Mark VII bearing replacement part

[mrcoffee]

Hi all,
I have an old Mark VII and the cam follower bearing disintegrated today. It is just gone and the cam follower was sitting in the end of the shaft the moveable sheave rotates and slides on to change speeds. Making a bit of a racket when it went, too. It didn't melt my plastic cam because I replaced it some years ago with a copy I machined out of aluminum. So now I am on a quest for a replacement bearing or suggestions on how to make one out of an available part.

Has anyone out there figured out a suitable way to adapt or otherwise obtain a bearing to replace the one that goes in the end of the shaft and holds the cam follower piece?

I have a milling machine so I am not averse to making one, although unless someone who understands bearings better than I can give me a few pointers, I guess I'll have to make a bronze bushing for the cam follower to sit in.

Thanks in advance for any thoughts and ideas,

And BTW, what is that bearing called and why can't I find a picture of it anywhere? <grin>

Bart

[JPG]

Hi all,
I have an old Mark VII and the cam follower bearing disintegrated today. It is just gone and the cam follower was sitting in the end of the shaft the moveable sheave rotates and slides on to change speeds. Making a bit of a racket when it went, too. It didn't melt my plastic cam because I replaced it some years ago with a copy I machined out of aluminum. So now I am on a quest for a replacement bearing or suggestions on how to make one out of an available part.

Has anyone out there figured out a suitable way to adapt or otherwise obtain a bearing to replace the one that goes in the end of the shaft and holds the cam follower piece?

I have a milling machine so I am not averse to making one, although unless someone who understands bearings better than I can give me a few pointers, I guess I'll have to make a bronze bushing for the cam follower to sit in.

Thanks in advance for any thoughts and ideas,

And BTW, what is that bearing called and why can't I find a picture of it anywhere? <grin>

Bart

My guess would be that it is a part of the control sheave just as the similar(function) bearing is on the Mark 5/Vs.

Another guess would be that the inner race is still attached to the follower and the outer race is still attached to the control sheave. These two races give you the ability to determine the size of the original bearing. It remains to you to find a way to reattach the follower using a new bearing. The outer race should press out of the sheave. It may be possible to peen a replacement onto the sheave.

Random thoughts(wishful thinking???). Good Luck

[mrcoffee]

JPG,
Thanks for reply.The inner race of the original bearing is still attached to the follower, but the rest of the race is just "gone". The outer race and balls are probably laying in the bottom of the headstock somewhere, but it's not still in the shaft coming out of the sheave. There is a recess, which appears a tad chewed from the follower jumping around after the race went supernova, but I think you're probably right that I can press fit the new race in, hopefully without having to re-machine the sheave.

I hope I can figure out how to get the sheave out again - it's been a while.

Thanks for the random thoughts and good wishes.

mr coffee

[JPG]

JPG,
Thanks for reply.The inner race of the original bearing is still attached to the follower, but the rest of the race is just "gone". The outer race and balls are probably laying in the bottom of the headstock somewhere, but it's not still in the shaft coming out of the sheave. There is a recess, which appears a tad chewed from the follower jumping around after the race went supernova, but I think you're probably right that I can press fit the new race in, hopefully without having to re-machine the sheave.

I hope I can figure out how to get the sheave out again - it's been a while.

Thanks for the random thoughts and good wishes.

mr coffee

I am concerned re your describing the shaft coming out of the sheave. I do not believe the shaft should be 'protruding'. Indeed I do not think it should even extend as far as the end of the sheave 'snout'. I do hope the 'snout' is what you are referring to as the shaft. The snout has a bore that slips over the 'shaft'. The sheave 'snout' is where the lubrication hole is. On the Mark 5/Vs anyway.

I have never done the belt in/out, but it appears to me that the speed dial/camshaft removal(it needs to be rotated to separate the cam from the follower)(If it was still there!) would allow the sheave and belt to just pull off the end of the shaft.

[mikemarkvii]

Hi all,
I have an old Mark VII and the cam follower bearing disintegrated today. It is just gone and the cam follower was sitting in the end of the shaft the moveable sheave rotates and slides on to change speeds. Making a bit of a racket when it went, too. It didn't melt my plastic cam because I replaced it some years ago with a copy I machined out of aluminum. So now I am on a quest for a replacement bearing or suggestions on how to make one out of an available part.

Has anyone out there figured out a suitable way to adapt or otherwise obtain a bearing to replace the one that goes in the end of the shaft and holds the cam follower piece?

I have a milling machine so I am not averse to making one, although unless someone who understands bearings better than I can give me a few pointers, I guess I'll have to make a bronze bushing for the cam follower to sit in.

Thanks in advance for any thoughts and ideas,

And BTW, what is that bearing called and why can't I find a picture of it anywhere? <grin>

Bart

Hi,
i believe that the sheave and cam follower is all one part. about a year ago i received an email from shopsmith about discontinued parts, and this was one. maybe if you called them they could help.
sorry that i can't help more, good luck
mike