:: II MK VII = I MK XIV?

[docmirror]

Well, things are not going swimmingly with the rebuild of Pollux. I got the inner race off my intermediate shaft, and the shaft is a mess. Where the two bearings ride, the shaft is ground down about 50-70 thousands in the grooves where the bearings should ride. These bearings have been grinding into the shaft for a long time. The C clip was also missing so one more thing to resolve.

All is not lost however. I have a hard chrome shop in town, and I will get the shaft to them to build back up and grind back to standard 5/8". I had them do one of my aircraft gear strut legs and it came out perfect. I know it can be done, just have to get on the ball and take it down there.

Unless, someone has a spare intermediate shaft for a Mark VII. Hmmmmmm I have no idea if it's the same shaft for a Mark V, but if so, maybe I can find one here online. Hmmmmmm

[docmirror]

Is there not a spacer between the two bearings inside the eccentric? IIRC the outer races bear against the spacer.

I have the spacer, I'm just concerned about applying axial pressure against the outer race, with no axial pressure applied to the inner race when I assemble on the shaft.

[JPG]

It ain't the same shaft!

BTW I gots a MVII idler shaft with the same issue(bearing wear/shaft od reduction and worse).

Any chance two could get the fix you mentioned?

[docmirror]

It ain't the same shaft!

BTW I gots a MVII idler shaft with the same issue(bearing wear/shaft od reduction and worse).

Any chance two could get the fix you mentioned?

We are in luck. I have a hard chrome plating shop about 20 min from me, and they can build up and surface grind the shaft(s) back to spec. Send me your shaft and we'll double dip. I'm going to try to send you my addr by PM. If it doesn't work I can give you my email.

Anyone else wanna join in just let me know.

It appears from our failure mode my concern about this type of bearing in this application is well founded.Yes, these machines are 60 YO units, and I suppose they've lasted their design life spec, but if it were a Timkin taper roller with shoulder notch inside the eccentric, the bearings would last forever. They could have drilled a hole in the end for a zerk and have it perm lubricated with the addition of two seals. I'm tempted to switch to tapered roller, but that means more machining. Guessing these new non-Chinese bearings will last my lifetime.

[docmirror]

Hmmm, sent PM but it is sitting in my outbox, with no way for me to send it. I will try a new PM, not sure how this software works.

[docmirror]

If the hard chrome and grind doesn't work, I'll just get some 5/8" shaft stock and u-make-it. Won't be the same nut profile, but who cares? Any nut will do. The hard job is the keyway. I'm not good a grinding keyways.

[rpd]

Hmmm, sent PM but it is sitting in my outbox, with no way for me to send it. I will try a new PM, not sure how this software works.

That is how the PM system works, the sent message sits in your out box until the recipient opens it,

[redleg]

I thought I took a picture of the shaft after turning and threading but can't find it. I cut the shaft off an old motor armature that already had a keyway. I think it was from an old Mark VII motor. I had to turn it down slightly and thread it. I'm still working on the headstock.
It was trashed when I got it so no loss but my time. Going to the bearing shop to see if they have a bearing retaining ring for the upper shaft and tabbed locking washer for the idler shaft.
Edit 3/5/2022: Here is another shaft from some round stock that I threaded 11 threads per inch so I could get another nut locally. The original was 12 threads per inch I believe.

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I added a wraparound bolt to hold the idler shaft.
Edit 3/5/2022:

This picture is with the 11 threads per inch shaft and new nut.

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This will be a Mark VII (sort of headstock) with a reversible GE motor from a Mark V and a Mark V speed control.
Edit 3/5/2022: Currently a wooden prototype insert with an aluminum 1/8" thick plate.

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This is the idler shaft bearing extended nub and prior to the aluminum plate install.

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Tried pouring an aluminum insert but my green sand was to moist and it didn't turn out.

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I left out 1/3 of the hole that would be in the Mark V headstock. The speed control fits fine through the other two. Is this going to be an issue that I'm not seeing?

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[JPG]

Hmmm, sent PM but it is sitting in my outbox, with no way for me to send it. I will try a new PM, not sure how this software works.

That is how the PM system works, the sent message sits in your out box until the recipient opens it,

Finally got to open the PM(s) - been off line.

Am putting shaft 'in the mail' today.

Thank You for consideration and patience!!!

[docmirror]

Finally got to open the PM(s) - been off line.

Am putting shaft 'in the mail' today.

Thank You for consideration and patience!!!

I got your shaft, and don't take it personally, but your shaft is in real bad shape. Not sure if we can save it. If not, I'll be making new. Will let you know next week.