Shopsmith Forums

The speed control on my Mark V has been getting progressively harder to turn so today I decided to do some maintenance and this is what I found. A couple of questions...

1. Is the piece that needs to be replaced the "Quadrant Assembly" PN 504221?

2. I never turn the speed control unless the motor is running so what is the likely root cause of this?

Thanks,
Bill
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I'll take a stab. Yes, you need a new one. Luckily this part is readily available. What causes it? Well a couple guys on here have dealt with this before. I haven't but I'll hazard a guess, that since it's only wearing in that one side that the arm has been forced in years past. I'll leave a specific diagnosis to a couple of the guys who have torn that part down. But it is beyond repair for sure. Easily replaced though.

I have been replacing the quadrant roll pin with a bolt, star washers and a Nylock nut. No quadrant teeth damage has occured that I am aware of in over 7 years in around 150 replacements I have done. I have instructions, pictures and a free bolt, star washers and Nylock nut available. Send me an Email (annbill.mayo@comcast.net). If unable to get a new quadrant from Shopsmith, let me now. I have to charge more than Shopsmith for the quadrant due to my additional shipping costs.

Although you may have been not turning it with the motor not running, if the motor sheaves are not lubricated or you turn the speed down too fast that wear will occur.

Notice the slop between the arms and the quadrant gear. That allows quadrant gear to shift off center of the worm gear. That in turn causes it to wear and that wear gradually gets eorse and forces a more off center condition.

Notice also the roll pin extending out the left arm. This indicates that the other end of the roll pin does not extend fully into the right arm.

This is a common occurrence.

I highly recommend the bolt replacing the roll pin as Bill Mayo has suggested. I believe your quadrant gear is NOT salvageable. Forming(very carefully) the arms back to their proper position is also needed(they break easily if over stressed). I also dress the mating surfaces(inside of the arms and outer surface of the quadrant at the pivot hole) so that the parts move smoothly.

A complete(less dial, crank, springs and screws) speed control is also available from SS. I would replace the roll pin with the bolt etc. even on a brand new one!!!!!

One caution: make sure you do not bend/break the arm(s) when driving the roll pin pivot out.

Thanks for the responses. I just want to be sure I am ordering the correct part number. Is that the Quadrant Assembly - part number 504221?

Also, what is the best method for bending the arms back into position?

504221 is correct.

I use a small vise to squeeze the arms back together. That eliminates the possibility of 'slipping' and bending them too far. I also hold them in a vise(with the quadrant gear in between the arms) when removing the roll pin.