"Tim Wescott" wrote in message
...
On Thu, 17 Nov 2011 15:12:28 -0500, Ed Huntress wrote:
"Tim Wescott" wrote in message
...
I'm building model airplanes. Nearly everyone bends up their landing
gear out of music wire (0.9% carbon, low alloy, hard drawn wire), and
either holds the wheels on with these really ugly collars, or they epoxy
on washers.
The washers won't come off when you want them to, and do come off when
you don't. I'm thinking up a few schemes to do a nicer job, some of
which would go a lot nicer if the steel were drawn a lot more than it
is. I don't want to go using my nice 5-44 die on hard steel, nor do I
want to try drilling .050" holes.
So: how to anneal, and how to just draw the temper a bit more? For
annealing I expect that I can just clamp the thing in my vise (both to
hold and to limit heat travel), get the end as hot as it'll get with a
propane torch, and let it cool. To just draw it, should I do something
like filing a spot shiny, then heating it to blue or purple, then
letting it cool? Or is there a better way to do this by eyeball
methods?
Comments appreciated. I know how to make it work with rocks and sticks,
I'd just like pointers on using hammers and screwdrivers for the job...
--
www.wescottdesign.com
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Anneal: Get it dull red, stick it in some ashes or powdered lime. Ashes
will be better with music wire. Lime might actually re-quench it, if the
wire is thin.
Draw: For music wire, drawing it locally, I heat a piece of steel rod to
red, lay it against the music wire; draw to the color you want; and
water-quench *fast*. If you're heating just the end and if you have an
electric stove top, you can just lay it on a burner coil.
Here's a color chart:
http://www.anvilfire.com/FAQ-article...odyName=/FAQs/
temper_colors_hardness.htm&titleName=Temper%20Colo rs%20and%20Steel%
20Hardness%20:%20anvilfire.com
The colors are really not that clear. They're more like this:
http://en.wikipedia.org/wiki/File:Te...s_in_steel.jpg
1095 is close to music wire.
Music wire should be shiny enough to see the colors without filing. If
you have to clean it, I'd use some 300/400 grit wet/dry sandpaper rather
than a file.
To safely thread it with a die, I'd go for at least dark blue.
Good luck.
(BTW, this is not the best way to anneal or draw plain carbon steel in
thicker sections. But the better methods aren't going to be very
practical with wire.)
================================================== ========
So if I just heat it to dull red and let it air-cool, will that be fast
enough that it'll actually quench, even with it being carbon steel?
It depends on the thickness. After seeing your photo, I'd say it probably
will NOT quench in air. It looks like it's maybe 1/8" or so, right?
It's hard NOT to quench a piece of, say, 0.020" wire. But thick wire should
be OK in air. To be safe, scrounge some ashes from a wood fire or a charcoal
grill. I keep a 3-lb. coffee can full of ashes just for little jobs like
that.
Strength in this spot is absolutely not an issue: the landing gear needs
to be very springy close to the center of the plane, with the needed
strength dropping off the closer you get to the wheel -- by the time
you're on that side of the wheel, it could no stronger than soft
aluminum, and you could safely retain it with a cotter pin and washer
(which is why I'm contemplating drilling little holes).
http://www.metalworking.com/dropbox/wheel.jpg
--
www.wescottdesign.com
'Should be no problem to cool that in air. And, from the colors, you'll be
able to tell hard far up the wire you've softened it.
--
Ed Huntress