8.12.1-5 Trim skin and fit tail spring mount

This is it! Making this cut will make this aircraft a tailwheel, a decision I agonised over for many hours. The plans gives a template for the cut but, like many other builders, I didn’t want to cut the original plans so I made a photocopy of the template from the plans and used that to mark the skin instead.

Once I marked the template I then used a 1/4″ drill bit to drill the end of the curve and broke out the dremel to rough cut the lines.

Next I used the dremel with the drum sander bit to tidy up the cut followed by hand filing for even more accuracy. The cut out is so that the tail spring mount can fit between the F-711 and F-712 bulkheads but when looked at the part it didn’t look quite square. I decided to check how far out of square it was…

Thankfully it looked worse than it was, it was actually only 1/32″ out of square. I can live with that. On first attempt I noticed the mount didn’t fit so I had to trim the cut I made earlier. Unfortunately it still didn’t fit but after referring to the instructions again I realised that F-712 also needs trimming to allow room for the welding fillets.

It took several iterations to remove just enough of F-712 bulkhead. I really didn’t want to take too much off so it was a case of trim a bit, check and repeat. Next I needed to drill the tail mount to the forward F-711 bulkhead through the vertical bars as well. The trouble is that is a deep hole and it was difficult to see in there. The instructions simply say to drill it square to the bulkhead, talk about understatement! Eventually I read Mike Bullocks blog which gave a fantastic tip of marking a line 12/32 from the top and from the edges.  It worked a treat though it was an absolute bear lining it up and clamping it all. In the end I got it done and the bolt holes are drilled #30. I’ll final size them later on.

This session was a lot of work for not much reward. I’m pleased it’s done though.

That’s all for today.

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