Upgrading My Cnc Machine

BobSchu

Registered
Registered
Joined
Jun 25, 2015
Messages
104
Tried asking several questions on a couple different forums and haven't been able to get a response so I'll try one more time here.
I have Tree 2UVRC mill with CNC but the controls are old Tektronix that are hopelessly outdated and not working. They will be going to the dump unless someone needs some parts for their old machine. My mill has servos on it, but none of the 3 have any labels or markings of any type on them so I'm in the dark what size they are, DC or AC, etc....
So, I've got a decision to make. Either make this into a manual machine (it was built as a CNC- not retrofitted) or find three new Servos, controllers, and the other hardware and software I need to upgrade the existing machine. My budget is kind of tight but if I could fit it into my budget or just a bit more then I would go for it.
So, the most important questions. Is there a way to determine what I have now for Servos- size, AC or DC ( I assume DC), what size Servos to replace them with if necessary, and what other hardware I need besides controllers?
Do I need a separate power supply for all of the new equipment and approximately what size would I need?

I've looked at the Gecko G320X Servo drives and it looks like they may do the trick for relatively short money, but what else would I need? Can I hook one of these up to my existing Servos to test them?

Tons of questions just to get to the point where I can make a decision but I need to start somewhere. Hope someone here can point me in the right direction.

TIA,
Bob
 
Is this for a hobby or production application? Being that you are a tight budget have you considered stepper motors and drives? This may, or may not, be a viable option for what you are trying to accomplish.

Tom S.
 
I RAN A TREE CNC MILL A FEW YEARS AGO .
GREAT MACHINE THAT WAS RUINED BY UNCONVENTIONAL USER HOSTILE CONTROLS .
 
I'm strictly a hobbyist, so I don't want to spend a ton of money on rebuilding the CNC on this machine. This machine was in storage for many years and is as tight as can be. The only reason really for upgrading the CNC is for the capabilities it gives me- arcs, circles, etc.... that I would like to do for some of the projects I've dreamed up.
If steppers are a viable option for a machine this size, what size would I need to accomplish this and what other equipment would I need to go with with the stepper motors and controllers?

Thanks,
Bob
 
Bob, please look for any data tags on your servos and drives, any part numbers are useful. That information would be very helpful in determining the best course of action. DC servos are not a bad thing, just a little outdated, but still being installed on new machines. If the servos and drives still work, then there is no reason to change them. It's easy to match new controls to the existing servos.

As far as power supplies, again, if yours is working then there is no reason to make a change. A 100VDC supply was common, but so are other voltages. If you are going to do a complete controls upgrade, then you would need to match the power supplies to the new hardware. We will be happy to help you through that process, there is a lot of experience here.

If you are comfortable doing so, it might be time to plug it in and see what happens;) A bit of probing around with a multimeter at that point might provide some useful information. Assuming DC servos, a car battery will run them at moderate speed to confirm that they are functional.
 
Thanks Jim,
I've looked everywhere on the Servos and there are no tags anywhere. I know what to look for, I'm an electrician- and this is so frustrating when someone removes the tags on these types of machines. The motor leads aren't marked either but I'll try the battery idea just to test the parts.
Unfortunately, I can't start the machine just yet as I took the control box off. It was in terrible condition and missing parts. I do have a VFD I can hook up and temporarily power the power supplies in the power box to see what I can figure out.
I've been trying to learn a thing or two about Servos, controllers, etc... and I'm starting to understand it a bit. However, if I have to replace the servos I don't have the foggiest idea how to size them. I'll also have to figure out how to test my encoders and limit switches to see if they are working properly.

Bob
 
I'm happy to hear you're an electrician, I get nervous having inexperienced people poke around in live equipment! :eek:

Servos on a machine that size normally are around 30 in/lb, I think mine are 27 in/lb, maybe a bit more. Should you decide to go with steppers you would want to about double that value, so NEMA 34, 1200 oz/in would be in the range you want to look at.

There are probably 4 wires going to the servos, not including the encoder if equipped. The two larger wires are motor power, the smaller 2 wires are tach feedback, if equipped.

If you have one, a scope is the best way to test encoders offline. They are normally powered by 5VDC.
.
 
Watching this with considerable interest.

What I'm trying to figure out is why the need for new motors? If the front end of the machine is faulty (controls, etc) then why switch everything else?

All the motors need is something that decodes the Gcode into a pulse train (more or less, yes). I would think the motors, resolvers, and amps could be re-used. Especially if a guy was on a budget.

It might take some laptop time, but laptop time is cheap compared to a new drive train, idnit?


Wrat
 
The only reason I'm considering new motors is because I need new controls. The existing controls are a tape driven cabinet full of circuit boards in poor condition and not working at this time and a junction box with unmarked transformers or rectifiers and controllers of unknown origin and no way to figure out how to reconnect without a wiring diagram, which is missing. Without knowing the size of the motors or if they work, I don't have any way to size my controllers and other components and I'll never know if the existing is faulty.
Of course, if the servos are in working order, that saves me considerable expense and time and I can find controllers that will work for the present system.

I'll take some pictures tonight after work and post them to see what I'm dealing with. Maybe someone can recognize something helpful in the pics.

Bob
 
Jim, thanks for the helpful suggestions. I took out my boat battery to check the servos, then took it back into the garage to charge it for awhile, then took it out again and checked the servos. They all function fine and extremely quiet. I could barely hear them run even when I was right next to them. Then I took out my camera to take some pictures, then took it back in to charge the battery, then took it back out again and took some pics. Not sure if these are helpful or not but I'll try posting some pics to see if you guys can make out what I need here. I don't have a wiring schematic or diagram of any sort so thrashing through this mess to figure out what works and what doesn't probably isn't worth the hassle. As long as the servos work, I can hopefully get updated and modern controllers to make a much simpler and more effective/understandable control scheme.006.JPG 007.JPG 006.JPG 007.JPG 006.JPG 007.JPG 006.JPG 006.JPG 007.JPG 009.JPG 010.JPG 013.JPG 014.JPG 011.JPG 012.JPG
 
Back
Top