[pzzamakr1980]

I just got my first actual machining contract today and had a question about surface finish. I am going to be making 100 small parts on the lathe and it specifies 64 rms. So the question is, what does the finish look like?

[Eurisko]

This is going to be tough to describe. A 63 finish falls somewhere between a very nice finish (32) and a "good enough for production" finish (125). The finish should be fairly smooth, no chatter.

You might want to invest in a set of surface finish standards, which are simply a set of blocks machined to various surface finishes. These blocks can be used visually as comparators, or used to calibrate surface finish measuring equipment.

Here's one link, there are many more (cheaper) ones out there, I'm sure.

http://www.edmundoptics.com/onlineca...productID=2468

[pzzamakr1980]

That is fantastic. Thank you very mucc for the info and the link. I just purchased a set at a great price. Thx again.

[NC Cams]

THe ID of a PROPERLY refinished auto engine con rod is 50-64.

Too smooth here and not enougt "bite" into the bearing to keep it from spinning. Too rought here and poor size control plus poor heat transfer out of the bearing into the rod.