Supermax manual mill re-retrofit

[macona]

Looks like I got a full size Vertical mill coming home. Its a Supermax ycm-16vs I believe. Ground and hardened box ways, 3hp varispeed head, one shot lube. From swarf in the nooks and cranies I have found it looks this machine was only used on aluminum and plastic. Not one steel chip in sight.

It used to be owned by tektronix and they retrofitted it to cnc. The replaced the lead screws in X and Y with ground ballscrews and removed the original knee mech. and replaced it with a custom made knee horn and ballscrew. It has three good sized PM servos with tach feedback. All axis' have heidenhain glass slide with pulse multipliers in the cabinet. I can remember who made the controls but it dosnt matter as I am not going to use them. I will use one of the cases

So my question. Whats the best way to re-retrofit it? I plan on using Mach. So far my possibilities include:

1. It has good servo drivers and motor power supply. +/- 10v in. Use either the skyko or rutex step to analog converters. Question is do I install encoders on the motors or can I use the glass scales as feedback? This would be the cheapest option since the skyko pixies are only $69 per axis.

2. replace the servo drivers with Gecko 320/340. Again, can I use the scales or do I need to install motors. Also should I go with the 320 or 340?

I eventually want to go with using the G100 as soon as it is a viable option to run the drivers (maybe after the next firmware update?)

Also the spindle motor draws 7 amps, I have a VFD that will output 6.8. Think I can get away with using it till I score a larger VFD?

Lastly the knee motor does not have a brake on it so when the machine shuts down the table drops down to the bottom. I was thinking of installing a brake? How could I hook up a electric brake to release before it makes a movement? Use something to monitor the state of the step pin and when it is idle for a long enough period the brake would come on?

[titchener]

Sounds like a nice machine. If the servo drivers appear to be in good shape I'd keep them and use the step converters, your current drivers probably put out more power than the Gecko drivers and they're already matched to your motors. Using the existing scales may be more hassle than its worth, I'd probably put U.S. Digital encoders on the motors.

Your 6.8 amp VFD should be fine with that motor. You may need to set the current limit parameter to 6.8 amps so it doesn't throw the current limit error, but I bet you won't even need to do that since the motor would only draw 7 amps at full load. You'll get just slightly less than full power, I doubt you would get much gain from replacing it.

Keep in mind that if you need the machine running pretty quickly the G100 is still a work in progress. I'm keeping an eye on it and will probably move to it at some point, but its going to take a while before they complete all the features and shake all the problems out of it.

Paul T.

[macona]

Yeah, the more I thought about it the more I want to keep the original drivers.

I worked out the final deal today. I am trading a plasma cutter + 750 cash for it. So all in all I will have $1100 to start. I am going to order three of those pixies and try the scales first. They have quadrature output after the pulse mutiplier and I cannot detect any backlash so far.

If that does not work I have three new 2500 line encoders here that I can attach to the backs of the motors. The pixies can handle 1.5 million counts per second so I think I should be OK. If not US Digital is in the same town I work.

This is just a hobby machine, so I can take my time, though the sooner I can get it up and running the better. I have projects waiting!