Pork Chop worn 'funny'

forrestb · Post by **forrestb** » Fri Jul 29, 2011 6:59 pm

My 1986 SS would not get up to the Saw/Joint speed yesterday. I took the speed control apart and found that the pork chop teeth were worn in a strange (to me) fashion. Pls see the pic.

Does someone know what causes this pattern? I did find that the control arms that hold the pork chop were slightly bent outwards.

All other parts just needed to be brushed off and they looked fine.

I plan to replace both but am wondering should check something else?

Forrest

wa2crk · Post by **wa2crk** » Fri Jul 29, 2011 7:23 pm

Forrest;
That condition usually comes from the speed control being forced. Improper lubrication, packed in sawdust, or a shop gremlin trying turn the speed control when no one was looking.
Check the worm gear for worn teeth also. My advice is to replace the pork chop as well as the worm gear. Easier fix is to replace the assembly. A bit more expensive but quicker reassembly. Be sure to clean and lube the control sheave shaft when you reassemble things. also polishing the control sheave shaft with some fine Scotch abrasive pad to remove the "crud" will help a lot. Also clean the interior bore of the control sheave but do NOT use a solvent as this may cause the grease in the little bearing at the end of the sheave to be diluted. While you wait for your parts put some oil in the control sheave bore and stand the sheave on the work bench so the oil runs down to the bearing and let stand overnight. This may extend the life of that bearing.
Bill V

forrestb · Post by **forrestb** » Sat Jul 30, 2011 12:02 pm

Thanks, Bill. I appreciate that lack of proper or adequate lubrication caused my problem. But I took to heart long ago to never, ever adjust speed without the shafts moving so I don't think that gremlin got my SS. I am the only user so have to take all the blame - darn it!

I guess I wasn't all that clear on my question.

My real concern is why is the wear pattern angled across the pork chop - from top left to bottom right when looking at the pic?

It seems that the pork chop was angled relative to the control screw - what could cause that is my concern for the future? Would a new control assembly fix that or is there something else wrong with my SS?

Forrest

firefinder · Post by **firefinder** » Sat Jul 30, 2011 12:25 pm

The first greenie I bought had the same damage.

nuhobby · Post by **nuhobby** » Sat Jul 30, 2011 2:37 pm

This would be a good time to check for the types of troubles highlighted by Bill Mayo in post #22 of this thread:
https://forum.shopsmith.com/viewtopic.php?p=43397

forrestb · Post by **forrestb** » Sat Jul 30, 2011 3:34 pm

Chris, thanks very much for the link to Bill's post. When my new pork chop arrives I will take his advice.
Forrest

wa2crk · Post by **wa2crk** » Sat Jul 30, 2011 4:10 pm

Forrest
I think that the angular wear on the pork chop is from the way the worm gear rides on the pork chop gear. A worm gear has to have a corkscrew type thread n order to work so if it bites hard into it's mating part then you get the angular wear angle.
I forgot about Bill Mayo's post but he does have a real good fix, and he has been doing it for years and he also has a lot of experience and knowledge.

Bill V

forrestb · Post by **forrestb** » Sat Jul 30, 2011 7:53 pm

Since I planned on replacing the control assembly anyway, I thought to try Bill's method with a bolt holding the pork chop on to the control. My local ACE and Home Depot did not have any 10-32 x 2 1/2 bolts that would show a smooth surface to the pork chop (instead of screw threads). Okay, I drilled both parts out to fit a 1/4 bolt that did provide the smooth surface.

That, and straightening the control arm, brought the screw back to the centerline of the pork chop and voila! I have full range speed control again. I did have to remove some of the 'crushed' portions of the pork chop teeth, so this is not a permanent fix.

I will try more hardware dealers next week (while waiting replacement parts) for a proper sized bolt as Bill used.

THANKS again to Chris and Bill!!!

Forrest

dusty · Post by **dusty** » Sat Jul 30, 2011 7:59 pm

forrestb wrote:Since I planned on replacing the control assembly anyway, I thought to try Bill's method with a bolt holding the pork chop on to the control. My local ACE and Home Depot did not have any 10-32 x 2 1/2 bolts that would show a smooth surface to the pork chop (instead of screw threads). Okay, I drilled both parts out to fit a 1/4 bolt that did provide the smooth surface.

That, and straightening the control arm, brought the screw back to the centerline of the pork chop and voila! I have full range speed control again. I did have to remove some of the 'crushed' portions of the pork chop teeth, so this is not a permanent fix.

I will try more hardware dealers next week (while waiting replacement parts) for a proper sized bolt as Bill used.

THANKS again to Chris and Bill!!!

Forrest

You might be surprised just how long your repair will last. Because you now have the gear faces properlly aligned, the pork chop is wearing properly and in a different location. As long as the speed control is smooth through the entire range, I believe you can consider it fixed.

JPG · Post by **JPG** » Sun Jul 31, 2011 12:48 am

It is the bending of the mounting arms that causes misaligned worm gear to quadrant gear. Also the tension pin can move in the arm holes allowing the arms to spread.

Since the quadrant gear is NOT concave cut like a true worm gear but flat, the contacting surface area is nearly point contact only. Add mis-alignment to that and the 'funny' wear results.

A 10-24(3/16-24) will work, but a smooth shank under the head is best. A full thread will however still be an improvement due to the 'anti-spreading' effect of the screw head/nut.

Well lubricated sheaves are the best prevention, but all 'anti-wear' stuff discussed here is relevant.

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