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Author Topic: bending copper pipe ?  (Read 9250 times)

red_noir

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bending copper pipe ?
« on: January 27, 2010, 02:25:03 am »
hey Guys I have a question about bending copper pipe. both sizes 1/8 and 5/32. When I bend the same sizes in brass it turns out well, but copper in these sizes seems to compress and flat spot <*<. I'm using a dubro bender with proper mandrels for each.

due to this issue Im debating doing all my plumbing in brass, are there any con's to doing so?
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derekwarner

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Re: bending copper pipe ?
« Reply #1 on: January 27, 2010, 03:41:23 am »
Red......are you using the Dubro spring benders or the two handled ...black plastic bodied individual benders?.....& what type of mandrel are you using?

I started with the spring set but my lack of success in maintaining a constant radius led to the two handled versions for both 1/8"& 5/32"OD tube.......have a look at the French JMC WEB home page.....he uses brass & you can clearly see the flattening in the bends

http://www.paddleducks.co.uk/smf/index.php?action=links;sa=visit;id=54

I find the 5/32"provides less flattening than the 1/8" in brass or copper.....so this points to the geometry of the benders

Just one consideration is to anneal the tubing [cherry red & let cool naturally] prior to bending........ :-)) ....Derek
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Derek Warner

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Illawarra Live Steamers Co-op
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red_noir

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Re: bending copper pipe ?
« Reply #2 on: January 27, 2010, 03:54:48 am »
Im using the two handle dubro style in both 1/8 and 5/32. they work well on brass but I cant say the same for copper.

after they have been annealed before bending how do you harden them again?
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derekwarner

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Re: bending copper pipe ?
« Reply #3 on: January 27, 2010, 05:52:43 am »
Red.....the standard K&S brass & copper tube is termed as DOM....which is drawn over mandrel + die......this mechanical process work hardens the tube......by annealing we are simply relaxing the mechanical stresses set up in the tube structure therefore making it easier to bend...it does not require any post bending heat treatment

If you were concerned about returning the mechanical properties you could gently reheat the previously annealed area to a very very dull red & quench in water....however the potential exists here in distortion of the bend accuracy >>:-( ....Derek
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Derek Warner

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Illawarra Live Steamers Co-op
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www.ils.org.au

Circlip

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Re: bending copper pipe ?
« Reply #4 on: January 27, 2010, 01:17:02 pm »
Annealing Copper tube, heat to cherry red and EITHER leave to cool normally OR quench immediately. Copper is the one metal that this works for.

   Regards  Ian.
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red_noir

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Re: bending copper pipe ?
« Reply #5 on: January 27, 2010, 01:41:34 pm »
wow ! thanks for all your help !!
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steamboatmodel

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Re: bending copper pipe ?
« Reply #6 on: January 27, 2010, 02:07:04 pm »
After annealing the copper fill it with water and put out side for a while, then bend the ice will help support the inside of the tube.
Regards,
Gerald.
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Bunkerbarge

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Re: bending copper pipe ?
« Reply #7 on: January 27, 2010, 06:55:35 pm »
That's assuming it's below zero outside.  It wouldn't work in Florida!!
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andywright

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Re: bending copper pipe ?
« Reply #8 on: January 27, 2010, 07:42:13 pm »
It will in the UK at the moment!!! :}
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steamboatmodel

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Re: bending copper pipe ?
« Reply #9 on: January 27, 2010, 10:57:48 pm »
red_noir
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Location: Canada ehh !
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derekwarner

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Re: bending copper pipe ?
« Reply #10 on: January 27, 2010, 11:08:09 pm »
Gerald suggests...... "After annealing the copper fill it with water and put out side for a while, then bend the ice will help support the inside of the tube"

....thanks Gerald.......quite interesting...I will try this   >>:-( ...but in OZ will need to place the tube in the kitchen freezer ........ {-) O0 :-)) ....Derek
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Derek Warner

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Illawarra Live Steamers Co-op
Australia
www.ils.org.au

red_noir

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Re: bending copper pipe ?
« Reply #11 on: January 27, 2010, 11:41:09 pm »
Freezer whats that? Surely you mean the back yard?
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steamboatmodel

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Re: bending copper pipe ?
« Reply #12 on: January 29, 2010, 12:29:24 am »
Quote from: red_noir on January 27, 2010, 11:41:09 pm
Freezer whats that? Surely you mean the back yard?
I think he is referring to the ice box, you know the one we keep ice in for the last week of July and the first week of August, I think if is known as Summer.
Regards,
Gerald.
PS -19 Celsius outside with wind chill.
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monarch

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Re: bending copper pipe ?
« Reply #13 on: January 29, 2010, 10:22:42 am »
Hi all
Have been following this topic with great interest, as I will have some tube bending tasks soon but can't find a stockists of the Dubro 5/32" bender DB786. Can anyone help on this.
Keep up the great discussion.

Lionel
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derekwarner

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Re: bending copper pipe ?
« Reply #14 on: January 29, 2010, 10:49:32 am »
Monarch........Dubro have a world wide mail order service....however their first point of reference is a nominated Hobby Shop in your local area......@  the same time... a good investment is the K&S Metals minature tube cutter..... just visit your local Hobby Shop or GOOGLE the Dubro WEB site ......Derek  :-))
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Derek Warner

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Illawarra Live Steamers Co-op
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www.ils.org.au

Circlip

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Re: bending copper pipe ?
« Reply #15 on: January 29, 2010, 12:02:13 pm »
Bit more for the home Alchemy department. One of the problems in using ice is that you have a limited time to be able to "Fiddle" the bend angles so by the time you've got it nearly right, it's time to put it all back in the freezer.

  Back to school Physics, " You can compress a gas, but you can't compress liquids". Fill tube with a liquid (water/Oil) securely plug the ends and away you go.  'Nother one, although some advocate filling with Sand, common Table Salt packs far more readily, again, SECURELY plug the ends.

  The various low melting point alloys tend to leave a smear trace inside the tubes.

  Regards  Ian.
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Brooks

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Re: bending copper pipe ?
« Reply #16 on: January 30, 2010, 01:47:15 am »
Torry Krutzke, well known US live steam modeler (his coal conversions of Accucraft K-27 are very nice) discusses a copper tubing bender device he made here (about half way down the page):
http://www.mylargescale.com/Community/ForumArchives/tabid/100/Default.aspx?TOPIC_ID=38464

I've made one and it works great. The idea could be adapted to other sizes, too, I expect.
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