Power Pro Aux shaft

texomawood · Post by **texomawood** » Sun Jun 16, 2013 4:22 pm

I've had my PowerPro Mk V for a little over a month now so I thought it was time to take the end cover off and blow it out as I had been doing a lot of work with it. Everything came apart fine, but I did notice a little rub of the lower aux shaft collar on the silver screen cover. When I was looking at the lower shaft it appears that it is shifted into (toward) the headstock about 1/8 to 3/16 of an inch. The drive belt on that shaft appears to be at an angle too. Has anybody notice that before? Could that shaft shifted in the housing? It appears to be held in place by to screws that clamp down on a ring which holds it in place.
I will call Shopsmith on Monday but would like to know what you all think. Also the lower hub had a crack in it where the set screw goes thru.

SDSSmith · Post by **SDSSmith** » Sun Jun 16, 2013 4:30 pm

If you bought a complete headstock, I have heard of other users having the high speed shaft pushed into the PowerPro headstocks during shipping.

wa2crk · Post by **wa2crk** » Sun Jun 16, 2013 8:52 pm

Hi Tex;
I agree with SDSSmith. That shaft can be pushed in during shipping. However, the cracked hub should be returned to SS for a replacement.
Also I have had both of the shaft hubs loosen on my PP and I had to put a little blue LocTite on the screw to keep them from loosening.
Bill V

redleg · Post by **redleg** » Sun Jun 16, 2013 8:58 pm

I believe you are speaking of item number 83 p. B 7 & 8 (Idler Shaft Assembly) in the Power Pro Mark 7 Instructional Manual. A couple months after receiving my Power Pro I was using it and smelled burning rubber. I pulled the end cover to see what the cause was and found as you did the idler shaft had moved in but mine to the point that the lower poly v belt (large) was rubbing against the motor housing. You probably should call Shopsmith and let them know the problem. I followed the procedure on p. E 6 &7 on Balancing The Belt Tension. Be aware of the warnings and cautions on those pages. Especially the one about over tightening the bolt holding the eccentric in the headstock casting. I have seen this notice from others on the forum of older Mark V's and have not experienced it myself with the Mark V. However I have seen broken ears on at least two of the clone Total Shop models that came to my shop for repair. I would suppose Shopsmith would use a torque value in initial setup but I haven't see one posted.

JPG · Post by **JPG** » Sun Jun 16, 2013 11:17 pm

redleg wrote:I believe you are speaking of item number 83 p. B 7 & 8 (Idler Shaft Assembly) in the Power Pro Mark 7 Instructional Manual. A couple months after receiving my Power Pro I was using it and smelled burning rubber. I pulled the end cover to see what the cause was and found as you did the idler shaft had moved in but mine to the point that the lower poly v belt (large) was rubbing against the motor housing. You probably should call Shopsmith and let them know the problem. I followed the procedure on p. E 6 &7 on Balancing The Belt Tension. Be aware of the warnings and cautions on those pages. Especially the one about over tightening the bolt holding the eccentric in the headstock casting. I have seen this notice from others on the forum of older Mark V's and have not experienced it myself with the Mark V. However I have seen broken ears on at least two of the clone Total Shop models that came to my shop for repair. I would suppose Shopsmith would use a torque value in initial setup but I haven't see one posted.

A good indicator is the split lock washer. Tighten until it is just barely squeezed flat. Courtesy Bill Mayo!;)

billmayo · Post by **billmayo** » Sun Jun 16, 2013 11:40 pm

I remember seeing in some Shopsmith document that 20 in. pds was the required torque on the eccentric bushing bolt. I believe 20 ft. pds would be more correct. Yes, thanks JPG, I found that 20 ft. pds would just flatten the lock washer. I recently hauled a few headstock casings to the salvage yard, good price for aluminum, where the one of the ears holding the eccentric bushing was broken off. WARNING: I have found that the bolt alone will not hold the Idler Shaft bearing from coming out the end of the headstock in a short period of time. I found a 3/4" washer or clamps ("A" headstock) are needed to hold the Idler Shaft bearing. Does the PowerPro headstock use a washer as the bearing retainer as I got the idea that they was using set screws from prior posts?

JPG · Post by **JPG** » Mon Jun 17, 2013 12:08 am

billmayo wrote:I remember seeing in some Shopsmith document that 20 in. pds was the required torque on the eccentric bushing bolt. I believe 20 ft. pds would be more correct. Yes, thanks JPG, I found that 20 ft. pds would just flatten the lock washer. I recently hauled a few headstock casings to the salvage yard, good price for aluminum, where the one of the ears holding the eccentric bushing was broken off. WARNING: I have found that the bolt alone will not hold the Idler Shaft bearing from coming out the end of the headstock in a short period of time. I found a 3/4" washer or clamps ("A" headstock) are needed to hold the Idler Shaft bearing. Does the PowerPro headstock use a washer as the bearing retainer as I got the idea that they was using set screws from prior posts?

I am not aware of any casting changes for the power pro(any casting can be 'upgraded' including an "A" headstock).

I believe all past references to set screws were to the cogged pulley on both the upper and the idler shaft. Make that poly-v!!!!!!

nuhobby · Post by **nuhobby** » Mon Jun 17, 2013 4:00 am

Going back a few years to some rebuilds I did, I had used a small torque wrench, to about 20-30 inch-lbs of torque, which does flatten the washer nicely.

charlese · Post by **charlese** » Mon Jun 17, 2013 9:09 pm

There are two bearings on the idler shaft of the PowerPro. Both are held by the eccentric. When the idler shaft get pushed in or works it's way in, the inner bearing is no longer firm in the eccentric. The inner bearing may be held by only half (or less) of it's width. I did not like to see this condition. Guess it could even get worse to make the belt rub on the motor.

Anyway a upper/lower belt adjustment is warranted. I have never used a torque wrench on the screw that tightens the eccentric, but it is safe to say that more torque has been used than needed to compress the lock washer. Yes, I grit my teeth and hold my breath trying to judge that torque.

So far no broken ears.

billmayo · Post by **billmayo** » Mon Jun 17, 2013 10:46 pm

I have always replaced thje 1/2" washer that holds the eccentric bushing in the headstock with a 3/4" and sometimes a 1" body washer. Not only do you have to hold the eccentric bushing but you must be alble to prevent the idler shaft bearing from coming out of the eccentric bushing. The eccentric bushing set screw does lose its grip and the eccentric bushing bolt will not hold the eccentric bushing from moving by itself. Are they using a too small washer that allows the outter idler shaft bearing to come out of the eccentric bushing on the PowerPro?

I have been switching from using the cone point set screw for the eccentric bushing to the 1/4" length knurled cup point set screws for some years. I find the cone point set screw (very small contact point) seems to loose grip on the idler shaft bearing where as the kurnled cup point set screw really digs into the bearing housing with a firm grip. Also the cone point if overtighten could cause a tick in the bearing operation. Not a problem with the kurnled cup point set screw, much more area being contacted.

I have found that the original double bearing idler shaft bearing did not fail at 18,000 RPM for hours when I tested. I replace less than 5% of the double bearing idler shaft bearing shafts. I have not seen a total bearing failure, only excessive wear, noise and rough feeling on the few I replaced. I test spin each double bearing on the idler shaft to around 10K - 12K RPM before I use them.