Isel CPM3020 cnc machine - electronics rebuild

[raynerd]

I put a low bid in for a CPM3020 that had just come from a school closure and managed to win it. Photos were rubbish and I expected very little but it's German made, ball screws and a good solid heavy frame and case - I thought it was worth the money and based on eBay believe I could double the price I paid just chucking it straight back in in a cleaner state with better photos



Gave it a clean up just for my own piece of mind and I was chuffed with it:



Sadly, but as expected it's an old integrated driver board.



Just stripped it down further to find some usable stepper motors. So the next step is to strip out all the electronics. See if I am confident enough in keeping the PSU or maybe pull this out and replace but the drivers are going to need to be replaced that is for sure. Lots of work to do.... Oh heck, my Orrey project!!

[tom osselton]

Shouldn't be that bad cost wise, I'm just starting to collect parts for a cnc router. I bought ballscrews and rails off ebay (China) 300 x 900 x1150 along with the control board so I will be following your progress!

[PK]

At this scale, IMHO,  it's hard to go past the G40 http://www.geckodrive.com/geckodrive-step-motor-drives/g540.html . Mainly because of the amount of fault protection it offers, but also because it's pretty much a drop in replacement for what you have...

[philf]

At this scale, IMHO,  it's hard to go past the G40 http://www.geckodrive.com/geckodrive-step-motor-drives/g540.html . Mainly because of the amount of fault protection it offers, but also because it's pretty much a drop in replacement for what you have...

The downside with a unit like the G540 (other than price) is that it's not modular so if one component goes down the whole lot goes down. On the other hand it saves a lot of wiring and Gecko drives generally get good press.

Is it not possible to get the existing controller up and running?

Phil.

[awemawson]

There is a thread on CNC zone about resurrecting one of these machines:

http://www.cnczone.com/forums/techno-cnc/157780-cad-autocad-software-forum.html

and a load of information here:

http://www.spline.nl/machines/cpm.html#Booster

[John Stevenson]

At this scale, IMHO,  it's hard to go past the G40 http://www.geckodrive.com/geckodrive-step-motor-drives/g540.html . Mainly because of the amount of fault protection it offers, but also because it's pretty much a drop in replacement for what you have...

The downside with a unit like the G540 (other than price) is that it's not modular so if one component goes down the whole lot goes down. On the other hand it saves a lot of wiring and Gecko drives generally get good press.

Is it not possible to get the existing controller up and running?

Phil.

Phil, they are modular, they hold 4 G250 drivers and you can swap them.

Only problem with these is by the time they get into the UK duty paid they are bloody expensive for what they are, a 3.5 amp drive which will be happier at 3 amp.
You could buy a USB breakout board and three 4.5 amp drivers for half the money.

More scope to use modern computers and a derated 4.5 amp driver is going to be far more reliable that a driver running at max.

[philf]

Phil, they are modular, they hold 4 G250 drivers and you can swap them.

Only problem with these is by the time they get into the UK duty paid they are bloody expensive for what they are, a 3.5 amp drive which will be happier at 3 amp.
You could buy a USB breakout board and three 4.5 amp drivers for half the money.

More scope to use modern computers and a derated 4.5 amp driver is going to be far more reliable that a driver running at max.

John,

Sorry - I thought it was an integrated control.

You're right - 4.5A drives are as little as £21 on eBay from China. (Just got to hope you don't get clobbered for VAT and the collection fee).

Am I still right in saying that you can't run a USB breakout board with Mach3? I know you can use a USB SmoothStepper but they don't come cheap either.

Phil.

[raynerd]

Hi, interesting posts. Sorry, but I'm staying away from Geko, they are just too costly especially with import and shipping. I'm sure they are good but can't see the benefit above 4.5a drivers or even a branded Leadshine DM556. Shine, these above nearly doubled since I lost got some...sure I paid £35-40 per drive from Arc Euro about six years ago.

It's a minefield but there is a lot of talk about motion control. Has anyone used these CSLABS I-PM
It's a heck of a price as well but MY UNDERSTANDING (!?) is that it acts as motion control and BOB all in one as is very good quality.

http://www.cs-lab.eu/en/produkt-18,2-CSMIOIPM_4axis_Ethernet_Motion_Controller_stepdir_with_connectors.html

Just to confirm, I need stepper drivers x3, motion control (or free parallel port!) and a bob to get this to move. Or I just need 3x drivers and then the CSLABS ip-m.

 The PSU is 24.5v so I guess I can use this or should I really swap this out for 36vdc??

Ahhhh remember my last cnc build now. Heads going to explode.....

[philf]

Chris,

Since my last reply in which I asked about Mach3 with USB I have found two USB offerings from CNC4YOU both compatible with Mach3:

https://www.cnc4you.co.uk/Motion-Control

One looks like a USB to Parallel Port adaptor but it's a lot more than that and takes a lot of work from the PC by reading in the code and then dishing it out to the CNC. This might mean it would work OK from a laptop. I think you'd still need a BOB with this one.

http://cncdrive.com/MC/UC100%20datasheet/UC100%20users%20guide.pdf

The second looks more advanced and gives 36 outputs and 49 inputs + 2 analogue inputs + 2 analogue outputs and can handle 6 axes. You wouldn't need a BOB with this. [Edit: The manual says you should use a BOB with opto-isolation to protect the inputs. The stepper drivers usually have opto-isolation on its inputs.]

http://cncdrive.com/MC/UC300%20datasheet/UC300%20users%20guide.pdf

I bought all my drivers and motors from CNC4YOU.

Looks like they are available from elsewhere and good reports on both on the Machsupport forum:

www.machsupport.com/forum/index.php?topic=25448.0


Cheers.

Phil.

[raynerd]

On one of the cnc forums someone is really plugging the digital stepper drivers. Apparently the ones you linked to are analogue. However, for the extra money and the ability to buy them from the UK - I`ll go with the ones you suggested if you have been happy with them?  I`d rather buy UK - estimated delivery for most China buys are between 6th and 28th Feb!

Any one else used the cnc4you 4.5A drivers or alternatives?

Chris

[PK]

The nice thing about the better drives (like the ones in the G540) is the amount of protection they have.
A broken wire to the motor, a short, an over voltage etc won't destroy them where as all of these things will reliably pop a cheap drive.

Add in step dithering and micro to full step morphing and they really are noticeably better.  My mill has a Gecko drive on Y and that axis is faster than X (same motor, same voltage) and smoother at low speed.

I get that the cost is a big consideration, and I'm not trying to bash anyone over the head with this. Just thought it worth including in the discussion.

[John Stevenson]

The last generation of Leadshine drives also has the full step morphing and they also do closed loop steppers in either standard DC or three phase AC.
The three phase AC are virtually servo motors but without the hassle.

[philf]

Chris,

Have a look at www.estlcam.com.

Estlcam is a 2d/3d cam package but it also includes a CNC control to drive your machine directly (no need for Mach3 or LinuxCNC).

It uses an Arduino via a USB port to interface your PC to your CNC machine. All the Arduino programming is done automatically from within Estlcam.

A license for Estlcam is only 39 Euros!

Cheers.

Phil.

[PK]

The last generation of Leadshine drives also has the full step morphing and they also do closed loop steppers in either standard DC or three phase AC.

Didn't know that.. Good to hear.

The three phase AC are virtually servo motors but without the hassle.

Yeah, I got some NEMA23 three phase motors with a laser XY table kit I bought a little while back. I did a double take at the cables then went and bought the drives. Really looking forward to seeing how they go..

[raynerd]

Phil, I`m in no doubt that I`ll crack on and upgrade the drivers and have a more 'professional' system using Mach3 - however, I think I may well order the Leadshine drivers from China and in the mean time, I`d like to give Estlcam a go especially since I have an Arduino Uno kicking around somewhere, it won`t cost me a bean. However, to use it, I guess I`ll have to identify the step and dir for each motor - but after staring at the large board, I`m not sure what I'm looking for or where! Based on my previous experience of CNC, I think I`m right in remembering that there was a step, dir from the BOB. However, this is running serial cable in with only three wires from the PC output and then if there is a BOB built into the motor, no idea where to look.

Anyone any idea where I would tap into step and dir ? 

[awemawson]

Chris,

Just guessing, but if it was RS232 driven, then the system board that you have probably receives G code, or a proprietary code, and drives the steppers directly. So you won't have an identifiable 'driver' that takes in step and direction, just a power stage for each winding of each stepper. This is likely an ic per stepper - probably with fins.

[raynerd]

Cheers Andrew. Just ordered stepper drivers, motion control and BOB so next step is removing all this existing electronics.

The PSU in here is 24.8v - is this good enough or do I need to swap out for higher voltage unit??

[Joules]

Chris, when you remove that controller can you have a look at the stepper chips and see if they happen to be Toshiba TA8435HQ's.  It's a long shot but my old cnc router has blown one of those and I can't seem to find any.  Thought it might be worth asking if you are just going to toss the controller.

[seadog]

There are plenty of them on eBay - http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p5468.m570.l1313.TR0.TRC0.H0.TRS0&_nkw=TA8435HQ&_sacat=0

[raynerd]

A little confused with this PSU.

I've taken a picture of the label and attached it. (One with light shining and glare is 10v )

I'm reading 29.8v across the capacitor which doesn't match any of the stated voltages?

[Bluechip]

Why should it ?????    They are full-load RMS AC voltages.

If you connect Sek2 from bl-bl @ 20.9VAC I would expect that to FW rectify to 29.8 VDC ish with a capacitor.

Multiply by SQRT 2 ie. 1.414 ...

If that is what you are doing ... not enough info really.

Dave

[philf]

Hi Chris,

The important winding is the 20.91v at 6a. If you rectify that with a bridge and put a big capacitor in you should get something like 30v which is better than 24v but 36v would be better still.

It would be OK for starters but if you want speed you may struggle. Also, if you've got three 4.2a stepper motors there may not be enough current if all three motors drive at the same time.

Phil.

[raynerd]

Thank you, makes sense now,

[raynerd]

Can anyone give me a little advice on home switches and limit switches.

My machine has 6 limits, 2 on each axis. I understand that to save inputs, most people wire them all in series. Obviously. You can't see that way which one has been triggered but inspecting the machine will make it obvious. What I then don't understand is why if you have limit switches, why home switches would be needed. Surely if you track back to your limits you could then move to a software "home" just like you can have soft limits. Also, a lot of people seem to home to the centre of the bed. Won't the limit switches keep getting triggered during general milling - they may be ignored by the software but it is this ok on the hardware side?

I'm obviously missing something... Help appreciated.

[awemawson]

Limit switches should be just that : an absolute limit to travel in that axis direction to save the mechanics and electronics if something goes wrong.

Home switches perform a totally different function : they give the software a reference point as to where the machine is for setting up purposes

[raynerd]

That's my exact understanding but if the limit switches are hit then what's the difference between hitting those and a home switch ? Why can't they be used as a home as they are identical switches?

I know I'm missing something...

[geoff_s]

On my CNC routers, the home switch is the limit switch for minimum direction. A separate switch is used for the maximum direction. When using soft limits, none of these switches is ever activated - except the home switch when initially homing the system.

Running Linuxcnc

[philf]

That's my exact understanding but if the limit switches are hit then what's the difference between hitting those and a home switch ? Why can't they be used as a home as they are identical switches?

I know I'm missing something...

Hi Chris,

Home switches aren't wired in series with the limit switches so triggering a home switch in the middle of running some g-code won't affect it. The home switch goes to a separate input.

I only have one home switch which is on my z-axis. Waiting for the z axis to go to its limit switch takes far too long so I added a home position (using a hall effect sensor and a magnet) so the table drops to the home position which is just enough to clear any tools in the chuck before the table homes in X & Y.

For those who aren't familiar with Mach3 you only need to use 1 input for all 6 limit switches. When you do a 'home all' it will drive the axes one at a time to a limit switch (or home switch if fitted). It knows which axis it's driving and the direction so it knows which limit switch it has hit. It drives until a switch changes state and then backs off until the switch switches back before setting the axis coordinate to zero.

Phil.

[modeldozer]

Hi Chris,

When I built my CNC router i fitted 6 limit swithes in series and 3 separate home swithes.  The limits tiggers an E- stop and the3 homes go to three different inputs.  To be honest I never use the home switches as I normally set machine zero (X, Y, Z) to a datum on the part.

Cheers
Abraham

[awemawson]

On a full size 'proper' cnc machine the limit switches will lock out the controller until someone with nouce can determine if it is safe to re-set them.

Remember you are playing with tiddly little stuff, but a full size machine can have several kilowatts of axis drive power that can shift things pretty fast and do very much damage.

On my Beaver Partsmaster the previous owner screwed up the Y limit switch setting, and it had managed to destroy a VERY expensive 40 mm ball screw and nut - if only those students hadn't fiddled ! (ex Bristol University)

On my Traub lathe the mass of the tool turret and slide mechanism is huge with servo drives of commensurate size  - you don't mess with the limits on those unless you have very deep pockets 

Good practise dictate that you have separate limit and home switches

[philf]

Hi Chris,

When I built my CNC router i fitted 6 limit swithes in series and 3 separate home swithes.  The limits tiggers an E- stop and the3 homes go to three different inputs.  To be honest I never use the home switches as I normally set machine zero (X, Y, Z) to a datum on the part.

Cheers
Abraham

Hi Abraham,

Certainly with Mach3 it's advantageous for safety and for the sake of the machine to drive to home or limit switches as a reference before you start machining. By setting the soft limits up correctly (and enabling "Use Soft Limits") you will then never run into the limit switches and before Mach3 will run any code it does a check that the soft limits won't be reached.

If the table or gantry is moving fast it may not be able to stop quickly enough before running into a mechanical limit which, as Andrew has pointed out, could lead to a ballscrew & nut being destroyed or worse.

I too always zero on a job but Mach3 works with two sets of co-ordinates akin to Absolute and Incremental on a DRO. I always home the machine on switch on and then I zero the edges of my part in the 'incremental' mode but the 'absolute' mode still knows the safe distance to the limits and thus can give you a warning.

Hope you're taking all this in Chris! If you get stuck you know where I am.

Cheers.

Phil.

[awemawson]

G54 Phil

[raynerd]

As always, appreciate your replies. Really helpful stuff and I think I now understand. Based on the info, I was fiddling last night I can see how you can set limit and home all on one pin - very smart.

I fully appreciate Andrew, based on what you said, that in industry or with big machines a limit is critical for safety of the operator but equally safety of breaking parts.

Thanks again for your time.

[raynerd]

The cnc machine is now up and running. I`m blown away with how fast and how accurate it is and how well it did with a 4mm cut depth in brass cutting some text.

[philf]

Excellent work Chris! 

Phil.

[awemawson]

Well done 

[raynerd]

Thanks Phil, Andrew and I appreciate how much help you have given me answering my questions through this thread. Its been a very nice build and it is great how much space there is in the back of the machine to fit the new drivers. I just can`t get over how accurate and quick it is - you can`t compare it to the TEP machine I converted some years ago.

Thanks again.

[DMIOM]

Well done Chris      

Can I repeat someone's earlier - the music really detracts from being able to hear you and appreciate the work you're showing - have it on the intro, and if you really really must have some quiet background at times, but not that loud please?

cheers / Dave

[raynerd]

No worries, cheers David - I presume no-one would really want to hear me blabbing on      - point noted. I think I have a poor ear for sound as to me, the music isn`t that loud at all after the first 10 seconds. I clearly need to drop it down to half of what I think. Cheers

Chris

[philf]

Chris,

Now you need a 4th axis connected in and try some wheel cutting on it and then crossing out the wheels!

Cheers.

Phil.

[raynerd]

Yes, now that certainly is on the agenda. Rather than build my own from scratch, I'd consider looking for a small 3" table and converting it just as I have my 4" vertex. It's too late now, but I've not actually sat my rotary table on the mill - expect it'll be a fraction too big.

Edit, RDG actually do a 2 3/4" table