PM932 CNC Build

I used 2005 on all axis. The X axis was the closest fit. I would pull the table and measure to confirm how much room you have. It seems all the RF45 clones vary a bit.

I'm assuming you are going to remove the gears from the head when you do the vfd conversion. If the machine spindle bearings are AC bearings you should be good. If they are taper roller bearings I would be surprised at that rating.
 
The lower is roller taper based off the grizzly model you said, Part #56 in the go755, Part number 30206-p5 this is the lower 75oo rpm rating one. I used that number and called a bearing company to get the specs, it can go to 12k but not continuously. The 2 upper bearings that you replaced , part number #29 of the manual is P6007zz. Bearing company said 12k rpm .

Now i haven't taken mine apart. Im just assuming its gonna be the same. Cause in my manual for my machine it only gives enco part number not the actual bearing part number like grizzly does. And yes all gears will be removed for vfd conversion.

Did you do double nut ballscrews?
 
There are two taper roller bearings on the spindle. On the Grizzly machine they are the 30206 & 30207. The two P6007zz bearings support the spindle drive sleeve that allows the quill to move up and down.

After I did the CNC conversion but before I did the VFD conversion I ran the mill a lot at the max 1970 RPM. CNC runs would go for several hours at a time. The taper roller bearings were worn when I removed them so I would be reluctant to run them at 6k for an extended time.

I used two single ball nuts on each screw and set the preload using Bellville washers on the mounting screws. It takes some trial and error to get them set. Tom S. started with a single ball nut and just recently switched to double ball nuts which are working well for him. I would probably go this route if I were to do it again.
 
well the bearings i can replace tapered ones are rated at 7500 continuously. maybe add a big oil cooler to help with the heat and changing the oil to a synthetic and frequently changing it. I personally only will make aluminum parts. And even then its not like im going to run for all day.

For the aluminum i need high rpm or it will take a long time to machine something. I also think i can get a better finish with pushing the tool faster. The tools for aluminum want the high rpm range so i would like to keep it in their happy zone. lol

I plan on doing it the same way you did and not make anything permanent. So if something happens i can still revert back to stock setup.
 
Oc Customs said:
How long of a run time are you doing at 6k? And is the head getting hot?
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I have run 3D parts in aluminum that have taken over 12 hours to complete. I use a high performance AC bearing grease. The spindle never gets more than 5 or 10 deg above ambient.
 
If i gave a cad file could you make me my pulleys i want? Im looking somewhere around 7.5 and 3.75 diameter ones. How much would i be looking at roughly. Im going to use the same belt style like you did. Probably just a wider rib belt like an 8 rib.
 
I could but I'm still waiting on my new lathe so it would be mid September before I have it up and running.

Send me a drawing and I can give you an idea.
 
Jbolt,
Hey all!

I have a pm940M for several months now and do plan on a cnc conversion in the near future. I want to start by converting the z axis first and would love to get a copy of your dimensional drawings if you don't mind sharing them.
 
ncf250sd said:
Jbolt,
Hey all!

I have a pm940M for several months now and do plan on a cnc conversion in the near future. I want to start by converting the z axis first and would love to get a copy of your dimensional drawings if you don't mind sharing them.
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Excellent! I will be envious of your extra Y travel!

I'm happy to share but you will have to confirm they will work for your mill. PM me your email and I will send what I have.

What type of motors will you be using? My Z is driven by a 42 size stepper with a 2005 ball screw and nut so parts were made accordingly.
 
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