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Bending standoff tubes

 
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DougJ



Joined: 10 Dec 2006
Posts: 41
Location: Kernersville, NC

PostPosted: Thu Sep 30, 2010 5:43 pm    Post subject: Bending standoff tubes Reply with quote

I suspect this has been discussed, but can't find it on the BB. What is a good way to bend standoff tubes? I'm replacing the wood formers back to the rear seat with new standoff tubes to be covered w/ aluminum and need to bend the new tubes to the same shape as the existing formers.
Thanks,
Doug
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Doug Jewell
N9776 - Starduster II
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Starduster History



Joined: 30 Nov 2006
Posts: 735
Location: St. Helens, Oregon

PostPosted: Fri Oct 01, 2010 1:06 pm    Post subject: Stand Off Tubes Reply with quote

Doug I am not sure what you are asking? The stand offs on the plans sheet# 9 aft of the rear cockpit are only straight pieces of 3/8"X035 4130 tubing that have an "L" shaped 040 piece of angle welded to the end that the stringer is attached to, and depending where they go would determine the length? Several of them are bent slightly after welding to better line up with the stringers. However your airplane may not have been built to the plans and might have had formers substituted for standoffs!

If you are talking about the actual formers that are at station 13, 34, and 83 they are also 3/8"X035 4130 tubing and in order to bend them one has to use all sorts techniques. I generally draw or lay out on my work table with a pencil the exact radius of the fairing bows that I am trying to make and then bend them to that.

My method is rather crude but it works for me. Most of the gradual radius I have bent over my knee. The tighter ones I have used an open vise approx open by 1" with magnetic plastic jaws installed and used this to bend the shape as the softer plastic jaws do not leave marks or notches in the tubing as I bend them.

Also you could cut off the existing formers you want to replace and use them as the template to reproduce and replicate the exact shape of the former you are working on.

Please pvt msg me with your phone number best time to call or your E-Mail address and I can send you pictures of my son Dans airplane and his formers. As always this is, only my opinion. Dave
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Dave Baxter
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Mike Harris



Joined: 01 Dec 2005
Posts: 175
Location: Baton Rouge, LA

PostPosted: Fri Oct 01, 2010 2:53 pm    Post subject: Reply with quote

Hi Doug,
Maybe your airplane wasn’t built to the plans (seen that before, huh Dave?) For what ever reason, what radius do you need to bend? What size tubing do you need to bend? I’ve built a tubing bender but it has severe limitations (one size tubing bent to one radius). I cold bent the tail feathers around plywood formers I cut to shape (but undersize by quite a bit to allow for spring back).

For small radius bends, you run a bolt up inside a 2 foot (or as long as you need plus a foot or so on each end for a handle) length of the tubing. Stand the tubing on end, like clamped to the work bench or in a vise. Dribble about 2” worth of clean DRY sand into the tube. Tamp it with a dowel or welding rod, repeat until full. Run or hammer a bolt into the top.

Break out the rosebud. Clamp the rosebud to the bench, (pointing AWAY from your zipper). Clamp something with same OD as the ID you want in the vise or on the bench. This “something” ought to be within arms reach of the rosebud. Light ‘er up. Put on your heavy arc welding gloves and slowly twirl the tubing in your fingers, evenly distributing the flame along the area of the intended bend. PULL on each end of the tubing as you PULL it around the “something.” Go have a beer, its hot work. Anyway that what work’s for me.

Mike
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John Singer



Joined: 03 Dec 2005
Posts: 131
Location: New London, NH

PostPosted: Mon Oct 04, 2010 8:38 am    Post subject: Bending standoff tubes Reply with quote

Why don't you consider making aluminum formers ? Attatch with tubing clamps. Easy to weld or braze flat, sheet metal studs to 1/4 inch steel tubing to attatch to the formers.

I used that system, works well and easy to do.
Singer
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DougJ



Joined: 10 Dec 2006
Posts: 41
Location: Kernersville, NC

PostPosted: Mon Oct 11, 2010 5:49 pm    Post subject: Reply with quote

Thanks to all. I'm working out the details.
Doug
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Doug Jewell
N9776 - Starduster II
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