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Empennage

Finished match drilling HS

I didn’t get into the shed during the week so I was itching to get in last night. Managed to get a good session in.

Using my #30 drill bit, I match drilled all the skins holes I hadn’t gotten to during my rilling of the forward spar and inner ribs. It soon became apparent that I needed a way to keep track of which holes I had drilled and what I hadn’t drilled yet. I used a mark on the blue plastic with a Sharpie pen which worked effectively. I was careful in match drilling so that the holes were in alignment before I drilled them out. The usual method of a cleco in every 2nd hole worked well, except for the main nose rib. For this area I had a cleco in every hole and I removed 1 cleco at a time to drill. Once drilled I marked that position and put the cleco back. The skin and rib weren’t exactly flush but this method seemed to work ok.

It took a while to get the upper and lower skins done on the left and right stabilisers but it wasn’t too bad with the radio cranked. I then took the skins off and match drilled the angle reinforcements to the forward spars. I drilled the out holes first and put a cleco in before I did the remainder so that nothing moved around whilst drilling. Worked out ok.

I removed the nose ribs to give me better access to drill the angles and noticed the aft notch catching on the angles on one edge. Looks like I need to sand off a touch to provide some clearance. I’ll do that when I’m deburring all the parts.

I hadn’t dimpled the forward spar channels or countersunk the angles yet, as I wasn’t sure an the setup required at the time. I’ve since got the advice from my SAAA Technical councillor (Thanks Bo!) and went ahead and dimpled the spar channels. I checked the plans about 5 times before I dimpled as heaps of builders have dimpled the wrong side here. The dimples need to be sunk forward into the angles, which is why the angles need to be countersunk.

I then set up my microstop countersinking tool. It took a minute or two to figure out how this tool worked, but once I figured that out I tested it on some scrap wood. I checked the countersink diameter with a vernier and erred on the side of “not enough”. I then countersunk one of the angles and checked for depth using a piece of scrap alclad that I had dimpled during my riveting practice. I hadn’t countersunk enough for a flush fit so I kept making a minor adjustment to increase, check and increase, check and increase…until I got it right. Then I countersunk the remaining holes.

Then it was time to take everything to pieces. Feel a bit like going 2 steps forward, 1 step back … but I know the importance of deburring and edge finishing. Must be done so here are all the HS parts laid out and ready for deburring.

Build time 2.5 hrs.

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About gstrack

Husband and father of 2. Control & Instrumentation Engineer. Flying nut. Gadget geek.

Discussion

2 thoughts on “Finished match drilling HS

  1. You building your own rc plane, mate? Looks like a mighty undertaking!

    Posted by Michael strack | May 7, 2011, 5:12 pm

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