A slightly different topic, my 1/4 scale Sig Extra 300 ARF, like many arfs, made overseas, used a mix of metric and SAE hardward. The plane came set up with 2 metal blind nuts tapped for some really small metic nylon bolts, I forget the size, but similar to 10-32. There was no way I was going to put this bird up, 2 grand before the transmitter with those 2 little nylon bolts, and it would have been a bit harder finding spares to carry with me. Ever lose a screw and not been able to fly? I swapped out the nylon ones for some steel allen head screws, running through a large fender washer and a dubro nylon washer between. The nylon washer has a small amount of give, to keep tension on it to prevent it loosening, without crushing all the wood. It has worked flawlessly. I just put flight #31 on it yesterday.
The instruction manual also said to mount the engine with 0 degrees thrust. I followed their instructions, and the pland tracked like crap on the vertical lines and loops. Maybe they got their test plane to fly straight with a 1.50 size engine and 16 inch prop, but with my 2.4 gas turning a 20 inch prop, I believe this added much more prop thrust/wash, making it track sideways. After making about 3 degrees of right thrust adjustments, it flew better, but now the engine was almost a half an inch off centerline. I never tried to remove blindnuts before, and I didn't want to mess up the firewall.......but I had to try. I unbolted the engine, and put a spare bolt into the blindnut. I found that if I pushed and wiggled the bolt, I could break it free from the epoxy. One I had to gently tap and squeeze with a pair of big pliers, but I got them all out. After I moved them all, I plugged the holes with some dowel, glued in and sawed off flush. Yesterdays flight showed the effort was worth the few hours it took me. Sorry if I rambled on, I hope others will benefit from the whole experience. Last thing, with nylon bolts, do not overtighten!!!!Think of them as rubber bands, too tight and when any more "stretch" is applied, they will snap, then your plane turns into a missle. It's got to have a little room. Thats all.