View Full Version : Supermax CNC mill re-re-retrofit

07-11-2011, 01:42 AM
About 5 years ago I got my Supermax YCM-16VS cnc mill from a friend. It had come out of Tektronix's model shop. It had an old control that was failing so I did the mach re-retrofit as logged in this thread:


Its been a good mill. A few little quirks. If you powered up the servos with the drives enabled it would jump and sometimes fault out or trip one of the breakers inside of the control for the drives. This was caused by the Pixie step/direction to analog control boards. These boards would take step and direction inputs and control standard analog servo drives with encoder feedback. They worked pretty well, but tuning was a nightmare. Not only did you have to tuned the analog drives, you also had to tune the position loop. It had some decent gui software but I really never got it tuned like it should. I would get random follow error trips when the machine changed direction.

Rather annoying. That and the X axis motor is rather long and I dont know how many time I have ran into it.

With this last week being a production break from Paranorman I figured I would finally have some time to do something about these problems. A couple years ago I got that Mitsubishi injection molder. Among the servos on it were two Mitsubishi MR-H series 1kw servo drives and motors. I also had another Mitsubishi 1.5kw MR-J series drive and motor from back when I was gearing up to do the servo retrofit on my 10EE. The 1kw motors were much smaller than the old ones and about 5" square. The 1.5 is a touch bigger than the old motor. Both models of drives have step and direction input native.

In anticipation of doing this project I had machined adapter plates and motor mounts for the motors ahead of time. I also hand some small circuit boards made up through the dorkbotpdx circuit board service. These boards broke out the 40 pin MDR connector to give me easy access to the step, direction, and alarm out lines.

This is what it looked like after the first retrofit. The gold parts in the control box are the servo drives, the main power transformer up top, aux transformer below that ran the old control, chokes below the drives. Also three contactors that controlled coolant, servo power, and a spare. The three Heidenhain boxes on the bottom are interpolators for the linear scales it had mounted for feedback on the original control. I initially tried to used the scaler but the performance was terrible.

http://farm7.static.flickr.com/6138/5924696189_c60fe37eaa_b.jpg (http://www.flickr.com/photos/67292116@N00/5924696189/)
DSC03386.JPG (http://www.flickr.com/photos/67292116@N00/5924696189/) by macona (http://www.flickr.com/people/67292116@N00/), on Flickr

http://farm7.static.flickr.com/6001/5924695897_973143a77f_b.jpg (http://www.flickr.com/photos/67292116@N00/5924695897/)
DSC02756.JPG (http://www.flickr.com/photos/67292116@N00/5924695897/) by macona (http://www.flickr.com/people/67292116@N00/), on Flickr

http://farm7.static.flickr.com/6022/5924695549_f582e54823_b.jpg (http://www.flickr.com/photos/67292116@N00/5924695549/)
DSC02758.JPG (http://www.flickr.com/photos/67292116@N00/5924695549/) by macona (http://www.flickr.com/people/67292116@N00/), on Flickr

07-11-2011, 02:23 AM
Wednesday night I decided to dig in. My goal was to finish it by sunday as I need it for work this week. I put it on rollers and slid it away from the wall.

Thursday I gutted the machine. Pulled out anything to do with the servos, transformers, drives, scales, contactors. Yanked of the servos and pulled off the pulleys. Bored out the pulleys to 24mm and broached a 8mm keyway for the motors.

Y axis motor installed without a hitch. Did have to use a rotary file to remove a little more of the motor mount casting but I expected that. It bolted right into place. The Z motor was similar. Mounted in place of the old one. The X axis was a little more painful, literally, I managed to get myself really nice like while trying to get the pulley off. Since the new motors have a larger face on them I had to mount the X axis to the sides of the casting.

Friday I did the motor and encoder wiring. Ran all over town to try and find the wire I wanted, ended up getting stuck with MTW. The machine has sealed cable carriers and I managed to get the new motor cables and encoder cables in them to the control box. The Z axis encoder had to go externally. It was just too fat to fit through the conduit.

Saturday I mounted the drives and support pieces. I wired in mains power to the drives breakers, contactors, and finally to the drives. The newer drives control the buss power and shut it down if there is a fault. I finished the connections to the motors and encoders. The Z axis encoder amphenol was a pain. Must have been about twenty wires. Differential A,B,Z plus hall tracks for UVW. X wasnt so bad, by that time they went to a serial interface encoder and there are only a handful of wires. I tied the motors into the drives and the encoder cables as well. I got initial power to the Z drive and was able to jog the motor from the test mode.

Originally the machine was ran off 4 wire 208 so it had 120v off the lines. I did a no-no and was using the ground as a neutral. With the extra space I installed a .5kva 240 to 120v control transformer to run the computer, contactors, and lube pump.

That night I also got the cables ready. I reused the drive cables that came out of the molder. They have 50 pin MDR connectors on one size and 40 on the other. I took one of the cables and put the 36 pin connector for the MR-J drive on the end for the Z axis. While doing this I found a mistake on the board. So I cut that trace and jumped to correct it.

So, finally, this morning I did the control wiring. I needed to mount the interface boards. For some reason I neglected to put in mounting holes so I had to add those. I too a piece of 3/8" white PVC sheet and made a plate to mount the three boards to. This mounted next to the drives. I wired up the contactors and estop interlock for the drives.

I went into the computer cabinet and yanked out the old pixie boards. I reused the analog signal wires for step and direction signals.

Finally it was time to make it move. Powered everything up, grabbed the pendant, and turned it. Nothing. Huh. Eventually after some probing I found I had mislabeled the silkscreening on the interface boards. I connected the signal wires to the correct spots and X and Y moved! But Z didnt. On the newer drives you can enable the drive in the parameters. I had forgotten that the old drives have to be hard wired. Jumped that and still nothing. Oh yeah, left and right stroke inhibit. Jumped those. Now it moved.

But it moved very slowly with the native encoder resolution the X and Y were at 81920 pulses per inch. The Z axis was 64000 pulses per inch. I used the internal electronic gearing to divide those numbers by 8 on the X and Y and 5 on the Z. Much better.

All while messing around with it I managed to get it to run through the Z bottom tie rods on the balance cylinder. The had been welded together from shorter screws. I repaired one, still need to do the other two. I also made a couple other mods, installed a SSR running off the computers 5v line to kill power to the servo contactors when the computer is off. Also tied the Z axis servo-on line to the e-stop loop. The older drives dont have a dedicated e-stop line like the newer ones.

So far it looks like it is going to work great. The Z (Knee) is a whole different creature now. Moves quick. I had to have the old motor's acceleration all the way down to 3 in/sec/sec. I can easily run the new motor at 50.

http://farm7.static.flickr.com/6003/5924694769_d594a5b4e0_b.jpg (http://www.flickr.com/photos/67292116@N00/5924694769/)
IMG_0939 (http://www.flickr.com/photos/67292116@N00/5924694769/) by macona (http://www.flickr.com/people/67292116@N00/), on Flickr

http://farm7.static.flickr.com/6028/5925259854_1ca994535e_b.jpg (http://www.flickr.com/photos/67292116@N00/5925259854/)
IMG_0940 (http://www.flickr.com/photos/67292116@N00/5925259854/) by macona (http://www.flickr.com/people/67292116@N00/), on Flickr

http://farm7.static.flickr.com/6126/5925261282_715aeef935_b.jpg (http://www.flickr.com/photos/67292116@N00/5925261282/)
IMG_0941 (http://www.flickr.com/photos/67292116@N00/5925261282/) by macona (http://www.flickr.com/people/67292116@N00/), on Flickr

http://farm7.static.flickr.com/6027/5924699445_fb68dd21d5_b.jpg (http://www.flickr.com/photos/67292116@N00/5924699445/)
IMG_0944 (http://www.flickr.com/photos/67292116@N00/5924699445/) by macona (http://www.flickr.com/people/67292116@N00/), on Flickr

07-11-2011, 08:31 AM
Great post Jerry! I love this kind of stuff. I'd otherwise never get to see the insides of "real" CNC equipment and appreciate your taking the time to post it here. You make it look easy.:)

I'm curious as to how you became so knowledgeable about CNC theory/design/maintenance/repairs. You may have posted about it previously; if so I missed it.

07-11-2011, 11:59 AM
Its been trial and error mostly. Started out building little machines. Retrofitted a HF Micromill first with steppers. Found out how completely useless that was for me and bought this mill. I had also built a little cnc circuit board router for a friend.

It was around that time I decided steppers suck and have no place on a machine tool. And that has stuck with me. Even at work where everything is stepper driven, we have literally hundreds and hundreds of steppers, we fight with lost steps, trying to figure out why something is not repeating. Is it cabling, bad motor, too much load, something binding? With a servo it will tell you on the display, most modern serve either have a LED display or connect to a PC through serial or a network and you can see the load, droop (Follow error), etc.

07-11-2011, 12:09 PM
Thanks for the pictures.
It looks like a very nice build.

07-13-2011, 12:40 AM
As I mentioned in Johns thread:

Oh yeah, Yesterday I inadvertently tested out how powerful the new Z servo motor on the knee is. Left the jack I was using to block the knee while I was working under it and homed. Snapped one of the two 3/8" tie bolts, pulled the threads off the other and bent the 3/8" steel end cap for the pneumatic cylinder. About a half hour with a hydraulic press and welded up the bolts.

I turned the max torque down to 50% after that...

Other than that goof it is working incredibly well. Its like a new machine. With the higher acceleration possible with these motors there is very little dwell time at the 4 reversal quadrants when doing a circle move. Where I used to get a little mark I get almost nothing now.

This is really phase one of the retrofit. Next step is to replace the spindle motor and varispeed drive with a 3.5kw servo I have and HTD belting to the spindle.

My ultimate goal is to eliminate that massive control cabinet. It takes up a lot of shop space around the mill.

07-13-2011, 01:14 AM
Why when you are getting a new machine working you have to break it in by breaking a few thinks.
As John would say
Clumsy Bastard :-)
Looking good

07-13-2011, 01:48 AM
This is really phase one of the retrofit. Next step is to replace the spindle motor and varispeed drive with a 3.5kw servo I have and HTD belting to the spindle.

Please hurry :) I also want to do this, but may as well see how you do it first:D

07-21-2011, 01:45 AM
I took some video of the thing working the other day while making some more parts for work. The video also shows my Nikken spindle speeder. Input is 4000 rpm and the output is 20000, makes 1/8" and smaller end mill usable.

One thing I noticed is the machine moves quieter. In other videos you could hear the servos sounding like steppers, with the new motors they are silent except for the PWM whine.

Click on the link to see it in its HD glory over on youtube.



07-21-2011, 02:11 AM
With the new motors are you using a belt or direct drive for your x and y leadscrews? Also, I am curious as to whether you are using Mach3 or something else for the control software.

07-21-2011, 02:30 AM
X and Y are 1:1 belt driven to 5 TPI ball screws. X is the only one you could direct drive without motors sticking out in odd directions. It appears they used OEM castings for the motors from Supermax from the YCM-40 which is a production cnc knee mill.

I am using Mach3 with the machstdmill screen set package. I am thinking of doing something else, maybe go to EMC2, to get rigid tapping. But I really don't like linux.

I have found there are two rigid tap solutions that do work with mach. One is the kflop. It is a USB motion controller, about $250, that will do the trick.

The other is a new guy in the cnc game. KSI Labs makes a board called the Centipede. It is a PCI card that has a CPLD on it that gives you all sorts of I/O, digital and analog. Right now it does not support rigid tap but it is a target the developer is working on. The board is more expensive. The PCI card itself is $250 and the breakout board (Which appears to be very nice) is another $250. The 100pin cable interconnect is made to length on order and starts at about $100. So you are looking at about $600. The PCI has expansion and he is working on cards with DSPs that can handle analog servos or absolute encoders on the axes for feedback. The plugin or mach allows you to still use the parallel ports for additional IO. http://www.ksilabs.com/