"Drive Belt Alignment

[mtseabee]

I'm new to site, so if there are any mistakes on my part, apologies in advance! Now, for the first question - my machine is around 15 years old, bought it from my brother along with belt sander attachment, band saw, vacuum system and other items. Anyway, since I've had the setup the drive belt (think it's called the Poly-V belt?) has been out of alignment between the top and bottom grooved pulley. I should have snapped a picture so you can see what I'm talking about, but you more experienced users would probably know what I'm talking about! How to fix it and is it a big worry?

[solicitr]

Yeah, that's not good. Not only will it lead to premature belt wear, it will put abnormal strain on the bearings and shorten their life. You need to take the tension off by rotating the eccentric bushing, and then work the belt over to vertical.

This is covered well in Nick's video: http://www.shopsmithacademy.com/SS_Arch ... _Belts.htm

[billmayo]

The Poly-V belt should have 2 grooves showing on each side of the belt on the top pulley of the Drive Sleeve Assembly. If not, you can shift the belt to the correct grooves when the eccentric bushing slot is down as described in the next paragraph. There should be a spiral type spring ring holding the back bearing on this shaft in place in the headstock housing. Therefore only the bottom pulley (middle shaft) on the idler shaft can be moved to align the Poly-V belt if needed.

I included a picture of the headstock end. There is an eccentric bushing bolt under the idler shaft end that needs to be loosen. Rotate the eccentric bushing with a narrow blade screwdriver until the cutout slot is straight down. There should be a 5/32" set screw in the bottom of the eccentric bushing. If the end of the eccentric bushing and the idler shaft bearing are not even with each other, loosen the set screw and make the bearing end and eccentric bushing end be even with each other and lightly tighten the set screw. With the back of the eccentric bushing and bearing even with the back surface around the eccentric bushing, rotate the eccentric bushing CW with a narrow blade screwdriver until the Poly-V belt has a deflection of 1/8"-1/4" when pressing hard on the belt. Using the 12" sanding disk, rotate the quill shaft and looking down from on top, see how the Poly-V belt aligns. By moving the eccentric bushing in or out, you can align the Poly-V belt on both pulleys to where the belt has no side deflection. Once this is done, check the belt tension again and if OK, then tighten the eccentric bushing bolt to about 20-25 in pds. I find that holding an "L" allen wrench by the short part with only two fingers, tighten this bolt does this. I normally find that with the eccentric bushing, bearing and back of the headstock lined up together, the belt will aligned on the pulleys.

I would recommend you order a DVD or VHS tape from Jacob Anderson on Repairing your Shopsmith Headstock and Repairing the Shopsmith Motor for ($29.95 + $3.00 shipping) email at jacobvb@yahoo.com or from Ebay (jacobvb_the_s_smith_doc) item #120269662141. These are excellant for learning how to repair your Gilmer and Poly-V headstocks and 4 different types of Shopsmith motors. Even through I have repair many headstocks and motors, I got the DVDs from him and review them again before working on a headstock or motor.

I'm new to site, so if there are any mistakes on my part, apologies in advance! Now, for the first question - my machine is around 15 years old, bought it from my brother along with belt sander attachment, band saw, vacuum system and other items. Anyway, since I've had the setup the drive belt (think it's called the Poly-V belt?) has been out of alignment between the top and bottom grooved pulley. I should have snapped a picture so you can see what I'm talking about, but you more experienced users would probably know what I'm talking about! How to fix it and is it a big worry?

[mtseabee]

Thanks for the information, but after reading your reply, I realize that the belt that I meant is the Gilmer (?) belt at the headstock end of the quill. At that location the belt is off of the grooved pulley by one or two ribs. I've worked on the lower V belt a few times and it seems fine, but the Gilmer belt has me concerned that I am putting undue pressure on the quill by having it out of alignment.

Again, to all, thanks for the help, and I will be checking into this site very often.

[solicitr]

I think Bill M gave you the right advice. If you have a grooved top pulley you have a poly-V belt (the Gilmer or cogged belt is only found on old green or gold Mk V's). This is the upper belt, the wide one that runs from the idler shaft to the main (top) spindle.

[nuhobby]

Hi,

There are instructions for replacing the Poly-V belt at:
http://www.shopsmith.com/ownersite/prod ... cement.pdf

Page 4 tells that there are 2 different setups for which grooves to lay the belt in, on the drive sleeve (upper) assembly. The older machines are for instance the "B" headstock / "removable nameplate" with older-style metal toggle switch. The newer machines are the "C" headstock / "pivoting nameplate" with the red-plastic-guard style switch.

Good luck,

[SDSSmith]

As I recall on the gilmer drive, the misalignment with the control sheave can be caused if the control sheave is not positioned correctly in the eccentric bushing. Or, there are a couple of keepers that position the eccentric bushing (and control sheave), and if installed backwards could affect the alignment of the gilmer belt to the control sheave. The instructions cited earlier also cover the gilmer belt (here is the link again).
http://www.shopsmith.com/ownersite/productmanuals/PolyV_GilmerBelt_Replacement.pdf

Good luck.