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Turning masts and other spars on small lathe


Jaager
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On small lathes, such as my Unimat there is a limit to how long the piece being turned can be and still have distant end support.  I have also seen pictures of the head stock being turned and a long mast being shaped with just the near end being secured.

I remember seeing a suggestion for using a ball bearing live center with the support tip removed.

I had the replace a frozen back support on my old band saw  what it was stuck.

 

513433665_ballbearings.jpg.40a3a5b8a61c6e243455bd4142213d1e.jpg

 

 

These come in multiple OD and ID.   I just bought a used steady rest for my Unimat yo hold one of these, but since I only heard from PayPal about it, I was thinking that it was not going to happen.   It dawned on me that I could make a support for a ball bearing out of wood and saved the $90, and be able to use a ball bearing with a larger ID that might have an OD larger than the steady rest opening.

 

A long mast could go thru a properly large ID unit and be supported by shims.  Not many masts will be twice the distance of the lathe ways, so the mast can be reversed to shape.   If it is that long the piece being shaped has support at two points with any outboard shaping.

For small spars, the end can be shimmed in a ball bearing with a small ID and have a friction free support for the end.

 

My apologies if this is common knowledge and I just missed being exposed to it.

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Ball-bearings can be bought rather cheaply today in any size you want/need from ebay.

 

Once you have the steady-rest for your Unimat, you may consider converting the brass fingers to ball-bearing supports. I don't know, how the fingers on this steady-rest look like, but it should be easy to fit a small ball-bearing on each. Opt for the closed-type of bearings to keep dust out. The fingers then can be adjusted to any desired diameter and re-adujsted as you take off material.

 

Another, old-time mechanic's option is to make a simple hole into a thick piece of cardboard and to fix this on the lathe bed as a steady-rest. It's kind of a disposable rest.

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Thanks Wel,

 

The Unimat rest is 3 adjustable points,  I do not have it yet so I don't know how large the opening is and thus the max for the OD for a ball bearing race. It is fairly small though. 

I did a back of the envelope calculation  and  based on this, an ID of 3/4" or 17mm should clear the diameter of the largest mainmast I will encounter @ 1:60.   $6/2 on Amazon. 

Cardboard shims should work.   

The main complaint about using a small watchmakers size lathe for shaping masts seems to be that the ways are not long enough, this covers that problem.

I also see it as a way to hold the end of square stock for turning guns and capstans.   Match the dimensions of the square stock to be a push fit into

the nearest size ID ball bearing race.  No locating the center of the square stock.

 

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