Sat Jan 17 2009

Fitting gear weldments

These first four photos are from the previous night.

Next, it was time to drill the side flange of the weldment through the skin and lower longeron. Here I've drilled #40 pilot holes.

Then drilled them up to #12 for the AN3 bolts that go here.

You might be able to see that after drilling, there's a gap between the side skin and the lower longeron. That's because there a bunch of aluminum and steel chips trapped between those two parts. If I had riveted this structure together already (as the instructions indicate), it would be practically impossible to get all those chips out. I'm more and more convinced that it's better to delay riveting until as late in the game as possible.

Next I drilled through the forward flange, the stiffening web, lower longeron and side skin. I drilled from the inside outward using a #30 drill bit at first, then opened these holes to #12 drilling from the outside inward. I also repeated the same processes for the right weldment.

Today I went into work and borrowed a drill and some reamers for use in match drilling the gear leg weldments and the gear legs themselves. On the bottom is a 19/64 drill. Above that is a .310 reamer. Lastly, the top reamer is .311 to create the recommended hole size per the plans.

After some wrestling, I was able to insert the left gear leg into the left weldment.

First, I drilled down through the assembly with the 19/64 drill.

Then I inserted the .310 reamer, chucked the drill up, and pulled the reamer through. I decided to pull the reamer through rather than pushing it through because I figured it would be easier to keep the reamer aligned with the hole. It worked great. After that I did the same with the .311 reamer.

The AN5 bolt fits nice and snug.

While I was at work on Friday, I called Tech Paint Industrial who we use to do our powder coating and spoke with the owner, Dan Denny, about fixing up the powder coating on these gear weldments. He indicated that it's not really possible to "touch up" powder coating and have it come out good like you can do with spray paint. He indicated the best thing to do is to strip off the old powder coating and recoat the whole weldment. So I stopped at Advance Auto Parts and picked up the paint remover that Dan recommended. I'll go into work to use the paint booth to strip the two gear weldments.