I have a brass bar, .250 thick, 1.5 wide and 12" long. I need to twist it so
the first and last 2" stay flat but wind up at a 45 º angle to each other. My
first thought was to bolt or weld two long angles to use as a wrench and put
one end in the bench vice and just brute force it. My question is: if I do
that cold will the bar twist or break? If I heat the bar with either a
propane or MAPP gas torch will that work. Is there a better way alltogether?
Thanks for your help and advice.
Roger in Vegas
Worlds Greatest Impulse Buyer
brass is kinda brittle, it will probably break.. even if your eyes are
not close to it, i would use caution and wear eye protection as brass is
know to break off and fly apart with force on it.... better than looking
for a new eye...
Just a guess- it will work as you describe even without the torch but
it's going to take a lot of torque. I hope your vise and bench are heavy
duty and your angle irons are a few feet long. Naturally, heating it
with the torch is going to make it easier to bend.
Roger Hull wrote:
I would think it would break just because it machines like cast iron.
But, that's not why I'm posting. I can't find you phone # again and I
saw this tracked machine behind Hanna's that you might want to look
The best way to do this is to set up the bar in a 4 jaw chuck with the 2"
mark level with the front of the jaws, then clamp 2" of the other end in the
When the bar is set up true to the center line, you can grip one of the jaws
with an adjustable wrench and twist the bar until you get 45 deg.
I don't keep the proportions of copper and zink in my head but there are
several types of brass. Some are mixed for machining some are mixed for
bending. It would help to know which you have. If it the latter you
should be able to manage with out annealing. If you only have one piece and
none to spare go ahead an anneal it just to be safe.
For optimum strength, if strength is needed, the bend should take the bar from
condition A to condition B. Condition B is the temper appropriate for the
application. I don't think there's any heat treatment to achieve condition B.
Condition A might be fully annealed, quarter or half hard, or near full hard.
To evaluate what can be done with your particular bar, saw off a piece from
the end which is Mill it if needed to get the proportions right,
while the absolute size matters little.
Then clamp the ends 0.2 inches and bend with no heat treat to the same 45
after springback as you want with the full 10x scale piece. Check for cracks.
If it cracks, or has stress marks, either full anneal and count on less than
full strength, or cut another piece and figure out how much to anneal it.
Whatever you do, don't bend it hot. Brass and copper are hot short, that is,
they sustain near 0 % elongation before rupture when hot.
So divide everything except the angle by 10, and make a trial. You're only
losing 0.025 off the end of a 12 inch piece, after all.
12 x 1.5 x 0.25....
12/1.5 = 8; 1.5 / 0.25 = 6. Using a larger scale will make the piece smaller,
12 / 8 = 1.5; 12 / 6 = 2. We don't have 2.
1.5 / 8 = 3/16 ; 1.5 / 6 = 0.25
So what will fit in the end of the bar?
Clearly scale 1/8. So the bit off the end will be 1.5 x 3/16 x 1/32.
Did I get that right?
Doug Goncz, Replikon Research, Seven Corners, VA
Unpublished work Copyright 2003 Doug Goncz
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