eccentric/idler shaft issues

cml · Post by **cml** » Mon Mar 29, 2010 9:15 pm

I'm trying to get the last of my 500 issues squared away, and one thing I noticed today was that the eccentric bushing and idler shaft had "walked" out of the headstock casing by about 1/2". I loosened everything and pushed it back in, clamped down the allen screw below the bushing on the casing, fired it back up, and low and behold if the thing didn't walk right out again.

I thought I followed all the SS manuals related to replacing the idler shaft when I rebuilt the headstock, but I am clearly missing something. I cannot tighten the allen bolt much more because the idler bearing compresses and gets too hot. The poly-V belt seems aligned.

What am I missing? Is this a speed control misalignment problem? I thought I understood the high speed adjustment procedure and the high speed stop, but I'm clearly doing something incorrectly.

As I am poring over my manuals, anyone have any words of wisdom on this?

Thanks,
Chris

JPG · Post by **JPG** » Mon Mar 29, 2010 9:45 pm

cml wrote:I'm trying to get the last of my 500 issues squared away, and one thing I noticed today was that the eccentric bushing and idler shaft had "walked" out of the headstock casing by about 1/2". I loosened everything and pushed it back in, clamped down the allen screw below the bushing on the casing, fired it back up, and low and behold if the thing didn't walk right out again.

I thought I followed all the SS manuals related to replacing the idler shaft when I rebuilt the headstock, but I am clearly missing something. I cannot tighten the allen bolt much more because the idler bearing compresses and gets too hot. The poly-V belt seems aligned.

What am I missing? Is this a speed control misalignment problem? I thought I understood the high speed adjustment procedure and the high speed stop, but I'm clearly doing something incorrectly.

As I am poring over my manuals, anyone have any words of wisdom on this?

Thanks,
Chris

The setscrew is intended to center the bearing in the eccentric sleeve. It should not be tightened excessively(puts too much pressure on the bearing).

The eccentric sleeve is retained by a bracket that spans the sleeve and is held in place by a bolt running through the casting under the sleeve bore. Later models used a screw and washer to hold the outer end in the casting.

A pix of this area of your unit would be helpful.

The bracket(s) have a longer finger on the outboard end.

cml · Post by **cml** » Mon Mar 29, 2010 9:47 pm

Well, I may have found my problem - There is a hole in the headstock casing directly above the eccentric bushing which looks like it may be designed to hold a retaining bolt and washer, which would prevent the idler shaft from walking out. I can't seem to find this on the exploded view in shopsmith's service catalog, though, all I see is the smaller hex head retaining screw.

So, is this my missing part? Anyone know what the dimensions of the bolt/washer are?

JPG · Post by **JPG** » Mon Mar 29, 2010 9:53 pm

cml wrote:Well, I may have found my problem - There is a hole in the headstock casing directly above the eccentric bushing which looks like it may be designed to hold a retaining bolt and washer, which would prevent the idler shaft from walking out. I can't seem to find this on the exploded view in shopsmith's service catalog, though, all I see is the smaller hex head retaining screw.

So, is this my missing part? Anyone know what the dimensions of the bolt/washer are?

10-24 x 3/4, common 3/16" flat washer. BTW 10-24 =====3/16-24.

Are there also 'casing' ears with holes below the sleeve bore. A bolt through them serves to squeeze(gently here) the 'casing' bore around the sleeve.

cml · Post by **cml** » Mon Mar 29, 2010 9:54 pm

JPG: Here's a pic

JPG · Post by **JPG** » Mon Mar 29, 2010 10:06 pm

cml wrote:JPG: Here's a pic

yes the tapped hole at the top is supposed to have the bolt and washer. the bolt underneath should be snugged up(do not overtighten as the ears may break). I do not recognize the 1/4" bolt head at the bottom, nor do I understand its purpose. The screw/washer at the top is supposed to retain all this.

Nice paint job!!!!!

BTW That is not the correct coupler on the main shaft!

charlese · Post by **charlese** » Mon Mar 29, 2010 10:24 pm

JPG40504 wrote:... I do not recognize the 1/4" bolt head at the bottom, nor do I understand its purpose. The screw/washer at the top is supposed to retain all this.

Looks like he has a newer eccentric. There is a tapped hole in the eccentric itself. This is to keep the eccentric from creeping into the headstock.

With these two holding screws, there is less need to over tighten the lower bolt through the case wings.

JPG · Post by **JPG** » Mon Mar 29, 2010 10:34 pm

charlese wrote:Looks like he has a newer eccentric. There is a tapped hole in the eccentric itself. This is to keep the eccentric from creeping into the headstock.

With these two holding screws, there is less need to over tighten the lower bolt through the case wings.

Ah so! Still not too old to learn!

cml · Post by **cml** » Mon Mar 29, 2010 10:52 pm

Thanks for the info! Yes, it is a newer eccentric with the tapped hole. I'll grab a 10/24 bolt and washer tomorrow and test it out. Everything makes much more sense now. :-)

Thanks also for the tip on the coupler. I have some that are rings and some that are caps like the one in the pic above, and I haven't really determined which is which.. the one above seemed to be the correct one to connect the power coupler to the air compressor I have.

The paint is rustoleum hammered green. I had a friend of mine bead-blast the casing, then I sprayed it down. It turned out well, I'm quite happy with it! My plan is to polish up the way tubes and get the bottom frames powder coated.

-Chris

JPG · Post by **JPG** » Tue Mar 30, 2010 2:06 pm

cml wrote:Thanks for the info! Yes, it is a newer eccentric with the tapped hole. I'll grab a 10/24 bolt and washer tomorrow and test it out. Everything makes much more sense now. :-)

Thanks also for the tip on the coupler. I have some that are rings and some that are caps like the one in the pic above, and I haven't really determined which is which.. the one above seemed to be the correct one to connect the power coupler to the air compressor I have.

The paint is rustoleum hammered green. I had a friend of mine bead-blast the casing, then I sprayed it down. It turned out well, I'm quite happy with it! My plan is to polish up the way tubes and get the bottom frames powder coated.

-Chris

There are four(yes there are variations, but these are the basic ones) versions of coupler hubs.

The one for the upper output shaft is long with an extended hub that is smaller than the splined portion. The smaller hub end goes on the shaft towards the headstock.

The one for the lower(center/idler) shaft has a closed end. It can only be inserted on the shaft one direction.

Both these hubs have 4 (four) splines and are mated to the end of the coupler that has the spring.

There are two types of SPT hubs that differ in bore size. The 1/2" is for the jointer,jig saw, and compressor(?) [Scroll saw??] Most all the other SPT's take the 5/8" hub. Both these have 5 (five) splines.