Miter Gauge Moves While Tightening

[JPG]

Dusty: My thinking re lub was to make sure the knob tightening would NOT cause the washer to rotate.

Ed: My 1963 Goldie parts listing has ONE washer.

I have never had this 'issue' since it was new in 63.

I usually use the 90 degree stop and push the miter gauge counter-clockwise while tightening the knob clockwise.

I double check the stop often and when it really matters.

I have used the cross holes sparingly and then only with very long work piece.

Not sure how two washers helps. I consider the washer is to both prevent the turning knob from exerting sideways force to the gauge and to bridge the gap in the segment slot as well as to prevent wear to the soft segment. Due to the smaller surface area with the slot, the segment would wear first. That is not a good place for wear to occur. That area beside the slot must be flat.

I gotta try two now!:rolleyes:

[algale]

This morning I removed the knob and washer. No wear or dirt. Went to my hardware drawer and found a washer that appeared to be the same size as the Shopsmith part so I installed the second washer per the drawing. Problem solved. The gauge no longer slips while tightening the knob. Even used the Allen wrench in the knob holes to crank it down. No slippage when before even hand tightening the knob moved it several degrees. Thanks Ed for the pick up on the missing washer!

Al

[judaspre1982]

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[judaspre1982]

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[JPG]

Took a look at my other two miter gauges. The 510 one has two washers. The third(history unknown) has only one. Both are SS Inc. vintage.

I am still unsure what the second washer adds other than an additional pair of surfaces to slide. It is important that a single washer NOT rotate on the segment and that the knob slips on the top of the washer.

I am inclined to think the stud the knob screws onto is bent in your case causing the outer side of the segment to contact the knob/washer before the inner side.

[algale]

I am inclined to think the stud the knob screws onto is bent in your case causing the outer side of the segment to contact the knob/washer before the inner side.

Your theory on the bent stud is an interesting one but I saw no evidence that the stud was bent when I examined it. Another beautiful theory spoiled by an ugly fact.

[JPG]

Your theory on the bent stud is an interesting one but I saw no evidence that the stud was bent when I examined it. Another beautiful theory spoiled by an ugly fact.

And what ugly fact does explain the segment movement?;)

Bet if it was bent the other direction, it would move the other direction!

Try it without a washer and push the knob in while tightening.

[algale]

[quote="JPG40504"]And what ugly fact does explain the segment movement?]

I don't have a fact to explain it. Based on my observation of movement with one washer and no movement with two, my hypothesis is simply that with two washers the bottom surface of the "upper" washer and the top surface of the "lower" washer make a better slip surface (have a lower coefficient of friction) than contact directly between the bottom of a single washer and the surface of the protractor head.

Hard to imagine why Shopsmith would show two identical washers in the drawing for the miter gauge unless Shopsmith believe that second washer performed some function.

As for your experiment, I frankly don't want to try that. I've only got one Shopsmith miter gauge and since the the stud does not currently appear to be bent I am loathe to put a sideways load on the stud that might put a permanent bend in it. If you have multiple gauges I might suggest you conduct the opposite experiment at your own peril by seeing if you can induce rotation in a single washer gauge by applying lateral pressure on the knob in the other direction.

A different experiment, and one that has no potential to damage anyone's gauge, is for folks still following this thread to remove one washer from their gauge (if they have a two washer variety) and see if this results in movement of the protractor/fence when tightening down the knob (without applying lateral pressure to the knob).

[dusty]

I don't have a fact to explain it. Based on my observation of movement with one washer and no movement with two, my hypothesis is simply that with two washers the bottom surface of the "upper" washer and the top surface of the "lower" washer make a better slip surface (have a lower coefficient of friction) than contact directly between the bottom of a single washer and the surface of the protractor head.

Hard to imagine why Shopsmith would show two identical washers in the drawing for the miter gauge unless Shopsmith believe that second washer performed some function.

As for your experiment, I frankly don't want to try that. I've only got one Shopsmith miter gauge and since the the stud does not currently appear to be bent I am loathe to put a sideways load on the stud that might put a permanent bend in it. If you have multiple gauges I might suggest you conduct the opposite experiment at your own peril by seeing if you can induce rotation in a single washer gauge by applying lateral pressure on the knob in the other direction.

A different experiment, and one that has no potential to damage anyone's gauge, is for folks still following this thread to remove one washer from their gauge (if they have a two washer variety) and see if this results in movement of the protractor/fence when tightening down the knob (without applying lateral pressure to the knob).

This is one of those procedures that that are done so often that you might not know exactly how it is performed. I don't know if I do anything to prevent the unwanted rotation while tightening the knob or not.

I do know that it has not been a noticeable problem and that thou I have only one washer on each of my two miter gauges - I am not going to add one. Now, if there is a reason why someone needs specific testing of a miter gauge - I am very willing to participate.

Furthermore, with regard to the variations in configurations, I believe that we are simply witnessing deviations in assembly that have occurred over time. These differences are likely the result of different manufacturers building units for Shopsmith or different crews (at Shopsmith) assembly parts differently.

I'd bet that if we could get a number of miter gauges together for a detailed components analysis, we would discover many deviations.

[JPG]

Your theory on the bent stud is an interesting one but I saw no evidence that the stud was bent when I examined it. Another beautiful theory spoiled by an ugly fact.

And what ugly fact does explain the segment movement?;)

Bet if it was bent the other direction, it would move the other direction!