In article ,
jim rozen wrote:

In article , B.B.
says...

In addition to my welding class I'm taking a machine shop class. Our
project involves a little piston air motor.
To make the cylinder for this we're instructed to drill & ream a
blind hole. I finished and reamed the hole, it's straight and clean,
except that it appears a chip wedged itself between the reamer and the
wall and scored the inside of the cylinder, making my piece scrap.
Is that just a danger of making a hole this way, or is there
something I can do to prevent such a problem? I did run the reamer a
bit faster than I was supposed to because the mill I was on had a broken
low range. Could that lead to this sort of thing?

How much material did you remove with the reamer?
IOW how much smaller than the nominal diameter of the
reamer was the hole?

Jim

Responding to this and all the other questions I've seen in this
thread so far:
I drilled undersize by 1/32", as our teacher told us is generally
correct for any hole over 1/2", I used lubricant, (though it's anyone's
guess what was in that bottle) and the material is aluminum.
The cutting tools are all in one cabinet that sees quite a lot of
abuse, so I wouldn't be too surprised if I picked up a tool with a bad
edge or a chip welded on already, though I did try to inspect anything I
got out of there and I am fairly certain my reamer was in good shape
when I used it.
Oh well, it was my first machined part ever, so no surprise I hosed
it. I still prefer blacksmithing as I can just hammer the damned thing
back the other way when this kind of thing happens. (:

--
B.B. --I am not a goat! thegoat4 at airmail dot net
http://web2.airmail.net/thegoat4/