Bending longerons

Other than get a good vice (I've got an OK one, not great, but not crappy either), any advice on this task?

Really wasn't a big deal. I used some maple scraps betweeen the jaws of the vice. Applied bending pressure with one hand and smacked the longeron with a big rubber mallet. Took it out of vice and checked fit, repeat.

don't hit too hard, and prepare a big bag of patience don't expect to get it done in one pass - eg. don't hit too hard because you can't see "progress" (bending) on first pass. I ended up asking a fellow (local) 7A builder to help out as I wanted to have someone who had been there done it.

Longeron Bending

Bob,

I tried an hour using the mallot but I found, with a sturdy workbench and vice, that just applying good pressure manually did the trick. The mallot tended to bend the longeron a little too much, but if done with arm strength only, you can feel the longeron as it begins to give. Work about an inch at a time and as stated earlier, bring a really big bag of patience. The second will go much faster than the first as is the case for all parts made a second time.

Jim
http://adap.com/rv7

I talked to Radomir before I did mine and took his advice. Used a big vise, a dead blow hammer, and made four passes through the vise. I moved the longeron an inch for each blow and had my father-in-law put a little bending pressure on it before hitting it. My blows were fairly light and they both came out great.

Don?t forget to cut the top off the every end of the longeron for the very end bulkhead and put the notch in it for the 2nd to last bulkhead. The longeron will come out a bit long and you will trim it a little (at least I did) once you put the side skins on. Apparently this is normal.

Good luck!

Hi Bill: Funny you should mention it. I started the bending this morning. I have already done the notch at the very end and have decided to wait until after the bending to do the notch for the second-to-last.

I have to say that -- at least so far -- I've found the process to be more nerve-wracking than difficult. That's mostly due to the prospect of screwing up and having to pay for another 15-foot box to be shipped than anything else. But it certainly causes one to pay attention.

My vice, unfortunately, has a feature that allows it to swivel, so I initi8atlly had dificulty getting that particular feature disabled by clamping it down.

Rather than making an initial pass, I'm giving it a bend by hand (and a couple of blows with a mallet), taking it out, checking it against the template and -- if all is well-- going another 1/2" along and repeating the process.

I thought about making a pass, however that puts me in the situation where I'd end up having to put a curved portion of the longeron in a vice that is straight and would pressure the curved piece to straighten when clamped and I don't want to go there.

I got about halfway done and then had to go to work. It's, like I said, nervewracking. I haven't found great difficulty. I did turn the longeron upside down and put it on the garage floor to see if it violated the vertical plane, and of course it did so I just -- like the instructions say -- put turned it 90 degrees, put it back in the vice, and gave it a tug to bring it back flat (mostly).

I hope to complete the bend on the left longeron when I get home and then I'll work on the sharp downward bend. I have no clue how I'm going to do that.

So, not hard. But, man, I'll be glad when it's done.

Oh dear, I spoke to soon. I came home from work tonight and thught I could finish up and ...well... what a mess. I've got one little bit that's bent toomuch, one that doesn't appear to be bent enough. Back...forth...back...forth...and it's like those games where you try to whack the rabbit int he hole but when you do it springs up somewere else. The template keeps slipping off when I try to measure it. Gosh.

At one point I threw the damned thing across the garage (it makes a nice noise).

Good time to walk away from the darned thing for awhile. Not fun.

BC

And just think

Bob,

When you finish bending it you get to drill holes all along it and then CS them ALL! You will be playing with that chunk of aluminum for some time to come!

Good luck!
Bill

Well, I went back at it this morning and used the Radomir method, which I should've used first. I got through the remaining left longeron fairly quickly and then zipped through the right one relatively quickly. I do find the twists a little annoying and I think I got them to an acceptable point.

I then put the two pieces of angle together and they seemed to behave together pretty well, but I clamped them together before coming to work anyway. I figure maybe they'll snuggle up to one another a bit better if I leave them alone in the garage.

But I would describe this as the most distasteful part of the project to date. But then again, I actually enjoyed making the fuel tanks. This I didn't enjoy.

Bob, If you find bending the longerons distastefull; take a looong vacation just before starting the canopy.
Mel...DAR

Now that the curves are completed (and upon checking and a little tweaking, I guess they aren't so bad), I'm drilling the aft cannopy deck rails...whatever.


The drawing --18-- shows Detail E with the aft two holes pointed out (apparently the side that gets trimmed for tip-ups) and says to backdrill through 721B-L into the longeron.

Fine. I got that. But that implies that ONLY the left side gets the aft two holes get drilled while both sides get trimmed.

Is that correct?

Both sides get drilled.

Yep, figured it out. The longerons actually came out pretty swell. And then yesterday I built the sawhorses and started assembling the aft fuselage. I'm almost embarrassed to say it, but I'm pretty sure I had the RV Grin all the time I was doing it. (Except when trying to fit the 711 and 712 in the tailcone, of course)