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Bending Strips for Ribs

Posted: Sat Feb 02, 2019 3:21 pm
by cantdrawatall
Hello Everyone,

I'm getting ready to start prepping the wood to the ribs, and I was wondering about the top cap for the ribs. I've seen some things about putting them in boiling water, or steam and then bending them over a form. What rigs have builders used for the boiling/steaming and for how long did they cook? Did the form you use have the same shape as the rib, or was it curved tighter to account for spring-back?

Thank you for the advise

Re: Bending Strips for Ribs

Posted: Sat Feb 02, 2019 5:29 pm
by EAB4
A general guideline is 15 mins. per 1/4" thickness
I did 4 or 5 at a time and I think I steamed them for 20 mins.

My form was actually cut slightly tighter but just cutting to the shape of the rib would work fine.

Here are a couple of pics of the form and the high tech steaming device.

Re: Bending Strips for Ribs

Posted: Sun Feb 03, 2019 7:08 am
by Brian Amato
I went to Home Depot plumbing dept. and bought a length of 4" PVC pipe and a PVC cap. I already had some PVC cement.
The tubing only needs to be about 4 feet long because you're only worried about wetting out the first foot or so of the cap strips anyway.
After I had a fist full of cap strips ready to go, I boiled some water on the stove, took the pipe out to the deck, secured it so it wouldn't fall down, poured enough boiling water in the tube until the water level was about a foot and a half and dropped the cap strips down into the water.
They wanted to float up ! I grabbed an adjustable squeeze clamp, clustered the strips into a little bundle and clamped them to the side wall of the tube and left them alone over nite.
Next day, took them out, wiped the excess water off them, put about 4 in the upper bending mold and 4 in the bottom mold and fastened them in place. I'll send you photos of the molds if you like.
Let them sit over nite and when I took them out, they were nicely bent (I made the molds so they were actually over bent to allow for spring back) and dry. Ready to go in the rib jig.
In later batches, I didn't even boil the water. Just used hot water and since they were soaking all nite anyway, they were just as supple as the ones I had used boiling water on.
As my daughter says "Easy Peezy"

Re: Bending Strips for Ribs

Posted: Sun Feb 10, 2019 9:23 am
by av8r2654
Try a crab cooker. 45 minutes boil time for about the first foot of length results in super bendable wood. Clamp in form block let dry. I use actual size form block no issues with springback. cap strips are 1/2x1/4 as per 1932 Hoopman drawings. I’m building with western hemlock. Nice wood to work with. Easier to source and much more economical than spruce.

Re: Bending Strips for Ribs

Posted: Sun Feb 10, 2019 12:03 pm
by Brian Amato
And, if you can, find you some nice, straight grain Douglas Fir. What your lumber guy will call Vertical Grain Doug Fir. It's an acceptable substitute for Sitka, according to the FAA and so much cheaper. Just look closely at the grain of the stuff you're buying.
I was talking to Andrew Pietenpol the other day and he told me "Grandpa always used to use Doug Fir in his airplanes".
Good enough for me.

Re: Bending Strips for Ribs

Posted: Sun Feb 10, 2019 10:38 pm
by VincentDunn
I used a 4 foot section of metal downspout, standing on end, on top of a pressure cooker with the pressure weigh off. Add cap strips and seal with a rag around the top. 30-40 minutes of steam works great. Just get the hot, steamed cap strips in the jig pronto. The heat seems more effective than soaking.