Saturday, October 31, 2009

Cutting Thin Plywood

One of the problems when working with plywood is that you get bad tear out of the plywood surfaces when cutting with a saw. When cutting out long curved panels, I have to use a jigsaw. I saw a good idea about making a zero clearance base for the jigsaw. I made one and it works great. It also helps to use a blade with at least 18 TPI (threads per inch).

Boatbuilding Plywood

I am starting a new boatbuilding project this fall and it will be made out of 1/4" plywood. One sheet of Okoume plywood costs about $50 and I need (4) sheets. I found this meranti plywood at Home Depot for $10 per sheet. Looks great and said it is exterior grade. It has 3 equal thickness plys but has a paper thin veneer on each side. I read about a boil and freeze test for plywood in Sam Devlin's book on Stitch and Glue boatbuilding. I cut a 3" square and boiled it for 20 minutes and then put it in the freezer to freeze it solid. I did this for three cycles and it delaminated by peeling apart. I will not use it for a boat but it was worth a try to find out if it would work. I also do not like epoxy gluing to a paper thin veneer that could peel also. I would recommend staying away from this even though it is tempting. Epoxy is not a cure all for bad plywood.