Shopsmith Forums

Last fall while cleaning and oiling my 40 year old Mark V, I noticed the Poly-V belt was fraying. I ordered new belts from Shopsmith and last week got around to changing both belts. It didn't go as quickly or easily as I hoped, but I got it done. The Poly-V belt was a little shorter than my old one, but I attributed that to years of use.
It was a tight fit getting the Poly-V sheave back in, but I thought things were fine. When it was all together, I found tried turning it with the disc sander and it was really stiff. I flipped the switch while turning the disc and it was able to turn. I ran it for a few minutes then turned it off.
It still won't start without help.
I have the eccentric bushing at the 6 o'clock position. Is there any way to loosen the belt? Has anyone else run into this problem. I searched the board, but didn't find this topic.
Any help would be appreciated.
Rex

Is the poly-v belt running perpendicular to both shafts? How many empty grooves on the inner end of the drive sleeve pulley?

JPG wrote:Is the poly-v belt running perpendicular to both shafts? How many empty grooves on the inner end of the drive sleeve pulley?

Well I thought they were, but after your post, I looked closer and they aren't perfectly perpendicular.

Start with the eccentric and retaining washer and screw. Use an oversize fender washer to prevent them from moving out of the headstock.

See illustrations

Everett

everettdavis wrote:Start with the eccentric and retaining washer and screw. Use an oversize fender washer to prevent them from moving out of the headstock.

See illustrations

Everett
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Tracking Off - Check Eccentric and washer retaining it and bearing.jpg

Here's my eccentric ring and retaining screw.



I'll find a larger washer and try to get things back where they belong, but the end of the Poly-V Sheave is up against the quadrant, so I don't think it can go back further.
Did I do something else wrong on the installation?
Rex

It went really easily this time around. I got everything lined up straight. The spindle spun freely. I didn't turn the eccentric ring because even in the down position, there was minimal deflection with pushing on the belt.
When I turned it on, it spun on it's own, but never got up to full speed before tripping the circuit breaker.
It is in the fast position. Should I turn it by hand and move to the slow position then try it again?
It was running perfectly before I started this.

Yes, always start on the slower end of the range, especially if you are using an extension cord or a 15 amp circuit.

Hoooookaaaay, gotta ask a couple of questions.

Which version of the idler shaft do you have?(1)

Is the eccentric the proper one for the idler shaft?

(1) is it a single long(water pump bearing) or a shaft with two typical ball bearings and a spacer.

In any event, there should NOT be a bearing external to the eccentric. I suspect the idler shaft extends too far towards the 'rear'.

I also question the positioning of the poly-v pulley on the drive sleeve too far towards the 'rear'(again).

Good eyes JPG!

I adjusted the eccentric and put on a larger washer. I rolled the controller back to slow and started the machine and no problems with the the speed. I moved it up to mid-range and let it run for ten minutes. Now it starts fine.

I don't know what version of idler shaft it is, but I believe it was made in the 70's. I bought it in 1983.

Now that is is up and running again, I have one new issue. At low speed there is a new noise. It sounds like a grinding sound. It seems to come from either the idler shaft or the lower sheave. It disappears by c or d speed.

I've oiled the sheaves. I made a video but couldn't seem to embed it.

https://youtu.be/Y9ISc52_CEM

I really appreciate all your help