Wings

Started off this morning not working on the plane directly, but wanted to make some improvements to my dimpling tool. When we started this project, I decided I wanted to make my own C-frame dimpler embedded into the work table. I've seen the commercially available ones, and of course the DRDT-2, but for me I couldn't justify the cost if it didn't do 'exactly' what I wanted. So... I got to work on an idea I had a while back to make the best dimpling device ever. If I failed, I told myself I'd just break down and get a DRDT. To my own surprise, I think I succeeded! Total cost? $0.00! An aviation first! :-)

The idea was to attach an air hammer (or rivet gun) to a swinging arm that could go up and down towards the very edge of the workbench. On the gun would be the male half of a dimple die, and then the other half of the die would be placed into a very heavy steel block, slightly recessed into the work table at the very edge. This way, the dimpler can accommodate very large sheets (i.e. wing skins) and process them very quickly and consistently, since the air hammer will always be held straight and level by the swinging arm. Also, since the lower block is embedded into the edge of the table, it will be perfect for dimpling the leading edge curves using the gun and dimple die by hand.

The dimpler was built using some leftover 1" x 1" square steel stock from the first dimpler, some angle iron, steel plate, hose clamps, and an old air hammer that I've had for a while and still works great. It felt very MacGyver-ish, only I didn't need to use a paper clip or duct tape. The air hammer isn't as "precise" to control as the rivet gun, i.e. there aren't numbers printed on the air control valve but otherwise I still can't tell the difference between the two for the life of me, other than the price (Maybe that's what the "3x" means? ;-)). Anyway the air hammer is perfect for this. I test-ran it on some scrap running the gun at 35-40psi with a 1-second or so burst and the dimples came out 100% perfectly coined! I think if someone wanted to go out and buy all the parts new for this they'd spend less than $50. Here's the completed setup:

Some steel stock, angle iron, and hose clamps and a couple bolts attach the gun to the swinging arm.

The gun, arm, and attachment to the table. It does have some side-side slop, but as long as you don't really torque on it, it is quite easy to line up with the die. You can also see the patch job I did to cover the previous hole where the old C-frame dimpler was set up. Not the prettiest, but it works.

Straight and level from all angles. I put black carpet over the lower block because it was an ugly mess of steel bars and cut-up 2x4's, this makes it look a lot better.

When you're not using the dimpler, you can swing it up and out of the way. I should probably put some sort of up-lock on it so that it doesnt get bumped and come crashing down. Maybe a spring too. We'll do that in v2.0.

Anyway, on to the actual work for the skins. We final-drilled all the holes in the top skins, and I also countersunk/dimpled the areas of the top skin that needed to be while still on the wing. No pics, since it pretty much looks the same as it did yesterday. Towards the very end of the day, I was able to pull the L top skins back off the wing for the exciting task of deburring/dimpling. I got through the wing walk doublers and the inner skin (the smaller of the two), and decided to call it a night. Good news though, the dimpler works perfectly!

The MikeyJ-2000 dimpler in action on the W-1002 top wing skin!

Dimpled, scuffed, and ready for priming!

And that's all for this weekend, folks! Hopefully this week we'll get through the top skins on both sides and be ready to tackle the leading edge!