I saw some cedar slabs locally, but they have a fair amount of large (1"-2") knots. I want to make a sign for myself that is 20"x24" but I’ll need to machine the design that will include those knots. I assume they are harder than the remaining cedar, so fair to say I just slow down FS…or, do people have experience with those knots causing other issues?
Kind of a broad question, but curious if others have ideas before I plunk down $120 for a slab.
Sometimes the knot will bust when hit with the bit. Fast or slow does not seem to matter. Also, the knots will sometimes come loose and cause a different headache…
My woman likes boards with defects…knots, gouges etc… I find them to be a PITA…
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That is my fear - I’ll need to make a mock of my design and see how many knots I hit or not…I assume the knots will be a bad idea over time as they weather differently, etc.
It is impossible to tell if the knots will shrink or come loose. The anatomy of a knot is the tree grows in long straws that travel in a vertical shape. The knots are also straws but they are coming out a an angle to the straws in the trunk. Some varieties of tree the knots will shrink faster because of the structure of the grain of that species.
Why not try. The outcome could be failure but you never know unless you try. One thing about cedar is it quality of being an oily species. Before applying a finish wipe it down with acetone to remove the surface oil. Also if you are going to glue up slabs of the cedar wipe down the jointed edges with acetone prior to gluing for the best chance of the glue sticking. PVA (Wood Glue) would work but to be sure you might want to use polyurethane glue (Foaming Gorila Glue). There is a cleanup that has to be made with polyurethane glue but you would get the best chance of a lasting bond. Epoxy could also work if you have epoxy but cleaning with acetone immediately before gluing will help.
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you gave me an idea…if I really wanted, I could cut out the knots and replace with a plug of sorts…but I like the idea of trying on a test piece - more to come 
Best thing to do is to stabilize the knots w/ a suitable adhesive, then machine the entire project at the reduced speed the heartwood of the knot and the epoxy/adhesive demand.
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