Just because you can

[Andy Howell]

This is mainly for manufacturing, but have a read if your bored.

I was watching a student cutting something with the hacksaw Monday. She
was having a hard time because she was trying to hard, and because the
vise was going all over the place. The first problem is quite common and
easy to solve. Don't push down on the hack saw. Start by lifting the
front a little bit, taking real light cuts. The blade should float over
the material. While taking cuts, using the full length of the blade,
slowly increase the downward pressure. Eventually the blade will jam.
Back off on the downward pressure a bit. When you find the sweet spot,
you'll be cutting quickly with minimal effort.

Now that second problem, the vise. Turns out it was broken. The first
picture shows the vise with the stripped bolt that failed to hold the
base to the fixed jaw. The threaded hole was beyond repair as well. I
tapped it for a larger bolt and put it back together. The rough,
painted, castings did not rotate very well on each other. No problem,
I'll smooth them out on the belt sander. Hmm. Better, but not great.

This is where the "Just because you can" part comes in. One of my
interests in repairing/rebuilding old machines. I had my tools in the
car, so I set out to make the parts really flat. Not at all required,
but satisfying to do. I've shown this before, but some may not have seen it.

The second picture shows the tools. The electric scraper has a very
sharp carbide blade the moves in and out, scraping off little bits of
metal. The blue ink is applied the very flat granite plate, and the part
is rubbed back and forth across it. This transfers ink where the high
spots are.

The third picture shows the vise base after I'd worked on it a little
while. You can see its blue in the center, but not at the outer edges. I
used the power scraper to scrape away the blue areas, rubbed a flat file
over it to remove tiny metal burs left by the scraper, and then blue it
up again on the granite plate. The fourth picture shows the fine metal
chips. They are like dust. Each pass removed about 0.0002 inches of
material. Fifteen to twenty passes to remove the thickness of a sheet of
paper.

After many cycles of bluing, scraping, deburing, the fifth picture shows
the much better bearing of the two pieces. If this were a machine tool,
I'd keep going. It would probably be a few more hours work to get it to
the precision needed. This is just a poxy vise, which won't be moving
that much. But it was a good little low risk item to practice on. So I
did. Just because I could.

Last picture. Happy hands. Never be afraid to get your hands dirty.
Literately or figuratively. They will come clean. Eventually :) In the
process you might learn something and make the world a little better.

Note to self, don't use red loctite until you are _REALLY_ sure all the
parts fit together correctly. All the parts.

I temporarily fixed the mill tonight. Anyone know what was wrong?
Someone should have, and should have mailed me about it.

These go back a couple weeks: Quotes of the day.

When asked how he got stuck cleaning all the mats and the case for the
pit truss: "I'm the pit manager, I figured it was my responsibility"

A statement by me, in response seeing a student sitting cross legged on
the shop floor, vacuum in hand, cleaning up the area around the grinder,
belt sander and band saw:

"If you are trying to get on my good side, its working"

Thats it folks.

Andy