Tubing bender

I just picked up a tubing bender from Harbor Freight

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and now I am trying to figure it out. I practiced on a piece of tubing I had ( a DBS mast, pretty thin) and it just wanted to crush and not bend. Well, I guess a crush is technically a bend, just not the way I was planning.

Anyone have any ideas?

TIA

Robert

-- Change rock to star

Reply to
RyPhil
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yes, its a pipe bender, not a tube bender. that is why the tubing which is thin never bendt but broke, crushed it.....

Reply to
jim

had

An old trick is to fill the tube with sand and cap both ends before you bend it.

Chris

Reply to
c

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and now I am trying to figure it out. I practiced on a piece of tubing I had ( a DBS mast, pretty thin) and it just wanted to crush and not bend. Well, I guess a crush is technically a bend, just not the way I was planning.

Reply to
Keith Marshall

Yes. Very carefully read that ad again. It says very plainly that what you bought is a *pipe* bender, not a *tubing* bender. A pipe bender is not the correct tool to bend tubing. Go down to your local muffler shop and watch a real tubing bender in action. You'll see it works very differently from the pipe bender you bought.

There are two main issues. First, pipe and tubing are measured differently. Pipe is measured by ID while tubing is measured by OD. So if you use dies for 2 inch pipe to attempt to bend 2 inch tubing, the dies will be the wrong size (too big) and won't properly support the tubing as it is being bent. Second, thin wall tubing needs to be pulled around the die rather than pushed by the die. Using the correct size die, and pulling rather than pushing, keeps the tubing from buckling.

Go get some pipe and bend it with your pipe bender. It'll work well for that. For tubing, you need a tubing bender, and what you bought isn't a tubing bender.

Gary

Reply to
Gary Coffman

You're always going to get some amount of collapse when bending tubing. There are several ways to reduce it. A ball mandrel is best. It is basically a series of balls linked together by swiveling links. The easiest way to visualize it would be to imagine one of the old bathtub drain plug chains. The last link mounts to a straight shaft slightly smaller than the tube ID. These are normally very expensive mandrels, and are limited as to how small you can go. The next best mandrel is called a shoe mandrel, which has a compound ground on the end which matches the theoretical ID of the tube after bending. These are also quite difficult to make, but not nearly as costly. The third choice is a blunt mandrel which is simply a hardened rod that is .010 to .020" smaller than the tube ID with a full radius on the end. These are relatively easy to make and are quite effective for all but the tightest bend radius or very light wall tubing. We used almost all blunt mandrels in the coupling factory I worked in and we were required to hold the bending crush to 10% maximum.

Chris

had

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long without it!

Reply to
c

I agree that a mandrel would be needed on a tight bend but not absolutely needed for bends with a radius greater than 3 or 4 times the tube diameter if you have the right tools.

I just came in from the shop after making seven darned near perfect 4" radius and two long sweeping bends in a 20' length of 1" polished stainless tube for the bow pulpit. Talk about proud of myself! My head is so big I had to turn sideways to get in the door. :-) Used a set of dies from Pro Tools with no mandrel.

I took it for granted that the bends would be smooth and even. What amazed me is that the darned thing fit when I put it on the boat!

Reply to
Glenn Ashmore

Hey Glenn,

Time for some up-dated photos on the web site?

Take care.

Brian Laws>

Reply to
Brian Lawson

Yeah, I have been very neglectful of the site lately. I tend to update it by the petition method same as I mow the grass. When the neighbors get up a petition... :-)

Reply to
Glenn Ashmore

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> > > and now I am trying to figure it out. I practiced on a piece of tubing I

To build brass instruments (horns) we fill the tube before bending. Each filler has its own pluses and negatives. We use Pitch (tar), ice made of soapy water, lead, or cerrobend.

LB

Reply to
Leonard & Peggy Brown

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