1946 Logan 820 Lathe and Acetal Half Nuts (Evanut)

[Michael_PE2003]

In my recent post, I mentioned making some of the parts for my Craftsman Mohawk slow speed attachment on my 1946 Logan lathe so I thought I post a little about it. I bought it from a Craigslist ad many years ago (12 I think?) as a well-used and pretty tired machine. Thanks to Scott Logan I found that it was shipped on New Years Eve, 1946 to the Moslo Machinery Company of Cleveland, Ohio. As near as I can tell they made plastic injection molding machines and/or parts for them.

This is the picture from the Craigslist ad...



Not going to win any beauty contests but it was nearly complete and came with some tooling.

After a complete teardown including replacing some bearings, a couple gears, new countershaft, etc., this is how it looked after it was finally ready to turn some parts...

 

[Michael_PE2003]

I used it like this (with the addition of a Chinese QC toolpost) for years to make a variety of parts, including parts for putting a couple of old motorcycles (the reason I bought it in the first place) back on the road. Below is the first part I made on the Logan which also happens to be the first part I ever made on a lathe...



It's a spacer to mount a modern (lighter) brake disk on a Yamana XS650.

The only thing the lathe wasn't capable of doing was cutting threads as the half nuts threads were so thin you could read a newspaper through them. (not really but close to it) After looking for quite a while and not finding a set that were in useable shape for a price I could swallow, I decided to try and make a set from Acetal plastic after seeing a post on another forum. They have since been called Evanuts after the orginal poster. If you Google "Acetal half nuts" or "Evanut" I expect you'll find all the info.

The basic idea is to form the Acetal around a piece of Acme thread by heating the threaded rod above the melting point and squeezing the Acetal around the rod in a vise. The Acetal shrinks tightly around the rod and can then be turned into whatever shape and size is needed to replace the original half nuts. That all seemed pretty straightforward and the real challenge was boring out the original cast iron half nuts without a mill. Here is what I came up with.



The Acme rod (same one used to form the Acetal) was held between centers to mount the half nuts to the face plate and hold them on center so the existing threads could be bored out and the mount opened up to accept the Acetal thread inserts. Maybe not ideal but good enough for my needs and you use what you have when you can't buy what you would like. (like a Bridgeport)



There is a plate bolted to the bottom of the half nut mount and a spacer between them that holds the two halves in the same position as when they are installed in the lathe apron.

 

[Michael_PE2003]

The final step was to form the thread blank to the threaded rod and turn between centers, split the two halves and install them into the modified original half nuts.



Not shown are the four 4mm cap screws (it's what I had leftover from another project) that hold the Acetal inserts in the original half nuts. The nuts have almost zero backlash and being made from a material often used for plastic bearings, they should last until long after I'm gone. The best part is it only cost a bit of time and about $4.00 worth of Acetal rod.

 

[alfadan]

Nice write-up and nice machine. Here is another approach: