Shopsmith Forums

It was mentioned to me on a different board that there are two problems with the VII. Ok maybe there are actually more than two problems but these two seem to be the most common and prevalent to most users.

These are the following and I quote from that thread

The first is the tendency of the speed control cam to melt under duress. That could have been cured with a switch to a cam made of aluminum or brass etc. instead of plastic.
The second is the plastic rack gear getting brittle and breaking. Again a change of material would have cured it.

I stated that I had looked at the gear rack when placing my motor back on the VII after getting it back from the shop. It was found to be in great condition and the only thing wrong with it was it was full of saw dust.

I also stated that I did not see how the use of aluminum or Brass would help make it better because when i first looked at these gears or sheaves as they are called according to the parts list. I did not look at them very well obviously and I though they were individual fingers that were attached to a hub of some king that held the belt in place and were made of plastic because of a flexibility factor of some kind.

After looking at my parts book I now see this matter in a completely different light and can actually see how this could be done and have a plan to actually try and the part by casting it and making it out of aluminum that I will melt my self and poor into the cast.

As for the Speed Control Cam I have tried to look in the parts book for it and have not found it list as that. are you talking about the

I am assuming these are the two Sheaves that I am talking about and not the two that are actually mounted to the Electric motor shaft. Which i did not notice were made of plastic or metal.

I wanted to post a note of clarification here just in case I confused anyone. When I spoke of the plastic rack gear I was speaking about what many call the "rack" that is riveted to the back side of the front way tube. I call it the rack gear because it is a gear, just a straight one. The other gear inside of the case mounted to the crank / headstock lock is the pinion gear. I don't think I ever heard of the pinion gear failing. It may well have happened, I just don't recall hearing about it. The "rack" gear was broken on all three of the ones I bought. I believe they were broken by being struck maybe by something when using it as a lathe or dropping a board or something. As I said they get brittle and become useless with age (The same thing is happening to me). None of the left over giblets of the ones on my Mark VII's showed any signs of tooth failure from use, just breakage. It is a pretty simple part and tooth profile and angle should not be hard to reproduce. The rack gear strip back has a concave profile to match the curve of the round way tube. Aluminum might be easier to machine but brass might be a little tougher and be harder to damage by being struck. A newer, tougher plastic might also be available and be very suitable. I have been away from the plastics industry for about 40 years and am not current at all on them.
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The "cam" sticks straight out the back of the speed control dial and as the dial is turned the cam puts pressure on the device that controls the variable speed sheave. Frankly as I made limited use of the Mark VII I believe I like the Mark VII speed control better than the Mark V. Of course if I was using it a lot I might look at it differently. It "was" intended as an improvement over the Mark V...

Could you post the part numbers for these items you are talking about that you have had trouble with this might help me locate them better. I admit I am a bot slow from time to time.

Thanks,

Stole this photo of the plastic Mark VII cam off farmers online photo album. Don't tell him.
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[ATTACH]6626[/ATTACH]
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This definately appears easy to duplicate if anyone had a trace or dimensions. Can anyone post either?

mickyd wrote:Stole this photo of the plastic Mark VII cam off farmers online photo album. Don't tell him.
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[ATTACH]6626[/ATTACH]
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This definately appears easy to duplicate if anyone had a trace or dimensions. Can anyone post either?

Don't worry, I won't tell him...
If I get a chance I'll pull one and trace it but it may be a while before I get that much time. I have a lot of engine work and tire work to get done over the next couple of weeks.

robinson46176 wrote:Don't worry, I won't tell him...
If I get a chance I'll pull one and trace it but it may be a while before I get that much time. I have a lot of engine work and tire work to get done over the next couple of weeks.

Thanks for the trace offer and also thanks for not telling him about the theft. He's a pretty big guy and I wouldn't want him hunting me down!!!

Looking at the cam pix I notice what appears to be a 'pop rivot' head on them back side of the way tube. I assume this originally secured the 'rack gear'.

[ATTACH]6637[/ATTACH] The Control Sheave is # 17

[ATTACH]6638[/ATTACH] The Cam number is not shown.

These parts are NOT available from SS Inc. Therefore the reason they are a "problem".

I ordered the mark VII info package from shopsmith, which had a drawing with all measurements for the machining of the cam. It was 10$ well spent for parts list etc.

mike

mikemarkvii wrote:I ordered the mark VII info package from shopsmith, which had a drawing with all measurements for the machining of the cam. It was 10$ well spent for parts list etc.

mike

Can't beat that price for sure.