal as motors will be working in their ideal region giving 7mtrs/min cutting speeds, but 5mm geared up will just about work without getting to close to the motors critical speed and screws whip speed. The calculations suggest 1200mm 1605 screw will whip at around 1000 rpm. So even with gearing up, the motors can now spin at 500rpm, giving the screw 1000rpm which is still 5mtr/min. Will I be able to go up to 7mtr/min cutting or just for rapids.
Then for machining ali, 5mm pitch is best, but can we cut with 10mm screws, or do we have to gear down? What is the cutting speed for ali? I had a number of around 2-4mtr/min. When you mainly machine ali why are you using 1:2 on your 5mm pitch screws?
Adil
Cutting aluminium will be fine regardless of which screw you use since it's only possible to use around 0.6-1.2m/min. With regards to resolution 5mm is better, but it's not a big difference and you're unlikely to notice it. If the critical speed is 500rpm, then yes that means you can get 5m/min, but not 7m/min since that would be exceeding the critical speed. The critical speed formula should be treated as a guidline, since it doesn't take into account the support from the ballnut and relies on a constant you select for the end-fixity, which is a bit of a guess. However I still wouldn't be happy with operating much above what the formula states, even if it looks OK. Have you seen irving's motor calculation spreadsheet on this forum - it may help clarify things.
Has Jon says the critical speed is a guide and the reality is that you'll possible double that and still get away with it.?. . My 1500mm x 20mm screws do.!
Regards me using 1:2 mostly well that's not exactly correct. Since the last time I changed back to 1:1 it's been left that way and when I do change back it's going to be 1:1.5 because I don't the speed. I don't really need the torque or the resolution either if I'm being honest but that little overhead helps when I do need higher feeds.
Seems to me from reading (and that is all I can base this on) that both 5 and 10mm pitches will work pretty well on most materials if set up correctly. I was getting all worried at one stage that my 5mm pitch screws would mean I was going to be burning up the wood I was cutting due to the low feed rates then I remembered back to when I started getting into all this lark seeing machines that cut wood pretty reasonably being driven by threaded rod with pitches so small you can hardly see them! Reckon our 5mm screws will be all right. But I may live to eat my words...
Ermm Ye understand what your saying Joe.!!. . . BUT don't be fooled.? . . . If truth was told there bull shitting you.!! . . . You'll see many examples of flimsy machines cutting Aluminium with dremels etc but what they don't tell you is the finish is shit and the machine/spindle curled up and died 2hrs after the video.!Quote:
Originally Posted by JoeHarris
Same goes with threaded Rod machines the finish is rubbish the cutters wore out in 30mins and the machine fell to pieces 10mins after that.!!
Your correct thou that 5mm will be ok if you already have them but if your mainly cutting wood then I'd look at gearing at least 1:1.5 or 2:1 has that will allow the speeds needed to cut MDF/plastics at correct feeds.
Oh yes I moved away from threaded rod a LONG time ago!!! Just comforting to know my £500 worth of ball screws were not a waste of money!!
I too was worried, that my 5mm screws won't be good enough, especially when spending close to £2k on the build. But then there no point on wasting valuable sleeping time, lol. Just going to use what I have, and if its too slow, and whipping about, I'll buy the 10mm pitch and use these for my plasma, or laser, or 3d printer. Got a lot of plans lol.
Hi, was just reading through your post and its helped me out a lot with design ideas. I'm still at the design stage at the minute, can't wait to get started on building.
Just wondering how yours is going? Do you have any images and more advice - do's and dont's. cheers!
Hi Dan,
I'm just waiting on the aluminium parts to get machined. To be honest, I'm not pushing on getting them done quickly, as I've got too many things on at the moment. That doesn't mean my minds not thinking about it, lol.
Since I've decided to go with dual x axis drive, my PC case control cabinet is looking too small to squeeze another am882 driver in, and also the recent decision to go with an ethernet SS and PDMX 126 BOB. So another part on my shopping list was a PROPER control cabinet, which as of today, am the proud owner of a used 600mm x 400mm x 200mm electric enclosure with slotted cable trunking, on/off switch and safety locks. Bargain at £40 shipped. Everything should fit now considering its twice the size of my PC case.
Attachment 8271Attachment 8272
As for advice, DON'T buy any electrical components till your machine is built. Mine are just sitting there, eating up their warranties.
May of missed this in your thread but why did you decided on 2 drives over the long belt option??Quote:
Originally Posted by Iwant1
After spending so many hours deciding between the two options, and after some emails with Jazz, I just bit the bullet and decided with dual drive. The main points in my decision were:
with AM882 there wasn't any issue with the gantry racking from one motor stalling as they have stall detection alarms, and the machine will E-stop before any damage is done.
Next, as for sync issues creeping in, Jazz says with descent drives this is drastically reduced compared to cheap Chinese drives. Obviously with one motor and belt its completely eliminated and is only a problem on very long jobs, which I doubt I'll be doing. Though you never know.
Then with 2 motors tucked away in the corners, it keeps the far end of my router free from belts and motors and tensioning arrangements, allowing for sliding long materials through.
With the long belt and one motor, I reckon a larger motor like a nema 34 would have been needed, and since I prematurely bought a nema 23, thought I'd use it on one side and buy another 23.
Also I think the 23 motor can spin faster at the top end, which will be ideal for my incorrectly ordered 5mm pitch screws, when traversing.
This is how I came to my choice, but it no big deal if I want to change change later. And I'm sure someone here will snap up my spare driver and motor, lol
Adil
I have been pondering over the 2 motors v 1 motor decision too. I think I will be going with the 1 motor option. You know you mention there may be issues with long jobs, what is the reason behind this.
I wanted the ability to slide large boards through the machine but may settle for turning them through 180 degrees instead.
From what I understand, long jobs are when you machine for 10+ hours without homing in between. Imagine one motor is losing a step here and there, and over a all those hours the missed steps could add up to a difference of a few mm's of one side of the gantry, taking it off square.Quote:
Originally Posted by Danielroyal25
Homing would normally square it up again, but I'm not sure why on long jobs, like 3d carving, why can't you program a homing function every hour, and then continue where it left off.
Adil
Hi,
I don't want to hijack this post but i have a similar design and I'd like to use your experience.
I've designed the frame etc. in inventor and from the simulation i get deflections smaller than 0,015 mm with the force of 500N excreted on a tip of an end mill. Thus, the design seems to be sturdy and good enough but I'm waiting for any suggestions.
My questions...
1. Chinese spindle - which one to chose
There is plenty of different looking spindles on ebay and even more sellers so I'm not sure where to buy and more importantly which model. Which one do you have or which one you know is safe to buy.
2. how to avoid two motors.
I tried couple designs of frames to hold one ballnut for one ballscrew in the center under the table but it's hard to get small deflection without making it very heavy. Do you have some ideas how to solve it without 2 ballscrews and motors on each side?
How is the solution, with line that winds up on a rotating drum, called?
3. what's the free play on a linear rail's open bearings?
Is there any free play on them, how much do they flex?
Also I saw couple times that max speed for linear rail bearings is 5 m/s. What happens above that speed and how does it affect service life.
4. whats the advantage of linear guidways over supported rails?
They would cost me at least 2 times more. I've read the spec and according to it they don't deflect almost at all. What are the other advantages and are there any disadvantaged besides the price?
5. End supports for ballscrew.
I saw a design where instead of end supports fixed to the gantry or frame there where bearings directly fixed to gantry/frame. It seams that it might be stiffer and cheaper. What do you think of it?
Attachment 9324Attachment 9325
Kind Regards
Bart
#1: This guy is ok. Most of them are the same spindle and probably out the same factory.?
2.2KW WATER-COOLED MILLING AND GRINDING SPINDLE MOTOR WITH 2.2KW INVERTER VFD q3 | eBay
#2: Honestly there is no solution to match driving from both sides whether twin ballscrews, R&P or belt drive it's by far the best and easiest way to get accurate stiff machine. The wire/drum is just a bodge and best doing it correctly first time.?. . You'll only end back there in the end.!!
Unless your machine is narrow format, which it doesn't look, then single screw just won't work good. Making gantry wide helps but there's a limit before it gets unusable or feasible.
#3 Can't answer that question without knowing which make and what size linear rails. What I can tell you is even the lower quality units are capable of handling forces far beyond what you throw at them or what your machine design will handle, so it will fail long before they do.!!
#4: No contest here linear rails win hands down in every department by a very big margin. They can't be compared really in accuracy and performance terms.
The other advantages are longevity, they will easily last several years longer than supported rails, even in very harsh conditions. Hassle free usage, fit grease occasionally and forget.
Disadvantages over linear rails is they don't tolerate poor workmanship and misalignment.
#5: Show us and will comment but until then not sure what you mean.?
Now your design.?? . . . You have a problem Houston (several actually).!!! . . . . but this one Is a common mistake easily missed.!
The linear bearings on the Y axis can't possibly be fastened like you have them drawn.? Chicken and egg problem.!! Fasten plate on one set and you can't access the bolts for the other bearings.!!
I'd also consider using different thickness material for the Z axis.? Those thin plates, even with the bracing will resonate while cutting which will affect quality of finish. Don't rely to heavily on the Cad simulation, without inputting all the variables and cutting forces then it won't show this. I know from experience that if you plan on cutting hard woods or hard material like aluminium then your Z axis just isn't strong enough.
Just remember no matter how well built or how strong or accurate the rest of the machine is it's the Z axis that takes all the cutting forces
and if this flex's or resonates the rest don't matter a jot.!! . . . The machine is only has good has it's weakest link, this Z design is weak.!
( Also Don't rely on the Linear rail adding strength they don't really add much.!)
Hi Adil, this is a very interesting build and a great deal of care has been give to getting the design right.
One question regarding the electronics, do you have a wiring diagram/schematic that you are using? If you do, could post it up as I'm currently struggling with this.
Jim
Hi Bart, welcome to the forum mate and don't stress over hijacking the thread, someone needed to bring it back to life.
Jim, honestly everything is as it was few months back, i.e. in pieces. Once I've got the control panel built and I'm happy the way it works, I'll make a schematic and post it for you. It will be quite tricky though coz' it uses a few linked relays.
Jazz, nice to see your back and in full swing.
Hi,
Thank you for your interest in my design
I guess I should have started with some spec of the design.
Frame dimensions
W x L: 1400mm x 1800mm
Red and Blue is steel
Yellow is aluminium 10mm thick
Linear rails
X: 1800mm x 25mm
Y: 1350mm x 20mm
Z: 380mm x 20mm
Motors:Four Sanyo Denki 103H7823-1730@$80 each - 4A, 2,2 mH, 0,65R, ~2 Nm up to 600 RPM
http://www.plccenter.com/en-US/Buy/
any suggestion of better value for the money?
Driver :TB6600
Gantry
Steel square profile 80x200x (4 or 5)mm
Z axis aluminium plate is all 10 mm
That's what I'm hoping for but almost every seller has a picture of slightly different design so I was wondering if any of them is better or more reliable then other.Quote:
Originally Posted by JAZZCNC
I've just google wire/drum and it's called cable drive and it's not as easy and cheap as it seams - if it is to be precise.Quote:
#2: Honestly there is no solution to match driving from both sides whether twin ballscrews, R&P or belt drive it's by far the best and easiest way to get accurate stiff machine. The wire/drum is just a bodge and best doing it correctly first time.?. . You'll only end back there in the end.!!
Unless your machine is narrow format, which it doesn't look, then single screw just won't work good. Making gantry wide helps but there's a limit before it gets unusable or feasible.
Belt drive is ok but it has a disadvantage of not reducing the moment of inertia of ballscrews. Right now, one ballscrew
has an equivalent mass of 60 kg, that is as mach as moving mass for X axis and same moment of inertia as motor.
Yes, I've seen the spec for the linear rails and linear guideways and bot of them are pretty strong for the size.Quote:
#3 Can't answer that question without knowing which make and what size linear rails. What I can tell you is even the lower quality units are capable of handling forces far beyond what you throw at them or what your machine design will handle, so it will fail long before they do.!!
So for the X axis, moving mass is 60 kg and max force when cutting would probably be around 500N which gives (simplifying) 125N per linear bearing.
However, when i asked about flexing of open bearing, what I had in mind was an order of magnitude. Is it 1 um, 10 um or 100 um of flex.
Homemade PCB milling machine - YouTubeQuote:
#5: Show us and will comment but until then not sure what you mean.?
start watching at around 1:35
Absolutely right :) - I've noticed it some time ago but i was too lazy to change all the constraints :)Quote:
Now your design.?? . . . You have a problem Houston (several actually).!!! . . . . but this one Is a common mistake easily missed.!
The linear bearings on the Y axis can't possibly be fastened like you have them drawn.? Chicken and egg problem.!! Fasten plate on one set and you can't access the bolts for the other bearings.!!
here is an updated photo
Attachment 9364
It's 10 mm aluminium plate - what do you think it should be?Quote:
I'd also consider using different thickness material for the Z axis.? Those thin plates, even with the bracing will resonate while cutting which will affect quality of finish.
I was thinking about making a sandwich of wood and aluminium to dampen vibrations. What do you think?
Sorry for slow replay but i was too busy to write a post
Best regards
Bart
Adil, what's occurring mate, still building this thing ??!Quote:
Originally Posted by Iwant1
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