Denford VMC1300 - Rescued

[Chas Ixion]

I recently picked up a Denford VMC 1300 from my local scrap metal merchant.

Here it is on the way into my workshop.


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I have no idea what condition it is in but I figure that it was (probably) sent to the scrap yard for a good reason.

My plan is to find a permanent place for it in my workshop then try and diagnose what does and doesn't still work. If its the electronics side of things I'll probably retrofit a LinuxCNC based solution.

However I have no idea how to figure out what is and what isn't re-usable so it will be a steep learning curve, any help/advice gratefully received....

[andy_con]

I'll buy it off you ;)

[m_c]

Chas,

post up some good pics of the control cabinet when you get time, and we can point you in the right direction.


I'll buy it off you ;)

I'd keep the Triac ;)

[andy_con]

Chas,

post up some good pics of the control cabinet when you get time, and we can point you in the right direction.



I'd keep the Triac ;)

Or have both ;)

[Chas Ixion]

With xmas out of the way I managed to get some time in the shed. After struggling to get the thing onto my workbench I removed the covers.

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I was able to have a poke around and establish that it did actually have steppers and ballscrews (I was worried it had been gutted of useful parts).

The Z-axis stepper has a sticker that I hope will help me identify it.
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As far as I can make out it looks like the part number is M60STH88-3008D and it was made by / supplied by Motion Control Products.

Poking around their website ( http://motioncontrolproducts.com/ (http://motioncontrolproducts.com/)) I found a spec sheet for a M60STH88-3008DF I'm not sure of the significance of the F on the end.

I've also discovered that the contol cabinet is accessed from the back not the side as I originally thought. This means I need to move the thing again to get access.

Oh and I haven't been able to release the tool holder, does anyone know if I just need to pull on the lever harder or if there's a drawbar or somewhere I can tap to break the taper?

[m_c]

That datasheet should be good enough. The main thing is once you have the machine running, make sure the steppers aren't getting too hot.
Is that a brake assembly on the end of the stepper?

You'll want to check the other stepper motors, as X and Y are often fitted with smaller steppers than the Z.


Regarding the tool holder, if it's been in there for a while, there may be a bit corrosion helping to stick it. You might need to get somebody to push/pull the release lever, while somebody else gives the toolholder a hit downwards with a hammer and block of wood.

[Gary]

The F means a flat on the shaft.
I sold those motors to denford when i worked at MCP, many moons ago.

[Chas Ixion]

That datasheet should be good enough. The main thing is once you have the machine running, make sure the steppers aren't getting too hot.
Is that a brake assembly on the end of the stepper?

You'll want to check the other stepper motors, as X and Y are often fitted with smaller steppers than the Z.


Regarding the tool holder, if it's been in there for a while, there may be a bit corrosion helping to stick it. You might need to get somebody to push/pull the release lever, while somebody else gives the toolholder a hit downwards with a hammer and block of wood.

No idea about the end of the stepper,

Judging by the state of the table corrosion is highly likely. I'll try and get some penetrating fluid in there to do it's work before getting the hammer out.

[Chas Ixion]

The F means a flat on the shaft.
I sold those motors to denford when i worked at MCP, many moons ago.

Thanks, thats a mystery solved then :)

[m_c]

No idea about the end of the stepper,

Judging by the state of the table corrosion is highly likely. I'll try and get some penetrating fluid in there to do it's work before getting the hammer out.
Penetrating fluid is more likely to do more harm than good near a spindle, and will make no difference to any corrosion that may be on the spindle taper. Just get somebody to swing on the release lever while somebody else taps the holder with the hammer.

[andy_con]

I wouldn't swing on anything if it were my mill!

if you remove the casing/cover around the spindle you will probably see a spindle motor connected to the atc spindle via a belt - that's how denford normally do it.

above the atc spindle is a powered drawbar, you need to remove the powered drawbar and then hit the end of the atc spindle with a hammer to release a tool.

all the powered draw bar down is push down on the sprung tip of the spindle atc

[m_c]

I wouldn't swing on anything if it were my mill!

if you remove the casing/cover around the spindle you will probably see a spindle motor connected to the atc spindle via a belt - that's how denford normally do it.

above the atc spindle is a powered drawbar, you need to remove the powered drawbar and then hit the end of the atc spindle with a hammer to release a tool.

all the powered draw bar down is push down on the sprung tip of the spindle atc

The manual toolchange VMCs have no pneumatics, instead you get a big lever on the side of the head for releasing the tool. I'm assuming underneath the cover, it's the same spindle/drawbar/spring stack as an ATC version, it's just using a lever instead of a pneumatic actuator.
Provided the lever is compressing the spring stack correctly, then all it's likely needing is somebody to pull the lever, while somebody taps the toolholder to give it a bit helping hand to pop it out.
I'd certainly be trying that before going to the extent of stripping of the spring stack and drawbar.

[Chas Ixion]

I had another go yesterday and all that was needed was a more confident pull on the lever, no need for further stripping or hammers.:thumsup:

[Chas Ixion]

In between doing 'other stuff' in my shed I had a look under the bellows on the y axis and under the guard on the z.

Not much to see under the bellows although the linear bearings and ball screw don't look obviously knackered.

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This is the x axis stepper motor,
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Its smaller than the z axis stepper. I'm guessing its a NEMA17.
I'm going to google the numbers on the sticker (3100422k) to see if it throws up any clues.

Finally I've had a look at the spindle motor wiring.
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My guess is that the heavy gauge wires are power feed. I'm not sue what the pairs of red/blue wires are for. The top pair both have yellow tags labelled 'T'. As far as I can make out the bottom pair has a red tag labelled 22 on the blue wire and a black tag labelled 11 on the red wire. The bottom pair are connected together by a short jumper on the other side of the block.

[m_c]

Have you downloaded the wiring diagrams from the Denford forum?

My guess would be one pair is a tacho feedback, and the other a thermal cutout (probably the ones that have been looped). If there's a model number on the spindle motor, you should be able to find a datasheet.
Also, check to see what wire numbers end up at the spindle driver, as that would give you a good idea, as only the power (probably via a relay or two), and tacho feedback will go to the driver. The thermal cutout would form part of the e-stop loop.

[Chas Ixion]

I have downloaded the wiring diagrams, and based on what I've seen so far I think this http://www.denfordata.com/bb/download/file.php?id=2528 is the right one for my machine.

I'm waiting for a m10 eye bolt I ordered from ebay (I ordered two but they only had one) which I am hoping will make lifting the thing a bit easier, then I can get into the guts of the electronics.

At the moment my plan is to replace the motion controller with either Linux CNC or something arduino based, but before I do I would like to establish if the steppers and drivers are functional. Is there an easy way to test the drivers and steppers without a motion controller?

[m_c]

It would depend what controller is fitted. I'd hazard a guess that it will be the later USB NextMove controller, but I've got no idea if it'll use the all in one daughter board like the smaller mills used, or if they'll of used separate drivers.
Either way, it would be a case of working out what the step/dir pins are, and patching into them, while also making sure power and enables have been connected correctly.

[Chas Ixion]

Making a bit more progress.

Eyebolt didn't work out, it fouls the casting and cant be screwed in. Resorted to using a crowbar on the legs of the stand and got it moved enough to get the backplate off.
Managed to get some photos of the main components. I'm guessing this is the main motion controller board.

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Power distribution (????)

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Stepper drivers

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The stepper drivers appear to be labelled XLT50-S which should help me identify the wiring diagram to use.

My plan is to replace the motion controller with this http://www.ebay.co.uk/itm/EU-Stock-4-Axis-500KHz-Offline-Controller-CNC-G-Code-100-Pulse-MPG-Handwheel-/112280872566?hash=item1a24762676:g:-qMAAOSwjDZYde-j

According to some documentation I have found online (http://www.parker.com/parkerimages/euro_emd/EME/Literature_List/dokumentationen/192_100616_xlt50-d_xlt50-s%203-axis%20stepper%20drive_manual.pdf ) the driver design is at least 14 years old, on the basis of this i'm going to investigate the options for replacing the drivers with something more up to date, any recommendations?

[Chas Ixion]

After spending hours on google I decided to go for Leadshine EM806 drivers from Zapp.... just placed the order.

[m_c]

EM806s are good drives. Did you order a programming lead, as it makes setting them up easier?


You'll need to study the wiring diagrams to work out what the power board does. I think some of the later Triacs used something similar, and some of the relays are used as interlocks, to ensure critical things weren't solely controlled by the controlled.
The top board is the later controller. Smaller machines used the in built stepper drivers in the lower board. If everything was still connected, you could possibly try powering it up and see what shows up on the 7 segment display. It would give an indication of if there was anything major wrong with the original controller.

[Chas Ixion]

Well only two years later and my mill has become my primary project and I have made some progress.

I have the RMHV controller hooked up to the EM806 drives connected to the original steppers. I have also connected the home switches. I have used the original power supply and relay board for this.

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This gives me the following good things.

1) Movement on all three axis
2) Control of all three axis using either the buttons on the controller or a MPG pendant
3) Homing set up.

What isn't so good is
1) the z axis brake is errrr .... broken (I managed to loose the spring that applies the brake)
2) More of an issue is I let the smoke out of the spindle dc driver. The good news is they are still available off the shelf the bad news is they cost about 200 quid....
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I have a replacement (https://www.transdrive.co.uk/shop/products/dc-drives/sprint-electric/analogue/2-quadrant/sprint-electric-1200-1-8kw-12a-240-110vac-2q-non-isolated) and I'm in the process of wiring it up.

To start with I have copied the settings (potentiometers and dip switches) from the old board but I'm now beginning to doubt the wisdom of this as the old board died on me and at some point previous to me finding it on a scrap heap someone has written the word BAD on the heatsink.

I'll need to find some info on the motor as the old board is set for max voltage of 50V which seems a bit low (ISTR Triacs go up to 180V). I'm also trying to figure out how to use the 0-10v output from the RMHV controller to set the speed as I'm not sure if I need some form of isolation between the two.

Hopefully I'm not too far from being able to cut some chips although I'm starting to think that I might be better off using MACH3/4 or Linux CNC rather than the rather limited RMHV controller.

[Clive S]

I'll need to find some info on the motor as the old board is set for max voltage of 50V which seems a bit low (ISTR Triacs go up to 180V). I'm also trying to figure out how to use the 0-10v output from the RMHV controller to set the speed as I'm not sure if I need some form of isolation between the two.

I have just converted a Novamill that seems to have had the same control board. I used one of these https://www.ebay.co.uk/itm/111654184682 and a small 230V ac to 15V V DC power supply https://www.ebay.co.uk/i/263040639593?chn=ps&var=562044038463 so to keep the isolation from the motor control board.

[m_c]

I have just converted a Novamill that seems to have had the same control board. I used one of these https://www.ebay.co.uk/itm/111654184682 and a small 230V ac to 15V V DC power supply https://www.ebay.co.uk/i/263040639593?chn=ps&var=562044038463 so to keep the isolation from the motor control board.

I think the RMHV is essentially the same as the DDCSV, and I don't think there is an option to use step/dir for spindle control. And I don't think the 0-10V is isolated. The only way you could get it to work with a non-isolated drive would be with a 0-10V to 0-10V isolator, but they aren't common or cheap (IIRC the last time I looked they were upwards of £150).
The easier option would of been to get an isolated Sprint drive, however experience has taught me the motors on these are far more likely to fail and cause the speed controller to fail, rather than the controller to fail.

[Chas Ixion]

Your right the RMHV and DDCSV are more or less the same.

I'll use a pot connected to the sprint board for speed control for now.

After a bit of digging on the internet and head scratching I *think* I've figured out why the speed control was set for 50v. I think that the 50v is the voltage from the tacho at max speed rather than the max output.

But worried about your comment regarding the motor failing taking out the speed controller, what tests can I do on the motor to establish if its good or not?

[Clive S]

I think the RMHV is essentially the same as the DDCSV, and I don't think there is an option to use step/dir for spindle control. And I don't think the 0-10V is isolated. The only way you could get it to work with a non-isolated drive would be with a 0-10V to 0-10V isolator

Not sure what you mean here, would you mind elaborating please.. I used the pwm signal from my bob and the https://www.ebay.co.uk/itm/111654184682 to convert it to 0-10V isolated for the spindle driver board.

[m_c]

Not sure what you mean here, would you mind elaborating please.. I used the pwm signal from my bob and the https://www.ebay.co.uk/itm/111654184682 to convert it to 0-10V isolated for the spindle driver board.

Does that board isolate the PWM in from the 0-10V output?
I'm not sure if the 0-10V output from the DDCSV/RMHV will be compatible with that board. It would depend on if that board is simply relying on referencing the PWM voltage (should be fine), or measuring the actual PWM.

Actually, I've just checked the spec of a DDCSV, and it states the spindle output can be configured as a PWM, instead of analogue. I can't find any mention of whether it's isolated though.


The problem with SCR type drives, is the far more common non-isolated versions have the control wiring at near mains voltage, so your 0-10V source has to be isolated. Denford did use isolated drives in some machines, so yours may have an isolated drive, or your BOB PWM may be isolated. The only guaranteed way to check without knowing the exact board you've got, is to power the controller up, and then measure the voltage between the speed control terminals and ground (or neutral/0V).

[m_c]

Your right the RMHV and DDCSV are more or less the same.

I'll use a pot connected to the sprint board for speed control for now.

After a bit of digging on the internet and head scratching I *think* I've figured out why the speed control was set for 50v. I think that the 50v is the voltage from the tacho at max speed rather than the max output.

But worried about your comment regarding the motor failing taking out the speed controller, what tests can I do on the motor to establish if its good or not?
Have a read of the manual for setting the pots. Plus I think there may be posts over on the Denford forum somewhere where the Denford guys give a few pointers for setting the drive.

Generally carbon dust builds up, causing ground leakage, and/or shorting between windings. However the motors are not the easiest of things to dismantle to clean properly. I damaged the tacho trying to get mine apart, but then I was more interested to see what was in it, as it was already destined for the skip as I upgraded to a servo spindle.

[Clive S]

Does that board isolate the PWM in from the 0-10V output?
This morning I checked the voltage between 0-10V and earth about 200V and between PWM and earth 1.5V so it isolates the two.

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[m_c]

This morning I checked the voltage between PWM and earth about 200V and between 0-10v and earth 1.5V so it isolates the two.



Good to know.
Although I assume you meant to have those two voltages the opposite way around? ;-)

[Clive S]

Good to know.
Although I assume you meant to have those two voltages the opposite way around? ;-)

Well spotted. I have edited mine would you mind editing to save confusion for others.

[Chas Ixion]

Just a quick update. Got a scope on the 0-10v spindle speed output from the RMHV and its analogue and not PWM.

The manual seems to suggest that it is possible to configure the unit to output PWM but I can not find anything in the manual to show me how.

[GND]

I'm in the process of planning the conversion of my recently acquired Novamill, and came across this during my research - https://www.summet.com/blog/2016/01/29/how-to-convert-a-denford-scantek-2000-micromill-to-linuxcnc-mach3-control-part-4-spindle-speed-control. It shows how to tap into the existing spindle drive isolation circuit with your own PWM signal, thus saving any new circuits or power supplies. In my case I'm just replacing the top controller board, and replacing it with a modern motion controller - but keeping the lower board and the stepper drivers - so this should work for me. Sounds like you may be replacing more of the electronics, so it may not be appropriate. But hopefully this is useful info for others reading the thread.

Cheers
Graeme

[Clive S]

If this helps you can get the connector here https://uk.rs-online.com/web/p/products/0406284/?grossPrice=Y&cm_mmc=UK-PLA-DS3A-_-google-_-CSS_UK_EN_Connectors-_-Pcb_Connectors%7CDin_41612_Connectors-_-PRODUCT_GROUP&matchtype=&pla-391579644947&gclid=Cj0KCQiA4aXiBRCRARIsAMBZGz_guE7rSBKZEZjkXmMf aZX1yFPnTIhbFkaO9KgX4cd_zNBuqCgQQLEaAh39EALw_wcB&gclsrc=aw.ds

I started doing this and changed my mind and threw the boards out. As you can see in post #28. unfortunately I also threw the connector out otherwise you could of had it.

Good luck with the conversion.

[GND]

Thanks for that, Clive. I'm just finalising my choice which motion controller to use. Too many choices! However my current plan is to make a kind of motherboard with one of those 96-way connectors on it, that replaces the existing top board. The motion controller will then sit on this. I can then provide any BoB type functions on my mini-motherboard - like voltage level shifts or opto isolation. Feels like quite a neat way to tackle the problem, but time will tell. As you say, we sometimes start with a plan and then throw it all away and do it differently!!

Just out of interest, what electronics did you use? I can see a BoB on your photo, and maybe a couple of stepper drives? But not anything I could identify....

All the best
Graeme

[Clive S]

I don't want to hijack this thread, It might be better to start another thread with your build !! I used a Mesa 7i92 but if I was doing it again I would use the 7i96 as that has opto's on it and screw terminals. View from the back.

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[GND]

Thanks Clive - I think I'd picked up previously that you are a Linux/Mesa guy, so this makes sense! I'm going via another route, but will likely start a new thread as you suggest. Didn't want to hijack this one either, but hoped my info on the built-in isolation would be useful.

Cheers
Graeme