New "old" tool for my other hobby

[Jeff in Pa]

One of the guys on a vintage forum ended up with this tool for cheap and posted a what is it? question and also asked if anyone needed it.

I knew exactly what it was and asked what he wanted for it. $20 plus shipping made me the happy owner of a crank pin turner.

The old engine have babbitt bearings and although they aren't real fussy as far as size, they do have to be round. When the crank throw wears out of round, the tool with the correct width cutter is placed on the crank throw and turned around to make the throw round again.

[olds45512]

congrats on the new tool Jeff, new tools are always the best.

[Sam Mac]

That is cool.

[J-Mech]

That's cool Jeff.

So, does it cut it, or are those stones that "grind" or file it?

[ACecil]

That's awesome, Jeff!

[Jeff in Pa]

Originally Posted by J-Mech

That's cool Jeff.

So, does it cut it, or are those stones that "grind" or file it?

It cuts. They are high speed steel cutters.

[john hall]

Never seen anything like that, cool! I assume it works kind of like a tubing cutter? I guess you just quit cutting as soon as it goes round? I would think the surface finish would have been horrible, is polishing afterwards required?

[Jeff in Pa]

Originally Posted by john hall

Never seen anything like that, cool! I assume it works kind of like a tubing cutter? I guess you just quit cutting as soon as it goes round? I would think the surface finish would have been horrible, is polishing afterwards required?

Surface finish is dependant on how well you sharpened the tool. Yes, once it's round ,you're done cutting. Surface finish can be improved with emery if needed.

The "saving grace" on this type of repair is that babbitt bearings are used. They work great as they form to any minor imperfections on the circumference of the throw. ( it must be round or the babbitt gets "pounded" out )

[john hall]

I've adjusted a few babbit crank bearings and will be honest, I never bothered to mike the shaft, just measure and remove shims until things got tight then added some back. Do you know if this was something more popular with auto engines than tractor and stationary engines? I'm thinking the "farm stuff" was ran slower and maybe more forgiving. I guess real repair shops may have been the ones using them, as crank grinding machines were few and far between. Certainly a cool item! I work with a guy who's father just retired as an engine machinist. Next time I see him I'll ask if he ever heard of one of these.

[Jeff in Pa]

Originally Posted by john hall

I've adjusted a few babbit crank bearings and will be honest, I never bothered to mike the shaft, just measure and remove shims until things got tight then added some back. Do you know if this was something more popular with auto engines than tractor and stationary engines? I'm thinking the "farm stuff" was ran slower and maybe more forgiving. I guess real repair shops may have been the ones using them, as crank grinding machines were few and far between. Certainly a cool item! I work with a guy who's father just retired as an engine machinist. Next time I see him I'll ask if he ever heard of one of these.

The patent date is April 4, 1922 on this cutter. Almost all the engines used babbitt back then. High rpm wasn't used since babbitt can give up quickly under heavy load. ( keep in mind that when you double the rpm, the centrifical force quadruples. )