total newbie with questions

[vidio1]

Hello all. I'm hoping to get a few questions answered as at this point i'm clueless.
I just bought an Alliant mill that had been retrofitted at some point with Millpwr. Naturally the controller and some of the electronics are missing.
It does have ground ballscrews and servos on 2 axis, and the servo amp boards, PS, and some sort of BOB is still in the enclosure.
The servos are marked SEM MT30H4-44, and rated for 140v 2.6a 3100rpm. The amps are marked Servo Dynamics SDPF 01525-17.

I would like to make it a functional 3 axis CNC machine for hobby use. I will most likely use Mach3 as it seems to be the industry standard as hobby software goes. And of course do all this without breaking the bank.

And now for the newbie questions.

As I understand it the servos use a tach and the scales are used for feedback or positioning. Do the tachs have to be replaced with encoders for a more modern setup?

Is it possible to use the servo amps for the time being to get it up and running?

Does anyone have a pinout for these boards?

What controller would I need to drive these boards?

Is there a "self contained" servo amp/controller that might be better suited?

Thanks for any answers or advice in advance...........

[vger]

Do your servo amps look anything like these?

http://www.servodynamics.com/Manuals/1525br_manual.pdf

Or are they bare boards?

You may find that the tach outputs lead back to the servo amp for velocity feedback. That is normal and should be left in that configuration.

Not sure about your BOB, but servo amps most often take a +/- 10V drive which will have to come from an analog source.

The scales would be used for feedback to the controller for positon.

There are other servo drives out there that could probably be used... like the Gecko 340. Although it's max voltage is 80 volts, it would probably work and has step/dir inputs that would work with Mach. It would require a quadrature encoder feedback without the tach, which your scales may provide.

Steve

[vidio1]

Thanks for the reply. No my amps are an open board design attached to a motherboard of sorts. I'll try to post a pic as soon as i can.
The quad encoder of the scales......that makes sense now. I was wondering how the scales were used for feedback. I'm still not sure how the tach part is used.
I'm not positive at this point, but I'm leaning toward selling the old analog parts if I can and replacing it with encoders on the servos and a modern drive that can take more advantage of the servo's 140v. and be used with Mach.
Is there a drive out there that could also be used for BL servos? I would hate to buy drives for the brushed servos I have now and a month later have a servo die.
I hate to get ahead of myself, but I'd like to someday have a powered knee and a driven quill. I'd like to plan ahead for those if possible.
Any advice, recommendations of parts or suggestions are welcome.

[vidio1]

I finally found my camera's download cable so attached are a few pics of the servo amps and BOB.

[Al_The_Man]

They appear to be identical to Westamp DC servo drives, these take tach input and ±10vdc analogue control.
Modern drives do not use the tach when used in the torque (current) mode.
Most of the replacement BLDC drives such as Advanced Motion, Aerotech and Copley are equally capable of running DC brushed and can be switched over to DCBL when required.
There are not many that offer step/dir unless you use one of the mach add-ons that use analogue control.
Al.

[vidio1]

The Advanced Motion drives look good. And they seem plentiful on Ebay.

So I need a drive for each servo and a single controller connected to each of the drives with a BOB.

If I replace the tach on the servos with an encoder do I need a drive that works from step/dir?

[Al_The_Man]

You must have had either encoders or resolvers on the old system for feedback, tach are not positional devices.
If encoder you can reuse, resolvers require replacing.
If you have linear scales then these would be used in place of encoders.
Al.

[vidio1]

Yes it used scales for positioning. I was under the assumption that an encoder can be used to replace the tach and scales for positioning. Is this correct?

[pofo]

vidio1,

You have a system that lists for $12,000 today (minus the controller). Acurite went through a lot of trouble and engineering to make a high quality system for professionals. I would suggest you keep the amps, power supply, and scales together. It is a system that was tuned to work well together.

For a Mach 3 solution, consider DSMPC or Galil controllers together with Mach 3. Both of these will drive the amps you have and give you the full power that those motors were designed for. Take advantage of those high precision Acurite scales.

Of course, I know less than you do about CNC, but these are the conclusions I have come to as I am in the same situation as you. I also have a mill with a 3 axis Millpwr minus the console. I also am seeking a solution. I've decided that this is the way I am going to go (unless I learn more to change my mind).

The one piece of information missing for me is the pin definition of the cables going to the motor units. On my system, the motor units have the power supply, the Servo Dynamics amp, and some additional control made by Acu-rite.

I'm hoping that Acu-rite will be supportive of the hobbyist community and provide us this information. I cannot afford their console, but I do want to take advantage of their very fine system. I'll be contacting them to see if they will help us out.

[vidio1]

Cost to maintain and/or replace faulty components to keep the Acurite working is of primary concern.
The lack of documentation and hobby community support is as well. My thinking is that I can sell the drive boards to someone with a working system. With the price they are likely to fetch I can keep out of pocket costs necessary to replace them with a more modern, much more supported drive like a Viper if I want to keep cost down or an Advanced motion if I want future support for BL motors.
Parts of the PS are disconnected and might be missing as well so that lends itself to an upgrade to most likely a switching PS.
The X axis scale is missing too. That would be a serious investment to replace when all the scales can be replaced by encoders at a fraction of the cost.
It all boils down to value.....To me a good value isn't spending money on a 20 year old electronic system when it can be replaced by newer, faster, better supported electronics at a fraction of the cost.......
Just my 2cents.

[pofo]

Ok, understood. It does appear you have an older set of electronics. Agreed that going with the +/-10V amp leaves you much fewer and more expensive options.

I've had the same arguments with myself. In my system, there is only a small bit of electronics on the power supply card that has some custom Millpwr control. The rest is generic electronics I can get from other vendors. I agree that using it puts you at risk.

Good luck with your project. Please continue to post with your decisions and experiences. I may follow in your footsteps.

[vidio1]

I will. It's going to be slow going both financially and with a steep learning curve, but it will hopefully be CNC usable soon. And not to worry, some of the Acurite parts will see new life. I think I'm going to use the Y axis scale to position a powered knee if possible. Just to raise the work. I'll still use the quill for Z.