PM-940m CNC - VS Motion Controller Conversion to Centroid Acorn

[phazertwo]

Thanks PZ they do have a great selection.


John

No problem. To give credit where it's due, Jake actually found those guys.

PZ

 

[N2XD]

Another question? I'm pretty sure I know the answer. On the Z-axis ballscrew did any of you provide support on both ends of the ballscrew? I noticed on some of the conversions on lighter machines only one end had support (the top end which would be the drive end). I'm just about finished machining the parts needed for the z-axis.
Thanks.

John

 

[cut2cut]

Another question? I'm pretty sure I know the answer. On the Z-axis ballscrew did any of you provide support on both ends of the ballscrew? I noticed on some of the conversions on lighter machines only one end had support (the top end which would be the drive end). I'm just about finished machining the parts needed for the z-axis.
Thanks.

John

My Z is only supported on the top because I removed the standard captured end. However i’m not certain it’s the safest approach due to the single ball nut being the only thing holding the entire weight of the head from crashing ( due to gravity if something fails in the ball nut assembly. )
Jake

 

[N2XD]

That is what I was thinking. What size ballscrew are you using?

John

 

[cut2cut]

That is what I was thinking. What size ballscrew are you using?

John

I don’t know off hand and cannot look now but have that info somewhere in my manual , I bought the pm940cnc so it’s not a retrofit.

 

[phazertwo]

Did anyone make a model of that air cylinder? I'm working on my PDB design, and want to use it...

PZ

 

[Rickwjenn]

For the fellows who have done the spindle belt drive mod. Where did you locate the pullies and belts? Thanks.

What are the key reasons to move to spindle belt drive setup vs. the gears? I have been machining a few CNC parts with my 940 CNC w/VFD and have not picked up an issue with the gears....

 

[TomS]

What are the key reasons to move to spindle belt drive setup vs. the gears? I have been machining a few CNC parts with my 940 CNC w/VFD and have not picked up an issue with the gears....

The main reason is RPM. The gears have a speed limitation. For instance, my PM-932 had a top speed of 1970 rpm. I called Matt and asked him about going with a 3450 rpm motor. He said don't do it as the gears aren't rated for that speed. Not to mention the potential for increased gear noise.

I converted my mill to a belt drive and with the pulley ratio I have I can get to 8800 rpm. And it's quieter than the original gearhead at 1970 rpm.

 

[Rickwjenn]

The main reason is RPM. The gears have a speed limitation. For instance, my PM-932 had a top speed of 1970 rpm. I called Matt and asked him about going with a 3450 rpm motor. He said don't do it as the gears aren't rated for that speed. Not to mention the potential for increased gear noise.

I converted my mill to a belt drive and with the pulley ratio I have I can get to 8800 rpm. And it's quieter than the original gearhead at 1970 rpm.

Got it - that makes sense. My PM-940 maxes out at 3200 rpm (in the "High Gear") setting and VFD motor flat out.

Without a VFD you have to change pulleys for different speeds. With a VFD, I could use three pulley ratio/sets to have a nice range of Low (100-500), Med (1000-3000), and High (3000+).

Will have to give it some thought. Thanks for the information.

 

[srecord1]

Wow, that's about half cost of the Centroid DP-4... But still way more than the cheapo Tormach unit. Hopefully you get what you pay for and judging by Sams review, you do.

It would seem that your panel layout is quite a bit different than mine. Can you snap an overall shot of the cabinet layout, I would like to see how yours is done. If I ever get my internet situation figured out I'll post some pics of how I mounted mine.

PZ

Did you ever get a response on advantages or disavatages over the centroid dp-4 probe? Im extremly interested as im ready to buy one as well!