SHAFTRU Milling Tool

[snoots]

Hello everyone.  I'm new to the board and did a search before posting but didn't see anything that matched what I have.

My grandfather had this tool for years, although I never saw him use it.  He said it was a crank shaft straightener for a Model A Ford.  The information on the tool is:

SHAFTRU Milling Tool
mfg ATHERTON SALTER MFG CO
ST Louis MO
Pat Jun 29, 20 No. 1344831
No. 2123

I have attached a couple of pictures and was wondering if anyone could tell me anything about it.  I did an internet search, but haven't run across anything yet.

[snoots]

Upon further research and looking up the patent, I confirmed with a magnifying glass that it is "Atherton" (not Atmerton) Salter Mfg Co.

The patent calls the tool a "Crank Pin and Shaft Truing Tool" so I suppose its use was not limited to the Model A.

Names on the patent were Charles Nicholas Atherton and Josiah Harvey Sutter.   Still digging...

[Papaw]

A new one on me, but I've been out of the loop on old engine repair for some time.

[rusty]

The only reference I can find is Motor Age, Volume 38 (1920)
Many companies coming out with gadgets for the early cars did not live long...