Shopsmith Forums

I am finishing a rebuild of a 1955 Shopsmith Mark V 510-R. I got everything back together and it seemed to operate fine. When I began changing speeds it seemed that the speed indicator was not matching the speeds (I went past highest setting and the machine was getting faster, but the dial was now on slow speeds). So I have removed the speed control (dial and quadrant). Now the machine runs without the quadrant in place. So it seems when I tried to adjust the speed dial by lifting the quadrant enough to turn the dial behind it I caused something to go wrong. Any help would be appreciated.

To start off, hopefully you have a manual for your Mark 5. That being said if it is the original Owner's Guide from 1955 it is not as much help as a more current one which hopefully you have from the 510 upgrade. The Speed Dial can be turned past fast if the High-Speed stop is not adjusted correctly. There have been instructions available for setting the High-Speed stop but unfortunately I don't have a PDF copy and cannot locate it here on the new Shopsmith Website. Someone else may have a PDF copy available and post. Later Manuals have those instructions. The adjustment is made by loosening the lock nut on the Set Screw at the center of the gear shown in the picture of the Speed Control parts below. That set screw limits the inward travel of the Quadrant and therefor the high end of the speed range.

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The System will still run without the Speed Control Assembly in place. I do NOT recommend running it without the Speed Control Assembly in place as there isn't anything to hold the moving Idler Shaft Pulley Sheeve in position.

As for the speeds seaming to be "off" the Motor to Ilder Shaft Assembly V belt could be the cause. An old worn V belt or even a new V belt that is not the original size will cause the speed to be "off" from what they should be. Use of a tachometer will help with diagnosing this problem.

Two versions that I have.

PAROSS wrote: ↑Tue Dec 12, 2023 12:41 pm I am finishing a rebuild of a 1955 Shopsmith Mark V 510-R. I got everything back together and it seemed to operate fine. When I began changing speeds it seemed that the speed indicator was not matching the speeds (I went past highest setting and the machine was getting faster, but the dial was now on slow speeds). So I have removed the speed control (dial and quadrant). Now the machine runs without the quadrant in place. So it seems when I tried to adjust the speed dial by lifting the quadrant enough to turn the dial behind it I caused something to go wrong. Any help would be appreciated.

Is your machine stalling, as the thread subject implies? If yes, it is possible that the motor belt has 'fallen' into the non-V portion of the Idler sheaves and lost tension. This can happen if the belt is too narrow, either sized wrong or worn, and/or if the high speed stop portion of the adjustment procedure wasn't set correctly. (Or if you ran the machine with the quadrant out, because as Russ pointed out there is nothing to limit the Control Sheave movement in that case.) Once the belt falls off into this non-V portion of the sheaves, attempting to adjust the speed will pinch the belt rather than causing it to return to the normal position. To correct this, I would take the belt off the motor sheave so you can get it out of the way while you get the Control Sheave back to its proper location.

Note - Ignore all of this is the machine is not stalling.

- David

1) You need to perform the high speed adjustment. It includes proper positioning of the ring indicator and reassembly.

2) The ring indicator cannot be adjusted with the speed control knob installed.

3) The ring indicator merely references the knob rotation.