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1" U in 1/4" copper tube

Posted: Sat Jul 07, 2018 11:51 am
by DianneB
I needed a U bent from 1/4" copper tube - that's pretty tight!

I tried packing a piece of 1/4" tube with fine sand, crimping and soldering the ends closed, and bending it around a 3/4" mandrel. Didn't work - the tube distorted! :cry:

I tried filling a piece of 1/4" tube with water, crimping and soldering the ends closed, and bending it around a 3/4" mandrel. Didn't work - the tube distorted! :cry:

Finally I crimped one end closed and melted the tube full of common solder, bent it around the 3/4" mandrel and IT WORKED! The tube did NOT distort! The solder made it pretty stiff to bend though! Melted the solder out and now have a nice even U with 1" between the legs.

Just thought I would share ....
1 Inch U.jpg

Re: 1" U in 1/4" copper tube

Posted: Sat Jul 07, 2018 3:27 pm
by Harold_V
Nice. Cerrobend is reputed to serve in that capacity, but my one and only experience didn't turn out all that well. I do not recall the details, as it was more than 40 years ago.

Well done!

H

Re: 1" U in 1/4" copper tube

Posted: Sat Jul 07, 2018 4:38 pm
by BigDumbDinosaur
DianneB wrote:
Sat Jul 07, 2018 11:51 am
I needed a U bent from 1/4" copper tube...I tried packing a piece of 1/4" tube with fine sand...I tried filling a piece of 1/4" tube with water...Didn't work - the tube distorted! :cry:
The travails you describe are what led me to invest in precision tube benders many years ago, some of which I've had since back when Pres. Gerald Ford was stumbling down the steps of Air Force 1. :D My 1/4 inch bender forms bends on a 0.563 inch radius, so it would produce a 1-1/8 inch U (center-to-center). All of the benders readily handle seamless 304 stainless tubing, which is what I used to do the air, fuel and hydraulic piping on my F-unit.

In the below picture, the smallest lines are 1/4 inch and the largest are 1/2 inch.

power_assy_es03.jpg
F7 Power Assembly, Engineer's Side

Re: 1" U in 1/4" copper tube

Posted: Sat Jul 07, 2018 4:45 pm
by Builder01
Yes, Cerrobend will do the same thing, and melts in boiling water for easy removal and to be used over and over. To assist during bending, you should first squirt some lube down the tube like LPS2. This keeps the Cerrobend from sticking to the copper pipe. If steam is going to go through a copper pipe, you don't want any stuck solder bits to come loose.

These pipes were bent using Cerro bend and a home made pipe bender, the radius is even smaller than 1/2" radius.
DSCN1543 - resized 4.jpg
DSCN1542 - resized 5.jpg
DSCN1546 - reduced.jpg
David

Re: 1" U in 1/4" copper tube

Posted: Tue Jul 10, 2018 10:47 am
by PeterCraymer
I have had pretty good luck making a "mandrel" of washers with the correct OD and stacking them to 1/4" with fender washers with a larger OD and bolting together to bend a radius in copper tubing. Wont work with brass as it wants to kink but 1/4" copper will make 3/4" and 1" diameter bends pretty well without any filler.

Re: 1" U in 1/4" copper tube

Posted: Tue Jul 10, 2018 2:47 pm
by gwrdriver
One of the items on my "To-Do" list . . . a small tube bender.

Re: 1" U in 1/4" copper tube

Posted: Tue Jul 10, 2018 7:28 pm
by shild
DianneB wrote:
Sat Jul 07, 2018 11:51 am
I needed a U bent from 1/4" copper tube - that's pretty tight!

I tried packing a piece of 1/4" tube with fine sand, crimping and soldering the ends closed, and bending it around a 3/4" mandrel. Didn't work - the tube distorted! :cry:

I tried filling a piece of 1/4" tube with water, crimping and soldering the ends closed, and bending it around a 3/4" mandrel. Didn't work - the tube distorted! :cry:

Finally I crimped one end closed and melted the tube full of common solder, bent it around the 3/4" mandrel and IT WORKED! The tube did NOT distort! The solder made it pretty stiff to bend though! Melted the solder out and now have a nice even U with 1" between the legs.

Just thought I would share ....

1 Inch U.jpg
Congrats on a well done, difficult to do bend. You are a steam clubbing man! I forget what they are called but in the automotive exhaust world there are a bunch of round plates they will the exhaust tubes with before bending.

Re: 1" U in 1/4" copper tube

Posted: Tue Jul 10, 2018 8:07 pm
by LivingLegend
A trick that makers of brass musical instruments (trombones, trumpets, etc.) use to bend tubing is to make a solution of water and soap... Like Ivory or Dawn dish washing soap for example. They pour the soapy water into the tubing, freeze the tube, and then bend the tube around a form to the radius/curve/shape desired.

LL

Re: 1" U in 1/4" copper tube

Posted: Wed Jul 11, 2018 1:46 am
by Harold_V
LivingLegend wrote:
Tue Jul 10, 2018 8:07 pm
They pour the soapy water into the tubing, freeze the tube, and then bend the tube around a form to the radius/curve/shape desired.
Any idea what function is performed by the addition of soap?

H

Re: 1" U in 1/4" copper tube

Posted: Wed Jul 11, 2018 6:02 am
by LivingLegend
Keeps the ice from cracking. They also freeze the ice to around -60 or -70 degree range. Cerrobend is also used for their bends. Some makers use pitch.

Re: 1" U in 1/4" copper tube

Posted: Wed Jul 11, 2018 9:25 am
by DianneB
LivingLegend wrote:
Wed Jul 11, 2018 6:02 am
....They also freeze the ice to around -60 or -70 degree range.....
I don't have dry ice in stock either and don't know how else you could get -60 or -70!!

Re: 1" U in 1/4" copper tube

Posted: Wed Jul 11, 2018 10:43 am
by Fender
Depending on the degree of bending, one might need to anneal the tube, fill with solution, freeze, bend, rinse, repeat....😀