Markl VII Idler Shaft breakdown

JPG · Post by **JPG** » Sun Dec 16, 2012 12:36 am

The Mark VII idler shaft is slightly different from the Mark 5/V. I has a dual bearing similar to the later Mark V and Powerpro. It has a nut securing the shaft to the bearings. The eccentric is larger than the Mark 5/V eccentric.

Once the idler shaft and sheaves are out of the headstock, the various parts separate easily. The sheaves slide off the inner end of the shaft since there is no hair pin clip like the Mark 5/V. This allows the key to be removed. It is retained by a recess in the shaft and an offset in the key just like a Mark 5/V.

The inner end of the bearing/eccentric is 'stopped' by a retaining clip. The outer end is secured by a nut. The shaft is a slip fit in the bearings.

[ATTACH]19509[/ATTACH]

The/a PO liked grease over machine oil. ugh!

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The idler sheave balance was achieved by drastic spot drilling(all the way through in some).

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The nut is prevented from backing off the shaft by a keyed and tabbed washer that is bent over a flat on the nut. The nut is removed by carefully prying the tab off the nut(limited number times before the tab breaks off)

This pix shows the set screw which resembles the Mark 5/V water pump bearing retainer. It will be shown below that it's function is quite different.

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Here is the next puzzle. How to get the bearings out of the eccentric. There is a bearing on both ends. They appear to be stopped internally, so they need to be pulled out each end.

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JPG · Post by **JPG** » Sun Dec 16, 2012 12:55 am

I made a crude bearing extraction tool to push the bearings out of the eccentric from the opposite end. The 'tool' has 4 slits that create 4 fingers with lips that are expanded by driving a gradual taper shank punch into a hole in the center of the 'tool'.

[ATTACH]19515[/ATTACH]

Once the bearing is free of the eccentric, the punch is driven back out from the opposite end(the hole extends from end to end).

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The 'tools' used. Two punches and the crude tool(and hammer).

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Once both bearings were out, the purpose of the set screw became apparent. The point of the set screw positions and retains an internal spacer that provides an internal stop for both bearings. So bearing removal could have been accomplished by removing the set screw and pressing the bearings and spacer from one end out the opposite end.

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This thread is linked to from https://forum.shopsmith.com/viewtopic.php?t=11373&highlight=journey

robinson46176 · Post by **robinson46176** » Sun Dec 16, 2012 1:08 am

It looks kind of like that bearing shield has been drilled for injection lubing...

Keep up the good documentation.

I may have to work on mine someday.

.

JPG · Post by **JPG** » Sun Dec 16, 2012 1:33 am

robinson46176 wrote:It looks kind of like that bearing shield has been drilled for injection lubing...

Keep up the good documentation. I may have to work on mine someday.

.

An 'attribute' common to all the bearings as acquired. They are all being replaced.

pennview · Post by **pennview** » Sun Dec 16, 2012 8:34 am

You're doing a great job there, JPG. Like Farmer, your work may get me going on a restoration of my Mark VII.