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I struggled with how to achieve a contact condition between the spar capstrips and the spacer bars and reinforcements. The factory rivets the capstrips to the spar webs first and hand fits the spacer bars to a snug fit. I did not feel that I could do that with any degree of success. Sand off just a tiny bit too much and you have a gap. If your doing it all day, I can see developing that skill, me not so much. So I developed a clamping method that seens to work. The clamp indexes to the outside surfaces of the capstrips and brings the inside surfaces into contact with the ends of the spacer bars. I built two clamps, one has a step milled in the clamping surface so that it fits on the aft side of the main spar. The only area I cannot clamp with these is the aft side of the rear spar. But I found a way to do that. Here is what the clamps look like. They are welded aluminum with all thread, std lock nuts and wingnuts. And here is what they look like installed. It takes very little clamping pressure to achieve a contact condition. To check for gaps I cut small pieces of print paper fron the pages of Sport Aviation. They mike about .0025. If I can't get that gage into the fay surfaces and a visual inspection shows no gap, I install four C clamps adjacent to the clamp structure, two on the top capstrips and two on the lowers to hold everything in position. Then I remove the clamp structure. and drill the capstrips and previously piloted spacer bars in that region. Then I move on to the next rib location. Seens to work great. For the aft side of the rear spar I use my barbeque tongs. I flattened and padded the ends. I place the ends of the tongs on the outside edges of the capstrips, squeeze with one hand to bring the capstrips and spacer bars into contact and add C clamps with the other. Again, pretty simple and works like a charm. I had all the spacer bars and reinforcements cut on a mill at the same time to insure they were all the same width. I feel this is a critical step. I had a pro do it and it wasn't expensive and it insures the ends are squared. Go to your local machine shop supplier and ask for the name of a one man shop. You want the guy with the gray beard with a Bridgeport and a lathe in his garage.Ask to see some of his work. No need to tell him it's for an airplane.
Cheers
Gerry
Patrol#30
No idea if the pictures will make it, if not I'll try again.
Cheers
Gerry
Patrol#30
No idea if the pictures will make it, if not I'll try again.