On 06/14/2010 03:42 PM, Wes wrote:
Tim wrote:

Then I thought "Ah ha! Delrin is a pain to machine because it squirms
away from the bit! I'll drill a 1/16" hole, then widen it with the
5/64" bit!" Success! the 5/64" bit took out enough material for a good
press fit on the shaft.

Never say die, and you may just succeed!

(Interestingly enough this also doesn't belong on _rec_.metalworking
because it's for a customer project -- I needed a flywheel on a test
article that I'm writing control algorithms for -- the _real_
metalworking involved was making the steel outer edge for the flywheel,
that the Delrin hub presses into).


What do you mean work doesn't count? I made a crappy little tool consisting of a .55 dia
pilot that fits into a pneumatic piston we have to put a U cup on. Round thing screwed to
a piece of .50 x .25 x 3" stock that has a strategically placed 3/16" dowel pin pressed
though the rectangle stock that just clears the edge of the piston by 0.010" so if they
get the U cup started, a twist of the wrist spins it on.

Request from one of the ladies on my assembly line.

Of course the engineer had to approve it, he of course started improving it (we will see)
but he did take it out to the line for use until he gets his tool made his way.

Well, if he does improve it then huzzah! And if he's smart enough to
get out of the way when yours works -- huzzah twice!

One of the things I needed to learn as an engineer is when you want to
just get by with a crappy little tool, and when it's essential that you
step back, take a deep breath, and really _design_ something.

I don't know if I'm there yet -- I've finished projects, fat and happy
in a pile of new tools, then realized that I could have done the whole
thing with a sharp stick and a rock.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com