forming control horns

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Brian Amato
Posts: 111
Joined: Fri Aug 31, 2018 9:23 am

forming control horns

Post by Brian Amato »

This has probably been covered in depth before but I'm not finding it in the archives:
Anybody come up with a clever way to form the concave shapes in the left and right control horn pieces?
I made the horn for the rudder last nite and, altho it didn't come out too bad, it's more a series of bends than a nice continuous dish.
I may go out in the shop and try to make a male/female "die" out of oak or ash. Take it to the hydraulic press, put the flat horn material between the two die pieces and squish the heck out of them. Who knows...might just work.
IF I had an English Wheel, that might be even better.
Of all the things Berny designed into this Air Camper, that are pretty slick, these two part, croissant horns still puzzle me. I know a lot of guys have just cut the horn out of one piece of thicker steel, bent the attach tab 90 degrees (like I did when I built the Jr. Ace) and call it good. Why this hollow affair I still can't fathom. Some of you have offered your opinions as to why you think he did it this way but I'm still not too sure about that.
Any suggestions?
Thanks
danoliver
Posts: 49
Joined: Sat Feb 25, 2017 7:58 am
Location: Cincinnati

Re: forming control horns

Post by danoliver »

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taildrags
Posts: 436
Joined: Tue Mar 07, 2017 10:39 pm

Re: forming control horns

Post by taildrags »

Brian; by fabricating the horns in the cupped-sandwich style, you get the torsional rigidity and bending stiffness of a tube without the weight of a solid billet of the same dimensions. There are several control horns back on the tail where weight needs to be kept to a minimum. I'm not a welder and from what I understand, welding thin stock is not the easiest task there is, but I work with a masterful fabricator for whom welding thin stock is just another work task and every bead is a beautiful bead. You're only going to have to build one set of horns, so if you're not comfortable with the welding, just get the shaping done (backing up the part with shot-filled bags and doing the shaping with a mallet and wooden tools is one method I've seen) and take the parts to a welder to join together.
Brian Amato
Posts: 111
Joined: Fri Aug 31, 2018 9:23 am

Re: forming control horns

Post by Brian Amato »

Oscar...and guys who have responded, yup, you're right about the "thin yet strong and light" concept. I'm doing it just like the plans.
So, follow up question: You guys who HAVE already made your control horns, and did the welding yourself, what did you use to weld them with?
I only have ox-acetylene tanks and torch and I'm pretty good with it but this thin stock the horns are made out of is something else again.
I've been practicing with some scraps of that material and it's so easy to blow right thru the stuff. Taking a tip from the guy at West Coast Piet, he "fusion welded" (no filler rod) on the trailing edge where the two pieces come together flat. Just used the heat from the torch to sort of melt them together. I've tried that too and was somewhat successful but the leading edge where you use wire rod....boy can you make a mess of that in a second.
I don't own or know how to use MIG or TIG.
What have you guys been using? Or, as Oscar says, is it time for me to go down to Ace Welding here in town and take the horns to those guys?
Thanks fellas
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KenBickers
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Joined: Tue Mar 07, 2017 7:00 pm

Re: forming control horns

Post by KenBickers »

Brian, I welded all my control horns using oxy-acetylene. I'm a rank amateur at welding. I think they turned out looking just fine, especially when viewed from at least 5 feet away. The key for me was using the smallest tip I had, which if my memory is correct was a size 0, and keeping the flame adjusted to be quite small. The other key was to clamp the pieces together with some old ratty c-clamps to keep the two sides from trying to walk apart during the tacking process. Once tacked, I could brace the horn between a couple of fire bricks so that I could weld from right to left with the weld line easy to see and access. Wearing extra powerful reading glasses helps a lot with seeing the puddle and weld line. (One final trick I learned along the way was to make some spare horn pieces. That way I could throw out one -- or two -- until I had some that I liked). Enjoy, Ken
Brian Amato
Posts: 111
Joined: Fri Aug 31, 2018 9:23 am

Re: forming control horns

Post by Brian Amato »

Thanks Ken. I appreciate everyone on this forum for helping each other.
I just came back from the welding supply store where I bought some threaded adapters for a small jewelers welding set I have. I'm going to see if that will be better for this fine work. I'll let you guys know more tomorrow.
B
tom kreiner
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Joined: Sat Feb 25, 2017 9:49 am

Re: forming control horns

Post by tom kreiner »

Brian,

The torch I use is an older Victor Journeyman, i.e. Victor 100, which has been cloned by lots of other companies, and torch tips are readily available. Recently, however, I did not have a sufficiently small tip to prevent blow thru of the material, which happens with very thin gage metals.

So, I did what we were taught to do in Metal Shop Class in the mid-60's; you file smooth, then hammer the tip - similar to striking a nail - right on the head. The hole will close down, and you use the torch cleaner/reamers to keep it round, and to size it. Do this several times, and any tip can be re-sized to its original size, or smaller. There is also a special pin vise and a set of drills specifically for re-sizing tips.

Here's the Victor size chart:Image

In my case, I had two #2 tips, one of which is now a #00 tip. Just keep hammering, filing, and reaming, and the tip will be just what you need to manage the heat on thin materials.
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Victor Chart.jpg
Brian Amato
Posts: 111
Joined: Fri Aug 31, 2018 9:23 am

Re: forming control horns

Post by Brian Amato »

Tom.....that's brilliant !!
Thanx
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Richard Roller
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Joined: Mon May 22, 2017 11:14 am
Location: Olathe, Ks.

Re: forming control horns

Post by Richard Roller »

Brian. Ken Perkins tig welded his horns. He made a copper heat sink to do the leading edges with rod. Then pulled the trailing edges together and fusion welded those edges. He used a technique that I was taught when I was still doing composite work on big a/c. I would weld my own thermo-couples. These were very thin wires. We would start the arc on copper, usually with the a.c. on all the time to stabilize the arc, then move over to the wires. Ken used this technique to weld the horns. He would start the arc on the copper heat sink and then move to the horn. Very low settings of course. This was all done on an old Miller Gold Star welder, made back in the 50's.
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