Jet mini lathe - spindle/ bearing side play?

[underdog]

What are the specs on side play of a headstock spindle of a Jet mini lathe?

I was spinning a bowl blank this evening, and couldn't get the tenon trued up. It looked fine while spinning, but then when I turned it over by hand, it was obviously not on center. I did this several times, and finally started checking things.

Since I had the blank on a worm screw in my Nova midi chuck, I checked to make sure the blank was tight against the jaws. Seemed to be - couldn't get it any tighter. Since it was seated all the way up, I checked to make sure the jaws were tight on the worm screw. I couldn't get them any tighter either. A back and forth side pull on the bowl blank revealed a "knocking" noise I couldn't pin down though. I took the blank off and the worm screw out, and thought it was the jaws clicking at first, so I took that chuck off and put another on. Same problem. REally curious (and aggravated) now, I took the chuck all the way off and checked the end play of the spindle. Not finding any play there, I pulled hard sideways on the threaded end of the spindle. Bingo! It made the clicking noise.

Now I was concerned. I loosened the belt tension, and checked again on the handwheel end. Yup. Definitely feeling motion in the spindle, I loosened the set screws in the hand wheel and tightened the hand wheel on the spindle as much as possible and re-tightened the set screws. A side pull still made the clicking noise. Durn! :mad:
I loosened the set screws in the hand wheel and the pulley and slid the spindle out. (yeah. it's that easy to change a belt!)

Close inspection revealed that the smaller bearing on the handwheel side had been "fretting" a little because the telltale rust marks were on the spindle and inner race. Still it doesn't seem that there's an appreciable amount of wear on the spindle. The bearing slides equally well on down the shaft as well as in the "wear" spot. The large bearing on the inboard end is tight on the spindle and will have to be pressed off if removed.

Subsequent measurements reveal the spindle to be about .001" smaller than the inside race of the bearing, and the bearing seems to be about .002" smaller than the hole in the headstock casting.

What are the allowable limits, and what should I do to fix this problem?

 

[waltben]

Bearings

Just replace the bearings. I've a variable speed mini and did it about four months back. It's not very difficult since the handle and collar both come off with set screws. Loosen the belt and pull out the shaft while holding onto the pulley. Use a hammer and wood block to tap out the bearings if you need to - they aren't that difficulty to get out. The bearings themselves are standard size and you can get them from Jet, off the Internet, or from an industrial supply company. May as well replace the belt if you've got it that far apart.

 

[waltben]

Might help if I read all your post!

Excuse me (haven't had my second coffee!), I gather the machined hole in your headstock is larger than the bearing? You may have the wrong size bearing at that location. The two are slightly different sizes, with one being a 6005VV (towards drive end) and the other a 6004VV (towards the handwheel). Check to be certain they are the correct size and location.

 

[underdog]

Thanks for the response.

There's no way those two bearings will interchange. The sizes are obviously different without even measuring. I'm sure the bearings are cheap, probably around $5 each.

I've not had it apart before either, so it looks like a wear problem or factory problem to me. I'd be surprised if it had worn that much, because I'm not a heavy user, and it's only a year or two old. Most of these minis will go a lot longer than that...

My bearings are the 6004RS and 6005RS, (RS = Rubber Seal). I'll call my local bearing house and see what the price is in a sec.

I'm tempted to loctite them all back in place and see if the slop goes away...

 

[underdog]

Durn! :mad:

SKF bearings:
6004RS --- $20.57
6005RS --- $23.28

Not near as cheap as I thought. The smaller bearings I replaced for in a friend's motor were a lot cheaper than these. I think it was less than $10 for both of them.

 

[Captain Eddie]

Step up

Of course you do know that you can step up in quality and put a better bearing in that spot. Check with a real bearing company and you may want to bring the lathe and spindle with you. I changed our club lathe's twice in 2 years because of abuse by demonstrators. I put a top-of-the-line set in and they have lasted about 5 years. I did the same when I changed the bearings in my woodfast. I went from about $25.00 to about $60.00 for a set, but what a set.
Standby for excellence.

 

[underdog]

Eddie,

You probably replaced those bearings because they were getting rough eh?

These are still smooth as glass. No problems with the seal either. I'm reluctant to replace them at $20 a pop, but the alternative is worse. The clearances between the bearings and the headstock/spindle seems to be the culprit in the initial lookover. Loctite looks better all the time...

I'll be putting a dial indicator on this setup this evening. I'll let you know what I find. I'll also try giving Jet a call to see if they can give me specs on the headstock bearing mount hole and spindle diameter.

 

[dkulze]

Definitely call Jet and talk to a customer service rep. I'd be surprised if you didn't have new bearings in the mail by the end of the day.

I've got an older non-VS jet with 7 years of hard use (read as abuse) on it and no appreciable wear on bearings yet. Have run into problems with the newer VS models several times, though. A friend's had the wrong spindle and so had nearly 1/8 inch of lateral play. She didn't figure it out till we were turning and couldn't eliminate chatter. Had to take it apart and shim it with washers till she could get a new spindle.

These little buggers are built to last so the kind of problems you're having after 1-2 years should concern the folks at Jet. They have a reputation to uphold, after all. If you call them, let us know how it turns out.

Dietrich

 

[Mike Gould]

For a cheap easy fix to the bearing seating in the flange. You can slide some shim stock material in the available space.

I use flat feeler gages as shimstock in a pinch. For extra security and to keep the shim in there. You can drizzle on a little thin CA just between the bearing and the flange.

I had to do this on my used Rikon Mini travelling lathe. Been a year now and no more wobble.

Good Luck,
---Nailer---

 

[underdog]

Well I did call Jet today, and the fellow in Tech Services told me to give him a ring back with the serial number and purchase date. So I'll call tomorrow with the info I wrote down this evening. Problem is that I only have the receipt for the first lathe I bought and then exchanged month or two later because of a a bad endplay knock in the headstock spindle, and a motor pulley that was not concentric with the motor shaft (and no the motor shaft was not bent). So this second lathe was essentially purchased a couple months later.

I also checked the side play (perpendicular to the axis of the spindle) this evening with a dial indicator, and it is indeed moving on the hand wheel side. I measured it at .003-.004", which is almost exactly the clearance I measured between the inner race and the spindle (.001") plus the clearance between the outer race and the headstock housing (.002").

I'll keep you posted on what happens...

 

[underdog]

I just got off the phone with the Jet Technician. He's sending me a new headstock casting and new bearings under warranty.

I didn't realize there's a two year warranty on these things...

I'll let ya know how it turns out when it gets here.

 

[underdog]

Well....

Tuesday night I put the new parts on the Jet mini, and all is back to a tight goodness.

Of course the manual is a bit vague on how tight to tighten the handwheel.

Anyone have any tips?

 

[Mr. Don]

Jet Mini

WAYULL!!!! Just shows to go ya...JET is #1 for a good reason!!! Try to get that kind of service out of Joe Blow's "save-a-buck" off brands!! I wish you MANY hours of trouble-free turning. :cool2:

 

[dkulze]

My understanding is that you tighten it to overtight (till it binds a bit) then back off 1/8 turn at a time until it spins free. Check for play at that point.

dietrich