:: II MK VII = I MK XIV?

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JPG
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Re: :: II MK VII = I MK XIV?

Post by JPG »

Where in S TN? It's kinda wide like it's northern neighbor.

Rolling in vert NOT recommended!!!

The bag needs an inlet/port/whatever - check the hole in the back cover.
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docmirror
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Re: :: II MK VII = I MK XIV?

Post by docmirror »

He's in Athens, just north of Chattanooga. Yeah, rolling while vert is a bad program. Not gonna try that again.
Last edited by docmirror on Thu Jan 20, 2022 7:14 pm, edited 1 time in total.
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JPG
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Re: :: II MK VII = I MK XIV?

Post by JPG »

Ditto raising to vert with the headstock unlocked.
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10
E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
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Re: :: II MK VII = I MK XIV?

Post by docmirror »

OK, back on refurb of Pollux. I was lucky to find the MVII headstock rebuild thread and am following that along pretty closely. My motor cover and motor are removed, and I have the aux or idler shaft out. My yucky shaft bearings in the eccentric are causing more pain, as I tried to press one off the idler shaft, and the outer hub shattered sending my balls hither and yon. It did hurt! Now, I have to get a mini bearing separator so I can get the inner race off as it's stuck on there real well.

Sadly also the bearing house I ordered my bearings from are on back-order. Raise your had if you are surprised. Yeah, me neither. Found a new supplier of non-Chinese bearings and ordered them today, may be in by Fri when I can start putting it all back together. There was a fair amount of discussion on the MVII rebuild threads. I'm shooting for a non-Chinese 29.5x0.5" I believe the orig belt had a custom end width and custom taper also due to it's use on a Salisbury type drive where edge traction is different than a standard tension V belt. I ordered a pair of belts for it and I'll have to measure to see what I got from the online vendor. Hoping I don't have to return them.

I haven't started fitting the plastic gear channel to Castor yet, as I was caught up with a few other tasks at the hangar. I may take that on later this week. Did do some drilling with Castor and it's doing yeoman work in that respect so I'm quite happy with it's new home in the shop. Also still waiting to clean and lube casters on both machines.

My rental is reno-ed and rented so I can get back on the SS machines now and finish them up. I got a hose kit for the vac and it fits the housing holes perfect. Once I reinforce the housing a bit with some JB Weld, it'll be back in service.
Last edited by docmirror on Mon Jan 31, 2022 1:09 am, edited 1 time in total.
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Re: :: II MK VII = I MK XIV?

Post by docmirror »

I have decided I've found a flaw in the design of the eccentric for the idler shaft. The bearings specified are being controlled laterally by the torque of the nut on the threaded end of the shaft. A ball bearing, or split race set of bearings like used here with the spacer collar is not the right type of bearing for axial pressure to align. It would be better to have the arrangement as is found on all tractor wheel hubs, with an inner and outer tapered roller(Timkin style) where the pressure from the pinch nut is applied to the thrust faces of the tapered bearings. I'm considering changing the type of spacer in between the two bearings from standing off the outer race, to a smaller dia spacer that would maintain distance of the pair of inner races on the outside and inside bearing pair.

Or, alternately I could use both spacers providing that they were the same thickness so there would be no side/axial load on the bearing balls, just torque from the end nut compressing the first inner race, the inner spacer, the second inner race, and finally up against the snap ring adjacent to the tapered sheave. These bearings are designed for radial loads, and they are going to do a fine job of that with the tension from the two belts, but the axial load from the nut torque is designed to deform the bearing race on either the inner or outer or both of each bearing.

If I were a real mech engineer, I would have the eccentric stepped for the tapered outer race, and convert over to tapered Timkin set. I might even thread in a zerk fitting where the set screw goes, and maintain it with grease every 500 hours. For future consideration. It wouldn't take much of a step in the eccentric to make a tapered bearing race work there.

Edit to add; rather than zerk fit the eccentric as it is a somewhat hidden location, it would be better to end drill the shaft to the thread end, then cross drill the shaft inside the bearing pair and have the zerk sitting on the end of the shaft where it could be lubed much easier.
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BuckeyeDennis
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Re: :: II MK VII = I MK XIV?

Post by BuckeyeDennis »

I don’t know any specifics about the bearings in question, but tapered roller bearings aren’t the only type that are designed for axial thrust loads. You may have angular-contact ball bearings, which are indeed designed for that application. And IIRC, even (non-offset) deep-groove ball bearings can be used for light axial loads. This isn’t the sort of thing that I’d expect Shopsmith engineers to get wrong.

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docmirror
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Re: :: II MK VII = I MK XIV?

Post by docmirror »

Yes, I'm aware of angular thrust bearings. That would be a third choice after tapered Timkin rollers. Based on what I found in my idler shaft, the bearings in there were destroyed mostly due to axial loads imparted by the torque on the end nut. If that type of arrangement were decided on and they use deep groove ball bearings, they should have a very light limit on the retaining nut. Sadly, It appears Shopsmith(Magna) decided that the bearing was 'good enough', or maybe that the idler bearing job was beyond the service level of owners.
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Re: :: II MK VII = I MK XIV?

Post by JPG »

My 'opinion' of the purpose of the nut is to eliminate end play only. I do not think it is intended to apply pressure against the bearings. The inner 'stop' for the bearings is a c-clip. Since the anti-rotation washer is present I think my opinion is verified(the nut is NOT intended to be torqued past taking up the end play.
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10
E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
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Re: :: II MK VII = I MK XIV?

Post by docmirror »

That would be the sensible method. Only a few inch-pounds of torque, and apply the anti-rotation tabs on the captive washer. I'm going to use the old inner race bearing as the shim between bearings to maintain any axial torque on the inner races of the new bearing against the C-clip. This will insure that little or no torque is applied across the bearing races or balls.

My neighbor is a cool old guy. He has a small shop with a press. He said he can get the inner race off no problem. I left it with him, and will bring the bearings over when they arrive. Once I get the idler shaft and eccentric put together I'll start re-assembly with the new bits and belts.
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JPG
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Re: :: II MK VII = I MK XIV?

Post by JPG »

Is there not a spacer between the two bearings inside the eccentric? IIRC the outer races bear against the spacer.
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10
E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
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