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Acceptable Spindle Bearing Freeplay?

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I'm not sure if I noticed because of Glenn's recent thread with his Nova 1624 but I recently noticed a bit of freeplay in both of the spindle bearings on my Jet 1221SP.

While squaring up an off-balance bowl blank I heard and felt some clunking through the workstand so I took off the bowl/faceplate and loosened the drive belt. For both the spindle and the handwheel, I get a clunk up and down as well as front to back. I don't have a good way to measure it but it's pretty obvious/easy to see and hear.

The lathe is about 6 months old but I have used it a lot. I would estimate that I've turned well over 100 projects on it and, as my first lathe, you can correctly guess there has been some rough use, tool catches and even a couple spinning pieces prematurely ejected.

So, should there be any easily detected freeplay in the spindle bearings? The lathe has roller bearings that are not adjustable.
 

Bill Boehme

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Is there enough movement that you can see it?

When you turn the spindle slowly by hand (belt still removed) can you hear any faint clicking or scraping sound?

Have you done anything that might damage the bearings ... a prime example is applying heavy tailstock pressure?
 

odie

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When you turn the spindle slowly by hand (belt still removed) can you hear any faint clicking or scraping sound?

......or, feel any lack of smoothness when you rotate the spindle, for that matter?

How much play is acceptable, you ask.........none, zip, zero, nada! :D

I suspect there may be more to this story, than normal learning consequences of a new turner. Have you checked for runout of the spindle? It is possible the spindle isn't perfectly straight, or even flawed bearings right from the git-go.....! It's hard to conceive of bearings wearing out on such a new lathe.

Anything that interferes with a perfectly smooth rotation is going to result in hindering your ability to get the most perfect cut possible. Bearings that do not rotate as they should are only one component in that equation that will act on this. There is almost never a piece of wood that is perfectly balanced, and that, along with resistance to the cut with long grain and end grain, the perfect RPM.......and the skill of applying a sharp tool......are all things that have to act in harmony to get that ever elusive "perfect cut". Bad bearings is a handicap that will prevent what is possible......no matter how good everything else is working for you! :eek:

-----odie-----
 
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How much play is acceptable, you ask.........none, zip, zero, nada! :D

No, that's not quite correct. All lathes have some acceptable amount of end play. The question is, how much is acceptable?

If a lathe like the Jet has ANY end play or up/down looseness that's visual without precision measuring equipment that certainly would not be acceptable. If you're still within warranty send it back (easier said than done, especially given our current virus situation). If not still in warranty, non-adjustable bearings can be relatively easy to change unless they've used shims to achieve acceptable end play. Unfortunately, you're somewhat screwed either way.
 

john lucas

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Not sure about the 1221 but the jet minis can get sloppy if the handwheel.comes loose. I would loosen the set screws on the handwheel and then tighten it. It might be left hand thread. If it tightens up and stops your spindle play your good to go.
 
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......or, feel any lack of smoothness when you rotate the spindle, for that matter?

How much play is acceptable, you ask.........none, zip, zero, nada! :D

I suspect there may be more to this story, than normal learning consequences of a new turner. Have you checked for runout of the spindle? It is possible the spindle isn't perfectly straight, or even flawed bearings right from the git-go.....! It's hard to conceive of bearings wearing out on such a new lathe.

Anything that interferes with a perfectly smooth rotation is going to result in hindering your ability to get the most perfect cut possible. Bearings that do not rotate as they should are only one component in that equation that will act on this. There is almost never a piece of wood that is perfectly balanced, and that, along with resistance to the cut with long grain and end grain, the perfect RPM.......and the skill of applying a sharp tool......are all things that have to act in harmony to get that ever elusive "perfect cut". Bad bearings is a handicap that will prevent what is possible......no matter how good everything else is working for you! :eek:

-----odie-----
No, that's not quite correct. All lathes have some acceptable amount of end play. The question is, how much is acceptable?

If a lathe like the Jet has ANY end play or up/down looseness that's visual without precision measuring equipment that certainly would not be acceptable. If you're still within warranty send it back (easier said than done, especially given our current virus situation). If not still in warranty, non-adjustable bearings can be relatively easy to change unless they've used shims to achieve acceptable end play. Unfortunately, you're somewhat screwed either way.

I have to agree with a Odie. Non, nada!
 
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I have to agree with a Odie. Non, nada!

Okay, you can disagree with me all you want. Practical experience tells you're wrong though.

When I had the bearings replaced in one of my lathes 30 years ago it cost $1800 plus the bearing's cost. From the certification included when the headstock was returned they indicated the new bearings had an end play of less than 50 millionths. Granted that's a very small amount, still end play though. 50 millionth end play was what that lathe manufacturer considered acceptable.

Read the first sentence of my reply again. It's about what is considered acceptable. There are no lathes in the world without end play.
 

odie

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I have to agree with a Odie. Non, nada!

You know, Glenn.......as I consider this, and try to see it from a general perspective, rather than from my own exclusively.........this whole thing about "acceptable play" in spindle bearings, may have relevance to individual requirements. There is no question that some turners don't give much priority to the finest cut they can possibly make. For those, the availability of power sanding components make giving the kind of effort required to eliminate sanding less of a priority than those who seek to have finely executed details.

There really isn't any right or wrong in the thought behind this discussion.......we all have our priorities, and understand what is required for the execution of the work we each individually pursue. :D

-----odie-----
 

odie

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Okay, you can disagree with me all you want. Practical experience tells you're wrong though.

When I had the bearings replaced in one of my lathes 30 years ago it cost $1800 plus the bearing's cost. From the certification included when the headstock was returned they indicated the new bearings had an end play of less than 50 millionths. Granted that's a very small amount, still end play though. 50 millionth end play was what that lathe manufacturer considered acceptable.

Read the first sentence of my reply again. It's about what is considered acceptable. There are no lathes in the world without end play.

Hi Doug.......I see we were typing at the same time.

Question for you:

When you say "end play" are you discussing play along the axis of the shaft, or radial play?

I would consider radial play more destructive to our purposes as turners, than axial.

Also, if we are discussing millionths of an inch play, then I think you may be correct about that.......If you are able to physically detect the play in the bearings, then it's too much for a turner's perspective.

-----odie-----
 
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I mentioned end play, axial play, down the axis of the spindle. If the problem is worn out bearings there could be a direct correlation between the radial and axial play for ball bearings. The way end play is usually measured is by exerting a force on the front of the spindle and precisely measuring the amount of movement at the rear of the spindle. Likewise radial play could be measured by prying up on the front of the spindle.

Spindles can also have run out. Like when the internal taper or threads of the spindle are not machined concentric with the bearing mounts on the spindle. These would be fairly likely on inexpensive lathes.

As an extreme example I mentioned millionths of an inch. That just happens to be one high precision lathe manufacturers definition of acceptable. Jet's definition of acceptable on a wood lathe would allow far more end play. The OP implied he can visually observe end play, by anybody's standard that would be excessive needing a fix.

My guess is Jet uses a common grade of bearings, nothing precision as bearings go and easily accessible by mail order from online bearing suppliers.
 
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I changed bearings on a fairly new lathe because a bearing heated up and had a flat spot on a roller that created a ticking-thumping noise, and destroyed the grease seal. I think the preload was incorrect at the factory. Preload on my lathe bearings was set with a locking collar tightened on a wave washer and it has run perfectly after the repair.

https://www.nationalprecision.com/library/articles/bearing-preload.php
 
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One quick correction, the lathe has a pair of single row ball bearings, not roller bearings as I typed originally.

I have also sent a message to Jet asking what is acceptable play in the bearings. We shall see if they come back with a number. Although, since I don't have a dial indicator or good way to measure I can only guess. Perhaps the upcoming stimulus payment will have to fund a dial indicator. Since any warranty repair requires return of the machine, I'm most likely on my own with this if any action is required. A pair of new bearings is well under $100. If required, I should be able to swap them out.

Is there enough movement that you can see it?

When you turn the spindle slowly by hand (belt still removed) can you hear any faint clicking or scraping sound?

Have you done anything that might damage the bearings ... a prime example is applying heavy tailstock pressure?

Bill, movement is visible but only just so with my aging eyes. I will have another look today for clicks, scrapes or bearings that go bump in the night.
As far as tailstock pressure, I have wondered all along what excessive tailstock pressure is. I do set the centers in work on the bench with a hammer before mounting them on the lathe but I have certainly used the tailstock to run drills and forstner bits into work. I do recall another thread where the manufacturer tech said a lathe is not a drill press or something to that effect. From the start I have been mindful of tailstock pressure but have seen others way more heavy-handed than I so I don't know if that's a factor.

Being a relative novice you should take my perspective as such but the 1221 is a very basic machine. I am already pushing its limits and wondering when I can step up. I strongly suspect that most of the bigger machines used by the more experienced folks among you have much stronger, tighter spec bearings and such.
 
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I changed bearings on a fairly new lathe because a bearing heated up and had a flat spot on a roller that created a ticking-thumping noise, and destroyed the grease seal. I think the preload was incorrect at the factory. Preload on my lathe bearings was set with a locking collar tightened on a wave washer and it has run perfectly after the repair.

https://www.nationalprecision.com/library/articles/bearing-preload.php

Interesting link. I know you have to properly preload tapered bearings. Didn't think it applied to ball bearings. I do believe, if applicable, this would be achieved with the hand wheel, which threads on and is secured with a grub screw.
 
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I mentioned end play, axial play, down the axis of the spindle. If the problem is worn out bearings there could be a direct correlation between the radial and axial play for ball bearings. The way end play is usually measured is by exerting a force on the front of the spindle and precisely measuring the amount of movement at the rear of the spindle. Likewise radial play could be measured by prying up on the front of the spindle.

Spindles can also have run out. Like when the internal taper or threads of the spindle are not machined concentric with the bearing mounts on the spindle. These would be fairly likely on inexpensive lathes.

As an extreme example I mentioned millionths of an inch. That just happens to be one high precision lathe manufacturers definition of acceptable. Jet's definition of acceptable on a wood lathe would allow far more end play. The OP implied he can visually observe end play, by anybody's standard that would be excessive needing a fix.

My guess is Jet uses a common grade of bearings, nothing precision as bearings go and easily accessible by mail order from online bearing suppliers.

I have not as of yet tried to observe end play. This may be simply adjusted via the threaded hand-wheel. I have casually looked for but not detected any spindle run out. Once again however, I do not have a tool to measure. Probably time to buy a dial indicator.
Yes, the Jet appears to use common grade single-row ball bearings. I think they are 6004vv and 6005vv. These numbers may be wrong from my short term memory but it is easily available in their manual. VV is a no-contact rubber seal.
This is an inexpensive lathe and perhaps some play that is not ok in higher end machines may be totally normal here. I'm hoping Jet will give a spec to answer that.
 
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Not sure about the 1221 but the jet minis can get sloppy if the handwheel.comes loose. I would loosen the set screws on the handwheel and then tighten it. It might be left hand thread. If it tightens up and stops your spindle play your good to go.

If this is the solution, it's simple and free. I like it. As I stated in reply to Ron above, I never considered preloading being applied to ball bearings. It is a reverse threaded hand wheel with a grub screw.
 

Bill Boehme

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If this is the solution, it's simple and free. I like it. As I stated in reply to Ron above, I never considered preloading being applied to ball bearings. It is a reverse threaded hand wheel with a grub screw.

I have a Jet 1014 mini lathe which is a predecessor to the 1221 so I would guess that there are some design similarities. As John Lucas said, you could indeed take out axial play in the spindle of older Jet lathes. I suspect that the same applies to the 1221. Check the owners manual for details. Basically, on the 1014 you loosen the setscrews (IIRC, there are two setscrews) on the handwheel and as John said, my recollection is also that it has LH threads. While holding the spindle so that it doesn't rotate, gently tighten the handwheel until you can't feel any axial play. Do not tighten it any more than that because additional preload will just result in the bearings running hot and wearing out the bearings at an accelerated rate. When done don't forget to tighten the setscrews on the handwheel.

Engineers cringe when hearing absolute terms (perfect and zero, for example) that woodturners bandy about as if they were factual. Doug is correct from a technical perspective that bearings have some degree of free play between inner and outer races. The only bearings that don't have any free play are those that have worn out and seized up. To a non-technical woodturner, if you can't see it then it doesn't exist.

My first lathe, a Delta 1440 Iron Bed Boat Anchor had a bent spindle right out of the box. Even though I was a greenhorn beginner I knew that something wasn't right, so nobody needs to convince me that bent spindles do exist.
 

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Engineers cringe when hearing absolute terms (perfect and zero, for example) that woodturners bandy about as if they were factual.
Mathematicians too but the applied mathematicians are more accepting
as their job is getting the wrong answer fast.

You will not see any spheres in nature. But we try to turn them anyway
 
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Following up,
Adjusting the end-play/preload with the handwheel seems to have resolved the issue.
As a few of you helped to deduce, there are two grub screws on the handwheel and a very small adjustment to the handwheel took out the play. I don't want the bearings to be overly tight in case it tightens up when it heats up so I left it with the smallest amount of play that I could feel. I will see what happens to that play after running it for a bit and adjust accordingly.
The bearings feel fine. No roughness or bumps when rotating the spindle.

Also, the spindle runs as true as can be. With the tool rest almost touching the spindle, I can see no change in clearance as I rotate it. Same is true with my G3 chuck mounted. With the tool rest almost touching the chuck body, I can see no change in clearance as I rotate the spindle.

Thanks everyone!
 
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I have an older Jet Mini that the hand wheel screws on and is set in place by a set screw. The set screw apparently came loose and the hand wheel then tightened and caused the spindle to turn hard and be very noisy. The lathe is not used much and the problem was corrected before any damage to the bearings. If the lathe you have is set up similar and used for an extended period of time that way then it would probably cause premature failure of the bearings. The tailstock pressure alone should not cause bearing failure, after all it is a lathe it should be able to with stand that pressure. If you can find a parts diagram of the headstock you should be able to determine how to get the spindle and bearing out then look on the bearing outer race or the shield for the number of the bearing, which I would bet is an industry standard part.
 

Bill Boehme

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The tailstock pressure alone should not cause bearing failure, after all it is a lathe it should be able to with stand that pressure.

It's not really the lathe, but single row radial bearings that must take the brunt of axial loads. Single row radial bearings are designed for radial loads and only support light to moderate axial loads without deforming. Besides, there's no reason to apply heavy axial loads ... although I see people doing it all the time. That's one example of why I don't loan my good tools to anybody.
 
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Now that I've learned, with the help of the group, how simple it is to adjust my spindle bearings, I have received an answer from Jet tech folks.

"Good morning,

You should not have any play in your bearings for this unit.You may need to get this unit over to the closest service center to you. Please visit jettools.com to find the closest service center near you.

Thank you for your inquiry.

JPW Industries Technical Service
..."
 
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Now that I've learned, with the help of the group, how simple it is to adjust my spindle bearings, I have received an answer from Jet tech folks.

"Good morning,

You should not have any play in your bearings for this unit.You may need to get this unit over to the closest service center to you. Please visit jettools.com to find the closest service center near you.

Thank you for your inquiry.

JPW Industries Technical Service
..."
Boy jet just opened a can of worms now, 50 millions of an inch is not acceptable to even them!!
 
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