Control Sheave Operation

kmklein · Post by **kmklein** » Thu Sep 23, 2010 11:14 pm

I recently purchased what I thought was a used Shopsmith Mark V that I hoped to be able to clean up and give to my son. Turns out that the worm gear on the speed control assembly is damaged, and the snap ring holding it in place will not stay in the groove. I ordered a new speed control assembly and a control sheave from Shopsmith (Order 06006098) a few days ago. The control sheave was snug on the idler shaft, but I was able to remove it manually without resorting to any of the mechanical measures suggested on the Owners’ Web Site. My question is just how easily the control sheave should slide on the idler shaft? Even after cleaning and lubrication, the control sheave on my “new” unit does not slide back and forth easily. On close inspection with the motor pan off and good lighting, I do not see any burrs or other evidence of damage on the idler shaft, and I would like to know how much “force” it should take to move the control sheave on the idler shaft. Thank you,

SDSSmith · Post by **SDSSmith** » Thu Sep 23, 2010 11:29 pm

kmklein wrote:I recently purchased what I thought was a used Shopsmith Mark V that I hoped to be able to clean up and give to my son. Turns out that the worm gear on the speed control assembly is damaged, and the snap ring holding it in place will not stay in the groove. I ordered a new speed control assembly and a control sheave from Shopsmith (Order 06006098) a few days ago. The control sheave was snug on the idler shaft, but I was able to remove it manually without resorting to any of the mechanical measures suggested on the Owners’ Web Site. My question is just how easily the control sheave should slide on the idler shaft? Even after cleaning and lubrication, the control sheave on my “new” unit does not slide back and forth easily. On close inspection with the motor pan off and good lighting, I do not see any burrs or other evidence of damage on the idler shaft, and I would like to know how much “force” it should take to move the control sheave on the idler shaft. Thank you,

It should slide easily back and forth.

charlese · Post by **charlese** » Fri Sep 24, 2010 1:35 am

Hi, kmklein! Welcome to the Forum! Yes, as Rob said, The control sheave should slide easily on the shaft - It should slide like a well lubricated trombone slide.

Two things I can think of to help - - 1) Check the seating of the key into the small hole in the shaft and that it aligns perfectly with the keyway. 2) Oil both the shaft and the inside of the sheave's brass tube. after putting the two parts together, pull them apart enough to create a void at the end of the shaft and put in some more oil into the small hole in the side of the brass tube. Be generous with the oil into the little hole, then when you close up the sheaves oil will seep out of the little bearing with the clip and ooze around the shaft.

This should help! Remember - that little hole will require 4 -5 drops of oil every 10 hours of operation. Use light turbine oil or 20 weight non-detergent oil.

What part of the World do you call home. Maybe there is one of us close enough to help! (provided you want help):)

billmayo · Post by **billmayo** » Fri Sep 24, 2010 9:01 am

[quote="kmklein"]I recently purchased what I thought was a used Shopsmith Mark V that I hoped to be able to clean up and give to my son. Turns out that the worm gear on the speed control assembly is damaged, and the snap ring holding it in place will not stay in the groove. I ordered a new speed control assembly and a control sheave from Shopsmith (Order 06006098) a few days ago. The control sheave was snug on the idler shaft, but I was able to remove it manually without resorting to any of the mechanical measures suggested on the Owners&#8217]

I find that there has always been small manufacturing differences (tolerances) for both the Control Sheave/Idler Sheave and the idler shaft. Many times the Control Sheave vanes will rub/bind againest the Idler Sheave vanes and cause the Control Sheave to stick/bind and make strange noises if just the vanes are just touching. Also the Control Sheave ID can bind/stick on the idler shaft as noted in the above post. I find the keyway and Control Sheave ID can be machined at different locations and sizes. (from .001-.020 off). So there are 2 ways the Control Sheave may not fit the Idler shaft and align with the Idler Sheave. I have to do a mix and match to insure I have a good combination of Control Sheave/Idler Sheave and Idler shaft.

The key for the idler and motor shaft has needed replacement when it becomes worn on the sides.

The motor's Floating Sheave, Fan Sheave and Motor shaft have the same problem with vane clearance and shaft/Floating Sheave ID so I fit them to the motor shaft. I only sell these parts with a motor to insure they fit.

I have my customers send me their Control Sheave, Idler Sheave and idler shaft when they are looking for a replacement Control Sheave or Idler Sheave and shaft to insure that the complete unit fits together.

Please feel free to contact me for a solution if you are unable to solve your problem. I am happy to answer any Shopsmith questions.

JPG · Post by **JPG** » Fri Sep 24, 2010 9:33 am

I think it is time to remove the idler shaft assembly completely out of the headstock and disassemble it on the bench. Then you can more easily determine what caused the original damage to both the control sheave and quadrant gear.

The key is a prime culprit, but possible galling is another.

dusty · Post by **dusty** » Fri Sep 24, 2010 9:55 am

kmklein reports "Even after cleaning and lubrication, the control sheave on my “new” unit does not slide back and forth easily".

Are you doing this with all new parts or just the shaft and control sheave?

If you have a new idler shaft and a new control sheave, the sheave should slide back and forth with "no effort" at all. With the shaft held at an angle the sheave should slide on the shaft under its own weight.

kmklein · Post by **kmklein** » Fri Sep 24, 2010 11:07 am

Thank you all for your prompt replies. As the wire clip on the control sheave was bent, and the gears on the speed mechanism were damaged, I have ordered a new control sheave and a new speed control assembly and arm from Shopsmith. I guess that if the new control sheave does not slide smoothly on the idler shaft, perhaps the shaft is also damaged and should be replaced. I am in a quandary, as the new control sheave should be tried on the idler shaft before “condemning” the idler shaft to be replaced, but I would like to take advantage of the 10% discount, if possible; however the new control sheave will not arrive in that time (it expires tomorrow).

dusty · Post by **dusty** » Fri Sep 24, 2010 11:54 am

[quote="kmklein"]Thank you all for your prompt replies. As the wire clip on the control sheave was bent, and the gears on the speed mechanism were damaged, I have ordered a new control sheave and a new speed control assembly and arm from Shopsmith. I guess that if the new control sheave does not slide smoothly on the idler shaft, perhaps the shaft is also damaged and should be replaced. I am in a quandary, as the new control sheave should be tried on the idler shaft before &#8220]
WHAT? I missed a parts discount offer!? Where are you located. You could come to my place and test using my spare idler shaft assembly.