tail feather steel ribs--- how to ?

[fairchild1934]

Looks like we will no linger be able to buy ribs- so we have to make them.
I just bought a HF 30 inch metal brake. It has a hold-down plate that appears to be about 3/8 thick. The edge of the plate is beveled to about 85 degrees-- I suppose to account for springback on 90 degree bends. I am wanting to bend the rudder ribs. I notice that the trailing edge of the ribs is pretty tight when you consider the 45 degree flange all most closes it up at the rear (because the rib tapers)

Seems obvious that the 3/8 hold down bar aint going to fit into that at the back to be able to bend the edge flanges.

I only see two possible solutions-----

grind/cut the edge of the hold down plate with a 30 (?) degree bevel--- hoping a thinner nose will go into the back.

second----- bend the ribs but omit bending the flanges with the brake. Bend a 3 sided box -- an then make a plug that will slide inside --- and have the plug have a beveled top edge. Lay that inside and bend the flanges down using the plug for support from below. Then slide the plug out .
Maybe the plug could be made from hard maple ?

any ideas ?

Tim

[alaskabearhawk]

The plug out of maple or oak is a good option.

[fairchild1934]

Maybe I will try oak with wood hardener saturated through it. And also maybe some pieces of 1/4 inch steel laid down and put into compression to work like vice jaws---- to squeeze the work inward against the oak core. I wonder if I made an aluminum V shaped pulley --If I could "wheel" that down the two upward facing flanges to roll them over onto the oak plug's bevels------- or would I be just as good or better to use the air hammer and /or an oak block and a mallet. ?????

[geraldmorrissey]

Eric Newtons builders manual shows an simple AL insert to hammer those edges over.

[fairchild1934]

I may go to AL if the hardwood doesnt give me a clean bend line in the metal.

I tried a test sample tonight. The HF bender looks like the hold down blade might be JUST barely narrow enough to work--- but if I have to thin it down just a bit I will. (like maybe 1/16) I tested some .030 plain steel from the box store. Across the grain. Bend fairly easily. I got the width just a hare too wide-- from not knowing exactly where to align my lines compared to the bend point on the brake. i bent a 3 sided channel. I will try some regular wood soaked in the wood hardener but i expect it will be too soft. I am about sure I will need side supports to trap the sides before I bend the edges over.

One difficulty I see is that the 45 degree flanges appear to be 1/4 wide. But if i hold that width to the narrow end (trailing edge) those flanges will be overlapping each other. What is the solution to that ? They look to be about 1/4 on the plans-- but there is no width listed for those flanges.

T

[fairchild1934]

all I can think of is to taper the outside edges o the blank a little bit to solve the problem at the small end.