Subject: tube bending questions

From: [email-masked] (bui tho xuan)
Date: 20 Sep 1993 16:20:09 GMT

Hi y'all.

I have the need to bend some chrome-moly and/or aluminum
tubing up to 1 inch in diameter and 1/16 wall thickness.

What is the best approach for a home craftsman, i.e., for
minimum cash outlay?

much thanks.

tho

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From: [email-masked] (Michael Burlage)
Date: 20 Sep 1993 21:08:13 GMT

>tubing up to 1 inch in diameter and 1/16 wall thickness.

You did not mention the radius that you need. 
A  conduit bender is cheap and works well, but has approx 6-8" radius of curvature.

-- 
"Onward through the fog"
                         - Power-Hitter
[email-masked]
[email-masked]

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From: Jim Jaskie <[email-masked]>
Date: Tue, 21 Sep 1993 00:15:37 GMT

Subject: Re: tube bending questions
From: Michael Burlage, [email-masked]
In article <[email-masked]> Michael Burlage,
>A  conduit bender is cheap and works well, but has approx 6-8" radius of
curvature.

Yes, a conduit tube bender works fairly well.  You can also get "Tubing
Benders" which look like long springs that you put over the tubes (I
don't know if you can get ones up to 1" though) and then bend by hand. 
They keep the tube from kinking.  WHile you might be able to bend the
Aluminum tubing this way, Moly tubing will probably require some
leverage.  Their are also metal benders for around $400 that do a nice
job, but the cost may be too high.

Now, I have a question on a related subject.  I'd like to bend square
tubing, 1 in (0.65 in wall).  Has anyone found a good way to do this? 
Has anyone tried to do this in a conduit bender?  I've seen this kind of
tubing nicely bent on industrial goods, but I can't even find a machine
in my catalogs that claims to be able to do this.  The stuff welds so
nicely that it would be very nice to have a method for bending it.  Any
ideas?

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From: [email-masked] (Richard Engelbrecht-Wiggans)
Date: Mon, 20 Sep 93 20:06:47 CDT

In article <[email-masked]>
 
>nicely that it would be very nice to have a method for bending it.  Any
 
I bend quite a bit of 1" square, 1/8" wall tubing at about
a 6" radius.  If you are satisfied with the same sort of
precision that you would get with a conduit bender, then
square tubing is in one sense easier to deal with than round;
you only need a cylindrical surface around which to bend it
rather than the circular groove needed for round tubing.
 
One setup goes as follows top view:
 
     C
     A
     R
 
     long piece of 1" tubing
         T
         r
         e
         e
 
Pull the "g" end of the tubing as if you wanted to pry
the car away from the tree.  Putting some 1.5" tubing
over the parts of the 1" tubing that you want to keep
straight helps control the bend.  (In my case, the
"car" and "tree" were actually two telephone poles
about 12" in diameter and about 12" apart.)
 
Using essentially this method, I had about 3/4 successes
at first--most of the failures being kinks, but some being
excessive twists--but got that up to about 90 percent.  Now
I have a jig consisting of two long 2x4's spaced 1"
apart, as follows (side view);
 
         Y
    two eight foot long 2x4's spaced 1" apart
    X
 
where X is a piece of 1" square solid stock and Y is a slice
off the side of a roughly 12" diameter cylinder (both are
bolted to the 2x4's spanning the 1" gap).  To use it,
the 1" tubing gets tucked under the X, the other sticks out
over and past the Y, and you hang/sit on that end.  My
success rate is now about 95 percent and I typically only
get a few degrees twist.
 
I don't know if 1/16" wall would be easier or more difficult.
 
..Richard E+17

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From: [email-masked] (Burl C. Tanner)
Date: 20 Sep 1993 21:42 CST

In article <[email-masked]>, [email-masked] (bui tho xuan) writes...

>What is the best approach for a home craftsman, i.e., for

like someone said, a conduit bender. you can buy or maybe rent one from 
an electrical supply house. the supply house would probably have a hydraulic
bender for the 1.5"+ conduit. 

if you have no luck renting one, hang around and ask the electricians
coming in for supplies if the could "do a quick contract job" in
the parking lit for you.

burl

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From: [email-masked] (Henry David Sommer)
Date: 21 Sep 93 03:20:40 GMT

I belaive a group called Wiliams low buck tools sells a cheap
bender for both square and round tubing. However, I don't know how to get
in touch with them. you can try looking inthe back of circle track magizine.
Don't the springs go in the tube to keep it from kinking?  Has anyone
treid filling them with sand?  BTW you'll need a strond mount for the
conduit bender some freinds of mine tried o put a 12" radias bend in .090
wal CoMo and it took them two bender handels and twelve hours.  They
didn't have any kinks except in the first one they tried to heat.

	Now to start another related thread what is the best way to cut
notchs in tubes about the same size to be welded?
-- 
        Henry Sommer               Mechanical Engineering student
        [email-masked]   Georgia Institute of Technology

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From: Jim Jaskie <[email-masked]>
Date: Tue, 21 Sep 1993 17:22:11 GMT

Subject: Re: tube bending questions
From: Henry David Sommer, [email-masked]
In article <[email-masked]> Henry David Sommer,
>notchs in tubes about the same size to be welded?

Good Question.  In machine shops they often have a special tool that can
cut the "Fish Mouth" required for niced welding of round tubes.  The
general principle is something like this.
          
                                    | Die       |           
                                    |_______|
                 ___________                   
---------                                     |
             |                                     | 
   tube   |       Receiving Tube      |
---------    ___________________|  
             ?  
(pardon the Ascii graphics)  The tube you want to fish mouth is inserted
into a receiving tube (large enough I.D. for O.D. of your tube).  The die
is round and connected with a ~18 inch lever.  You lean on the lever, and
the die punches through your tube, leaving the fish mouth.  The ones I've
seen are big monsters with multiple receiving tubes, and multiple die
shapes.  You can also punch holes in strap with them.  

I've thought  about building a fish mouther (?) using a "Chassis Punch"
(with the bolt and nut for the pressure), but haven't gotten around to it
yet.  The truth is that I use a lot of square tubing, which is so
wonderfully easy to work with.  Just cut it on the chop saw and weld it
up, that I'm not terribly motivated to use round tube.  The big advantage
I see with round tube is that it can be bent easily, something that is
often attractive.  For example, bending tubes removes problems with
square corners and safety.  Luggage racks are nicer when made with bends
than with welded square corners.  Now if I can get the square tubing to
bend nicely, and then have the advantage of square surfaces to weld,  all
my problems will go away........;>)

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From: [email-masked] (Chris Kent Kantarjiev)
Date: Tue, 21 Sep 1993 21:00:40 GMT

Eastwood has lately been advertising a jig to use with a hole saw to cut round tubing. I
don't have any experience with it, though.

Name:        Eastwood Company
Address:     580 Lancaster Avenue
             Box 296
             Malvern, PA 19355
Phone:       (800) 345-1178
-- 
Chris Kent Kantarjiev, Xerox PARC, Palo Alto, CA USA 	<[email-masked]>
 "Eating chile peppers is like gustatory skydiving. More than just food, 
  these little hot pods give eating the kind of thrills and excitement 
  usually associated with reckless gambling, fast cars and strong liquor."

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From: rey@safn2 (M Reynolds McClatchey Jr)
Date: 21 Sep 93 23:57:34 GMT

I have no idea how to bend square tube at home; but do know it is done
by stretch forming on aluminum, commercially.

The idea is to pack the inside with plastic or something that will keep
it from collapsing; but will still curve. I wonder how they get the plastic
out?

The tube is put in tension (stretched) by pullers at each end. And
bent around a mandrel. Probably heated some too; but not enough to melt
the filler. Al is also bent on a pin table; packing the hollow with sand;
then heating it.

I have only read about these processes and not performed the operations.
We buy bending services; and it is a skill that we pay big bucks for.
To several shops.
-- 
Reynolds McClatchey (Southern Aluminum Finishing Co, Atlanta, GA, USA)
Architectural Aluminum. Custom Fabrication. Paint, Powder Coating, Anodizing.
MCImail 414-2935  Voice 404-355-1560  Fax 404-350-0581
uunet!safn2!rey			KQ4TS				[email-masked]