# PM940 Spindle



## fritts (Jan 26, 2021)

Recently tore down my spindle on the PM940 to do a belt drive retrofit.   Running at 3200 rpm was unbearably loud plus I was wanting to check bearing preload and condition after a maybe 20 hrs of runtime.   I was appalled by how much foreign material was in the lube.   From small machining chips, rtv chunks, paint and other what appears to be sand from the casting process.   The spindle I tore down was not much better.   Plenty of debris in the upper and lower taper roller bearing.   Most from the inside of the spindle where the casting slag was not removed.   The spindle nut was loose which may have attributed to my surface finish defects.   The grease had coagulated as well.   Bearings to my surprise appear to be ok after cleaning.   I removed as much scale as I could from interior of the spindle and then sealed the surface.   I repacked bearings with Kluber grease and reset the spindle nut torque.   Will have to check temps as it is slightly tighter than before.   Hoping to have all my hub adapters and plates done by next week to get it run in.   In hindsight though I highly suggest people review the spindle/gearbox sooner than later in case of damage.

On other item is I really would like to get a BT30 spindle.   The current spindle is a 75mm diameter setup.   I have gotten a quote from KAMI in Germany for the 75mm BT30 spindle in the FKM350.   All appearance seem to be that this FKM350 mill is the same gearbox setup as the PM940.   Anyone tried this spindle?   I was quoted $230 shipped which I think is very reasonable but don't know the quality to know for sure.   Also anyone else interested in one of these spindles?   I believe they are the same ones that MTW has brought in before?

Thanks
Ryan


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## cut2cut (Jan 26, 2021)

I too experienced the horror of debris in the "stock" PM940 spindle.  I soon replaced the bearings with higher rated ones and converted to a belt drive ( my gears were noisy straight away ).  But ultimately I've made my own head and installed a chinese belt driven BT30 spindle as well as a high speed ATC spindle motor ( BT30 as well ).   If I had found a drop in replacement spindle, as you have, I'd surely have tried it, at that price especially.  I hope you can update everyone on it, very cool if it drops right in and has decent runout.  What rpm is it rated for ?

Cheers,

Jake


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## 7milesup (Jan 26, 2021)

fritts said:


> Recently tore down my spindle on the PM940 to do a belt drive retrofit.   Running at 3200 rpm was unbearably loud plus I was wanting to check bearing preload and condition after a maybe 20 hrs of runtime.   I was appalled by how much foreign material was in the lube.   From small machining chips, rtv chunks, paint and other what appears to be sand from the casting process.   The spindle I tore down was not much better.   Plenty of debris in the upper and lower taper roller bearing.   Most from the inside of the spindle where the casting slag was not removed.   The spindle nut was loose which may have attributed to my surface finish defects.   The grease had coagulated as well.   Bearings to my surprise appear to be ok after cleaning.   I removed as much scale as I could from interior of the spindle and then sealed the surface.   I repacked bearings with Kluber grease and reset the spindle nut torque.   Will have to check temps as it is slightly tighter than before.   Hoping to have all my hub adapters and plates done by next week to get it run in.   In hindsight though I highly suggest people review the spindle/gearbox sooner than later in case of damage.
> 
> On other item is I really would like to get a BT30 spindle.   The current spindle is a 75mm diameter setup.   I have gotten a quote from KAMI in Germany for the 75mm BT30 spindle in the FKM350.   All appearance seem to be that this FKM350 mill is the same gearbox setup as the PM940.   Anyone tried this spindle?   I was quoted $230 shipped which I think is very reasonable but don't know the quality to know for sure.   Also anyone else interested in one of these spindles?   I believe they are the same ones that MTW has brought in before?
> 
> ...


Hi Ryan.
Could you put links to the equipment or suppliers you are referencing.  I have an 833T mill and am looking to convert to CNC.  I have no idea who KAMI from Germany is, and my google search turned up basically nothing.  
Thanks.


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## fritts (Jan 26, 2021)

Kami Machine Tools.   What I believe to be the PM940 clone the FKM 350 is here.








						KAMI Werkzeugmaschinen
					

KAMI Maschinen - Ihr Partner für Industrie, Handwerk und Hobby.




					www.kami-maschinen.de


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## fritts (Jan 26, 2021)

cut2cut said:


> I too experienced the horror of debris in the "stock" PM940 spindle.  I soon replaced the bearings with higher rated ones and converted to a belt drive ( my gears were noisy straight away ).  But ultimately I've made my own head and installed a chinese belt driven BT30 spindle as well as a high speed ATC spindle motor ( BT30 as well ).   If I had found a drop in replacement spindle, as you have, I'd surely have tried it, at that price especially.  I hope you can update everyone on it, very cool if it drops right in and has decent runout.  What rpm is it rated for ?
> 
> Cheers,
> 
> Jake


I'm assuming its the same rating as the stock PM940.   Which means move to AC bearing or repack tapers for max 5k.


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## Janderso (Jan 26, 2021)

That's ridiculous.
Most hobby guys who buy these lathes don't have the desire or know how to tear into a spindle to replace the bearings.
I can understand the need after hearing the story about chips, sand from the casting, paint etc. =no excuse.
I guess the Precision Mathews products made in Taiwan are assembled with more care. I know they have better quality bearings.
It seems many of us replace bearings in the headstock way before they should be needed on these Asian lathes.
My 50 year old Clausing Colchester has the original bearings.
I bet many of you have older lathes with the original bearings.


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## Jim F (Jan 26, 2021)

Janderso said:


> That's ridiculous.
> Most hobby guys who buy these lathes don't have the desire or know how to tear into a spindle to replace the bearings.
> I can understand the need after hearing the story about chips, sand from the casting, paint etc. =no excuse.
> I guess the Precision Mathews products made in Taiwan are assembled with more care. I know they have better quality bearings.
> ...


I have a SB9, so no bearings, but the full stack of shims are in the clamps and I have no movement on the spindle.
Lathe was made in 1947.


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## Janderso (Jan 26, 2021)

Janderso said:


> That's ridiculous.
> Most hobby guys who buy these lathes don't have the desire or know how to tear into a spindle to replace the bearings.
> I can understand the need after hearing the story about chips, sand from the casting, paint etc. =no excuse.
> I guess the Precision Mathews products made in Taiwan are assembled with more care. I know they have better quality bearings.
> ...





Jim F said:


> I have a SB9, so no bearings, but the full stack of shims are in the clamps and I have no movement on the spindle.
> Lathe was made in 1947.


My 1941 South Bend 13 had cast iron bearings with several shims remaining.
I think that's a testament to quality.


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## fritts (Jan 26, 2021)

PM940 is a mill not a lathe.  I have no experience with PMs lathes.


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## Jim F (Jan 26, 2021)

fritts said:


> PM940 is a mill not a lathe.  I have no experience with PMs lathes.


Does not matter, it is a quality thing, I doubt a SB mill or shaper from that time frame would be any different.


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## Larry$ (Jan 26, 2021)

I have a PM1440HD and having heard the stories about garbage in the housings, I  opened mine soon after getting it. It was very clean. We have a BT30 (10 hp) spindle on a Komo router. Spins @16,000 for thousands of hours. Italian.


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## Janderso (Jan 26, 2021)

fritts said:


> PM940 is a mill not a lathe.  I have no experience with PMs lathes.


Well, don't I feel silly.


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## Janderso (Jan 26, 2021)

Larry$ said:


> I have a PM1440HD and having heard the stories about garbage in the housings, I  opened mine soon after getting it. It was very clean. We have a BT30 (10 hp) spindle on a Komo router. Spins @16,000 for thousands of hours. Italian.


Very good news!!!


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## phazertwo (Jan 26, 2021)

fritts said:


> Recently tore down my spindle on the PM940 to do a belt drive retrofit.   Running at 3200 rpm was unbearably loud plus I was wanting to check bearing preload and condition after a maybe 20 hrs of runtime.   I was appalled by how much foreign material was in the lube.   From small machining chips, rtv chunks, paint and other what appears to be sand from the casting process.   The spindle I tore down was not much better.   Plenty of debris in the upper and lower taper roller bearing.   Most from the inside of the spindle where the casting slag was not removed.   The spindle nut was loose which may have attributed to my surface finish defects.   The grease had coagulated as well.   Bearings to my surprise appear to be ok after cleaning.   I removed as much scale as I could from interior of the spindle and then sealed the surface.   I repacked bearings with Kluber grease and reset the spindle nut torque.   Will have to check temps as it is slightly tighter than before.   Hoping to have all my hub adapters and plates done by next week to get it run in.   In hindsight though I highly suggest people review the spindle/gearbox sooner than later in case of damage.
> 
> On other item is I really would like to get a BT30 spindle.   The current spindle is a 75mm diameter setup.   I have gotten a quote from KAMI in Germany for the 75mm BT30 spindle in the FKM350.   All appearance seem to be that this FKM350 mill is the same gearbox setup as the PM940.   Anyone tried this spindle?   I was quoted $230 shipped which I think is very reasonable but don't know the quality to know for sure.   Also anyone else interested in one of these spindles?   I believe they are the same ones that MTW has brought in before?
> 
> ...



Well I am very interested... You can see pics of what I found inside mine here: https://www.hobby-machinist.com/threads/another-pm940-cnc-vs-thread.68291/page-2

My first two concerns are, can it spin faster than 3k RPMs, and does it use a draw bar with a pull stud?  If it uses a pull stud than it should be pretty simple to convert it to a real PDB (non of that impact wrench stuff), which is a must at this point.  The price makes me wary that these features are not there...

but dang, for $232 it would be nice to have BT30...

PZ


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## fritts (Jan 28, 2021)

Was 232 but I just submitted my payment and with shipping and it came to $280.   I'll do an unboxing when I get it.


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## 9t8z28 (Jan 28, 2021)

I have a 932 which I’m sure you know is the 940‘s baby brother and I was wondering, how do you adjust the spindle bearings?  Where is the adjustment and what is your procedure for preloading the bearing?


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## fritts (Jan 29, 2021)

I don't believe there is anything in the manual.  With a dual taper setup you tend to snug the spindle nut up and rotate the spindle several of revolutions to seat the cups and cones tighten spindle nut again a couple of in lbs of torque (hand tight). Then lock the spindle nut.  Afterwards check running temps of the spindle.  Slight preload on a temper set actually provides best life but measuring that is difficult.


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## 9t8z28 (Jan 29, 2021)

fritts said:


> I don't believe there is anything in the manual.  With a dual taper setup you tend to snug the spindle nut up and rotate the spindle several of revolutions to seat the cups and cones tighten spindle nut again a couple of in lbs of torque (hand tight). Then lock the spindle nut.  Afterwards check running temps of the spindle.  Slight preload on a temper set actually provides best life but measuring that is difficult.


I am guessing the oil needs to be drained and the motor and top cover need to come off?

What is a temper set?


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## fritts (Feb 1, 2021)

Yes, gotta dump the oil and pop the top cover.

Meant taper set,  taper roller bearing set


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## fritts (Feb 1, 2021)

Well I'm a bit disappointed.  Was hoping for a full spindle but only got then inner spindle.  Looks as if they pulled apart a spindle to provide as it appears to have had bearings on the journals.   Spindle other than the BT30 portion is similar to the current PM940 R8.


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## 9t8z28 (Feb 1, 2021)

fritts said:


> Well I'm a bit disappointed.  Was hoping for a full spindle but only got then inner spindle.  Looks as if they pulled apart a spindle to provide as it appears to have had bearings on the journals.   Spindle other than the BT30 portion is similar to the current PM940 R8.


Very interesting.  So it appears as though the OD and length of the steps of the BT30 spindle are the same diameter as the R8 ?


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## fritts (Feb 1, 2021)

Yes, will need to disassemble the R8 shaft to know for sure.


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## fritts (Feb 1, 2021)




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## 9t8z28 (Feb 1, 2021)

What are you going to do for a drawbar?  It appears as though the german machine uses some type of drawbar.


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## fritts (Feb 1, 2021)

I'll have to make one that can use a petal for the BT30 pull studs.   Plan on making it pneumatic release.


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## 9t8z28 (Feb 1, 2021)

fritts said:


> I'll have to make one that can use a petal for the BT30 pull studs.   Plan on making it pneumatic release.


For $280 for a BT30 spindle, I just might have to jump on that but since my machine wont be CNC'd, I'd prefer to go with a threaded drawbar instead of using pneumatics.  Can this be done or has anyone accomplished this?  Sorry to be somewhat off topic.  Thanks for finding this spindle!


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## 9t8z28 (Feb 1, 2021)

I guess I would need the BT30 pedal and then a drawbar and that should be it, right?


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## fritts (Feb 1, 2021)

If you are not using the pull studs you should just use a threaded drawbar.  My guess is those can be ordered as well.


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## 9t8z28 (Feb 1, 2021)

fritts said:


> If you are not using the pull studs you should just use a threaded drawbar.  My guess is those can be ordered as well.


That would make sense since the holder is threaded.  Thanks.  Subscribed to see if the 2 spindles are interchangeable.


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## fritts (Feb 2, 2021)

Didn't go through all the dimensions but its the same setup except the lower cover will have to be bored out to fit the new spindle.    Oh and a pic of the belt drive and plate.


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## fritts (Feb 4, 2021)

Anyone know how far the lower spindle nut should thread into the spindle?   Mine is not flush with the lower portion of the spindle.   Also is this helping retain anything or just to keep out chips?  I don't see any contact surfaces based on what I can measure.


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## 9t8z28 (Feb 4, 2021)

fritts said:


> Anyone know how far the lower spindle nut should thread into the spindle?   Mine is not flush with the lower portion of the spindle.   Also is this helping retain anything or just to keep out chips?  I don't see any contact surfaces based on what I can measure.


Its more or like just a cover for the bottom bearing.  My cap sits flush with the bottom of the spindle but I don't think it really matters.


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## fritts (Mar 1, 2021)

With ~28mm of press width on the lower bearing it looks like we could almost get a matched pair of 7207 in there.   Then could go with a standard roller bearing for the top bearing.   Anyone try that?









						NEW NSK 7207CTYNDBLP4 Abec-7 Super Precision Spindle Bearings Matched Set of Two  | eBay
					

Find many great new & used options and get the best deals for NEW NSK 7207CTYNDBLP4 Abec-7 Super Precision Spindle Bearings Matched Set of Two at the best online prices at eBay! Free shipping for many products!



					www.ebay.com


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## rmantoo (Aug 18, 2021)

Fritts, will you post the exact part number you ordered from Kami, please?  I want to order this.  I will order this.  Thanks


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## fritts (Aug 18, 2021)

Invoice didn't have much of a part number.


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## rmantoo (Aug 19, 2021)

fritts said:


> Invoice didn't have much of a part number.
> 
> View attachment 375658


THANK YOU!!!    I appreciate that.  Just sent them an email...and I haven't even taken delivery of my PM, yet.


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## pburgh (May 11, 2022)

fritts said:


> Invoice didn't have much of a part number.
> 
> View attachment 375658


Hi Fritts,
I too have a PM940 and i came across your post for the BT30 spindle.  Have you implemented the change successfully, and would you recommend this as a solution?

Thanks for any info on this matter,

Regards,
Doug


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## fritts (May 12, 2022)

pburgh said:


> Hi Fritts,
> I too have a PM940 and i came across your post for the BT30 spindle.  Have you implemented the change successfully, and would you recommend this as a solution?
> 
> Thanks for any info on this matter,
> ...


This is a bit sad but I haven't run the mill that much with the new spindle setup.   Everything so far has been successful and I do believe I have increased rigidity with this setup.   I'm still playing around with the belt drive I also changed at the same time.  I still wish I had more RPM but I'm at the limit of the inside of the mill casting.


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## pburgh (May 16, 2022)

Hey Fritts,
Thanks for the reply.   I know too well about getting away from things.  I'm starting to scratch around again at mine and when i saw that you found this spindle shaft that picked my interest.  What did you use for your clamping?  Were you able to incorporate a pedal clamp pneumatically?

Regards,
Doug


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