PDA

View Full Version : BUILD LOG: My 1st Hybrid Steel/Ally (1150 x 850 work area) (comments/advice please)



lebies
12-08-2014, 08:13 AM
Hi all,

My first post after spending much time soaking up some really great ideas.

I must confess though, I'm suffering from information-overload! - there's just too much to take in, and not be able to apply directly.

Anyways, I've always wanted a cnc router - and now I finally get to build one :tennis:. So, in preparation I've been trawling forums like yours and without doubt - you guys rock for friendly, solid advice.

The beast:
- I want something that I won't have to say, "damn...if only I had this (longer, wider, 4th axis, etc) or that!" I figure around 1200 x 800 x 300 (X,Y,Z as you guys reference it) would do nicely.
- 4th axis is a requirement.
- Working mainly wood and perspex but must be able to do aluminium as well. I don't mind shallower cuts, slower feed rate and/or more runs to do it, but I must be able to do it.
- As accurate as possible, repeat-ability very important.
- One thing I learned over the years from my electronics career is that when you do something, do it well (as you can, budget permitting) - and don't skimp! If you're investing in something, get the best you can afford, and if you can't afford it, save up for it.
- I've only been considering Hiwin and/or SKF for the profile linear guides and rails and ballscrews.
- Base:
I'm thinking of going 50x50x3 square tubing for most of the frame. I've probably gone over-kill on the supports but what the hell - can't do any harm.
Comments will be most welcome (thanks in advance :))

- Axis:
X (1200-ish):
I was going to use a single ballscrew down the center, until I came across a post(s), I think from jazzcnc, that completely changed my approach (and kicked off yet another design iteration). I think it's a brilliant idea for the 4th axis and so this design based on it.
I'm unsure whether to go with 2 x 12mm or 2 x 16mm x 5 (or 10) for the long axis. SKF (BK/BF) fixed and floating bearings.
Profile rail guides and blocks SKF 15mm profile (LLTHR15 rail, LLTHC1 carriage).
NEMA-23 3Nm stepper motors on either side, reverse polarity on one of them, driven from same driver board.

Y (850-ish):
For this axis I'm thinking of using Ally profile. There's a guy down here in my neck of the woods that has designed and has manufactured a really nice (versatile) 90x45 profile. A big advantage is that the rails (15 and 20) drop right into slots provided, and bolt down via t-bar.
I'm also thinking of a "C-section" to beef it up some (see pics). MUCH more expensive than steel, but then a LOT less tinkering and engineering work negated - which probably justifies the decision. Also, I don't have access to the machinery you'd need to be able to work the engineering.
Profile rail guides and blocks SKF 15mm profile (LLTHR15 rail, LLTHC1 carriage).
12mm x 5 ballscrews, BK/BF end bearings again.
NEMA-23 3Nm stepper motor.

Z (300-ish):
The main decision driver for the 300mm Z-axis is to be able to do up to about 150mm radius wood/perspex lathe work.
Profile rail guides and blocks SKF 15mm profile (LLTHR15 rail, LLTHC1 carriage).
12mm x 5 ballscrews, 15mm profile rail.
NEMA-23 3Nm stepper motor, belt & pulley driven. No idea of ratios!

4th Axis:
100/110mm chuck and tailstock.
90x45 Al profile across the front, provides for a moveable tailstock, running on the profile.
NEMA-23 3Nm stepper, belt & pulley driven. No idea of ratios!

Spindle:
GDZ-80-1 Spindle motor, 12000-24000(RPM), 1.5(KW), 220(V), 5(A), 100-400(HZ) Φ80*188, water-cooled, ER11 Collet


I'd love to buy the following spindle (http://www.cncdirect.co.za/htm/control.html) but it'll have to wait until I can justify the cost! And, there's no local stock at the moment!
I'm a bit concerned with the Chinese spindle having read about guys having had to open them up to properly earth units, sub-standard wiring, and the likes! Hopefully this is not the case on this one.

I'm as yet undecided on the breakout board to use.
I'm very comfortable on Linux and was thinking of going with linuxcnc over mach. I can develop and/or write my own stuff, and/or add embedded controllers if and where necessary. Plus of course, it's free, and I have all resources on the PC available to me if needs be.



Here are some links to the electronics I have in mind to use:
Stepper motors: https://www.robotics.org.za/index.php?route=product/product&path=18_94&product_id=123
Drivers: https://www.robotics.org.za/index.php?route=product/product&path=18&product_id=69

And, here are some pics for reference. I would really appreciate all the help and advice I can get.

1302713028130291303013031

Thanks folks, appreciate.

Cheers

mitchejc
12-08-2014, 09:38 PM
Ah, good to see another South African on the forum. I'm very much in the same boat as you trying to figure out what's the right direction for my build. There's much more knowledgeable people on here than me so I'll leave the comments on your design to them.


Apart from the great build threads here's some of the stuff I found extremely helpfull with a design


To calculate critical speed on ballskrews and motor sizing a great help is also. Can't find the link now but If search on here you'll find it
MotorCalcs.zip


Extremely usefull to compare stiffness of different design options.
cnc_stiffness_calculator_v8 (look at post #26)
http://www.mycncuk.com/threads/7733-Well-here-goes-Aluminium-frame-router-design/page3
Or you can just spend endless time fidling with FEA software and be none the wiser :-)


A few general comments:
Helped a friend of mine build a router and he got those Wantai steppers and motors from MicroRobotics and he's very happy with them.


Not sure what your requirements are wrt the 4th axis but be realistic in your expectations. I have a UniCam router with a 4th axis and I have not used that functionality in the 5 years I have the machine. Maybe it has changed recently but in my experience I have not found any reasonably priced software that can do true 4th axis toolpathing. Sure, if you want to engrave text around a cylinder there's plenty free stuff around that will wrap a 2d path around a cylinder.


The stuff from CNCDirect are top notch. Piles of wood dust made on my router over the years and the SKF bearings are still smooth as silk. You may also consider the Hiwin rails. I ordered Hiwin rails from Wendy's Bearing Store http://www.aliexpress.com/store/637430 Payed on the Wednesday and they were in my hands the next friday so I'm very happy with her service and the rails seems to be of very good quality and probably comparable to the SKF suff. The chinese ballskrews and nuts is not comparable to the SKF producs but considering the price I think they are great value for money. I decided to give them a go so we'll see how that works out.


Good luck with your build and if you find other useful local suppliers for the bits and pieces please let me know, I'll do the same.

EddyCurrent
12-08-2014, 10:22 PM
@lebies
There are other things but for a start these jump out at me.

1. A spindle with at least an ER20 collet is a MUST I would say, also a 2.2kW spindle would suit the machine better.
2. The Z bearing blocks are too close together in the vertical direction, these will be weak regarding twisting as they are.
3. With an X of 1200 you might find 16mm ball screws will whip at higher speed but I'll let jazzcnc comment on that, he might suggest changing the pitch to slow them down.
4. You might need to think about 20mm rail instead of 15mm
5. Rather than a long Z travel, think about an adjustable bed. The Z will be very weak at full extension as shown.

I look forward to seeing your control panel design.

routercnc
12-08-2014, 11:23 PM
Hi Lebies,

Welcome to the forum. Agree with Eddy, plus a couple more views on your design:

That is a large machine to also cut aluminium. It's not so much about taking lighter cuts and going slowly to compensate for lower machine stiffness (which will be likely with a large machine), but just that you don't have the stiffness at the cutter so it will vibrate, get hot, and go blunt. To compensate you will end up beefing things up but at this size it all gets heavy and the design could run away with you. Just be realistic about what it could do at this size and don't expect too much on the aluminium cutting.

You have a very large offset from the Z axis to the Y rails - I can see that you are trying to mount them on the rear part of the gantry where the gantry is locally stiffer, but I think you will be worse off overall due to the offset. I would mount them on the front of the gantry closer to the Y rails, then if the ballscrew clearance allows push the central extrusion forward as much as possible. Then close off the open back with a simple plate of moderate thickness, say 10mm. That way you are getting back towards an overall box section.

The end plates on the gantry look very thin. I would use 12mm minimum here (aluminium), and for the ones underneath to mount to the X axis bearings.

Will you add a bed to this? The spacing of the cross members of around 600mm is quite large. Another 2 member would be my minimum. Don't underestimate the bed stiffness as this is what hold the workpiece against the cutter forces. Vibration here is just as bad as vibration on the tool - difference is it is much easier to do something about by adding more support.

X axis motors - you mention running them in opposite directions to each other? Not sure why you need to do that. They should normally run the same direction (both clockwise or both anti-clockwise) otherwise the gantry will be pulled into a serious racking problem! Perhaps you are confused about running twin ballscrews on one axis, or maybe I misunderstood your intentions there.

Looking forward to see how it progresses. I'm sure you'll get plenty of other support as you go . . .

Clive S
12-08-2014, 11:32 PM
I'm very comfortable on Linux and was thinking of going with linuxcnc over mach. I can develop and/or write my own stuff If you are going to slave your x axis you might have to re think Linuxcnc unless you drive both screws from one motor. Linuxcnc don't seem to have a system for homing 2 motors (joints) there is a lot of debate over on the Linux forum about this. Its a shame its not been sorted by now. I use linuxcnc for my mill and Mach3 for the router. Driving both screws from one motor is no problem though. Good luck with the build. ..Clive

lebies
13-08-2014, 09:19 PM
Hey all,

Thanks for the great input so far, I'm sure there'll be more as we go ... :).


mitchejc
Ah, good to see another South African on the forum...

Thanks man,
been lurking for a while now, and now I'm sorry I didn't get my act together and post a lot earlier.
Thanks for the links, already learned from them...

I'm really glad to hear the steppers are good enough, was a bit concerned there. I've used their smaller steppers on a project and also found them to be very good.
Yep, Greg's stuff is very good, and he's a very knowledgeable and approachable guy as well. I'll definitely look into Wendy's. I sourced the local (jo'burg) Hiwin agent and got what I thought to be very reasonable prices from him. My main concern with China was the shipping time, but your deal is great as far as that's concerned. Also, I've heard that a lot of the Hiwin stuff coming from China is not the same quality that comes from the Taiwan factory. Apparently they pick up the stuff (from Hiwin) that doesn't quite make Hiwin's standard, and sell that. i.e. it's not reject, just not what you'd get from the original manufacturer. I'd be interested in hearing how yours go for you.

As for the 4th Axis, you guys are all right, I'm probably overstepping the bounds. I'm going to reduce the 4th axis radius to around 75mm (1/2 it). Then again I hear what you're saying, and will look into the whole software thing in a lot more depth ... even if I have to look at writing something to accommodate (on the longer term).


EddyCurrent
There are other things but for a start these jump out at me...

Thanks for this.
1. I'll take your good advice and source the suggested spindle and collet.
2. I am going to reduce the working radius on my 4th axis (hence the longer travel) and go to around half of it. I'll also increase the distance between the blocks as suggested. What should I look at for a minimum please?
3. Hopefully jazzcnc does comment, I'd be very interested in hearing his suggestions.
4. I started out on 20mm rail originally, only to be told by the manufacturers that 15 would more than suffice in terms of loading, etc. As I downsize the Z axis, I'm going to also downsize on the other axis as well. Not a whole lot, but a fair amount.
5. With the reduced Z axis and added other suggestions, I don't think I want to go adjustable table (for now anyways).


routercnc
That is a large machine to also cut aluminium...

Agreed. The main materials I'll be working with will be hardwood and perspex. For the occasions I'll want to work ally, it probably doesn't justify it anyway.


You have a very large offset from the Z axis to the Y rails - ...
There's another way I can do the Y-axis, and that's to use 2 of those profiles atop of each other, i.e loose the center piece - but that's if I insist on going that route. If I do, although simpler, it's a hellova lot more expensive and again, probably not worth the expense. I'll look at going back to an earlier design which was an all steel machine (and stop being so damned lazy :) ). In that version, I got the the ratio down much better.


The end plates on the gantry look very thin.
My bad! I should have said the end plates are 5mm steel plate, as are the gantry cross plate (bottom plate) and 4th axis mount plate.


Will you add a bed to this?
Yep, 32mm MDF, and I'll add 2 additional cross members to stiffen it up as well as suggested.


X axis motors
Yes, I got THAT one wrong, didn't I :). Not quite sure what I was thinking of on this one, probably one of my earlier version designs!


Clive S
If you are going to slave your x axis you might have to re think Linuxcnc ...
Thanks for pointing this one out to me. I'll rehash it and also better research it.

Thanks all so far for the great feedback. With you all pointing me in the right directions I'm really looking forward to getting this thing done.

EddyCurrent
13-08-2014, 11:07 PM
I'll also increase the distance between the blocks as suggested. [I]What should I look at for a minimum please?

Well mine have a gap of 95mm, that is inner face to inner face, I calculated that as the best for my machine.

With regard to the bed, I urge you to use birch plywood rather than MDF. I used two layers of 19mm and sealed it all with a 50/50 mix of polyurethane varnish and danish oil. That's after leveling the bed by running some G code to run the router over it with a large end mill cutter.

With regard to aluminium, I thought I might do some cutting of this myself but when you consider the requirements for lubrication/coolant, a wood cutting router just does not have the appropriate bed arrangement.
You might want to think about that in your design before starting the build i.e. an aluminium T slot bed might be a better alternative.

Boyan Silyavski
15-08-2014, 01:48 AM
With regard to aluminium, I thought I might do some cutting of this myself but when you consider the requirements for lubrication/coolant, a wood cutting router just does not have the appropriate bed arrangement.
You might want to think about that in your design before starting the build i.e. an aluminium T slot bed might be a better alternative.

One of the best ways to cut aluminum is to use old fridge compressor that blows cheap airbrush that spays mist of alcohol at the cutter. The mist evaporates instantly and leaves everything dry and cool. So coolant is not a problem.

lebies
15-08-2014, 03:39 PM
One of the best ways to cut aluminum is to use old fridge compressor that blows cheap airbrush that spays mist of alcohol at the cutter. The mist evaporates instantly and leaves everything dry and cool. So coolant is not a problem.

Cool (no pun intended) idea :) ...

After all your initial input (for which I'm very grateful thanks), here's take 2:

- Z-Axis travel now 100mm (all dims +-)
- Y & Z axis now welded plate (mainly 5mm with 8mm spindle mount plate.
- Used 100x50x4 to mount X and Y-axis rails onto
- Widened guide rail blocks all-round

A pic paints a 1000 words ... so here ya go (2ns is just the Y-bed detail construction):

1311213111

As always, your feedback valued :)...

lebies
15-08-2014, 04:49 PM
Well mine have a gap of 95mm, that is inner face to inner face, I calculated that as the best for my machine.

With regard to the bed, I urge you to use birch plywood rather than MDF. I used two layers of 19mm and sealed it all with a 50/50 mix of polyurethane varnish and danish oil. That's after leveling the bed by running some G code to run the router over it with a large end mill cutter.

Done ... thanks.



With regard to aluminium, I thought I might do some cutting of this myself but when you consider the requirements for lubrication/coolant, a wood cutting router just does not have the appropriate bed arrangement.
You might want to think about that in your design before starting the build i.e. an aluminium T slot bed might be a better alternative.

Have rehashed my thinking. I'll be able to do it on my updated version but it's no longer a high priority.

I wanted to use the al T-slot bed, but I'll buy it piece-meal for future. This stuff is extremely expensive around here - very, very nice, but damned costly for now :).

Thanks for your help, appreciate.

Boyan Silyavski
16-08-2014, 12:51 AM
Hi,
just read all you said and need carefully.

Some thoughts on your design that come to my mind, just what i would do., Having in mind the results you desire. I will try to resume so you dont have to look million threads for pieces of information:

- Beef up everything to 80x80x3 and the gantry to 2x 80x80x4 soldered together, or keeping your aluminum gantry design take a look at other threads to see how people do it properly with say 20mm thick plates
Beefing the structure is the cheapest thing to do on a machine. So why not do it. I have done extensive calculations and assure you that this table design is the stiffest and cheapest and lightest possible and at the same time easier to make, simple. Also doing so you avoid the necessity of diagonals. I am talking about 80x80 as ideal, to 100x100 as overbuild. I do it 100x100. You can find more info here (http://www.mycncuk.com/threads/5302-Tiddy-CNC/page2), Tonys CNC is very good example of what you can achieve with this type of structure, of course accustomed to your needs + alu gantry

-Make the Z travel 200mm, its good compromise between stiffness and length. Take a look at how i did it here (http://www.mycncuk.com/threads/6457-Sturdy-and-Fast-all-Steel-CNC-my-first-build?p=59627#post59627) post #109 and how looks finished from 12mm steel plate a bit up at the same page. Your design will not work for that length/ or any/. The alu profile is too flimsy. Make the plate exactly as i did from 12mm steel, or 20mm aluminum at least . The plate should have ribs that dont allow it to bend in the long axis directions. In my design the ribs are the formed on the back by the steel that supports the rails and the rails themselves. Either way in front or back it must be ribbed.
The Z in question reaps fully extended through aluminum like a butter with 1/4 router bit and surfaces alu glass like finish.

-normally for multi material machine people here on forum use 1610 on all axis and 1605 on Z

-15 size linear rails is in the ball park of amateur machine. most machines that want pro results start fro 20 size linear rail, that is assumed the typical in a well made diy build. The price is almost the same.

-Hiwin from China is original. And probably the most used rail that i know of. Dont be mistaken here. Contact Fred (bstlinear@gmail.com) / BST automation (http://www.aliexpress.com/store/314742)/ from my name and he will beat any price of linear stuff you see on ebay or aliexpress+ offers perfect machining service. You can source almost all for a build from him, including spindle and VFD. Stuff that is not listed at his store i mean.
China ball screws are acceptable, cheap and at the end do the job perfectly. Usually the quality of a build suffers from many other stuff than to concentrate on the quality of ball screws.

-on the table bed the beams should be from 200 to max 300mm separated. At 300mm you must fit sth at least 6cm thick not to vibrate. So as the steel is the cheapest thing in a build i don't see why not do it properly. Proper alu bed is very expensive. So do your self a favor and make it right.

- Now that you want 4rth axis to be 300mm OD is not a problem with 200mm axis and 2 beams separated on bed say 350mm where you can fit the axis and when not in use cover it with sheet.

-If you were inspired by Deans/Jazzcnc/ or Johnathans build (http://www.mycncuk.com/threads/6484-A-sufficiently-strong-machine) to design the structure, have in mind that these machines use toolplate as table bed that makes thing very stiff.
So its not just paste and copy thing.

-Speaking about bearing spacing of bearing blocks i see as absolute minimum 260mm end to end outside measured, having in mind The long, not short Hiwin 20 carriages which each is 90mm long. That on all axis and in all directions! . Compromise can be made on the back Z plate width as Eddy said above and on the front Z plate width. i dont see though how the Z plate could be wider less than 150mm without compromising something

-that drivers you point to will Not work. you need 550-650W 70VDC non regulated power supply, and drive the motors at that Voltage 70VDC not 50VDC, so you need drivers like Leadshine AM882 which typically is the most recommended drive here. 3Nm Low Induction motors is what you need and drive them at 4.2A with the drivers at 70 VDC.
With the before mentioned you can drive all with short HTD 5M 15mm short belts and 20T pulleys 1:1, To calculate the center distances and other measures http://www.bbman.com/catalog/belt-length-calculator.html

-There are many BOB and when you search to buy happens that all of them have some trade off. Money must be spend here if yo want smooth motion. Ethernet is the way. ESS+126 PMDX board. You can buy first the board only if money is an issue. I use other board due to other reasons but it also works with ESS.

Hope that summary helps you save time fiddling and shortens the time till when chips will be flying around.

Last note is to analyse and not simply copy, cause simple stuff like simple looking structure has a lot of thought gone into it and changing little things can compromise many things, as usually the designs are quite perfected by themselves.

lebies
17-08-2014, 10:05 AM
Hi,
just read all you said and need carefully.

Some thoughts on your design that come to my mind, just what i would do., Having in mind the results you desire. I will try to resume so you dont have to look million threads for pieces of information:

Thanks for this detailed answer, very much appreciated.

I'm not a mechanical engineer, so the best way for me to learn is by burning my fingers. To do so I guess I must expose my weaknesses but have the balls to put it out there and trust folks with experience will come to the rescue - as has been the case here (thanks all). Collectively that makes of us a better, stronger community. I look forward to when I can start contributing and in so doing free up the folks with their vast knowledge to spend more (quality) time innovating and have drones like me help newbies get going :sneakiness:.

On to the business at hand.

Not sure you saw my revisions (we posted at around the same time) but I've made some significant changes to the original. I went back to one of my 1st designs and have decided to go all steel.



- Beef up everything to 80x80x3 and the gantry to 2x 80x80x4 soldered together, or keeping your aluminum gantry design take a look at other threads to see how people do it properly with say 20mm thick plates
Beefing the structure is the cheapest thing to do on a machine. So why not do it. I have done extensive calculations and assure you that this table design is the stiffest and cheapest and lightest possible and at the same time easier to make, simple. Also doing so you avoid the necessity of diagonals. I am talking about 80x80 as ideal, to 100x100 as overbuild. I do it 100x100. You can find more info here (http://www.mycncuk.com/threads/5302-Tiddy-CNC/page2), Tonys CNC is very good example of what you can achieve with this type of structure, of course accustomed to your needs + alu gantry

Nothing to loose and much to gain, will implement.



-Make the Z travel 200mm, its good compromise between stiffness and length. Take a look at how i did it here (http://www.mycncuk.com/threads/6457-Sturdy-and-Fast-all-Steel-CNC-my-first-build?p=59627#post59627) post #109 and how looks finished from 12mm steel plate a bit up at the same page. Your design will not work for that length/ or any/. The alu profile is too flimsy. Make the plate exactly as i did from 12mm steel, or 20mm aluminum at least . The plate should have ribs that dont allow it to bend in the long axis directions. In my design the ribs are the formed on the back by the steel that supports the rails and the rails themselves. Either way in front or back it must be ribbed.
The Z in question reaps fully extended through aluminum like a butter with 1/4 router bit and surfaces alu glass like finish.

Done. I cut it down to even less. In fact 150mm diameter is probably more than enough for my needs.


-normally for multi material machine people here on forum use 1610 on all axis and 1605 on Z

Thanks, will do.


-15 size linear rails is in the ball park of amateur machine. most machines that want pro results start fro 20 size linear rail, that is assumed the typical in a well made diy build. The price is almost the same.

I'm going Hiwin 20 on everything now.


-Hiwin from China is original. And probably the most used rail that i know of. Dont be mistaken here. Contact Fred (bstlinear@gmail.com) / BST automation (http://www.aliexpress.com/store/314742)/ from my name and he will beat any price of linear stuff you see on ebay or aliexpress+ offers perfect machining service. You can source almost all for a build from him, including spindle and VFD. Stuff that is not listed at his store i mean.
China ball screws are acceptable, cheap and at the end do the job perfectly. Usually the quality of a build suffers from many other stuff than to concentrate on the quality of ball screws.

Fred and I are speaking and sounds like we'll come up with a solution. Ridiculous thing is, for a set of ballscrews at $90, DHL want to charge $92 for shipping!
If we're going to find a good shipping solution between us, my costs drop to the extent I can use Servos and an alu bed. :livid:


-on the table bed the beams should be from 200 to max 300mm separated. At 300mm you must fit sth at least 6cm thick not to vibrate. So as the steel is the cheapest thing in a build i don't see why not do it properly. Proper alu bed is very expensive. So do your self a favor and make it right.

I'm going to buy the alu bed piece-meal over the next few months, so I'll work to it in good time and give it high priority.



- Now that you want 4rth axis to be 300mm OD is not a problem with 200mm axis and 2 beams separated on bed say 350mm where you can fit the axis and when not in use cover it with sheet.

Will now go less radius as stated, but I can't quite picture what you actually mean here :).



-If you were inspired by Deans/Jazzcnc/ or Johnathans build (http://www.mycncuk.com/threads/6484-A-sufficiently-strong-machine) to design the structure, have in mind that these machines use toolplate as table bed that makes thing very stiff.
So its not just paste and copy thing.

I was definitely inspired by their builds, hence the strategy on the alu bed in good time. Also, I've now got the message - go overboard on the base, it's worth it!


-Speaking about bearing spacing of bearing blocks i see as absolute minimum 260mm end to end outside measured, having in mind The long, not short Hiwin 20 carriages which each is 90mm long. That on all axis and in all directions! . Compromise can be made on the back Z plate width as Eddy said above and on the front Z plate width. i dont see though how the Z plate could be wider less than 150mm without compromising something

Thanks to Eddy (and locating his stiffness calculator) I was able to learn a whole hellova lot, and improve on my original design. Mostly though, many of the critical principles were highlighted for me to learn from and/or about.


-that drivers you point to will Not work. you need 550-650W 70VDC non regulated power supply, and drive the motors at that Voltage 70VDC not 50VDC, so you need drivers like Leadshine AM882 which typically is the most recommended drive here. 3Nm Low Induction motors is what you need and drive them at 4.2A with the drivers at 70 VDC.
With the before mentioned you can drive all with short HTD 5M 15mm short belts and 20T pulleys 1:1, To calculate the center distances and other measures http://www.bbman.com/catalog/belt-length-calculator.html

-There are many BOB and when you search to buy happens that all of them have some trade off. Money must be spend here if yo want smooth motion. Ethernet is the way. ESS+126 PMDX board. You can buy first the board only if money is an issue. I use other board due to other reasons but it also works with ESS.

Great! I'm going to use this combo myself. Just busy sourcing motors to match.


Hope that summary helps you save time fiddling and shortens the time till when chips will be flying around.

Last note is to analyse and not simply copy, cause simple stuff like simple looking structure has a lot of thought gone into it and changing little things can compromise many things, as usually the designs are quite perfected by themselves.

As stated above, once these things have been pointed out, it's easy enough to pick up on. Without Eddy's sheet (and/or knowledge thereof) I'd have been fumbling around in the dark for quite some time I can tell you. As a suggestion (very humbly), a place to put all such info in it's own right on the main board?

Thankfully there's a community of very helpful folks to nudge one in the right direction, and once you've found the proper info, you can actually do precisely what you recommend :acne:.

Thanks again for the detail, really appreciate and it'll definitely shorten my build time.

Boyan Silyavski
17-08-2014, 11:01 AM
Thanks, will do.

Fred and I are speaking and sounds like we'll come up with a solution. Ridiculous thing is, for a set of ballscrews at $90, DHL want to charge $92 for shipping!
If we're going to find a good shipping solution between us, my costs drop to the extent I can use Servos and an alu bed. :livid:

Thats why the suggestion to buy everything from him, cause shipping costs are high, so they could be spread among all pieces. i have done the calc and seems cheaper to buy all, pay shipping, duty, than buy from Europe, where i live. 1/3rd cheaper. you will have to do your calc though. Dont forget to tell him to state lower value.




Will now go less radius as stated, but I can't quite picture what you actually mean here :).



i mean this, the green is the 300mm diameter workpiece

13119
13120

lebies
17-08-2014, 11:23 AM
Thanks for this detailed answer, very much appreciated.

I'm not a mechanical engineer, so the best way for me to learn is by burning my fingers. To do so I guess I must expose my weaknesses but have the balls to put it out there and trust folks with experience will come to the rescue - as has been the case here (thanks all). Collectively that makes of us a better, stronger community. I look forward to when I can start contributing and in so doing free up the folks with their vast knowledge to spend more (quality) time innovating and have drones like me help newbies get going :sneakiness:.

On to the business at hand.

Not sure you saw my revisions (we posted at around the same time) but I've made some significant changes to the original. I went back to one of my 1st designs and have decided to go all steel.



Nothing to loose and much to gain, will implement.




Done. I cut it down to even less. In fact 150mm diameter is probably more than enough for my needs.



Thanks, will do.



I'm going Hiwin 20 on everything now.



Fred and I are speaking and sounds like we'll come up with a solution. Ridiculous thing is, for a set of ballscrews at $90, DHL want to charge $92 for shipping!
If we're going to find a good shipping solution between us, my costs drop to the extent I can use Servos and an alu bed. :livid:



I'm going to buy the alu bed piece-meal over the next few months, so I'll work to it in good time and give it high priority.




Will now go less radius as stated, but I can't quite picture what you actually mean here :).




I was definitely inspired by their builds, hence the strategy on the alu bed in good time. Also, I've now got the message - go overboard on the base, it's worth it!



Thanks to Eddy (and locating his stiffness calculator) I was able to learn a whole hellova lot, and improve on my original design. Mostly though, many of the critical principles were highlighted for me to learn from and/or about.



Great! I'm going to use this combo myself. Just busy sourcing motors to match.



As stated above, once these things have been pointed out, it's easy enough to pick up on. Without Eddy's sheet (and/or knowledge thereof) I'd have been fumbling around in the dark for quite some time I can tell you. As a suggestion (very humbly), a place to put all such info in it's own right on the main board?

Thankfully there's a community of very helpful folks to nudge one in the right direction, and once you've found the proper info, you can actually do precisely what you recommend :acne:.

Thanks again for the detail, really appreciate and it'll definitely shorten my build time.


Thats why the suggestion to buy everything from him, cause shipping costs are high, so they could be spread among all pieces. i have done the calc and seems cheaper to buy all, pay shipping, duty, than buy from Europe, where i live. 1/3rd cheaper. you will have to do your calc though. Dont forget to tell him to state lower value.




i mean this, the green is the 300mm diameter workpiece

13119
13120

Gotcha, thanks.

Been buying all my electronics from China for a while now, so have learned a few tricks :).

I'm thinking of pairing the AM882 with 86HS35 steppers. Good match?

Not sure I should belt-drive both X-axis ballscrews from one motor, or drive each individually.
If I go belt-driven both from 1 motor, I'll go look out around here for some examples.

If I go individual drives, what size motor should I be thinking of?

EddyCurrent
17-08-2014, 03:06 PM
I'm thinking of pairing the AM882 with 86HS35 steppers. Good match?
If I go individual drives, what size motor should I be thinking of?

The AM882 manual I have lists these motors as being already configured in the drive, selection being via an 8 position rotary switch.
57HS09 , 57HS13 , 57SH22 , 86HS35 , 86HS38 , 86HS45 , 86HS85
But of coarse the drive can be configured for any other motor.

Are the 86HS35 Nema34 ? you should be okay with Nema23, these are the ones I use with AM882's and have loads of power/speed. http://www.cnc4you.co.uk/index.php?route=product/category&path=20_27 I'm using two of them for X axis.

This thread might be worth reading; http://www.mycncuk.com/threads/6671-I-NeeD-HeLp-PLease-AM882-a-good-choise

Boyan Silyavski
17-08-2014, 03:17 PM
Gotcha, thanks.

Been buying all my electronics from China for a while now, so have learned a few tricks :).

I'm thinking of pairing the AM882 with 86HS35 steppers. Good match?

Not sure I should belt-drive both X-axis ballscrews from one motor, or drive each individually.
If I go belt-driven both from 1 motor, I'll go look out around here for some examples.

If I go individual drives, what size motor should I be thinking of?

No. this is nema 34 stepper . You need Nema 24 stepper 3Nm 4.2 A and look for the Low Inductance. I mean if you can not source that exact one below, which most people here use with the AM822 drivers or similar.

13121


That in case you decide to move the gantry with 2 motors which i recommend personally. Otherwise you will need to investigate Low inductance nema 34 motor which is not easy to come by at all. In that case you can look what motor they sell at http://www.cncrouterparts.com/960-oz-in-nema-34-motor-p-112.html. its not so easy to source such motors as one may suppose.Read more here (http://www.cncrouterparts.com/why-should-i-buy-your-motors-company-xx-has-higher-torque-motor-p-187.html) why it matters. But may be some one here can enlighten me which China guy sell them. Its good to know.

lebies
19-08-2014, 08:21 AM
No. this is nema 34 stepper . You need Nema 24 stepper 3Nm 4.2 A and look for the Low Inductance. I mean if you can not source that exact one below, which most people here use with the AM822 drivers or similar.

13121


That in case you decide to move the gantry with 2 motors which i recommend personally. Otherwise you will need to investigate Low inductance nema 34 motor which is not easy to come by at all. In that case you can look what motor they sell at http://www.cncrouterparts.com/960-oz-in-nema-34-motor-p-112.html. its not so easy to source such motors as one may suppose.Read more here (http://www.cncrouterparts.com/why-should-i-buy-your-motors-company-xx-has-higher-torque-motor-p-187.html) why it matters. But may be some one here can enlighten me which China guy sell them. Its good to know.

Thanks,

Either I'll go 2 motors (NEMA23 3Nm my preference at the mo as well) but I'm also looking into going with belt & pulley on the y-axis, using 1 motor. Lots of advantages, just have to mess with different configs. i.e. these options (tensioners not included - yet):

13134131351313613137

Where 1 & 2 are single belt and 2 & 3 are 2 belts, 1 to each side from the center. I'll do the calcs and maybe present for comments.

I'm moving house at the mo, so will only really be online again in about a weeks time from Thursday.

Thanks so far for all your comments.

EddyCurrent
19-08-2014, 12:21 PM
This might be worth reading, there's also a belt length calculator link in there.
http://www.mycncuk.com/threads/5146-Belts-pulleys?highlight=belt+calculator

lebies
19-08-2014, 01:00 PM
This might be worth reading, there's also a belt length calculator link in there.
http://www.mycncuk.com/threads/5146-Belts-pulleys?highlight=belt+calculator

Great! Thanks Eddy.