Re: Mark VII Cam follower sheave
Posted: Tue Oct 25, 2022 12:39 am
The 'thin' side faces the expanding face of the cam.
Like this?
- SmartSelect_20221025_063829_Gallery.jpg (77.54 KiB) Viewed 2079 times
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Mark VII Cam follower sheave
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Re: Mark VII Cam follower sheave
Posted: Tue Oct 25, 2022 6:39 am
Re: Mark VII Cam follower sheave
Posted: Tue Oct 25, 2022 8:39 am
Yes IF the "thin" side is "up" in the pix.
Re: Mark VII Cam follower sheave
Posted: Tue Oct 25, 2022 10:37 am
It is, so all good. From the other thread about runaway speed, I thought I had to do it the other way around.
I'm suffering from the runaway speed issue...beyond 1000rpm, she self throttles to 4600rpm and it's because the grooves that hit those détentes have totally worn out.
I am at a crossroads of what to do. I currently use a clamp to push the speed dial into the headstock but it's clumsy and unsafe.
Has anyone managed to replace the speed dial? Or any other clever tricks?
I'm suffering from the runaway speed issue...beyond 1000rpm, she self throttles to 4600rpm and it's because the grooves that hit those détentes have totally worn out.
I am at a crossroads of what to do. I currently use a clamp to push the speed dial into the headstock but it's clumsy and unsafe.
Has anyone managed to replace the speed dial? Or any other clever tricks?
Re: Mark VII Cam follower sheave
Posted: Tue Oct 25, 2022 11:15 am
Something that I have not tried is to insert a thin shim washer so the 'bullet' detent has greater spring tension.
Also slop in the shaft that allows the dial to extend outward can be reduced by a shim washer between the cam and the headstock casting.
I have searched in vain for a replacement detent part.
Be advised that too much shimming will cause the detent pins to bottom out and damage the dial detent groove high points.
P.S. e-bay for a used replacement dial. Not often but they do appear. Verify condition before bidding!!!!
Also slop in the shaft that allows the dial to extend outward can be reduced by a shim washer between the cam and the headstock casting.
I have searched in vain for a replacement detent part.
Be advised that too much shimming will cause the detent pins to bottom out and damage the dial detent groove high points.
P.S. e-bay for a used replacement dial. Not often but they do appear. Verify condition before bidding!!!!
Re: Mark VII Cam follower sheave
Posted: Tue Oct 25, 2022 1:58 pm
A couple of ideas:
I drilled and tapped the speed control shaft for an 8-32 screw; removed the snap ring and installed a screw to pull the shaft and speed control knob tighter to the detent balls (see pic). It works great.
If your detent grooves are completely worn out I would get some glass-filled automotive putty(bondo) ; fill the worn areas and grind smooth with a dremel. This may not work but glass- filled bondo is pretty tough and sticks pretty good.
Lastly, if these don't work and can't find a replacement there is a thread somewhere on this forum where someone replaced the MKVII speed control with a MKV speed control.
Here are some liks to MKVII speed control issues.
viewtopic.php?t=20249
viewtopic.php?t=13906&start=40
I drilled and tapped the speed control shaft for an 8-32 screw; removed the snap ring and installed a screw to pull the shaft and speed control knob tighter to the detent balls (see pic). It works great.
If your detent grooves are completely worn out I would get some glass-filled automotive putty(bondo) ; fill the worn areas and grind smooth with a dremel. This may not work but glass- filled bondo is pretty tough and sticks pretty good.
Lastly, if these don't work and can't find a replacement there is a thread somewhere on this forum where someone replaced the MKVII speed control with a MKV speed control.
Here are some liks to MKVII speed control issues.
- ss speed control2.jpg (178.41 KiB) Viewed 2040 times
viewtopic.php?t=13906&start=40
Re: Mark VII Cam follower sheave
Posted: Wed Oct 26, 2022 6:36 am
This is extremely helpful. Tapping the control shaft was also something I considered and now I validated. Any tips on doing this? I imagine I should go slow and use pilot holes but I've never really drilled into aluminum so thought to ask.lahola1 wrote: ↑Tue Oct 25, 2022 1:58 pm A couple of ideas:
I drilled and tapped the speed control shaft for an 8-32 screw; removed the snap ring and installed a screw to pull the shaft and speed control knob tighter to the detent balls (see pic). It works great.
If your detent grooves are completely worn out I would get some glass-filled automotive putty(bondo) ; fill the worn areas and grind smooth with a dremel. This may not work but glass- filled bondo is pretty tough and sticks pretty good.
Lastly, if these don't work and can't find a replacement there is a thread somewhere on this forum where someone replaced the MKVII speed control with a MKV speed control.
Here are some liks to MKVII speed control issues.
ss speed control2.jpghttps://forum.shopsmith.com/viewtopic.php?t=20249
viewtopic.php?t=13906&start=40
It looks like you have a stack of washers to push the dial as the screw pulls in the shaft...is that right?
Re: Mark VII Cam follower sheave
Posted: Wed Oct 26, 2022 3:51 pm
- SSMKVIIsp cont1.jpg (496.75 KiB) Viewed 1984 times
I used .760" OD, .430"ID, .120" thick washers (one .120" washer will do. All I had was 2 thin ones to get .120") to fill in where the snap rig was and the large washer to pull the shaft tight to the speed control knob. See pics.
BTW after 5 years the detent grooves were filled with sawdust. Looks like it should be cleaned every few years.
Also, you are drilling into the steel speed shaft, not aluminum.
Hope it works for you.
Re: Mark VII Cam follower sheave
Posted: Wed Oct 26, 2022 9:22 pm
Best way to drill/tap the hole is to remove the shaft from the cam. Now is where two drill chucks comes in handy. Put the shaft in a drill chuck mounted to the quill shaft. Mount a second chuck to the tailstock. Use small pilot drill first then drill out to tap drill size. Drill will be stationary while the shaft rotates. Tap hole while shaft is still in the quill chuck.
Re: Mark VII Cam follower sheave
Posted: Fri Oct 28, 2022 5:19 am
You're a genius.JPG wrote: ↑Wed Oct 26, 2022 9:22 pm Best way to drill/tap the hole is to remove the shaft from the cam. Now is where two drill chucks comes in handy. Put the shaft in a drill chuck mounted to the quill shaft. Mount a second chuck to the tailstock. Use small pilot drill first then drill out to tap drill size. Drill will be stationary while the shaft rotates. Tap hole while shaft is still in the quill chuck.