[rlaury]

Just bought the mill waiting on delivery. Planning to convert it to CNC.

Any suggestions?

[cncmakers001]

Just bought the mill waiting on delivery. Planning to convert it to CNC.

Any suggestions?

What are the original motors sizes of XYZ axis and Spindle? By KW or NM.
and the motor speed?
You can take photos of the motor labels.

[lucidCnC]

I just received mine just yesterday and waiting for the ball screw kit from PM to be in stock, so for now it'll be a manual machine

[currinh]

lucidCnC:

I just ordered a PM-728VT and saw they are offering a conversion kit. But they had no information. Can you tell us anything about the kit? Motor sizes, etc.?

I just received mine just yesterday and waiting for the ball screw kit from PM to be in stock, so for now it'll be a manual machine

Thanks.

Hugh

[rlaury]

Kit does not include motors. Just ball screws and mounting hardware.

[currinh]

RonL:

Do you know what type motors the brackets are for? I suspect NEMA 23 and/or NEMA 34. That would give some information about what motors they expect to be used.

Kit does not include motors. Just ball screws and mounting hardware.

Thanks.

Hugh

[currinh]

I emailed Precision Matthews about their 728VT CNC conversion kit. They responded:

- The kit comes without motors.
- The motor mounting is for NEMA 23 on X and Y, and NEMA 34 on Z.
- They did not respond to my question about measured backlash.
- The ball screws are double nutted.
- Angular contact bearings for lead screw thrust.
- Not positive but thought the ball screws were C5.

This sounds like a nice kit. Now I really want to see pictures.

Thanks.

Hugh

[BBMNet]

Hello.

May I add one more question? Two nuts for the ball screws make me think of ACME threads than real ball screws. Has anyone received this kit already. Can you clarify?

Thanks for your attention.

Regards.

[currinh]

BMMNet:

I'm certainly no expert. But I think it is common to use two ball nuts with a stiff spring between them, like bellevilles. The nuts work against each other and lower backlash as long as the load doesn't override the spring preload. I believe most kits depend on a single nut with oversized balls to take up slack. I like the idea of a double ball nut better.

I emailed PM with a follow on request for pictures and/or a manual. I was told those aren't available yet. When they are they'll post those to their website. They are advertised to be available late July so I doubt any are out in the wild yet. I thought they might have a prototype to take pictures of, I guess not yet.

Still sounds like a good kit. I'll keep my eyes on the PM website.

Thanks.

Hugh

[Daniel92563]

I emailed Precision Matthews about their 728VT CNC conversion kit. They responded:

- The kit comes without motors.
- The motor mounting is for NEMA 23 on X and Y, and NEMA 34 on Z.
- They did not respond to my question about measured backlash.
- The ball screws are double nutted.
- Angular contact bearings for lead screw thrust.
- Not positive but thought the ball screws were C5.

This sounds like a nice kit. Now I really want to see pictures.

Thanks.

Hugh

Did you ever find out what the backlash is on these?


Sent from my iPhone using Tapatalk

[BBMNet]

Did you ever find out what the backlash is on these?


Sent from my iPhone using Tapatalk

Hello.

You need to confirm on the precision of the supplied screws. It's common to be supplied with C7 screws which work fine for me as I work with fabrics.

You must also ensure that a minimum of modifications and mechanical adaptations to the receiving machine will be needed as accuracy will suffer from improper installation.

Another important factor is the control software. Is it already included with the kit? What about the interface card (breakout card if I'm not mistaken)?

Please post back as your experience will certainly be helpful to many of us.

Regards.

[yelims20]

Real industrial machines have double nutted ballnuts, by adjusting the thickness of the shim in between the two nuts is how they get the backlash so low. It's not just common, it's pretty standard stuff. My G0704 has single nuts, I may upgrade later.

[currinh]

Daniel:

I haven't heard from PM regarding backlash. However, I purchased their CNC kit and have it working on my mill. They offer two kits and I have the "Ultra Precision" kit. I believe I posted on the Hobby Machinist forum regarding backlash and I've now forgotten the exact numbers. (Good discussions on Hobby Machinist about this kit.) I'm away from the machine right now so can't check. When I get back to it I'll re-adjust the bearing load on all axes and re-test. However, I found them acceptable for my work, well within what I can compensate for with LinuxCNC.

The kit I have has double ball nuts on all axes. I don't know what the grade of ball screw is. It does use double angular contact bearing on all axes. The motors and controller are up to you, either steppers or servos. I used steppers, Gecko drives, Mesa boards and LinuxCNC control software.

I hope this helps. Thanks.

Hugh