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Deckel FP2 (vertical) spindle bearing replacement sizing

sigurasg

Aluminum
Joined
May 4, 2018
After using my new-to-me FP2 mill a little, I discovered that there was excessive axial play in the vertical spindle. It also seemed the radial play might be out of spec.

I pulled the spindle apart, cleaned it, and then with the spindle oiled with light oil only, I measure about 0.0008" or 0.020mm radial play. The spec I've seen is for 0.010-0.015mm, which means the radial play is well out of that spec.

I believe the two needle bearing sizes for this spindle are K-50x57x18 and K-45x52x18?

Now, I'm going to replace those bearings. Ideally I'll just buy a pair of replacement bearings, polish the races, drop the new bearings in, run the spindle in and then live happily ever after.

I've been in contact with DeckelDoctor about replacement bearings, and I've shot emails at Franz Singer and FPS also. Maybe they'll be able to tell me the appropriate size to buy, but I'd also like to understand how to size the new bearings.

It seems fairly standard for roller cage bearings to be size bucketed such that the needles in a single bearing have no more than 2um diameter variation. The nominal sizes of the buckets are 1um apart, as described e.g. in this document - see page B5.

The good DeckelDoctor sent me some size charts and by those charts, I believe that the bearings in my spindle are INA brand. The cages are each stamped - on both sides - with a number representing the size class (aka diameter tolerance). See this image of the larger bearing:
IMG_20200106_181654.jpg

In my spindle, the KS-50 cage is stamped "3", which I believe corresponds to the -2 to -4 (um) size class, meaning the needles are nominally 3.5mm - 3um.
The KS-45 cage is stamped "7", which by the same chart is the -6 to -8 size class, with needles nominally sized 3.5mm - 7um.

To get into the spec above, I need to take out at least 0.005mm of play, which means I need needles that are larger by at least 2.5um. I believe my choices in size classes might run on even numbers, so I'd have to go to nominally 4um larger rollers.

This would translate to 0.020mm - 0.008mm = 0.012mm play.

Does my math check out here?
 
I spoke with NTN tech support, and they tell me there aren't really any precision classes for these needle roller bearings. The precision classes refer to the races, in terms of things like runout and thickness variation. All the precision classes end up containing the same rolling elements, e.g. balls or needles.

The guy also seemed to think there'd be no problem ordering a particular size class of these bearings from any bearing supplier - so I guess I'll find out.
 
Mkay, so I've contacted several local bearing suppliers, but so far only one has even responded to me. He's forwarded "my query" to NTN, although I've heard nothing but silence since.

However, I did manage to get in touch with a local Schaeffler technical and sales representative. He promises to send me a quote for (INA) bearings with the specific sorting I requested via a local bearing supplier by Monday.

By my 'rithmetic I think I'll need nominal +2-0um size at the front of the spindle nose - e.g. the K50x57x18 bearing. After grousing through INA, NTN and SKF bearing catalogs, it looks like INA are the only manufacturer who list over-nominal sizes as "standard".
 
While not directly related to my vertical spindle, there’s a fair bit of practical info on spindle rebuilds in this video.


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Singer has a assortment of 10 or so different tolerances on these bearings
I do not know where he gets them from
They install and test Install and test
Not that terrible expencive to have it done
Transport is the dealbreaker here
Perhaps ask him for a set and then return and refund the ones you did not use

Peter
 
I managed to find a pair of bearings that have nominally 2um larger needles each. They’re coming out of Holland at roughly twice shipping to purchase price. Beggars can’t be choosers I guess. I’ll see whether that gets me into spec.
I also inquired at Franz Singer, where Igor quoted me what I regard a supremely reasonable price for a refurb. If my bearings don’t put me in spec, this old spindle will be making a visit to its birthplace :).


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Mkay - so I finally got a useful response from the Schaeffler representative. He tells me that the bearings I want are orderable, so you can e.g. order:

K50X57X18-A/+2+0
K50X57X18-A/0-2

K45X52X18-A/-3-5
K45X52X18-A/-4-6

The gotcha is that the minimum order is 500 pieces.
Group buy - anyone, anyone, Bueller ;)?
 
On the topic of spindle bearing replacement, both the DeckelDoctor and Igor Singer will polish the races on the sleeve and the spindle.
The DeckelDoctor uses 1800 grit (or 9um?) diamond compound for the purpose.
When I brought this up with Igor, he cautioned me not to use diamond compound, but only "400 grit" - I assume he meant sandpaper or emery cloth.

How do you all do this?
 
I suppose diamond compound might remain embedded in the metal and keep on acting as an abrasive even after a thorough cleaning. I suppose this is a place one wouldn't use diamond compound but instead garnet compound (e.g. clover compound).

400 grit regardless of it being a compound or sandpaper, sounds pretty darn coarse....
 
Oh I had a brain fart when I said Clover compound, I did mean the Timesavers stuff. Most of Clovers stuff is silicone carbide based, but they do have some garnet based lapping compound, it's the garnet that does the trick of being non-embedding and becoming so fine it no longer laps.

So as long as you get garnet based lapping compound it's ok. Brownells also sells some meant for rifle bore lapping, I got mine from a musicians shop.
 
Replacement bearings test-fitted

Ok, I got my replacement needle bearings and I tried a test fit just now. By going up nominally 2um in both bearings, I drop the play from 0.0008" to about 0.0006" - that is from 0.020mm to just over 0.015mm. The math from the first post checks out. Bumping up by 2um would take out 0.004mm of play, assuming the wear was all in the spindle and sleeve. From the numbers I get, it looks like there was a little bit wear in the needle rollers themselves, though it's hard to say how accurate my respective measurements are.
I can definitely tell by feel that there's less play, as I could feel the side-to-side play with the old bearings.

However, I think I'll be sending my spindle to FS for a refurb, as I don't think I can trust these bearings:
IMG_20200202_115704.jpgIMG_20200202_115718.jpgIMG_20200202_115731.jpg

The K45x52x18-A/-4-6 bearing in particular has been repackaged. It's been without rust preventative and open the environment for god knows how long. I also feel the size provenance of both bearings is in question, as neither one has any size markings on the cages.

I'd also bet that FS will bump the bearing sizes another 2um, and take the play down to below 0.015mm, which is right on the outer limit of the spec.
 
I think I'll be sending my spindle to FS for a refurb.

I am in favor of doing most jobs myself, and like to learn and try new things. But I didn't regrease the vertical spindle of my machine. I sent it to Franz to do, because he and the others there have a century of collective experience, so are a lot less likely to make a mistake than I am.

Socrates wrote, "to know thyself is the beginning of wisdom.”
 
I am in favor of doing most jobs myself, and like to learn and try new things.

Speaking of trying new things - I've just re-greased and assembled the bevel gear into the vertical head. I'm wondering how to gauge the preload or play for the thrust bearings. I had a feel around for it with the head alone, and I think if I go finger tight with the lock nut, then back it out 1/8th of a turn, the bearing is running free. To tighten the lock nuts for realz, I'm mounting the head on the mill, putting it in the lowest gear to hold the bevel gear still while I tighten up the lock nut - the problem being I can't really feel the bearing resistance when mounted on the mill.

Does this sound like a sane recipe?
 
I'm wondering how to gauge the preload or play for the thrust bearings.

I was told by several people how to do this but have forgotten. I have the impression that I preloaded this thrust bearing very slightly, but I suggest you wait until one of the pros here (Ross, Peter, others) has confirmed or corrected this.
 
Ballen, how often should a mid sixties vert. head be re-greased ? We've never done ours since install 10 years ago. Spindle will warm to touch when run all day in production, no issues so far and normal noise for that type head.
 
Ballen, how often should a mid sixties vert. head be re-greased ? We've never done ours since install 10 years ago. Spindle will warm to touch when run all day in production, no issues so far and normal noise for that type head.

The manual says that the spindle should be regreased after a few thousand hours. If you run 8 hours a day x 5 days a week x 50 weeks/year that is 2000 hours/year. So after ten years I think the time has come. Better to clean and regrease the spindle now rather than wait for signs of trouble.
 
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Ok great thanks for info Ballen will get the ball rolling on this shortly. Asides from Singer in Germany has here have a reputable source for this in North America ? I'm not confident in being able to reload the spindle properly following disassembly.

Sigurasg I sent you a PM I noticed you are near by to me !
 








 
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