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Thread: How to flatten brass bar
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22nd June 2013, 09:25 PM #1
How to flatten brass bar
I think it's high time that I left the woodies alone and pestered you metal folks with my incessantly idiotic questions instead
I've got a strip of new brass about 20mm x 180mm x 3mm that I'd like to use as the blade in a square, but it has a slight twist in it that is stopping it from laying completely flat.
Is it possible for a complete duffer to fix it up so it's nice and flat and even on both sides?
I figure twisting it the other way is only going to make it more wavy along the length and I'm not sure of the technique, or usefulness, of beating at it (gently) with a hammer and a bit of finish sanding/lapping.
I have wondered if chucking it in the oven (or under a blowtorch) on a flat surface would let gravity do the work for me once it was hot enough...but I reckon I'm just making up my own physics and metallurgy.
Have at meEvery time you make a typo, the errorists win.
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22nd June 2013 09:25 PM # ADSGoogle Adsense Advertisement
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22nd June 2013, 10:03 PM #2
Brass ( and bronze for that matter ) comes in a huge variety of alloys, some can workharden vey quickly and become brittle, and will crack when hammered.. some, like alloy 260 is softer and more malleable.
Start out by annealing it, heat it to red hot for a bit and just let it air cool naturally, if you are in a hurry you can water quench quite happily, it's not like steel which needs to be cooled slowly to anneal
If it's just a twist, then try and straighten by un-twisting it.. if it's more distorted than just a simple twist then you might be able to flatten it against an anvil.
Do you have a flat surface you can use as an anvil?
And a hammer with a clean face? if the face of the hammer is all dinged up then you will just transfer those marks to the brass.. if the hammer is all dinged up, then polish the hammer face with flap disk, and buffing wheel..
Hammer it flat against the anvil as best you can, turning it over as you go, you don't need to hit very hard, just tap tap tap is all you need... when you are happy it's flat enough for your purposes, then anneal it again to remove the stresses, if you want to harden it then work hardening is the best way, that might mean hammering all over with light taps and skip the final annealing step... sort of like planishing..
Sand or lap flat and polish..
Regards
Ray
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22nd June 2013, 10:26 PM #3
Thanks Ray
I had no idea about the annealing. Had a quick little read up on it and it makes complete sense.
I'll see how I go with just the twisting, and I've got a big honking thick block of steel that should do as an anvil for this task (I'll clean up a face first, like with the hammer) if push comes to shove...or tap in this case
I'll give the workhardening a crack too. But will I (should I) be able to do it on the thin edges as well? It would be good if a marking knife couldn't easily take nicks out of it.
And just to double check...if workhardening, I should anneal only once...at the start, before removing the twist.
Should be a fun little job with a few new things to try and learn.Every time you make a typo, the errorists win.
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22nd June 2013, 11:39 PM #4SENIOR MEMBER
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Just to add to what Ray has said, you can use a flat piece of steel laid on top of the brass and hit that with the hammer. The heavier the piece of steel the better. I have a piece 75mm wide x 35mm thick and about 350mm long. It works a treat.
Phil
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23rd June 2013, 01:47 AM #5
Ooh...a local fella...thanks too Phil. I'll give that a go as well if I can rustle up something suitable.
Every time you make a typo, the errorists win.
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23rd June 2013, 07:40 AM #6SENIOR MEMBER
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If you can't find anything, you can borrow mine. If you have time you could bring the brass around and we can give it a shot. I should be in the shed all day...fingers crossed .
You'd have thought I would have realised you were local
Phil
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23rd June 2013, 03:18 PM #7
Gah. I miss my oxy
I've been trying for the last hour or so and I can't get the brass hot enough or remotely evenly with my wee propane torch. Tried it in a fire with even less of a result.
Time to PM Phil with a bribe me thinks.Every time you make a typo, the errorists win.
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1st July 2013, 09:17 PM #8
I just wanted to send out another huge thanks to Phil/Steamwhisperer for surrendering a couple of hours of his own play time to help me out with this this morning. He's done a great job of annealing and flattening out a couple of these crappy strips for me.
It's always nice to meet another forumites, especially locals, and I learned a thing or two while I was there (and not just about metal) and got to see some great stuff (his big Weir boiler pump project looks brilliant).
A big thumbs up for a top blokeEvery time you make a typo, the errorists win.
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