Bending Spar channels??

[dcstrng]

I note that spar channels are out of stock, so on a whim I had some 0.040 2024 blanks shipped to me (hope that’s the right thickness) to see if I can bend them myself on my homemade brake – anyone have any guidance… These blanks are pure through-away, so I am experimenting to see if I can do it (being a weekend hack, with no particular shop skills other than those I learn along the way…).

I’ve been able to bend 8’ 6061T6 0.032 for Zenith HT spars, but am leery that with 0.040 2024 I may have bit off more than my home-brew “brake” can chew – yah, I know the right way to do this is to take of three days of work, drive eighty-gazillion miles to find a shop that will do it to the correct radius and dimensions – but where’s the fun in that. Anyone done this on their own; all guidance, hints and cautions gladly accepted…

 

[pilotsailing]

You would have to have an industrial grade brake to bend .040 in 8 feet lengths. If you take it to a sheet metal shop they will probably bend the radius too small and crack or weaken the metal at the bend. Also hard to get the right spar dimensions to match the ribs doing it freehand, and you only get one try. How long will you have to wait for new ones to be available ? It might be worth the wait.

 

[dcstrng]

Am not too worried about bend radius, I can make as many test pieces as I need to get that right… but I may have found a place within driving distance who can do it for me, once I can drive my truck again… (stick-shift, my leg is in a splint for another month or so). But I still think I’ll give it a try myself and see what happens…

 

[pilotsailing]

Let us know how it works out.

 

[Tom H]

Dcs, I tried to do it on a homemade leaf brake. I could bend short sections to get the dimensions right, but bending a 8 ft length required too much force.

Took material to sheet metal shop I used at work, with a sketch and instructions for required bend radius. Was assuring they understood. Later got a call saying they cracked the metal at the bend. I had more metal, and they got it right on second try. Those guys probably had not concerned themselves with bend radius since trade school.

Good luck.

 

[dcstrng]

Dcs, I tried to do it on a homemade leaf brake. I could bend short sections to get the dimensions right, but bending a 8 ft length required too much force.

I expect I'll have exactly the same results -- but it's an experiential, and at least this 2024 is to see what is(n't) possible...

 

[dcstrng]

Well, I had to try it just for my own amazement... I did a trial bend with about a 0.100 radius and, frankly, I think it could be done -- there was very little meticulousness in my trial, but the brake didn't seem to be in any great strain... In the pics, some of the "wobbliness" is an optical delusion due to the plastic coat still on... I haven't looked closely at the bend with a magnifying glass to make sure on any cracking, but my DIY brake allows as much setback as I might need and the upper clamping surfaces has a clamp every 12-14" so there is very little bowing...

I've got enough 8-foot 0.040 stock for a few more practice bends, so we'll see; I suspect the product will be improved with more care and practice... but I was encouraged since this only took about two minutes...

 

[Tom H]

Nice! I see you put an extension on the leaf lever - before or after you busted a gut???!!

 

[dcstrng]

- before or after you busted a gut???!!

-- actually did that some years back, can't recall exactly; partheimers -- I think it was when I was bending up the Zenith HT spars and decided that there had to be a better way...