Normally when the tool quits adequately performing its intended function. This could be leaving an excessive burr, bad finish, using more power than would be expected.
2. What do you do to get them back into usable shape?
Normally tools are sharpened by grinding and/or honing. In many cases this can be done on a bench grinder and hand stoning, or may require dedicated sharpening machinery which would be the case for endmills and reamers.
It depends on what you consider "sharp".
Much lathe tooling for steel is not what many hobbyists would consider sharp, as in a knife edge.
When a tool stops producing the desired surface finish and dimensions then it is time for a new one.
This is a new insert for steel, I use these often and they produce a very nice finish and last a very long time.
It is very dull as far as knife edges go by design.
Not the nose radius but the actual cutting edge has a small radius of .001-.004" depending on its intended purpose. Knife sharp tools will not last long.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.