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Date:  1-19-2017
Number of Hours:  10.00
Manual Reference:  IIL page 6
Brief Description:  Engine Mount 9

With the holes marked how in the world do I get perfect holes in an area that is very hard to jig??

Well I asked an engineer who has built a Rutan design. He said use the mark one eyeball with small drill sizes and edge up to the bigger ones with a bit of pull and shove to get things looking parallel.

WOT???!!! Well thats what I did. The beginnings of this are shown in pic 1 with getting smaller pilot holes in pretty good alignment. Then I mounted the mount, if you'll excuse the phrase, and got it all perfect again and used a serious number of clamps to keep it there. I slowly went through the drill sizes until I was close to my .025" for the AN4 bolts.

Now before we got here I found that I had a nice reamer for the job but it was marked 0.251" and my bolts micoed up at 0.248" So my trial holes gave a sloppy result. I asked the online experts what is the correct size reamer and got answers saying it wasn't critical and after all you measure with a micrometer and end up using an axe to cut things ...everyone's a comedian.

It took a couple of days but I ordered a 0.247" chucking reamer from a real engineering shop. It worked a treat and I have nice holes that need a slight tap with a plastic hammer to get the bolts in. I'm happy.

I do have some special washers planned that I've asked a machine shop to make for me. So for now I just put in some longish bolts with lots of washers as you see in pic 2. I'll show the washers in a later log when they arrive and you'll see what I'm on about. That said the mount is on.
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Pilot holes

Pilot holes

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Underside drilled out

Underside drilled out

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Top side pretty

Top side pretty

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