Test-Bending the Leading Edge

[TimHicks]

Getting ready to fit the leading edge on the wings.
By examining the old L.E., I decided to try the centerline of the bend at 4.5" from one edge (both the old and new stock is 12" wide).
I bent the last 3/8" of the long edges up a bit on a sheet-metal brake.
Then I used the wooden jig with a 1" dia steel pipe to bend the nose radius.
It looks about right.

[Larry Lyons]

Re: Test-Bending the Leading Edge

As I have this project ahead of me I will watch this thread closely. L

[TimHicks]

Re: Test-Bending the Leading Edge

I seem to have loaded my pictures above out of order. Sorry about that.

I should mention that I'm using 0.020" aluminum. I think that the original was 0.016" thick. But it seems like I took the advice from others on this forum in consideration when making the decision.
Also, my old leading edges were really beat up and had lots of bondo on them. It just seemed like .020" thick was a chance to get tougher L.E.'s

[N96337]

Re: Test-Bending the Leading Edge

Looks like a good fit. I've done alot of leading edges in a "jig" just like what you show. It works just fine! Now comes the fun part, with plenty of ratchet straps and tiny adjustments to get it all just right!
Nice work!
John

[TimHicks]

Re: Test-Bending the Leading Edge

It's good to know that this is fairly normal way of doing it. I didn't make the jig. It was in the back of a dusty hangar. An old timer pointed at it and said, "That's what you need. Take it. Use it. Then pass it along to the next project." He gave me about two cryptic sentences on how to use it. That was it. I had to buy the pipe.

SInce the pipe covers the bend centerline of the aluminum, I made parallel lines on the aluminum that lined up with the edges of the jig.

[Hank Jarrett]

Re: Test-Bending the Leading Edge

Tim,
Are you in to drawing at all? Drawings of the bending jig would be a great addition to the groups tools. If you don't like to draw, how about some pictures of all the key parts with a ruler.
Hank

[TimHicks]

Re: Test-Bending the Leading Edge

Oh all right. See below. I made some quick sketches of the jig.

My assumption is that whoever sees these knows what a 2x4 is. If you're reading this in Australia and your dimensional lumber is different than in the US, you're responsible for understanding and compensating for the difference.

[Hank Jarrett]

Re: Test-Bending the Leading Edge

PERFECT!!! For all others who have useful parts or tools, we don't really need professional engineering drawings to keep our planes up. We need drawings that will let us make what we need. Anyone who has gotten any of my drawings will know I don't put much "fluff" into them unless they are going to someone who requires it (like the FAA). It just takes too much time and costs too much.
Our planes were originally laid out on a loft floor with chalk (why it is called "lofting") not on the pretty, fully documented engineering drawings. If we open a Taylorcraft factory in the future we will have a LOT of these great sketches to convert to full drawings for the feds to check, but we will probably be USING these kinds of drawings.
Thanks Tim!
Hank

I will be printing these up and building a jig in the future, so if someone needs a "conversion" for lumber from somewhere else, let me know. I will try to account for it in any new drawings.

[TimHicks]

Re: Test-Bending the Leading Edge

It would have been easier to do the actual bending with two people.
The picture below is an attempt to show how I did it solo.
I cut two little sticks of wood with v-notches for the pipe in one end. One of those sticks I cut just long enough to put under the fulcrum on the left and hold the pipe just submerged between the dies.
The second stick (on the right) was cut a little shorter. I put it under the lever.

The test piece of aluminum shown is fairly short. I was able to bend it by putting the lever in the one location shown and bending it in one swoop. The pieces that I have to bend for the airplane are about 48" long. I'll probably roughly center the aluminum under the fulcrum on the right and try to work on both sides of the fulcrum.

So the parts list for the tool should probably include the 1" pipe, the little foot-long sticks of wood (they could be other materials), and the lever (I used a 1" square steel tube with about 1/8" wall, about 3 feet long)

[Larry Lyons]

Re: Test-Bending the Leading Edge

This is what was missing. I wondered how you pushed the aluminum in to the die! L

[swoeric]

Re: Test-Bending the Leading Edge

I was thinking that i had seen a vacum bag and pvc 3inch ish it wrapped pretty well...here is a thread that may help quite a bit i think i have seen it done here..... http://www.supercub.org/forum/showth...her-neat-stuff


when i made them for a major repair station on the big stuff i had a taco shell mold that i had to carefully squeeze the leading edge into....this was two sheets and a sheet of bonding glue inbetween then bake at 350 for couple hours......


the leading or trailing edge was then fit about 1inch from where it would meet the opposite leading or trailing edge and a duplicator scribe was dragged along so you could cut a seam that disappeared into the previous hand cut seam....

[TimHicks]

Re: Test-Bending the Leading Edge

Maybe this one:

http://www.mybearhawk.com/wings/skin1.html

[TimHicks]

Re: Test-Bending the Leading Edge

I've been meaning to follow up.
I've got all of my leading-edge pieces bent.
Most of them are installed now. (All of the left wing and half of the right.)

But on the bigger pieces, using the lever was just too hard and a bit scary (scared that the lever would slip and I'd hurt myself or damage some aluminum).

So I ended up using these two jacks to do the work. Notice that the scissors jack is upside-down. Its top was just narrow enough to fit between the dies. So I could push the pipe well into the dies.

I tried using the bottle-jack upside down. But it just wouldn't operate that way.

Anyway, this method was very controlled and worked well.

I also screwed the aluminum to the pipe with PK screws at the bend line to keep it from getting crooked in the setup.

Tim

[Larry Lyons]

Re: Test-Bending the Leading Edge

Tim in the pic it looks like the pipe is bowed. Was it and did that have any impact on the results or technique you used. L

[TimHicks]

Re: Test-Bending the Leading Edge

Yes the pipe did bow at this point in the bend. When the forces were the highest.
I thought about welding a strongback onto the pipe.
And ultimately, this is the reason that i found a jack that would fit between the dies.
Because if I just pushed the pipe into the dies such that the top of the pipe was flush with the top of the dies at the extremes of the pipe, the center of the pipe might be bowed sufficiently to make an incomplete bend in the middle of the aluminum.

But by pushing the pipe well into the space between the dies, I could be certain that every part of the aluminum got bent 180°.
And once the bend was mostly complete, the forces got a lot smaller and the pipe stayed a lot straighter.

The end result looked fine. I couldn't discern any difference in the bend in the middle of the aluminum compared to the bend at the ends of the piece.