Straightening out the center ribs

[Chris In Milwaukee]

Good morning all,

So this new technique I described last week while re-doing my nose ribs is working out fabulously for the center ribs as well. I wish I'd had done it this way the first time around. I'd have saved myself a lot of time! Live and learn. Education and recreation, right?

Posted below is last night's progress. These are the .032" ribs. I "accidentally" flanged the lightening holes, but it can only make them better, right?

Left-siders are done, right-siders to go, then on to the .025" ribs.

~Chris

[Bcone1381]

Chris,

Clarify for me one thing. Using this method, are you pressing the flang on the lightening holes prior to creating the 9/16" outer rib flange? Does the order of doing these flanges seem to make a difference?

[Chris In Milwaukee]

This is actually the second time working on these ribs. The first time around, I flanged the edges, fluted them with pliers like these (http://aircraftproducts.wicksaircraf...=100|1028|1144), and then came back and flanged the holes using a press-and-plug method that many others have used. Those particular fluting pliers are the worst, in my opinion. I recently bought these pliers (http://www.aircraft-tool.com/shop/de...RODUCT_ID=FP21) and I'm much happier.

The lightening hole pressing really did a number on the ribs, twisting them up quite a bit, and I was having a rough time straightening them out. I was becoming a bit disenfranchised with the whole (hole?) effort. No amount of tweaking I did would relieve the mess they'd become. I was about ready to hang it up and either start over, or wait and buy a QB kit!

After a rest period where I could gather my wits, I went back in and decided to try another approach: the one you see above and in my last post. Lo and behold, I had a winner. I actually routed circles into the surface of the form boards so that there was room for the lightening hole flanges I had already made in the past. So I hope to have all of these confounded ribs re-done and straightened in a few weeks so I can get caught up and move on to better things. Like spars!

If I had to do it over (like I nearly did), I'd use the rubber press method like N3UW did to do the lightening holes first:

https://www.youtube.com/watch?v=SYnX5-2m4HQ

Then do the outer flange:

https://www.youtube.com/watch?v=jYHzPskP7fc

This method yields minimal twisting of the rib, and barely requires any massaging at all. John also used a better set of pliers than I did at first, so it probably would have worked out better if I had as well. So I had to use a bit more brute force to get mine back into a usable shape. I can't say that I'm disappointed with my results, though. They look amazing (the second time around).

I also made a few new ribs where I used a press to flange the lightening holes first, and then put them in the bending form and hammered out the edges. I think the few that I remade this way turned out a lot nicer than the ones that I flanged the holes afterward.

~Chris

[Bcone1381]

Thank you so much for your response, Chris. You just shared something here that is rare...a method tried that did not work. I thank you opening up and sharing failure with us, followed by trouble shooting, brainstorming options, and trying a new game plan. This will help me in my build.

This will help us all in our builds. In fact, it would be my wish that we users of this sight would create a set of Best Practices. Declare the Best Practices, amend them as better methods are discovered, and help the Bearhawk Community improve on the completion and success rate of building. My feeling is the Builders Manual is a good document sharing one persons method of building a four place Bearhawk. Its goal was never intended to be Inclusive of nor in pursuit of Industry (EAB) Best Practices, or updating as tools and methods improve over time.

Our Group needs that. (Probably should be a separate post.)

[N3UW]

This is actually the second time working on these ribs. The first time around, I flanged the edges, fluted them with pliers like these (http://aircraftproducts.wicksaircraf...=100|1028|1144), and then came back and flanged the holes using a press-and-plug method that many others have used. Those particular fluting pliers are the worst, in my opinion. I recently bought these pliers (http://www.aircraft-tool.com/shop/de...RODUCT_ID=FP21) and I'm much happier.

The lightening hole pressing really did a number on the ribs, twisting them up quite a bit, and I was having a rough time straightening them out. I was becoming a bit disenfranchised with the whole (hole?) effort. No amount of tweaking I did would relieve the mess they'd become. I was about ready to hang it up and either start over, or wait and buy a QB kit!

After a rest period where I could gather my wits, I went back in and decided to try another approach: the one you see above and in my last post. Lo and behold, I had a winner. I actually routed circles into the surface of the form boards so that there was room for the lightening hole flanges I had already made in the past. So I hope to have all of these confounded ribs re-done and straightened in a few weeks so I can get caught up and move on to better things. Like spars!

If I had to do it over (like I nearly did), I'd use the rubber press method like N3UW did to do the lightening holes first:

https://www.youtube.com/watch?v=SYnX5-2m4HQ

Then do the outer flange:

https://www.youtube.com/watch?v=jYHzPskP7fc

This method yields minimal twisting of the rib, and barely requires any massaging at all. John also used a better set of pliers than I did at first, so it probably would have worked out better if I had as well. So I had to use a bit more brute force to get mine back into a usable shape. I can't say that I'm disappointed with my results, though. They look amazing (the second time around).

I also made a few new ribs where I used a press to flange the lightening holes first, and then put them in the bending form and hammered out the edges. I think the few that I remade this way turned out a lot nicer than the ones that I flanged the holes afterward.

~Chris

Chris,
I did find that using the rubber press that there was almost no distortion of the ribs. It was also very fast and required very little setup. There are different rubbers that can be used but if you do not use a dense rubber it will not fully form the flanges. The type is used is used by the commercial presses. This method also requires you flange the lightening holes before you flange the sides. I was not successful flanging the sides first. It would create a crease if I did. I was also not successful flanging the sides and lightening hole with the small press I had. If I had a 100ton press or larger it might have been possible.

I also had problems with the commercial fluting pliers. I made the ones in the bearhawk a guide and they worked great. I like the idea that someone else did where they made two sizes. I would have liked a larger size for the nose ribs on the patrol. I had to double flute the ends of my nose ribs.

[Chris In Milwaukee]

I used a 12-ton press, and it was barely enough. The 20-ton press you have is definitely better suited for the holes. I think I've already ruptured the seal on the 12-ton pneumatic bottle.

[Glenn Patterson]

We bent the outside flange first and they square up fast with the fluting pliers. We had a clamp board that kept the rib flat to the female die by securing it with heavy C clamps before pressing the flange. The female die was undersized to allow the flanges to hang over the sides. The clamp board restrains & prevents the rib from buckling. There is a very minor curve put into the rib that is taken out very quickly with a small pry on the lightening hole flanges. Once the male die is seated into the female die that is as far as it goes.
Thus shows what the clamping arrangement looks like. I am sure that it could work with using a bolt to squeeze the dies as well. Clamp all the layers together before pressing the flange. Our ribs went formed easy and we only disposed of one rib. We threw away the first rib that we did all our learning with.
We built the press that uses a bottle jack. Worked very well. Presses are inexpensive.
This illustrates the clamping and control of rib distortion through the flanging process.

http://bearhawkforums.com/forum/tools-technics-and-best-practices/233-routering-methods-for-bearhawk-jigs-dies

Glenn
BH727