Bending brass tube

This topic is empty.

Viewing 19 posts - 1 through 19 (of 19 total)

Author

Posts
17 May 2012 at 22:07 #3846
Bob Abell 2
Participant
@bobabell2
A novel method
Advert

17 May 2012 at 22:07 #34435
Bob Abell 2
Participant
@bobabell2
Hello chaps

Just been watching…."How it's made"………on tonight's TV

They were making trumpets with thin wall brass

Having rolled and soldered the main body of the trumpet, they ended up with a Post Horn shape. The next job was to bend the thin end back through 180 degrees!

This should be interesting, I said to myself

They filled the tube with water and froze it in Nitrogen!

The tube was then bent around a former, quite easily with no collapsing!

Never seen that done before!

Bob
17 May 2012 at 22:39 #34436
Colin Bishop
Moderator
@colinbishop34627
Easy if you happen to have the frozen nitrogen I suppose….

Colin
17 May 2012 at 22:46 #34437
Bob Abell 2
Participant
@bobabell2
I assume the household freezer would be suitable?

They were using Nitrogen just to speed up the freezing process….I think

Bob
18 May 2012 at 06:32 #34441
Paul T
Participant
@pault84577
Hello Bob

Many years ago I was shown how to bend copper (and brass) tube with dry sand. Cap one end, fill with dry sand and ram to compact then cap the other end.

The sand prevents the tube walls from deforming whilst being bent.

Make the bend and then remove the sand.

I can understand how the process you watched would work but I dont think that a domestic freezer could get the ice hard enough to prevent the tube from collapsing (hence the Nitrogen)

Paul

Check your messages old chum
18 May 2012 at 07:41 #34442
Bob Abell 2
Participant
@bobabell2
Hello Paul

You are probably right about the freezer, but annealed 10 thou brass is very soft

They did most of the early bending round a mandrel, with just fingers alone

This reminds me of another little novelty……

When champagne is being processed, dregs form at the top of the bottle behind a temporary bung

With the super fizziness of the liquid, they have to freeze the top with Nitrogen, remove the bung, then scrape out the frozen dregs somehow and replace the stopper. Or something like this

No messages recieved in my mail box, at the moment?

Bob
18 May 2012 at 08:00 #34445
Paul T
Participant
@pault84577
Hi Bob

I have seen the same thing about champagne….how did they do it before the use of Nitrogen became available?

Sorted out the message (blame the computer)

Paul
18 May 2012 at 08:07 #34447
ashley needham
Participant
@ashleyneedham69188
Paul, they probably didnt, and no one noticed! in any event, when opening the champas, an amount of said liquid gets expelled behind the cork, and takes the gunge with it ???

Bending small diameter brass tube is the trick….how?

Ashley
18 May 2012 at 08:16 #34449
Bob Abell 2
Participant
@bobabell2
Just had a thought!

Almost a Eureka moment?

Wouldn't it be nice, if handy lengths of brass tube was sold, already filled with lead?

There yer go!……….Could be a nice little earner?

Bob
18 May 2012 at 08:19 #34450
Paul T
Participant
@pault84577
Nice idea Bob

How do you get the lead out after the tube has been bent?

Paul
18 May 2012 at 08:23 #34452
ashley needham
Participant
@ashleyneedham69188
Would likely double the price of a bit of tube Ashley
18 May 2012 at 09:13 #34454
Bob Abell 2
Participant
@bobabell2
Paul and Ash

The lead can easily be removed with a blow lamp

Paying extra would be ok, if a nice bend was essentia

Filling a tube with molten lead is not recommended for most model makers, you would need some very specialised tackle…..viz

A safe stand to hold the tube vertical, a very neat pourer, probably a fine funnel and a steady hand and good eyesight!l

Not forgetting safety goggles also.

When I was a young lad, my elder brother tried to cast a strip of lead….. In a wet clay mould!!!

It exploded and covered the kitchen ceiling and us with lead splatter! How we weren't blinded was a miracle!

Safety equipment is essential for most engineering undertakings….As most of us already know of course

Bob
19 May 2012 at 07:10 #34464
Paul T
Participant
@pault84577
Hello Captain Bob

I think the problem with the average model maker melting lead out of the brass tube is summed up in the graphic description of your kitchen experiment.

But the prospect of having such fine control over bending tube has considerable merit and is a true engineers solution , I am going to have a play with your suggestion this afternoon but instead of lead I am going to use plumbers solder simply because it has a lower melting point and should flow better.

Paul
20 May 2012 at 16:50 #34492
David Marks 2
Participant
@davidmarks2
Gentlemen

Hopefully i am not informing you of something that you are already aware.

Attending the local Technical College when I was a Mechanical Engineering apprentice back in the late 1960s, we had a regular dose of Metalurgy i.e. learing about the chemical, and mechanical properties of different metals and more importantly thier appropriate use.

Woods Metal is an alloy containing Lead, Tin and Bismouth (to name jus ta few). It has an extremely low melting point andone of its uses was for a sealing plug in fire sprinkler systems i.e it melted when if got hot and in doing so actviated the sprinkler. Also you could fill a copper, brass or stainles steel tube with the molten material, allow it to solidify, bend the tube, then reheat to remove the alloy……..leaving one `formed tube'. In its latter format it was called Cerrobend (a tradename).
20 May 2012 at 17:04 #34493
Bob Abell 2
Participant
@bobabell2
Hello David

That sounds just the right sort of stuff for the job!

Where can it be obtained?

Bob
20 May 2012 at 18:22 #34494
Kimosubby Shipyards
Participant
@kimosubbyshipyards
Hi Bob and others,

cerrobend can be got here http://www.bendalloy.co.uk/page5.html

never used it but might want to, let us know if it works ok Bob.

Kimosubby
20 May 2012 at 22:32 #34504
David Marks 2
Participant
@davidmarks2
Bob

Yes a quick "Google" identified Bendalloy as a UK supplier of Cerrobend. Via their STD Code., they are in Huddersfield. May be worth an email to outline what you are trying to achieve i.e. tube bore size, wall thickness, bend radius etc. and seek thier comments, advice etc.

As you will see from the information available, Cerrobend melts at around 70 Centigrade i.e. well below the boiling point of water.

Regards – David
21 May 2012 at 07:09 #34514
Paul T
Participant
@pault84577
Bob

Loading the brass tube with plumbers solder works well as I could form some very tight bends, the tube walls remain smooth with no deformation.

Good idea Bob

Paul
21 May 2012 at 07:18 #34516
Bob Abell 2
Participant
@bobabell2
Many thanks to all concerned!

I was only proposing a method of bending thin brass tube, as seen on the TV prog

I haven't got a reason at the moment, for bending the stuff!

Bob
Author

Posts