"B.B." u wrote in message
news
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?

As another poster said, using a lubricant is important -- but it still won't
prevent the odd errant chip from wedging, if it moves around enough.

One way to help prevent this is to ream upside-down, so the chips fall out
as you work. This isn't very practical on most work, and only good for dry
reaming, like on cast iron.

Another way is to fill the flutes of the reamer with a sticky wax (like
toilet bowl ring wax) to catch and hold chips as they leave the cutting
edge. This works nicely, but if you do it, you must clean and re-wax
frequently to prevent loading the reamer.

Some old guys swear by wrapping the reamer in waxed paper. But I've never
been able to get the thing started in a hole without its shedding its
wrapper.

LLoyd