J

JurgenRoeland

Well Known Member
I have a small and probably stupid question on construction of a bending brake. I'm at the point of bending my trailing edges of the elevators.

When attaching my doorhinges to the two wooden 2 by 4's, I have attached the wooden blocks clamped together and attached the hinges. This leaves no space between the blocks when the brake is closed.

Calling a fellow builder, he told me this will not work and that their should be a spacing between the blocks when the blocks are closed to allow for the radius of the leading edge.
On the other hand, I have seen pictures on this forum where the blocks were also closed. I'm a bit confused now on what is best

Can someone with elevator edge bending experience tell me what is the best technique. And if spacing is needed, how much this should be between the two blocks.

Thanks in advance for the info.
 
Break

Jurgen,

I don't think there is a best technique. I'm certainly not claiming mine was the best, although it did work for me. I left a 3/16" gap. I used 2x6 lumber and used the short 2" face for bending. My theory was that all the magic happens at the bend line and all of the other material is just along for the ride. That said, I've heard guys say they have used all dimension of lumber, including doors. I did run the bending faces of the lumber over a jointer to true them up.

I think best advice would be to use heavy duty hinges and plenty of them so you don't get any bending in the wood between the hinges. If you set the gap at 0 locate the trailing edge a little forward in the break for the bend. If necessary you can always slide it a little deeper in the break and hit it again.
 
I did the 2X6 and door hinge method also, straight lumber with no gap, I did install and tape in place an 1/8 inch welding rod inside the bend radius of the elevator, came out great.
 
1/8" dowel and a tight radius will dramatically increase the heaviness of your elevators in flight. A 1/4" dowel works much better.
 
rocketbob said:
1/8" dowel and a tight radius will dramatically increase the heaviness of your elevators in flight. A 1/4" dowel works much better.
Click to expand...

Do I understand it well that you say a 1/4" radius in the back of the elevator gives better flight performance. I would have expected the opposite
 
ah yes off course. the english translation is sometimes creating a cloud in front of my eyes :)

so the radius of the bent should be 1/8" and the rod you insert for that should have a diameter of 1/4".
 
Follow the instructions from Vans.

Jurgen, four nights ago I built my brake with 1/4" gap as per advice I received here and it was a miserable failure. I am having to buy all new elevators.

Make the brake with no gap, like Vans says. As for putting a wooden dowel in the part to help shape the radius, I cant say. Makes sense, but I'm now very sensitive to deviating from Vans instructions.
 
No gap needed between the boards. Just place the bend a little ways out from the hinge and there will be space between the boards when you close the brake. Van's has a spec on the radius of the bend - I thought it was 3/32?? I inserted a small dowel inside the bend to maintain the internal radius when I closed the brake.
 
Many people here reference to 1/8" radius as in the plans. Others 3/32".

I'm wondering. Where on the plans did you guys find those nrs. I have plans from dec2010 and have been staring for hours to them in order to find the bend radius for trailing edge and can't find it.

The instructions say, bend according to description in 5G. In 5G they say the radius is on the drawing. But I don't find it. Can someone give me a hint on that.

The only 3/32 I find is the minimum opening between trimtab and elevator.
 
Pine tends to warp. Find some really good hard wood or fir if you can. Most of the big box stores only sell 2 X 6 in SYP in my area, so you may have to find a good lumber store/speciality lumber store.
 
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