PM30 bearing replacement.

[Livnpaintball]

Well I got my little cnc conversion complete and busted out some parts, all is good until my last run and now my bearings in the spindle have some grittiness. Should I try the angular contact bearings or just go back with the easy to source tapered rollers?

 

[Ischgl99]

Why do you want to change to angular contact bearings from tapered roller? Are there performance problems with the TRBs?

 

[Richard King 2]

The machine is designed for Tapered roller bearings. The spacers, the quill clearance, the thrust is set at the factory. Check with Precision Mathews factory and unless they have a conversion kit leave it alone and replace what was in the machine. Pages 21 and 22

https://www.precisionmatthews.com/wp-content/uploads/2017/05/PM-30MV-v3-2020-10.pdf

 

[Livnpaintball]

The machine is designed for Tapered roller bearings. The spacers, the quill clearance, the thrust is set at the factory. Check with Precision Mathews factory and unless they have a conversion kit leave it alone and replace what was in the machine. Pages 21 and 22

https://www.precisionmatthews.com/wp-content/uploads/2017/05/PM-30MV-v3-2020-10.pdf

Mine are overheating and are gritty when you rotate the spindle, toasted.. not sure if it’s because they lack lube or what because I haven’t torn it apart yet. The reason for angular contact bearings are in case I decide to spin it over 3k rpm With a different motor.

Why do you want to change to angular contact bearings from tapered roller? Are there performance problems with the TRBs?

the stock bearings have a RPM limit that a may exceed in the future. But that being said I ordered tapered bearings, I can always change them out later if I get a different motor.

 

[Richard King 2]

Mine are overheating and are gritty when you rotate the spindle, toasted.. not sure if it’s because they lack lube or what because I haven’t torn it apart yet. The reason for angular contact bearings are in case I decide to spin it over 3k rpm With a different motor.

the stock bearings have a RPM limit that a may exceed in the future. But that being said I ordered tapered bearings, I can always change them out later if I get a different motor.

The machine is a low cost machine. You would be better off buying a machine designed to have angular contact bearings and higher spindle speeds. I bet you will be kicking yourself in the behind if you do what your thinking.

 

[Ischgl99]

Richard is right, putting ACBs in there doesn’t sound like money well spent. Switching to an ACB will give you higher speed capability, but it is less rigid than a TRB of equivalent size, so you might end up with worse performance. The same size ACB also has about half the load capability of the TRB it was designed for, so your life is going to be significantly less unless you run at much lower loads. To get an advantage from the angular contact bearings, you would need to go bigger.

Another issue to consider, most angular contact bearings have a contact angle of 40 degrees and are meant for high axial loads, TRBs are in the 10 to 20 range depending on size and design as a comparison. You would want a spindle bearing in a milling operation that have either 15 or 25 degree contact angle to better handle the radial loads. Not much of a selection of those in P5, usually they are P4 and $$$.

 

[theNOTORIOUSmo]

This is what I'm using for my spindle upgrade.

Lower Spindle Assembly:
1x - 7007A5TRSULP3 - NSK Precision Angular Contact - 35x62x14mm

1x 7006CTRSUMP3 - NSK Precision Angular Contact - 30x55x13mm

4 mm worth of 30x55 shims for the 7006CTRSUMP3 Bearing (this bearing is 4mm shorter and need the space taken up)

Upper Spindle Assembly (you can probably go cheaper with these, just find the right rpm range for your need):

2x - Bearing 61910-2RZ/P5 made by SKF

1x - Bearing 6207-2RZ/P5 made by SKF

 

[stefan63]

This is what I'm using for my spindle upgrade.

Lower Spindle Assembly:
1x - 7007A5TRSULP3 - NSK Precision Angular Contact - 35x62x14mm

1x 7006CTRSUMP3 - NSK Precision Angular Contact - 30x55x13mm

4 mm worth of 30x55 shims for the 7006CTRSUMP3 Bearing (this bearing is 4mm shorter and need the space taken up)

Upper Spindle Assembly (you can probably go cheaper with these, just find the right rpm range for your need):

2x - Bearing 61910-2RZ/P5 made by SKF

1x - Bearing 6207-2RZ/P5 made by SKF

Did you complete your modification/upgrade? I so how does it perform? Kind regards/Stefan

 

[theNOTORIOUSmo]

It actually worked really well. Run out was barely moving the needle on the tenths indicator and I was able to keep it spinning around 11k all day long without it getting hot.

The only thing i had to add was 3 or 4 mm worth shims on the top bearing as those are 4mm shorter if I remember right so I can get the preload set without bottoming the nut out.

I also completely removed the quill setup so I didn't need those other t bearings. I ended up turning the shaft on the spindle to accept a bearing which went in a plate bolted to the top to keep its rigidity. But that was because I wanted to remove any backlash and it was cnc controled and wanted to rigid tap. Side benefit was that the smaller bearing I used was much cheaper than those 2 bearings.

 

[verbotenwhisky]

Mine are overheating and are gritty when you rotate the spindle, toasted.. not sure if it’s because they lack lube or what because I haven’t torn it apart yet. The reason for angular contact bearings are in case I decide to spin it over 3k rpm With a different motor.

the stock bearings have a RPM limit that a may exceed in the future. But that being said I ordered tapered bearings, I can always change them out later if I get a different motor.

I had to replace a couple bearings in my mill and I replaced them with the same type bearings but used a better quality and I can see the difference.