Those of you who scratch build using various types of brass stock might be familiar with this problem - I picked up a few pieces of brass 1/8 x 1/4 rectangle (hollow, like a square tube) at a local craft shop. Each piece is about a foot long or so. There wasn't much of a selection so I had to take what I could get. Each of these pieces has a slight bow to it, up to a couple of millimeters when measured from a flat surface.
My question - how do you get these closer to dead-straight? They flex a little but not much, I don't want to over-bend them or end up making them worse. Any ideas? Heat, maybe? I need them to be nice and flat...
Thanks!
Mark in Okinawa
Straightening Brass Stock
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Straightening Brass Stock
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I haven't worked with tubing that small or fragile before but one of the methods I have used on large diameter steel tubing might help you.
Keep in mind these methods were for times when I didn't have proper tools i.e. mandrels, dies, etc.
You have to support the inside of the tube the enire length or more to prevent the sidewalls from kinking up (game over then) . If you can find solid polystyrene stock that fits the inside dimensions of your tubing then that will work. Another method I used was to pack the tubing full of sand (dry, dry ,dry) . If heat is used with this method the sand MUST be dry or the heat will cause the moisture to expand and split the tubing open at any weak point.
Once the tubing is supported internally then find something with a diameter large enough ( or as close to ) to mimic the bow your trying to remove. Using this item then overbend the tubing SLIGHTLY in the opposite direction of the bow your trying to remove. Remember that a small adjustment and check is better than one big bend and an "Oh c&%p".
After that, remove whatever you used for internal support and see if the tube retains the corrected shape.
It's not easy to get a couple of the more critical parts across by writing, it works best if you could see it first hand. Good luck, I hope this helps you.
Keep in mind these methods were for times when I didn't have proper tools i.e. mandrels, dies, etc.
You have to support the inside of the tube the enire length or more to prevent the sidewalls from kinking up (game over then) . If you can find solid polystyrene stock that fits the inside dimensions of your tubing then that will work. Another method I used was to pack the tubing full of sand (dry, dry ,dry) . If heat is used with this method the sand MUST be dry or the heat will cause the moisture to expand and split the tubing open at any weak point.
Once the tubing is supported internally then find something with a diameter large enough ( or as close to ) to mimic the bow your trying to remove. Using this item then overbend the tubing SLIGHTLY in the opposite direction of the bow your trying to remove. Remember that a small adjustment and check is better than one big bend and an "Oh c&%p".
After that, remove whatever you used for internal support and see if the tube retains the corrected shape.
It's not easy to get a couple of the more critical parts across by writing, it works best if you could see it first hand. Good luck, I hope this helps you.
There is allways something in the dark beyond the firelight.
You could just bend it back gently by hand. Hold the piece against something flat, and hard. Then you should be able to press against it lightly a little at a time. Hold it out from a table, or other flat surface a few centimeters at a time, and bend it ever so lightly a little bit, then check it as you go. This is the only thing I can think of to make this straight. It's even harder with round tubing. I just hold it over a flame, and heat it a little at a time while bending it. I think you might want to put something inside the tubing to support it so that you don't overbend it. Styrene, or something similar is definately advisable. Let us know if you have success with this.
It's a Pain In The Ass - not pita! Pita is what all the morons keep calling "flatbread"!
I have done is by hand like outlander suggests but never with heat. So my answer is "Very carefully!" 
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"In the universe, space travel may be the normal birth pangs of an otherwise dying race. A test. Some races pass, some fail."
- Robert A. Heinlein
Our only chance of long-term survival is not to remain lurking on planet Earth, but to spread out into space.
- Stephen Hawking, 2011
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blckbuster
- Posts: 4
- Joined: Sun Aug 04, 2002 2:28 am
Yes! I saw them making a trombone on "How it's made" a few weeks ago and they were doing this to bend the thin brass tubes.blckbuster wrote:I have had success with filling tubes with water and freezing them before carefully bending them
BUILDING THE FUTURE!
"In the universe, space travel may be the normal birth pangs of an otherwise dying race. A test. Some races pass, some fail."
- Robert A. Heinlein
Our only chance of long-term survival is not to remain lurking on planet Earth, but to spread out into space.
- Stephen Hawking, 2011
The Blaposphere
"In the universe, space travel may be the normal birth pangs of an otherwise dying race. A test. Some races pass, some fail."
- Robert A. Heinlein
Our only chance of long-term survival is not to remain lurking on planet Earth, but to spread out into space.
- Stephen Hawking, 2011
The Blaposphere
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Tankmodeler
- Posts: 949
- Joined: Fri Jul 30, 2010 12:04 am
- Location: Ontario
The key thing here is that to straighten or flatten a piece of bent metal you absolutely must overbend it in the opposite direction, at least a little bit. You have to overcoem the natural spring that is in the metal.
If you can afford the brass to be permanently softer, then heat it cherry red & let it cool. You will have annealed it, but beware, the tube shapes will easily collapse, so support the inside as was said above when you go to overbend it. Another way to support the inside is to fill it with fine sand or powder.
HTH
Paul
If you can afford the brass to be permanently softer, then heat it cherry red & let it cool. You will have annealed it, but beware, the tube shapes will easily collapse, so support the inside as was said above when you go to overbend it. Another way to support the inside is to fill it with fine sand or powder.
HTH
Paul
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