Forums: Whisstock Designs: Plywood for Frames? New Topic Post Reply
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clintk
Posted: Sep 21st, 2010 at 21:38   |   Subject: Plywood for Frames?
Hi George, I have bought the plans for design 55. Over the last few nights I have been carefully reading through the downloaded plans and perusing your site to get familiar with the building tasks etc. I did notice that your new design 152 uses CAD cut plywood for the frames. Would this work with the smaller design 55 using the same dimensions as the original plans? I have started inputting the offsets into a CAD program to create full size patterns and thought that with the cost of khaya veneers now this might be easier and cheaper.

Regards, Clint.
debenriver
Posted: Sep 21st, 2010 at 23:41   |   Subject: Plywood for Frames?
Hi Clint

Yes that would work fine. You could use 3 layers of 6mm ply to make the frames 18mm sided. You can leave them at 27mm moulded depth. You can increase this to 30mm if you wish.

Thinking about the frames in the fwd part of the boat, you can make the aft layer to the larger dimensions and the fwd layer to the smaller dimensions. For the centre layer you can interpolate between the two. This will give you your frame edge bevel near enough. Except where there is a lot of bevel (perhaps right forward), the thickened epoxy bonding the skin on should fill any small gaps. Right fwd, you may need to clean the frame edge off a little. It's the reverse for the aft frames, where the fwd face is the larger.

Incorporate the floor sections of the frames with the frame ply layers. If the ply layers are butted together, then stagger the butts from one layer to the next.

You will need some location holes to keep all the parts accurately together. Then you get a nice inside edge and a nice top to the floors. And everything is correct. 6mm holes would be fine – just push a length of 6mm dowel rod through them. Remember to locate the holes from the inside edges of the frames as these are the same on each layer.

As I progress (slowly) with full-size files for CNC cutting for each of the designs, I shall be adding ply frames like tis to many of the designs.

Use a decent quality ply that doesn't have bad voids etc. inside. It needs to be WBP grade. Good quality Gaboon ply would be fine.

Best regards – George