TOS-KURIM CNC Upgrade

Hi Guys,

Stumbled across this site yesterday after doing some research, some awesome info on here!

I currently have an old TOS-KURIM converted knee mill which uses an Anilam Crusader II and analog Indramat drivers for the DC motors. When I bought it everything was working fine but three years in storage while I sorted a home for it seems to have finished it off!

I've had enough of putting hours into trying to fix it and decided it may just be better to upgrade it to something more modern.

My plan is to rip everything out and replace all motors, and electronics and use something along the lines of MACH/Centroid to run it.

That's as far as the plans gone though, I've got plenty of experience running machines but not building them! I'm a bit overwhelmed with all the different motors and the sizes and control boards etc.

Any help would be awesome on what I need for a low budget install, this is purely a home machine for odd jobs so doesn't need to be amazing. I have access to much better machines at work for anything serious.


Thanks,

Jamie

Hi Jamie,

Some pictures of the machine will help to get a feel for what you have. I've not seen or heard of TOS-KURIM and a quick google showed me a gantry Mill with a boat on it.!!! . .Pretty sure your not milling boats...Lol

Provided the machines not too massive then you might get away with some large Closed-loop mains driven steppers. They are very powerful and a lot cheaper and simpler than AC servo's. They won't give the speeds servos will but they will do the job if your not chasing high feeds.

Centroid Acorn would be a good match for the controller.

haha! definitely not going to be getting any boats in the garage any time soon! I've added some photos to help give you an idea of size but its not really much bigger than a standard Bridgeport to be honest. table length is a little over a metre..

Attachment 27814
Attachment 27815
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Attachment 27817


Ok that's great, I'll have a look into those.

The other things is I am almost certain the motors I have on it are still working well, so is it possible to leave them on and swap out the existing drivers for something newer/more reliable? apologies for my lack of knowledge on this...

Thanks again

That should be a simple upgrade you have most of the hard work done in the form of mountings etc, just a few adaptor plates for different size frames with motors will sort it.
I'm presuming you don't want to CNC the Knee.?

You just need to decide if want servos or steppers.? Quite a lot more work in setting up along with big learning curve involved with servos but they do give higher feeds, more power along with smoother operation and accuracy.
The downside is they also cost more money and require a higher level of the controller to get full use out of them. They can be much more temperamental than steppers and very unforgiving on poor wiring quality or practices.

Steppers, on the other hand, are much simpler to set up with hardly any learning curve involved and quite a bit cheaper. They can be run on a lower level of controller.
The downside is they are limited to roughly 1200 to 1500Rpm so feeds are lower. Resolution is lower compared to servo's but still more than enough for milling at this level.

Choosing the correct drives and size is critical with large steppers because you don't have lots of spare power as you do with servos. So if you take this route then look for 220V Mains powered Drives rather than lower AC/DC drives running say 80Vac or 100Vdc.

I've used these many times and they are a great set up with lots of power and provide reasonable torque even at high feeds. More than enough for your machine.

https://www.aliexpress.com/item/3279...3cac6f37OxW5VA

Hope this helps, got any questions just ask.

It depends really on the servo drives and motors you have. Depends if they work properly and the cabling works properly. Meaning what type of signal the servo drives work with and if the board is closing the loop or the servo drives.

If the board is closing the loop probably you will need new modern servo drives and board, suitable to your machine.


Find the drives and motor names and you can start from there.


Most of all solution will depend what type or style of machine and manual control you will like to have as an end result. A big fancy display and a lot of buttons and dros to play with, or just bring an USB stick, stick it in the machine, zero and play / thats me/

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Originally Posted by JimJam

The other things is I am almost certain the motors I have on it are still working well, so is it possible to leave them on and swap out the existing drivers for something newer/more reliable? apologies for my lack of knowledge on this...

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Can't answer that without knowing more about the motors and the drives.
They are probably DC Brushed motors and It's quite possible you can get away without drives but it will probably require a different controller that uses +/-10V analog signals and these get expensive quick and are not so popular as Step/Dir controllers. You can get DC Brushed drives which accept Step/Dir signals but they are often not cheap.
It's often cheaper and better to just replace them as a set with modern AC motors and use a Step/Dir controller.

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Originally Posted by Boyan Silyavski

Most of all solution will depend what type or style of machine and manual control you will like to have as an end result. A big fancy display and a lot of buttons and dros to play with, or just bring an USB stick, stick it in the machine, zero and play / thats me/

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Aww no Boyan it's a milling machine for god's sake don't start muddy the waters by suggesting to using one of those DDVS stand alone things will be ok for this machine.! . . It needs more control that those things allow.! :thumbdown:

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Originally Posted by JAZZCNC

Aww no Boyan it's a milling machine for god's sake don't start muddy the waters by suggesting to using one of those DDVS stand alone things will be ok for this machine.! . . It needs more control that those things allow.! :thumbdown:

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I was going to say that it needs from the advanced standalone controllers or a good software/hardware solution. But now that you say it, DDSV could do the job fine :joker: Now you dont tell me that Mach3/4 is the way to go

Ok that's brilliant, I've decided to just ditch the old motors now and start again. Not knowing the true condition or specifications of the original motors I would rather not put more money into them and still be no further forward if they don't work.

So based on my knowledge (lack of) and limited use it will have, it looks like I'm going to be better off heading down the stepper route.

The link you sent through with the motor and driver, I would require three of those (one for each axis), plus a control board of some kind, and a PC based control system... Am I somewhere on the right lines here for all the stuff I need for a basic setup?

Regarding PC control Software, what are the preferred options available? I don't want anything too fancy, just something that will jog axis, display DRO, and run code...

Thanks for all your help so far :thumsup:

Quote:

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Originally Posted by JAZZCNC

Steppers, on the other hand, are much simpler to set up with hardly any learning curve involved and quite a bit cheaper. They can be run on a lower level of controller.
The downside is they are limited to roughly 1200 to 1500Rpm so feeds are lower. Resolution is lower compared to servo's but still more than enough for milling at this level.

Choosing the correct drives and size is critical with large steppers because you don't have lots of spare power as you do with servos. So if you take this route then look for 220V Mains powered Drives rather than lower AC/DC drives running say 80Vac or 100Vdc.

I've used these many times and they are a great set up with lots of power and provide reasonable torque even at high feeds. More than enough for your machine.

https://www.aliexpress.com/item/3279...3cac6f37OxW5VA

Hope this helps, got any questions just ask.

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Crikey these are hard to come by in the UK! plenty of 80V and 100V ones around but no luck on any mains powered ones!

is that link you posted somewhere you've bought stuff from before?

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Originally Posted by JimJam

is that link you posted somewhere you've bought stuff from before?

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Yes I buy from them all the time. Don't worry about buying from China as they are trustworthy and well proven with many users in UK.

Also if you buy them thru the Aliexpress link I gave you then your protected by Aliexpress guarantee, they basically don't pay the seller until you have received them and say you are happy. They still charge you upfront but do not pass the money on until you are happy.

Edit: You will get charged VAT and Admin fee of around £15-20 on top of that price when they enter this country. You don't get charged Import duty.

CNCdrive sell a step/dir DC servo for brushed motors. I've got 2 of them on my Shizuoka and they have been a great experience. These are about £100 each, which hardly breaks the bank. They also avoid the need to mess about with a perfectly good installation.

http://shop.cncdrive.com/index.php?productID=366

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Originally Posted by Muzzer

CNCdrive sell a step/dir DC servo for brushed motors. I've got 2 of them on my Shizuoka and they have been a great experience. These are about £100 each, which hardly breaks the bank. They also avoid the need to mess about with a perfectly good installation.

http://shop.cncdrive.com/index.php?productID=366

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oh ok, that does sound like another possible route to take then. So with those drives, I would just need to buy a breakout board to link up to a PC and some control software and I would have a useable machine? providing my motors are still good...

If I did take this route the current setup uses linear scales for position feedback, would that be easy enough to incorporate into this type of system somehow?

Quote:

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Originally Posted by JimJam

oh ok, that does sound like another possible route to take then. So with those drives, I would just need to buy a breakout board to link up to a PC and some control software and I would have a useable machine? providing my motors are still good...

If I did take this route the current setup uses linear scales for position feedback, would that be easy enough to incorporate into this type of system somehow?

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You will need separate DROs which are not expensive. Can not be integrated on a cheap or middle priced board. This could be done on very expensive boards only like the Galil and such that support double control loops

Yes, there's no magic solution to backlash and accuracy. The idea of closing the loop with external DRO scales sounds pretty neat but as Boyan says, it's only very expensive controllers that support that concept. And an expensive system using such a controller probably has very little mechanical nonlinearity and/or backlash to start with.

If you have a basic system with loads of backlash, no controller in the world will be able to able to make sense of the nonlinear behaviour in a sensible way. Imagine trying to drive a car down a windy road with half a turn of lost movement on the steering wheel, then trying to fix that by adding some form of simple closed loop.

Your system is either going to be worn out in which case you need to either live with it or fix it - or it's in good shape in which case you should just fit a modern controller and get on with life. Sounds as if it's quite a decent machine to start with. Apart from bragging rights, what accuracy do you think you actually need? 10-20um? That's still 50th - 100th of a mm. I would start by measuring what I have and take it from there.

Quote:

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Originally Posted by JimJam

If I did take this route the current setup uses linear scales for position feedback, would that be easy enough to incorporate into this type of system somehow?

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I've got a feeling Jamie means the machine is using linear scales rather than encoders for position feedback, which the Anilam Crusader II controller would allow. And wants to know if the scales can be used with the CNCdrive.! Am I correct Jamie.? . . . If not the ignore me and listen to the others because it's correct what they say.!

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Originally Posted by JAZZCNC

I've got a feeling Jamie means the machine is using linear scales rather than encoders for position feedback, which the Anilam Crusader II controller would allow. And wants to know if the scales can be used with the CNCdrive.! Am I correct Jamie.? . . . If not the ignore me and listen to the others because it's correct what they say.!

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Yes exactly as you say, sorry I probably didn't explain that very well. I meant that it is currently using linear scales and wasn't sure how it would give positional feedback to the controller if using the CNCdrive muzzer posted without encoders on the motors..

Apologies again for not understanding what's probably the real basics for you guys! Appreciate your patience and sharing your knowledge.

You could try connecting the DRO encoders to a DC servo drive but unless you had near-zero backlash, the drive could be almost impossible to tune. This also assumes the encoder signal is a compatible (TTL A/B quadrature) type. If you have no backlash, it might be a workable solution.

Do the Indramat motors have encoders built in already? If not and the linear encoder doesn't work out, you'd need to fit a rotary encoder to each of the motors so the CNCdrives could work with them. You can buy suitable Haidenhain clone encoders from China for peanuts. Failing that, you'd probably be looking at acquiring some proper AC servos which would cost a lot more and need mechanical buggerage to fit them where the Indramats were. Not sure I'd want to waste my time and money fitting steppers to a decent machine like this.

Be aware that early analogue DC brushed systems often had tachometers mounted in the motors. They can't be used as encoders, as they only report speed, not position. However, you could remove them and use the freed up space to mount encoders.

Quote:

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Originally Posted by Muzzer

You could try connecting the DRO encoders to a DC servo drive but unless you had near-zero backlash, the drive could be almost impossible to tune. This also assumes the encoder signal is a compatible (TTL A/B quadrature) type. If you have no backlash, it might be a workable solution.

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Don't think these will be your typical magnetic linear encoders you see used on DRO's. These will be full blown Glass linear scales that are much more accurate and commonly used on high end machines.

If it was me I'd get the details of the Linear scales and drop CNCdrive an email asking if they can be used. I think they will be able to be used but you might need to convert from Single ended to Differential, which isn't a big issue. But they will be the one's to tell you, but they will need details.

Regards Steppers or Servo's then like I said if you want it cheap go with steppers as they will get the job done, maybe not as fast or smooth, but still done and reliable along with simple.!

Quote:

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Originally Posted by Muzzer

. Imagine trying to drive a car down a windy road with half a turn of lost movement on the steering wheel, then trying to fix that by adding some form of simple closed loop.

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I can identify with that having once borrowed a friends Series 1 LandRover that had 30...40 degrees play in the steering wheel before anything happened :confusion:

When you say full blown glass linear scales, that's what most of your Chinesium scales are these days. I have several sets, for my smaller mill and my lathe. They are both single ended TTL output, which is what the CNCdrive servos are looking for - I have those drives on my Shizuoka, so I'm familiar with them. They would certainly connect up OK but whether they'd be happy driving an old machine with backlash would remain to be seen.

The accuracy is down to what you want to pay. I think mine are the basic 5um ones from HXX in Shenzhen but you can get resolution down to 0.1um from them and others.

It's possible that high end ones might have differential outputs which are more noise immune, in which case you'd need a line driver to TTL converter.

Whatever encoder you end up with, the driver needs to know how many pulses per rev. This will be a function of the ballscrew pitch, belt reduction ratio and linear encoder resolution but the sums are very simple.

Ok, so some info I have found about the motors which also seems to match what's on the motor plates (photo attached):

permanent magnet DC servo motors
2000RPM
170V DC
tachometer mounted on rear (I think.. photo attached), but no idea of what output this gives...

with regards to the backlash and scale accuracy asked previously..
They are Anilam linear scales with 0.01mm resolution, again no idea of output type but photo attached if anyone might recognise it.

Done some measurements on the backlash, it's a lot worse than I thought to be fair!
X: 0.15mm
Y:0.04mm
Z:0.06mm

On a side note, the X axis moves faster than the pitch of the ball screw, does that mean there will be some kind of gearbox on the ball screw itself?

Like I say accuracy isn't of too high importance with this, I can sneak high accuracy stuff into lunch breaks at work if I do need that.
The main type of work I will be doing on it is very agricultural low tolerance stuff that I can't always get away with at work :whistle:! In all honesty I don't really need CNC functionality for most of it, its just a nice bonus to have!

With all that taken into account, Is a stepper setup going to be best for me? I know its probably not the best end result for the machine but it will keep it nice and simple for me to convert and use for now.

It would be nice to keep all the original motors but its sounds like it may be a bit more complicated to get running?

Or will this be realistically unusable as a CNC with that amount of backlash until I get that sorted?

That is a tacho you are looking at. They have no purpose nowadays, what with digital drives. You should try to remove it to see what the end of the rotor shaft looks like. A rotary encoder typically has a small (6mm or so) shaft and creates negligible torque drag, so mounting one in place of the tacho could be quite simple. Something like this Chinesium clone would be suitable https://www.ebay.com/itm/OMRON-Rotar...g/332386539771

One of those CNCdrive brushed servo drivers would be fine for a motor like that and the encoder would connect directly to it. https://www.cncdrive.com/DG4S_16035.html The bigger one is rated at 160V / 45A and although your motor is rated at 100A, it's a beast (47Nm!), so you can probably manage very nicely with half of that. The advantage of going this route would be minimal messing with the mechanical parts. You can probably just leave the encoders where they are for now unless you could hook them up with one of the Chinesium DRO displays just to frighten yourself.

This would be a good time to get a parts list / exploded / section view / manual for the machine. There's a good chance TOS would still have documentation, or you might find a user who could scan one for you. Then you can see how to dismantle it and how it works.

I would expect that the ballscrews will be fitted with double ballnuts, so you'd have some degree of adjustment for taking up some of the backlash. There's likely to be two ballnuts with a shim between them. You can fit additional shims to reduce backlash, possibly without having to even remove the ballscrew. Going to the extreme of fitting bigger ball bearings would likely require you to dismantle the machine, which is quite a large beast.

Sounds like we might have a plan here then, I think you've convinced me to keep the motors on it and go for those drivers.

So in terms of parts I need to purchase:

-Three servo drives (the ones you linked me to)
-Three Rotary encoders for back end of motors ( I'll make them fit somehow I'm sure!)
-Breakout board to link drivers to PC? (this is where I start getting a bit confused...)
-PC control software (any recommendations that would be compatible with all these parts?)

I must be missing lots of other stuff I'm sure?


Before I order anything I think I'll give it a bit of a strip down and try and sort out some of the backlash issues. Good idea about the machine drawings, I'll see what is around.

I'd agree it's probably the plan with least effort, least cost and best performance although there may doubtless be other opinions. I don't have any particular technology to promote, having closed loop steppers, DC brushed servos and AC servos on my machines. But my Shizuoka is similar to your TOS ie old and solidly built with old but well specified motors, so it sounds very similar in many ways. The controller on that thing also came from the ark.

Almost any controller will do as long as it outputs step and direction signals and has some spare IO. My machines have Centroid Acorn (the Shiz) and Newker 990MDCa (Bridgeport) and they both have their pros and cons. Can't comment on other controllers from personal experience but I've heard UCCNC also good. They are from the same place as the DC servos (CNCdrive).

I quite like the Acorn but it requires a PC to run on and the cost adds up by the time you've got the full cream licence and expansion board. The Newker is pretty good value at under £400 being fully self contained but the Chinglish has been a bit of a hurdle. I prefer the Acorn of the 2 but as I say, I have little experience beyond them unless you count a near miss with LinuxCNC.

Would be interesting to see the manual if you can find one. I have one for my Shiz and it made rebuilding it considerably easier than it might otherwise have been.

Just having a look at the centroid Acorn kit and its not too bad price wise but probably a little more than I can stretch at the minute.

The UCCNC looks to be a good option with good reviews considering the price.

would this combination get the mill running:

3 of these: https://www.cncdrive.com/DG4S_16035.html
1 of these: https://www.cncdrive.com/AXBB.html
Software: https://www.cncdrive.com/UCCNC.html
plus one 5VDC and 24VDC power supply
and the three motor encoders

Think I'm finally getting my head around it thanks to you guys!

Know what you mean about Acorn. By the time you've coughed up for the digitising (probing) version and the expansion board, you are at $1000 before you even find a PC to run it on. Then the wireless MPG is another $240. It works well and the support forum is very good, so I'm very happy with it. Depends if you have the dosh available.

The AXBB looks pretty interesting. No experience of them but they seem to have all the bumps in the right places and the pricing looks attractive.

FWIW, they also seem to sell several different encoders. Presumably they will be compatible with the controllers and the pricing seems similar.

That looks about right for the kit of parts. I assume you have a main PSU from the original system that can supply the bulk power at around 140Vdc or so? I ended up getting a 120V 3kW isolation transformer from Screwfix and removing some turns from the secondary to get the right output, as the original 3 phase transformer was the size of a house..

I did see the encoders on there as well, probably just worth getting it all from them, as you say it should all be compatible then!

I've sent them over an email to check it is all going to work how I need, will have to wait and see if they get back to me or not though.

I hadn't thought about the main power supply actually, good point! The current set up has a fairly substantial transformer unit that appears to output various voltages, I know there is a supply at around 140V in the unit supplying the current drives but can't remember if its DC, will have to check!

If it's like mine, the DC was supplied from a massive three phase transformer. The winding would need to be about 100Vac so that you end up with around 140Vdc off load. Here's how I did mine, way back when https://mightyshiz.blogspot.com/2017...an-handle.html I welded the cores back up afterwards with the MIG.

One additional component I bought was the braking module http://shop.cncdrive.com/index.php?productID=260. This allows you to decelerate quickly without risking overvoltage damage to the servo drivers. This clamps the voltage at around 180V. I must admit I haven't ever checked to see if it cuts in on my system but I didn't plan to risk my drivers to find out. One braking module would be enough per system.

Just had a look through your web page, some good stuff on there, really useful!

My transformer isn't quite the size that came on yours! I think I will repurpose what I have if possible. I found a 'specification sheet' for the transformer that seems to suggest that when used with the motors I have it should be set up to output 150V... but I may be reading it completely wrong! attached photo.

The braking module seems like a good idea for the price of it, better than potentially spending another £300 on new drivers if they go bang!

That's handy - you should be able to reuse that. It appears that the left hand three connections are for the secondary (black-black and blue-blue), forming the centre-tapped secondary. You will note that the centre tap is currently connected to ground. If you have 150Vac, you will need to remove turns from the secondary (taking the same number of turns off each leg) but luckily the secondary is on the outside and you won't even need to dismantle the transformer to do so. If it's 150Vdc, it should be fine as it is. The 3kW isolation transformer I used is about £140 https://www.screwfix.com/p/carroll-m...mer-110v/43658 - depends how much weight and space you want to free up.

I originally tried to fit everything in the original operator console but that was a daft idea. Much better to have a cabinet on the side of the machine where you can work on it, with a remote display. With my Acorn system, the PC, display and keyboard etc are on a desk alongside so I can run Fusion (and music) and operate the machine from there. You soon get a stiff neck if you mount the console at the machine around head height.

Bugger! turns out its 150Vac after all, so that will require some work as well! So with getting the DC output you need to use the centre tap and wire in some diodes or something like that?? to make a rectifier?? I've not done much in the way of electronics since my engineering apprenticeship if you couldn't tell! that was over 10 years ago and I didn't know that much then either!

Yeah I think I will try and get everything in the cabinet that's already on the side of the machine and then just use a laptop on a bench beside the machine for now. I did see someone had a nice setup with a mini PC in the cabinet and a touchscreen monitor mounted beside the machine, that looked like a nice setup which I may look into for a future project. Need to make sure I can get the thing working first though!

You should be able to find and reuse the old bridge rectifier and large electrolytic cap(s) from the old system. Alternatively, you could get new replacements from somewhere like CPC Farnell (Part of the Farnell group but cheaper than Farnell and RS).

To reduce the transformer secondary voltage from 150Vac to 100Vac you'd need to remove 1/3 of the turns from each of the secondary windings. Ideally you'd remove the same number of turns from each side rather than remove 2/3 of one and none from the other. You could power it up (carefully!) and use a voltmeter to check where you are if you are not sure how may turns to remove.

You don't need to connect the centre tap to ground but somewhere you may want to connect the secondary (well, 150Vdc) to ground to stop it floating. Some industrial systems leave the circuit floating so that it can tolerate one fault to ground without the system bombing out. It's not a massive consideration here, though.

You can get those tiny NUC / SFF PCs these days that fit on the back of a monitor or inside the cabinet. But as I said, I like to be able to sit down and it's handy to be able to use the same PC to make last minute CAD changes and regenerate the g code.

Ah ok that will be handy, I'll try and see if I can work out where it is tomorrow then.

Ok that sounds within my ability I would think, Ill have to drop it off the machine and have a proper look at it. Although this is turning into what looks to be a long term project now so I may bite the bullet and go for something a bit more modern like you suggested the other day, when money permits.

Found more issues today as well, Z axis ball screw is heading for the bin! crack in screw itself and lots of wobble! I could probably have just cut the crack out and machined the feature back on the end but I don't think its worth it with the play that it has.. that said there is no way I'm getting a direct replacement so going to have to buy something and modify it to match the existing.

Started making some progress finally!

X and Y axis ball nuts rebuilt with new oversize bearings, and also new AC bearings on the screw shafts seems to have sorted the backlash issues!

Started moving on to the electrical side of things and I've come to a bit of a halt already trying to work out the transformer..

In the attached picture, the right three wires should be the primary coil supply, so according to the diagram on the transformer that's either 415V or 380V supply going in? And on the left are either end of the two secondary coils which are labelled as 2 x 140V...


So I guess what I'm trying to verify is that I will really only need to connect my 415V AC supply to the primary, and then remove some winding from both secondary coils until I achieve 100V across them?


I have also attached a photo of how it was wired in the current setup, I got a little confused with what appeared to be a 140V leg attached to ground? everything the same colour wire makes it so confusing!!

One of the windings is across 1 and 2 - it's the winding at the top of the RH photo. The other winding is between 3 and 4 and is wound on the bottom of the photo. They are connected in series, so that you end up with double the voltage of each winding, from end to end. The centre of the combined winding is grounded. You could remove that unless you want your system voltage hard connected at its midpoint - at least this way the DC is at a known potential.

Looks as if you have both 380Vac and 415Vac primary taps.

If you are going to use a 415Vac connection, the primary would be connected across any 2 of the 3 phases of the 415Vac mains. However, if you were to connect it across single phase 240Vac, you'd get proportionally less output voltage. That might actually be handy here.

If you had 2 x 140Vac connected in series and full wave rectified them, you'd end up with 1.414 x 280Vac, which would be almost 400Vdc. You probably don't want that! If those really are 140Vac each, your original rectifier must have been half wave rectifying the outputs with the 0V at the grounded centre tap, so that each winding only conducted half of the time, giving a final DC voltage of around 200Vdc.

If you were to connect up the 380Vac primary tap to single phase 240Vac you'd get 88-0-88 Vac, which would get you about 125Vdc if you used half wave rectification. That would be a simple solution if you don't mind a slightly lower max speed. Probably wouldn't be an issue really.

If you want to get closer to 140Vdc output with 380Vac or 415Vac input, yes you'd want to be seeing 100Vac on each winding and connect it up as it was originally ie half wave rectification. One diode on the end of each winding, each pointing to the electrolytic cap, with the "0V" cap negative taken from the centre tap. To do that, you'd need to cut the big black wires on the outside of the windings and remove equal turns from each until the output is 100Vac. That's about 30% of the wire.

Do you have either a schematic or a photo of the capacitor and rectifier(s)?

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Originally Posted by Muzzer

If you were to connect up the 380Vac primary tap to single phase 240Vac you'd get 88-0-88 Vac, which would get you about 125Vdc if you used half wave rectification. That would be a simple solution if you don't mind a slightly lower max speed. Probably wouldn't be an issue really.


Do you have either a schematic or a photo of the capacitor and rectifier(s)?

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This would probably be a sensible solution a least for now to get the system running.
That was going to be my next plea for help, I can't confidently say I have located the capacitors and rectifiers! I have attached a load of photos of the internals, if you wouldn't mind casting your expert eye over them that would be much appreciated.

Hmm, that seems to be a set of 3 SCR phase angle controllers rather than "normal" (to us) DC servo drives. These run from ac, so you can look and you can look but you won't find any big electrolytic caps anywhere. The 3 axis drives are those power modules in the 4th photo. You can see there are 6 of them in the 3rd photo. The drivers for the SCRs are in the 2nd photo. The date codes on the compts suggest the boards were built in 1980, so it's an old beast. Technically, they operate at 50Hz, rather than several kHz and vary the duty cycle to modulate the motor current / torque.

Bottom line is that there is no electrolytic cap(s) and the rectification is actually done by the SCRs (thyristors) and the SCRs are commutated (turned off) by the alternating voltage. The supply voltage is indeed two lots of 140V - but ac not dc. The labels on the axis / SCR controllers mention "2x140V", or 280Vac centre tapped in fact.

I think you can safely bin all the contents of the cabinet, as there is almost nothing you can reuse. Even the mains transformer is of questionable value to you. If I were you, I'd want to run the whole thing from 240Vac single phase and keep away from 415V, as there's really no benefit. You need 100Vac on the secondary, a simple bridge rectifier (600V) and an electrolytic cap rated at around 200Vdc.

The servo motors look like good machines and are indeed DC brushed motors. As I said earlier, you can get rid of the tachos and replace them with simple encoders. Indramat is nowadays part of Bosch Rexroth etc, so these drives and motors were probably designed like brick shithouses.

I'm not certain what those 3 transformer-like things are. They are labelled "Drossel" which means something like "choke", so probably line inductors to filter out the current lumps and improve the mains current waveform / power factor. Again, almost certainly of little or no value to you.

You certainly know your stuff when it comes to this! Everything I have found dated suggests it was built in the 80s (1983 was the latest date I found) so its certainly not cutting edge technology in there!! I'm glad you said to bin it all, I'm sick of the sight of the inside of that cabinet!!

I'll have a play with the transformer today, if I don't get anywhere I'll look into something a bit more suitable..

so if I went single phase and got the 100Vac, would these do to get the DC:

https://cpc.farnell.com/multicomp-pr...ule/dp/SC15622

https://cpc.farnell.com/panasonic/ec...dc%20capacitor

If single phase is the best option, would you completely get rid of the 415V and us a VFD to power the Spindle motor? or Could I still use the 3 phase supply with a relay or something to switch spindle power on from the controller? I know the controller module I bought shows a VFD on the wiring diagram so that may have to be the way to go anyway..

Yes, that's the right kind of voltage and current for the diode bridge - and CPC is a good place to buy stuff. A lot of their stuff is identical to Farnell (sister company) but inexplicably sometimes a lot cheaper. You need to bolt it to some form of heatsink but unless you plan to push the spindle to its limit and keep it there for hours, it won't need much. I just fastened mine to the steel backplate and it's been fine. I have something similar on mine which I scavenged from the original VFD in my 1983 Shizuoka.

I think I mentioned earlier that I repurposed a 110V site transformer for my machine. If you are feeling flush / tight for space, that's an option. https://www.screwfix.com/p/carroll-m...mer-110v/43658

Here's my transformer / rectumfrier / VFD installation. The relay next to the rectumfrier is a time delay jobby to allow the caps to charge over a second or two. The caps themselves are hidden behind my Centroid Acorn board further down.
Attachment 28127

For the caps, I used a couple of these in parallel https://cpc.farnell.com/vishay/mal21...P=TREML007-005. You could probably get away with one if money is tight.

That cap you linked to is FAR too small. It needs to be about the size of a coke can, speaking technically.

Here's my cabinet. No, it's not a textbook example of cabinet installations but it works.
Attachment 28128
Doesn't seem to matter what I do here, I can't get the photo orientation right. What's the trick? It seems to be using the iPhone metadata to determine the orientation.