Shopsmith Forums

I just picked up a low hours Mark V but the variable speed control is quite hard to turn. Is it a good idea to lube the curved rack gear? This is probably my fourth mark v that I have owned over the last 20 years and I have never found one with a VS control that operated smoothly. Is this just the nature of the beast or am I not lubing properly? Thanks.

bestdust wrote:I just picked up a low hours Mark V but the variable speed control is quite hard to turn. Is it a good idea to lube the curved rack gear? This is probably my fourth mark v that I have owned over the last 20 years and I have never found one with a VS control that operated smoothly. Is this just the nature of the beast or am I not lubing properly? Thanks.

It is impossible to determine what your expectations of the speed control are but I would say that if you have never had one the worked smoothly - somethng is bad wrong. Be aware that a proper functioning speed control feels different going up than when going down.

I believe this shows all that needs to be known and done.

I am going to assume you are aware to not turn the dial unless it is runnimg or you are rotating the pulleys manually.

Now understand the reason for that 'no-no' is that when turning the dial to reduce speed, the control is squeezing the motor belt(closing the control sheave). This squeeze is relieved by the spring loaded floating sheave on the motor shaft(sheave opens).

If this is attempted with the pulleys not turning excessive stress is caused on the quadrant gear and its pivot arms and pivot. The same stress is caused if the dial is turned too fast(the sheaves do not keep up).

The strain resulting from this stress causes the pivot arms and the pivot to malform. The result of this malformation is the displacement of the quadrant gear relative to the worm gear(driven by the dial). This displacement causes undue wear to the softer quadrant gear to the point of reshaping the gear teeth. The reshaped gear does not have an ideal profile and the resulting friction causes a 'less than smooth feel' fed back to the dial.

I prefer graphite as a lubricant for the quadrant gear(it does not have an afinity for sawdust).

The application of Bill Mayo's bolt replacing the roll pin as a pivot and the restoring(careful) of the pivot arms to their original position)are extremely effective in reacquiring smoother(turns easier) action. Some filing of the quadrant gear will also be required to restore that 'original' feel.

Once ya get er 'back to normal' judicious speed while lowering the speed will prevent a recurrence of all that damage.

Raising the speed is not a problem since turning the dial to a higher speed setting opens the control sheave while the floating sheave closes to maintain belt tension.

It is truely amazing the difference this alteration(and that judicious speed of turning the dial down)makes in the 'smoothness' and lack of undue future wear!

If I can find Bill's post describing his 'fix', I will insert it. http://www.shopsmith.net/forums/showpos ... stcount=11 Close enough!

I agree with JPG that graphite is a better lube since it does not hold onto sawdust. If you use graphite suspended in a solvent, you can squirt a bit into a long spoon and 'pour' it onto the gear through the removed back cover plate. The solvent evaporates quickly (sorry atmosphere) leaving the graphite mostly where you want it.

Now, if they can figure out how to get a SS to work properly when cut-out as Nick uses our maintenance will be a breeze!!!

Forrest