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Cattrell
Member since Nov-4-05
62 posts		 Jan-21-09, 09:35 AM (CST)
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"Bending 4130 tubing"
 
   I am trying to find a good way to bend 4130 tubing.

I have tried building the plywood bender that is shown in the newsletter and I didn't like that. I have tried a conduit bender, didn't like that either.

My question is.....
What is everyone else using? Is there a small comercial bender that will work well????

There aren't that many tubes to bend, but I want them to look good.

Thanks for the help!!!

Jeff Cattrell

www.cattrell.net


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  Subject     Author     Message Date     ID  
  RE: Bending 4130 tubing Bantam21 Jan-21-09 1
  RE: Bending 4130 tubing Clifford Hatz Jan-21-09 2
  RE: Bending 4130 tubing jwhanson Jan-21-09 3
     RE: Bending 4130 tubing Ser248 Jan-22-09 5
  RE: Bending 4130 tubing splischke Jan-21-09 4
     RE: Bending 4130 tubing Cattrell Jan-22-09 6
         RE: Bending 4130 tubing splischke Jan-22-09 7

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Bantam21
Member since Mar-5-08
15 posts		 Jan-21-09, 12:45 PM (CST)
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1. "RE: Bending 4130 tubing"
In response to message #0
 
   I'll admit to not being an expert by any stretch. I had the same question and there were many answers. What I did on the fuselage longeron bends was simply heat it up with a propane torch to a dull red and give her a little nudge. Of course the tubes were already on the jig table and I had the lines marked where to stop. I had a flat piece of steel under the tube between it and the wood, but I still smoked the wood a little. I was really concerned about the bends and they ended up being a total non-event. Took about 5 minutes each and they were done. Those bends are so slight that its not a big deal.
I have yet to do the tail surfaces so those bends will probably be a little more difficult, but at least I now have the confindence to do it.
Dave
CB-1 #910

Dave
CB-1 #910


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Clifford Hatz
Member since Feb-8-08
13 posts		 Jan-21-09, 01:53 PM (CST)
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2. "RE: Bending 4130 tubing"
In response to message #0
 
   Jeff, How big is the tubing you are trying to bend?

Clifford Hatz


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jwhanson
Charter Member
21 posts		 Jan-21-09, 06:23 PM (CST)
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3. "RE: Bending 4130 tubing"
In response to message #0
 
   Hi Jeff,
I cut the radius I needed for the stabilizer tip from 3/4 inch plywood and screwed it down to the bench with another block to hold the end of the tube. I put some aluminum tabs under the plywood form to prevent the red hot tubing from burning away the former. Then I started heating up the tubing with a torch and slowly moved around the curve and it bent exactly to the form. The bench smoked a little.
John Hanson

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Ser248
Member since Sep-16-04
119 posts		 Jan-22-09, 06:04 AM (CST)
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5. "RE: Bending 4130 tubing"
In response to message #3
 
   Don't forget that it is extremely tempting to heat the outside of the curve and then make the bend. This will reduce the wall thickness in this area. Try to heat the tube all around the diameter concentrating on the inside of the curve.
On the large diameter tubes, I put sand in the tube, held in with wood plugs, so it wouldn't kink.

Jeff Moore


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splischke
Member since Jul-21-05
40 posts		 Jan-21-09, 08:51 PM (CST)
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4. "RE: Bending 4130 tubing"
In response to message #0
 
   Jeff,

I know you said you didn't like the conduit bender but I found it to be a useful tool for bending the 3/4" stabilizer leading edge without the use of heat. I achieved a very nice curve in little time.

For bending smaller tubing used for the rudder, I used a form block much smaller than the bend radius and cold bent the tubes by hand. The trick is to go slowly, bend a little at a time and measure often against a full size drawing.

-Scott

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http://www.hatzbiplane.com/dcforum/User_files/4977ddba1c4025c9.jpg

http://www.hatzbiplane.com/dcforum/User_files/4977ddd71cb825e6.jpg

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Cattrell
Member since Nov-4-05
62 posts		 Jan-22-09, 09:39 AM (CST)
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6. "RE: Bending 4130 tubing"
In response to message #4
 
   Thanks for the input, I am going to try the form and heating. I think that will work well. I bent my fuse with some heat with no problem.

I will try the conduit bender again some this weekend, I only tried a few small bends, I might try the sand add to see if that is better.

What has everyone done on the seats for the sharp bend? I think that will be a heated bend also, but I would like to hear what others have done. I have also thought of making the seats with hard corners, has anyone done that?

Thanks for the help!!!

Jeff Cattrell

www.cattrell.net


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splischke
Member since Jul-21-05
40 posts		 Jan-22-09, 04:02 PM (CST)
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7. "RE: Bending 4130 tubing"
In response to message #6
 
   Jeff,

I made my bottom seat frames with 90 degree welded joints. This was much easier to do than making the sharp bends in 3/4" tubing. I used 0.025" 4130 strips for the basketweave seat bottoms and 0.040" 2024-T3 for the seat backs -- a method borrowed from the Acro Sport II plans. The seats are still detachable.

-Scott

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