Machine pulley wobble issue

[BMD]

Hi everyone

I recently bought an old Seiko LSC 8BV machine with servo motor and just noticed that there is a wobbling motion in the machine pulley.  I.e. if you look at the machine pulley while sitting at the machine and then run the machine the pulley doesn't spin 100% straight, it wobbles quite a bit. 

I tried taking the belt off and turning the machine pulley by hand and I can still see/feel the wobble.

Any idea what this could be and how I can adjust/fix it?

Thank you!

Edited May 19, 2020 by BMD

[CowboyBob]

It will need to be straightend IF you want to get the wobble out,I've done alot of them over the yrs BUT it really won't hurt to run it that way.You would have to turn it around & find the high side,take the handwheel off & put a pipe on it 2 meters or so long with an inside diameter close to  the shaft & give it a good push.Then put the handwheel back on &give it a few spins & see how it looks & keep doing this until it's straight.

[BMD]

Thanks for your reply and advice. What causes the wobble? Is it just wear and tear? What part actually needs straightening, the shaft and can I not just replace that?

The wobble is transferred to the servo motor. I.e. I can see the wobble in the servo pulley too and I'm concerned it will damage the motor. Or do you think it's fine?

[Constabulary]

post a video if possible.

hand wheel / pulley wobble is either a bent shaft or hand wheel / pulley it self. Probably because of an accident or mishap during shipping / handling.

if it is just the hand wheel I would guess one of these could be a placement:

https://www.ebay.com/itm/V-BELT-DRIVEN-PULLEY-WHEEL-INDUSTRIAL-SEWING-MACHINE-Juki-Brother-15mm-shaft/132487025827

https://www.ebay.com/itm/INDUSTRIAL-SEWING-MACHINE-V-BELT-DRIVEN-PULLEY-WHEEL-BIG/132486870387

Edited May 20, 2020 by Constabulary

[BMD]

Heres a link to the video. At the end when I am spinning the machine pulley by hand is after I loosened the screws that hold the hand wheel to the shaft. I.e. the pulley/hand wheel is not driving the shaft. Seems like it is not the hand wheel to me.

Are there any other areas that could be adjusted that might fix and if not what do I need to replace? If anything at all. 

Will I damage the machine/servo if I continue as is? 

 

[RockyAussie]

I would be following the advice as Bob Kovar advised above. As long as the pipe is a fairly close fit to the shaft it will work quite easily pushing downward.

[MikeRock]

After 35+ years in a machine shop, Bob's advice is right on the money.  Rocky's comment is spot on as well.  At some time the machine either fell over or was hit in some way.  That shaft is certainly not hardened material and a close fitting pipe will do the trick.  Take it slowly.  You will be surprised how easy this is to bring down to manageable levels if not a perfect fix.   If you have a buddy with a magnetic base dial indicator you could get down to within a few thousandths quickly.  Do NOT smack the shaft with a lead mallet just yet. 

[BMD]

Thanks Mike. How strong is the shaft. I.e. is there any risk of it snapping?

[MikeRock]

When you take the pulleys off you will get an idea of how the holes intersect the bent area.  There might be some risk of breakage, but it bent out of alignment once, bending it back should carry no greater risk of breakage.  When you go to bend it back, put the shaft in position so you will be pushing straight down on your bending pipe.  That position will be the safest.  Post some photos after you take off the pulleys.

God bless

[BMD]

 

Edited May 20, 2020 by BMD

[BMD]

Do I need to take anything else off? I assume i need to bend only that small section of the shaft that is sticking out?

[dikman]

If you can make a very simple jig to just touch the shaft you should be able to see where the bend is by rotating it.