Thanks Bruce, I ended up leaving the cap strips on the mould around 40 minutes which seemed to work well. I kinda suspect longer would be even better, but will try that next time. On the plus size, they came off the mould and were screwed straight onto the ply webs which will help as well.
Glad to hear. I know longer times in steamer(up to a point) and longer on shape form will help. It will slow you down making the ribs though. Maybe construct 1 or 2 more forms ?? I watch on RU-vid a guy that rebuilds stage coaches. And he has to make the wagon wheels. He utilizes a long steamer and bends really thick lumber laminations. Amazing to watch him. I never thought of using a wallpaper steamer for steam. I have one of those. Hmm
looks like the cupping of flat sawn timber. If you need the flat sawn timber as spec then maybe try it up the other way. it will still cup but maybe a slight up round may be beneficial to a fabric covered wing. just thinking out loud.
Hi Russell, yep I have seen that in flat sawn timber but typically the timber is still drying, warping as it loses moisture creating uneven stresses. I have seen it most in wet flat sawn fence palings and weatherboards that have not been nailed up promptly.. Tight grain and dry tends to eliminate most issues. So far my experience with this timber is that it is remarkably stable given some pretty extreme environmental conditions. I'm laying this one down to me abusing perfectly good timber!!!
The strip cupping is probably due to grain direction, it really should be vertical not horizontal. You should also leave the strips in the mould overnight if possible. Not criticising your work at all, just trying to help.
Thanks Phil, longer in the mould has definitely helped. I haven't done overnight but will with future pieces. Grain direction for cap strips is an interesting discussion. When I started someone raised it but I couldn't find anything to support it. I since have (can't remember where, but I did find it) but I stuck with horizontal because of the screws that penetrate the cap strips (into the ply webs and the spars), thin vertical grain may split under pressure from screws while horizontal grain is somewhat better. The shorter cooking time has resolved the cupping, longer in the mould should help retain the form and perhaps help with reducing spring-back. Thanks for your comments Phil, I'm a novice working it out as I go, feedback or queries are welcome :-)
