Converting a CNC knee mill to LinuxCNC

I have a SuperMax cnc knee mill (3 axis) with an Anilam Crusader M control that is no longer functioning.
I'm beginning to research some different methods for getting this machine running again. It will be used in my small machine shop, on a near daily basis. I have other CNC machines and a lot of CAD / CAM experience along with some electronics and PLC experience, but I have never done a CNC conversion like this before. I'm looking for some guidance on the best path to take for this conversion.
I've done some reading on cnc zone and this site on similar conversions, so I'm a little familiar with the process. However, I definitely need some help with the fine details.


Here's a few details about the machine and items that I want or need to achieve as parts of the conversion:
1. I would like to retain some of the original components such as the power supplies and servo drives to keep cost down. The controller has Westamp servo drives. However, I would like to eventually upgrade these drives to something better / newer as money permits.
2. I would like to eliminate the current card cage with all of the circuit boards, as this is where the current problem is occurring that is preventing the controller from booting up.
3. This machine uses glass scales instead of a rotary encoder. I believe I'll need to eliminate these as well, but not sure.
4. This machine has a Speed-Rite spindle motor conversion, which consists of a Baldor Super E motor, Baldor VFD, and a control panel that is mounted to the head of the machine. All of the original mechanical variable speed parts have been eliminated from the head and replaced with two v-belt pulleys that were part of the Speed-Rite kit. I would like my new controller to have the ability to control the spindle speed through this Speed-Rite VFD conversion.

I'm looking for some feedback on the best components to use for this conversion based on my info above.
I noticed that many people use the Mesa 7i77 and 5i25 boards, so I've been doing some reading on those.
I have attached a few photos of the mill.


Thanks
btmcad

btmcad wrote:

1. I would like to retain some of the original components such as the power supplies and servo drives to keep cost down. The controller has Westamp servo drives. However, I would like to eventually upgrade these drives to something better / newer as money permits.

Nothing wrong with Westamp servo amps. You can probably get Copley or AMC
amps with equivalent ratings if the old amps start to give trouble.

3. This machine uses glass scales instead of a rotary encoder. I believe I'll need to eliminate these as well, but not sure.

If the ballscrews are good, you can keep them, although the resolution is probably a bit low. If the ballscrews have a lot of
wear (=backlash) then the linear scales are on the opposite side of the backlash from the motors, and the
servo loop will rattle back and forth. I think the Anilam encoders are ANALOG output, so you need a
comparator to convert to digital signals.

4. This machine has a Speed-Rite spindle motor conversion, which consists of a Baldor Super E motor, Baldor VFD, and a control panel that is mounted to the head of the machine. All of the original mechanical variable speed parts have been eliminated from the head and replaced with two v-belt pulleys that were part of the Speed-Rite kit. I would like my new controller to have the ability to control the spindle speed through this Speed-Rite VFD conversion.

That should be easy, the VFD probably accepts an analog voltage for speed control.

The Mesa boards are good, but you might also take a look at the Pico Systems PPMC
pico-systems.com/PPMC.html
which is an interface for analog velocity servos. The "price list" link at the
bottom will take you to our web store for the price details.

Jon

Thank you John and Jon for the input.
I do believe my servo drives require +/- 10VDC input. I'm going to do some testing on the drives later this week to ensure all three are still functioning properly.
I think I'll eliminate the glass scales and use the rotary encoders.

I've read good things about the Pico Systems products, so I'll be reviewing those products as well before I decide which components I'm buying. I'm going to create a parts list and wiring diagram later this week and I'll post it here for review / feedback.

Thanks
btmcad

As far as I know (which is not that much) nobody managed to set up a reliable system using only a motor and a linear scale. Any significant nonlinearity such as backlash causes real trouble in such a setup. Usually there is some kind of shaft velocity or shaft position feedback from the motor to the drive to make the loops more reliable.

But if you maintain the current servos there is no need to worry about that; you feed the drive the desired velocity and let the drive handle the details of fullfilling your desire. In such a setup a linear scale as feedback device would work.