Precision Matthews PM-728VT CNC conversion

cncjoe21 said:
thanks for the info. I have basically done the same. I have replaced all screws and put it back together. Also got my Acorn controller kit but haven't got the motors yet. How do you like the Clearpath servos? I would appreciate it if you provide me a complete list of your electronics items I see in your pictures when you have some time. I'm a CNC machinist but need to learn more about electronics and components.
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Joe, you have at least the advantage of understanding the machine part; I know nothing of either the mechanics or electronics. I am happy to share everything I do so that you can hopefully progress faster and avoid the mistakes I make.

I like the Clearpath servos very much. The product seems great, you get a well-featured, well-thought out package, with great instructional videos and quality support on the phone. They also offer a sophisticated diagnostic software with an oscilloscope built-in; I am not schooled in electronics, so not sure how to use it, but their engineers use it if they need to debug a malfunction on your end.

Here is my order:
Order 1 2020-12 .png


I forget one cable so I had to put in a second order. Don't be like me :)

Order 2 2020-12 .png


The proximity sensor is listed above. The Acorn package is the basic + software + pendant. I think the pendant is a must.

I have not ordered an enclosure box yet, and in fact I might not buy one at all. Instead I will mount the DIN rails and circuit boards on stand-offs on 1/16" aluminum plate, and enclose that in sheet aluminum. Will fabricate a gland plate though, and will use aviation connectors (6 pin for the motors and to control the spindle speed/direction, and 4 pin for the sensors):

Automation Direct order connectors.png
 
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koenbro said:
Joe, you have at least the advantage of understanding the machine part; I know nothing of either the mechanics or electronics. I am happy to share everything I do so that you can hopefully progress faster and avoid the mistakes I make.

I like the Clearpath servos very much. The product seems great, you get a well-featured, well-thought out package, with great instructional videos and quality support on the phone. They also offer a sophisticated diagnostic software with an oscilloscope built-in; I am not schooled in electronics, so not sure how to use it, but their engineers use it if they need to debug a malfunction on your end.

Here is my order:
View attachment 356614

I forget one cable so I had to put in a second order. Don't be like me :)

View attachment 356615

The proximity sensor is listed above. The Acorn package is the basic + software + pendant. I think the pendant is a must.

I have not ordered an enclosure box yet, and in fact I might not buy one at all. Instead I will mount the DIN rails and circuit boards on stand-offs on 1/16" aluminum plate, and enclose that in sheet aluminum. Will fabricate a gland plate though, and will use aviation connectors (6 pin for the motors and to control the spindle speed/direction, and 4 pin for the sensors):

View attachment 356620
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Thank you so much!! this will be a big help, much appreciated!
 
I believe a counterweight will be needed for the Z-axis. I think the head is too heavy and will put a lot of stress on the Z-axis ballscrew. Any thoughts on that?
 
cncjoe21 said:
I believe a counterweight will be needed for the Z-axis. I think the head is too heavy and will put a lot of stress on the Z-axis ballscrew. Any thoughts on that?
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OK, the conversion is FAR from ready, but I just had to turn it on and make a few chips even if just to hear it run. When I think about what is left to do, the list seems endless: sort out the electronics, measure and correct backlash, tram the head, get a real vise (ordered, promised for late March) and indicate it, add a flood coolant tray, and connect the pump and hoses; finally, make an enclosure and a base. So, not even half-way done! Have not even thought about a counterweight, do you mean a pulley with some weight, or a hydraulic system?

BTW here it is, untrammed, just with a drill press vise, and a bit of scrap, making its first noises:

 
koenbro said:
OK, the conversion is FAR from ready, but I just had to turn it on and make a few chips even if just to hear it run. When I think about what is left to do, the list seems endless: sort out the electronics, measure and correct backlash, tram the head, get a real vise (ordered, promised for late March) and indicate it, add a flood coolant tray, and connect the pump and hoses; finally, make an enclosure and a base. So, not even half-way done! Have not even thought about a counterweight, do you mean a pulley with some weight, or a hydraulic system?

BTW here it is, untrammed, just with a drill press vise, and a bit of scrap, making its first noises:

Click to expand...
I'm thinking pulleys and weight. Did your Z motor lift the head with no problems?
 
cncjoe21 said:
I'm thinking pulleys and weight. Did your Z motor lift the head with no problems?
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Yeah it does not seem to struggle or anything. When you power it off, it tends to come down though, so I put a piece of 2x4 underneath. A pulley and weight seems reasonable, just not sure how I can hide it. Is there some off the shelf hydraulic system one can add, or is that overcomplicating things?
 
koenbro said:
Yeah it does not seem to struggle or anything. When you power it off, it tends to come down though, so I put a piece of 2x4 underneath. A pulley and weight seems reasonable, just not sure how I can hide it. Is there some off the shelf hydraulic system one can add, or is that overcomplicating things?
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yeah, the z comes down, and had to put a 2x4 as well. I've seen some people run a counterweight with chains and sprockets with linear rails behind the z column, I think I'll go that route.
 
cncjoe21 said:
yeah, the z comes down, and had to put a 2x4 as well. I've seen some people run a counterweight with chains and sprockets with linear rails behind the z column, I think I'll go that route.
Click to expand...

How far have you gone through the conversion?


Sent from my iPhone using Tapatalk Pro
 
I’ve replaced ball screws and reassembled it but have yet to do the electronics of it. Just ordered the clear path motors and necessary accessories. I have the acorn kit already. Hopefully it won’t take too long until I get my motors and start doing the bench testing so I can finalize it.
 
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