jig pin location.

[papakeith]

I'm still in the process of building my formblocks. The plans call for one jig pin in the nose rib section and one in the tail rib. If you look at the image I've loaded, I've marked the original pin locations with blue dots.

Since the ribs aren't all full length, I wanted to add additional pin locations on each section of rib (nose, mid, tail). I've seen this done in photos from other builders and it makes sense to me.

Now, bear in mind I've already asked and gotten an answer to this question from the Bearhawk list. I just wanted to see what you guys n gals would come up with for an answer.

The question is: How do I figure out a good location for the additional jig pins in the individual ribs?

the red dots are aprox where I want the new pins, the blue is where the plans has pins. The verticle lines are spar locations. Circles are lightening holes.

[captain_john]

Keith, I have given your question considerable thought and I have a question for you.

Why do you feel they are needed?

It seems that a single location point will suffice and more would only complicate the manufacturing process. If I were doing the project, I would try several with only one point and see how it goes.

Criteria would be consistency, simplicity and speed... in that order.

Anyone else?

CJ

[papakeith]

John if I were cutting the whole wing rib in one piece it would probably suffice. The trouble comes when you are making the individual sections of rib (nose, middle, tail). When forming the flange the blank is pressed between two formblocks. With only one jig pin the blank could have the oportunity to move about. The extra hole would add a bit of extra security by keeping the noserib, or other section, indexed in the formblock while I bang out the flange.

Right now my answer is to leave it out and save the cutting of the lightening holes until later. I cut pilot holes marking the centers of the lightening holes. This will give me a point to set my fly(circle) cutter and, it also gives me a minimum of two locations per section for added indexing without cutting addional holes in the rib structure.

simple and effective yes? I hope so.

I was able to spend three hours out in the garage yesterday. I'm (honest) almost to the point that I can cut aluminum and attempt to form my first rib.

[captain_john]

I understand the process. We did it at the SportAir Workshop. I agree that the second hole would be more secure. I would try it without first, adding it only if the part gets squirrely.

As I recal the process, once a side is formed the bending of the opposite side tends to tighten instead of loosen the fit.

Let us know how you make out!

CJ

[Bob Barrett]

Van's instructions for making ribs calls for two tooling holes in each form block. Quikbuilders are required to make one rib for each wing and one rib for each flap. The two tooling holes should be located one at each end of the form blocks. I used 1/4" screws or bolts with wing nuts. This securing clamps the sheet aluminum in place when both ends are tightened. If you can locate them in manner that will allow you to use the holes as centering holes for lighting holes go for it. However, I strongly recomend two tooling holes. I also had two vices that I mounted on a piece of 2"X6" to hold the form blocks and aluminum while pounding etc. It saved a lot of grief.

[papakeith]

alright, I'm back to wanting the second jig pin hole. When it comes time to cut the lightening holes out. the second jig pin hole will come in handy.