Epoxy all applied

Eventually I applied the final External Fillet Epoxy to the air-frame.  They all looked reasonably good, all quite similar in profile and size to the photo below.

Preparation

I wanted to avoid sanding the air-frame and fins at all costs. I decided that if I employed masking tape, I’d have to sand through the masking tape before sanding the fins/air-frame and I’d notice in time that I was sanding the wrong thing.  Below is a picture of it all taped up.

Sanding

The next step was to sand them. I had gone to extraordinary lengths to glue Sandpaper to a long stick to sand the fillets. I realised pretty quickly that this was overdo and I did not need along sheet and I did not need a long stick. In-fact, having a long doweling with long strip of sandpaper was counter-productive because the fins, even though they were VERY well aligned, the slight differences in epoxy between Fore/Aft fins meant that the sand paper would not reach all along the whole length of the fillet. The other fin was “in the way”.

So I pretty quickly went for a smaller doweling with about 10 cm of Sand paper just wrapped around it with some masking tape to hold it in place at one end. This allowed me to sand each fillet individually. No glue, it was so much easier.

I used the following sandpaper in the order shown:-

• Grit 60
• Grit 240
• Grit 600
• Grit 1200

I used water for Grit 600 and Grit 1200. i.e. Wet and Dry.

I had to be very careful to keep the doweling parallel to surfaces, to ensure I produced a curved profile along the whole length of the external fillet.

The results

The results were good, but not as impressive as I had hoped. Near the edges of the fillet there were craters. I couldn’t risk sanding into the air-frame, so I had to think about how to deal with them.

I didn’t keep a photo of the cratering, so I’ve retrieved a photo of cratering in some of early practice fillets.

I’ll leave the solution to this in the next Post.