Lathe Spindle End- Play

[thestelster]

I wanted to check my spindle endplay to see if the taper roller bearings need adjusting. I couldnt find anything specific to my lathe (Standard Modern Utilathe 1654).

I did find some adjustment torque specs in the Standard Modern 1340 lathe, but on the diagram it seems to show 2 taper roller bearings back-to-back. It tells you to put an 8oz weight on a 3/8" steel rod 12" from the spindle center.

I also read (on-line) that there should be zero play.

My taper roller bearing are on either end of the spindle, and preload is adjustable. (See picture from my owners manual).

I put all the gearing into neutral.

The lathe has not been run, but it's in my heated garage at 21°C.

I checked for endplay with a piece of wood and I can get almost 0.001" of axial movement with me pulling back on the piece of lumber with not too great of a force 2' out. (I looked around to find my luggage weight gauge to get an accurate-ish number, but it's nowhere to be found....of course)!

I then gripped a 5/16" threaded rod (couldn't find 3/8") in the chuck, and put an 8oz weight at the 12" mark. The spindle easily rotated.

Some feedback from you guys would be extremely helpful please, before I bugger things up.

 

[Dabbler]

.001 axial play results in about 3 tenths radial 'extra freedom'.

When you run your lathe at about 400 RPM for say 20 minutes, are your bearings still at around 21C? You should do this test without a chuck.

Ideally, you should adjust your end play to see a small rise in temperature. 30C isn't a problem, but 60C would interfewre with the effectiveness in your lubrication... Some manuals say 40 C, but I shoot for a 'small rise', as extra pressure shortens lubrication life, and then messes with the bearings.

 

[thestelster]

.001 axial play results in about 3 tenths radial 'extra freedom'.

When you run your lathe at about 400 RPM for say 20 minutes, are your bearings still at around 21C? You should do this test without a chuck.

Ideally, you should adjust your end play to see a small rise in temperature. 30C isn't a problem, but 60C would interfewre with the effectiveness in your lubrication... Some manuals say 40 C, but I shoot for a 'small rise', as extra pressure shortens lubrication life, and then messes with the bearings.

Does it matter which taper bearing I measure from? The front is encased by a hell of a lot of cast iron. The rear one, once the cover is off, is easily accessed.

 

[YotaBota]

IIRC @RobinHood tried the suggested process and the result was to tight, @RobinHood correct me if my memory has failed.
You should have no chatter when cutting and the headstock in the bearing area should be just warm to the touch. I have read that in neutral if you give the chuck a healthy spin it should go around about one full rotation, this should be a good starting point.

 

[Dabbler]

I check both with an IR thermometer.

 

[thestelster]

IIRC @RobinHood tried the suggested process and the result was to tight, @RobinHood correct me if my memory has failed.
You should have no chatter when cutting and the headstock in the bearing area should be just warm to the touch. I have read that in neutral if you give the chuck a healthy spin it should go around about one full rotation, this should be a good starting point.

Yeah, I read about the spin test, but that also tests your wrist strength. But, I just tried it and I get 2 revolutions.

So I think I'll tighten it a bit to get tharound that torque suggested by Standard modern, and then take temperature readings. Does that make sense?

 

[YotaBota]

Sounds like a plan. I think it's a better idea to start a bit loose and work in to the best feel.

 

[140mower]

Sounds like a plan. I think it's a better idea to start a bit loose and work in to the best feel.

..... Yes, bearings will last much longer a 'tich on the loose side rather than too tight.

 

[RobinHood]

IIRC @RobinHood tried the suggested process and the result was to tight, @RobinHood correct me if my memory has failed.
You should have no chatter when cutting and the headstock in the bearing area should be just warm to the touch. I have read that in neutral if you give the chuck a healthy spin it should go around about one full rotation, this should be a good starting point.

Yes, using the recommended pre-loading procedure in my SM1340 manual (the same one @thestelster is referring to above), made for a nice, smooth running spindle and better cut-off performance.
The bearings did get warmer than I liked and thus I backed off the pre-load by a tiny bit. This kept the bearing temp rise (and subsequently the running temp) where I like it: ~30-40*C rise for a max running temp of ~50-60*C.

@thestelster : I would take out all end play for sure.
Then I would use the looking washer and add pre-load one tooth at a time until you are happy with the bearing temperatures. Give it lots of run time before you tighten the collar more.

 

[RobinHood]

I think the reason Standard Modern (and probably many others) switched from tapered bearings at either end to a back-to-back tapered bearing in the front and a “floating” rear bearing is because of temperature related expansion issues with the spindle. If you consider a 2 foot long spindle with a bearing on either end, the amount these bearings separate with given temperature rise is much larger that in a B-t-B system with the two bearings only 1 apart (for the same temp rise). Thus, with the second bearing arrangement, it is much easier to keep the preload within a given range.

There is still a better way: design an automatic, temperature compensating pre-load system. This is usually done with a fixed front bearing(s) and a spring pre-loaded, floating, rear bearing. Both my Colchester Master and my CMT Ursus use that system.

As an aside: talked to Colchester [actually Clausing here in NA] technical department about the amount of spring pre-load. They would not give me the number, but would happily set it for me if I sent the lathe their way… I thanked them very much and did it myself by the trial and error method of starting with all end play taken up and then increasing the pre-load slowly (over many hours of operation) until I got the bearings warming up relatively quickly and stabilizing at around the 50*C mark and not going higher even during an extended period of running time.

 

[thestelster]

Ok, I tightened the nut to the next locking ring tab, and it required a bit of force with the pin spanner, (had to put an extension to the handle.)

I can get a little more than I full rotation in the wrist spin. Putting the 8oz weight at the 12" the spindle is held until I just touch it and it drops.

 

[thestelster]

I just checked end play in the same fashion as earlier, and we're down to 0.0006". I think maybe I should let it run for a while, take temperatures, and measure play at that time and decide if I need to tighten it up a tad more.

Sounds right?

I really appreciate everyone's input.

 

[Mcgyver]

You are coming at it very methodically, which is good. i wonder what the with bearing manufacture's catalogue/info has to say on it. While they are the most horrific bits of prose mankind has ever concocted, they do give lots of info on the installation of different bearing types.

My personal experience is the same as Robin's and from about 30 years ago when I didn't know my ass from a .....anyway, I did have a fantastically helpful old boy who taught me tons. Dave, English trained tool maker, was an expert in these machines and did all the service work for the the schools boards, Etobicoke, NY, Toronto, York region etc. He's also the one that taught me scraping, and did he know that topic! I ended up with SG, bandsaw, arbor press and Brown Boggs shear from the Etobicoke board through Dave for stupidly small amounts of money.

Anyway, Dave helped change spindles in my SM. We found a 4.5 MT spindle and "upgraded" so I could use 5C collets. His process was to gently tighten the nuts until there was no end play. Run the lathe, if the bearings started getting hot (hand on the relevant part of the HS), back off the nuts. Not super scientific, but he sure knew his stuff and I never had a problem with that lathe afterward. (It was a GREAT lathe I originally bought from Dave, I think it was the nicest one that he came across so kept for himself, miss the lathe....readily recognizable by the graduated leadscrew handwheel by yours truly)

 

[thestelster]

You are coming at it very methodically, which is good. i wonder what the with bearing manufacture's catalogue/info has to say on it. While they are the most horrific bits of prose mankind has ever concocted, they do give lots of info on the installation of different bearing types.

My personal experience is the same as Robin's and from about 30 years ago when I didn't know my ass from a .....anyway, I did have a fantastically helpful old boy who taught me tons. Dave, English trained tool maker, was an expert in these machines and did all the service work for the the schools boards, Etobicoke, NY, Toronto, York region etc. He's also the one that taught me scraping, and did he know that topic! I ended up with SG, bandsaw, arbor press and Brown Boggs shear from the Etobicoke board through Dave for stupidly small amounts of money.

Anyway, Dave helped change spindles in my SM. We found a 4.5 MT spindle and "upgraded" so I could use 5C collets. His process was to gently tighten the nuts until there was no end play. Run the lathe, if the bearings started getting hot (hand on the relevant part of the HS), back off the nuts. Not super scientific, but he sure knew his stuff and I never had a problem with that lathe afterward. (It was a GREAT lathe I originally bought from Dave, I think it was the nicest one that he came across so kept for himself, miss the lathe....readily recognizable by the graduated leadscrew handwheel by yours truly)



View attachment 43020

What does the handwheel on the leadscrew do?

 

[RobinHood]

if the bearings started getting hot (hand on the relevant part of the HS), back off the nuts. Not super scientific, but he sure knew his stuff and I never had a problem with that lathe afterward.

Thanks for chiming in @Mcgyver . Much appreciate your experience with all things machine maintenance / rebuilding.

I like your mentor’s thermometer: “hand on the relevant part of the HS”. That is exactly how I do it. TBH, was afraid to mention that method here for fear of not sounding scientific enough...

The human hand is a marvellous scientific instrument - one just has to keep it out of harm‘s way at all times in order to enjoy its capabilities for the longest possible time.

 

[Ian Moss]

Allows measured advancement of the carriage pre DRO.

 

[Rauce]

There was a rule of thumb about bearing housing temp and hands I was taught in millwright school.

Something like if you can keep your hand on it comfortably for more than 10s that tells you it’s less than 60C.

Regarding setting preload the only thing I’d add is that you might find that a very small amount of endplay at rest/room temp might be necessary. The spindle will warm up faster than the headstock in use and the endplay might disappear.

 

[thestelster]

Allows measured advancement of the carriage pre DRO.

Hi Ian, what does that mean?

 

[Mcgyver]

What does the handwheel on the leadscrew do?

same as the graduated dial on the cross feed screw, lets you advance the carriage along the Z. Engage the halfnuts (leadscrew in neutral) and you move the carriage exact amounts. Standard fair on some lathes, e.g. Myford. Tell you the truth, I didn't use it much after picking up a micrometer carriage stop.....but fondly remembered as one of my earliest projects. I think it came out of a Guy Lautard book.

from the earliest days of (my) digital photography.....

 

[thestelster]

I decided to tighten just a smidgen before running the lathe. And after 40 minutes of running at 425rpm, with no chuck, the running temperatures are 27°C (82°F), which seems pretty low. And the endplay is 0.0005".

I think I'll tighten a little more and run it again. Yes?