[Spridgets] No LBC ....used watch makers lathe wanted for my students.

bjshov8 at tx.rr.com bjshov8 at tx.rr.com
Wed Dec 1 15:16:32 MST 2010


I mentioned my friend that had the big Bridgeport mill in his garage.  I told
him I couldn't have one of those- I would try to make an airplane or something
and get myself into trouble.  But it was really neat to learn how it works and
watch the students make parts with it.

I already mentioned our robot competition: One of our tasks was to make a
piece out of sheet aluminum to mount an electric motor to.  The motor was
about 1 1/4" diameter, 3" long or so.  Looking at the end of it there were 4
threaded mounting holes and a shaft.  Three of the holes seemed to form an
equilateral triangle, with the 4th hole opposite one of the others, and the
shaft itself was offset from center a certain amount.  We measured the holes
with a digital caliper and determined that the 3 holes did form an
equilateral, and the 4th hole was on a circle that passed through the other 3
holes.  Then we could do the math to calculate X and Y coordinates for all 4
holes plus the output shaft.  The father insisted that we drill holes the
exact diameter for an 8-32 screw.  Using the digital readout of the mill the
student placed all 5 holes per our calculations.  We held the finished piece
up to the motor and it looked like it was made in a factory.  Every hole lined
up as perfectly as we could detect by eye, and the bolts screwed in with no
interference.  In the old days we would have eyeballed it, centerpunched
holes, drilled them oversize with a hand drill, then reamed or filed the
varous holes until all 4 bolts would screw in.  This would have been faster
but messier and not as much fun.


> Boy, like that but would have to go next to my computer, Tis a lovely peice
> of work.
>
> Subject: Re: [Spridgets] No LBC ....used watch makers lathe wanted for my
> students.


More information about the Spridgets mailing list