Crankshaft journal polisher - GIF

Crankshaft journal polisher.

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Previously:

https://www.homemadetools.net/forum/...841#post186777
https://www.homemadetools.net/forum/...836#post179135
https://www.homemadetools.net/forum/...0885#post73315
https://www.homemadetools.net/forum/...562#post174092
https://www.homemadetools.net/forum/...565#post166765
https://www.homemadetools.net/forum/...031#post157113

Since that process is making sparks, I am thinking that is not just polishing. What kind of tolerance can be held with that belt in place vs a wheel?

Quote:

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Originally Posted by hemmjo

Since that process is making sparks, I am thinking that is not just polishing. What kind of tolerance can be held with that belt in place vs a wheel?

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Most likely they are just taking off a few .0001" or so. I believe it's one of those experience things where the guy knows how long to polish to just out a better surface finish on the journal. Quite adequate for most engines.

I prefer to polish them further to a mirror finish after the machine shop is done with them for racing and heavy duty use. I can't say that it makes a bit of difference, but I have had race engines that showed some wear on the bearings, and the crank was still perfect, so it must do something.

My line of thought was that if you take a piece of chalk and a chalkboard, the board is very smooth, yet the chalk sticks to the fine imperfections of the board. Now try to write with the same chalk on a piece of glass, you get nothing. The bearings are softer than the crank journals, somewhat like the chalk, so if you have a glass finish on the crank journals, it should help if you ever have an oiling issue or the engine is abused in racing conditions.