{"id":168,"date":"2020-09-12T22:20:33","date_gmt":"2020-09-13T06:20:33","guid":{"rendered":"https:\/\/blog.aviate.org\/rv7\/?p=168"},"modified":"2020-09-28T10:22:51","modified_gmt":"2020-09-28T18:22:51","slug":"fabrication-challenge","status":"publish","type":"post","link":"https:\/\/blog.aviate.org\/rv7\/2020\/09\/12\/fabrication-challenge\/","title":{"rendered":"Fabrication challenge!"},"content":{"rendered":"\n
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The next chapter in the saga was to fabricate something from scratch. The instructions call for making this special dimple\/bucking bar for the small area of the ribs that you can’t fit any other tool into:<\/p>\n\n\n\n

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No way that’s gonna fit in that small space!<\/figcaption><\/figure>\n\n\n\n

The tool we need to fabricate is only 3\/16″ thick, so it can slide inside the rib and let us both dimple the holes near the end as well as set the rivets. I lucked out and found that Home Depot had a 3\/16″ x 1\/2″ inch bar. The problem was it was 36″ long! I only need 4″.<\/p>\n\n\n\n

Not having done any kind of metalworking since jr. high school shop class (and even then I’m not sure we did any metalworking), I had to go check out YouTube to see how I could cut down the bar to 4″. I could, of course, leave the bar as-is, but I want to practice all these new skills.<\/p>\n\n\n\n

I found a video that showed 5 ways to cut steel, ranging from a plasma torch to a die grinder to a chop saw. Since all I have is a couple compound saws and a circular saw, I decided to try a metal sawblade in the smaller of compound saws.<\/p>\n\n\n\n

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But before we go there, I have to drill a hole near the edge of the steel. I read that using cutting oil would help prolong the life of the bit and help keep the shavings in one place. The video, found here<\/a>, showed using a dpring-loaded punch to make a starter hole. Well, I had to have one of those! So, off to Home Depot I went, where I picked up the bar, a 7″ diamond metal cutting blade and a bottle of the closest thing I could find to cutting oil.<\/p>\n\n\n\n

Drilling the hole went smoothly. First I used the punch to make a good-sized hole 1\/4″ in from the top and side. Drilling was uneventful. One thing I learned was that drilling metal works best if you drill SLOWLY. So I kept the speed down and got through the piece.<\/p>\n\n\n\n

Next was the daunting part…at least for me…countersinking the hole. I had tried this on the first part and it didn’t end well. I asked Grant Powers, who is also doing an RV-7 build vlog<\/a>, how to make sure the countersink is not too large. He pointed out Van’s instructions in section 5 regarding countersinking, which has the correct procedure, down to adding 7 clicks on the microstop pilot cutter to underset the dimple just enough.<\/p>\n\n\n\n

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An AD-3 rivet sitting comfortably in the newly-cut countersink.<\/figcaption><\/figure>\n\n\n\n

That’s it for tonight. Tomorrow we set up the saw and try to cut the bar down to 4″!<\/p>\n\n\n\n

Follow Up<\/h2>\n\n\n\n

Here’s the finished piece! The saw worked very well, and the sparks gave quite a show!<\/p>\n\n\n\n