rmac wrote: I'm not planning to try this [trepanning exercise] again, since it seems iffy even under the best of conditions.
Harold_V wrote: A shame, as staying the course would be a great learning experience. We gain strength by failures like this.
The above is from a couple of months ago when I had some trouble with trepanning when I was working on one of the Moriya engine parts. So now it's later.rmac wrote: You're right. A better plan is to go ahead and make these engine parts using the mill and the rotary table, and then to continue with the trepanning and tool grinding exercise later.
I ground a proper tool this morning from a HSS blank rather than the cut nail I was using before. It's got just a little front relief, and no top rake. Although it chattered pretty bad when I first tried it out, I was able to get good results by slowing the lathe way, way down. The chips didn't curl up into little watch spring spirals like they do sometimes with a parting tool, but otherwise it seemed a lot like a parting operation.
Question: Given that my cutter seemed to do the job, is there any reason to think it would work better--whatever that might mean--with a little top rake?
-- Russell Mac