sheperd80 Posted August 20, 2016 Report Share Posted August 20, 2016 Hey folks, ive gotten myself into an unusual project and could use some advice. A customer has a few of these antique plate holders and wants 9 more. The plate sets into a rabbet in the back and is held in place by the small metal stays, it hangs from a wall by the d-ring. The originals are bent lamination half circles, butt-joined together but Im not constructing them that way. They are 9" in diameter, 1-1/8" thick and the band is 1-1/8" wide. Ive decided to turn them on the lathe so i can duplicate the face profile. My question is about construction. I have a few ideas but all are a bit unconventional. . 1. Turn them from solid hardwood. Ive got poplar wide and thick enough. But im concerned about the weak cross-grain sections that will be created by cutting a ring out of a single board. They dont need to be incredibly strong but id like them to be able to withstand a straight fall. And i can imagine that shape warping. . 2. Laminate 2 pieces of thinner hardwood with perpendicular grain direction. This would eliminate the weak spots but possibly warp as well. 3. Laminate hardwood to mdf. Hardwood face for turning, mdf back for stability? But now the hardware is screwing into mdf. Weak. Maybe an mdf sandwich would be better... . 4. All mdf. Ive never turned mdf but dont imagine its great. The ring would also be quite weak but i could reinforce it with hardwood around the inner diameter. Least favorite idea. . Any help is appreciated, thanks for looking! Sent from my SAMSUNG-SM-G890A using Tapatalk Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted August 20, 2016 Report Share Posted August 20, 2016 Assuming these are painted, so that grain appearance doesn't matter, I suggest a variation on option 2. Either laminate the hardwood yourself, three layers for balance of stress in the lamination, or just turn them from a quality plywood. MDF might produce a smoother surface to paint, but would be easier to damage. 2 Quote Link to comment Share on other sites More sharing options...
sheperd80 Posted August 20, 2016 Author Report Share Posted August 20, 2016 Yes theyre painted. I considered plywood but im leary of trying to turn a profile into the face. Not to mention the cost/availability of quality 1-1/8" ply. 3 layer lamination would be ideal strength-wise. Its alot of work though. Id have to source or mill lots of 3/8 hardwood. Do you think just 2 layers would be too unstable? Sent from my SAMSUNG-SM-G890A using Tapatalk Quote Link to comment Share on other sites More sharing options...
wdwerker Posted August 20, 2016 Report Share Posted August 20, 2016 Any lamination needs to be an odd number of layers. It's called balanced construction. 1, 3, 5,7,9, etc layers are what you see in plywood. An equal number of layers on either side of the central layer. Each layer should have the grain going 90 degrees to the previous layer. An even number of layers usually ends up curling like a potato chip. Quote Link to comment Share on other sites More sharing options...
sheperd80 Posted August 20, 2016 Author Report Share Posted August 20, 2016 Yeah, i hear ya. Im trying to avoid a ton of milling if possible. What do u guys think bout option 1? Turning them out of a solid board, and maybe reinforcing the weak cross-grain section somehow. Sent from my SAMSUNG-SM-G890A using Tapatalk Quote Link to comment Share on other sites More sharing options...
wdwerker Posted August 20, 2016 Report Share Posted August 20, 2016 The front and back plys do not have to be the same thickness as the center layer. But making all 3 the same might be easier to mill. Front and back plies should be roughly equal in thickness. Trust me don't try a shortcut, it will circle around and bite you in the butt. Speaking from experience here, just trying to prevent you from learning the hard way. Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted August 20, 2016 Report Share Posted August 20, 2016 Steve is right, an unbalance lamination is almost guaranteed to curl. Quote Link to comment Share on other sites More sharing options...
sheperd80 Posted August 25, 2016 Author Report Share Posted August 25, 2016 I understand what you guys are saying. The 2 lam idea is out. But 3 layers is more work than i have time for on this project. I dont have an efficient means of making several 9" wide, 3/8" thick boards. So do you guys think turning them from 1 solid piece of hardwood is safe? My gut tells me it would be weak and unstable but im not sure how a ring shape will behave. Sent from my SAMSUNG-SM-G890A using Tapatalk Quote Link to comment Share on other sites More sharing options...
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