I used a 3/4" router bit to create a dado for 3/4" plywood. Yep, you
know it. And I know it too. How and why I did it is beyond me. At any
rate, the wood does not have a tight fit. I'd like to fill the dado (or
even a partial fill) and do it again. Can this be done? If so, with
what? Will it be as strong or should I try something different?
Damn, talk about taking the easy way out.. lol
I'm trying to decide if a 3/4" strip to fill the dado or a thin piece inside the
dado would be best, and you come up with a logical answer... not fair..
Please remove splinters before emailing
You jest, but a gap-filling glue (Liquid Nails is cheap)
can make it work. When my tenons are too loose,
and it's not an heirloom project, out comes the caulk gun
and thick glue...
If it has to be 'right', a 1/8" veneer ripped with the
table saw can be glued into the dado, then router-trim one
side of the inset piece to match. Fully housed tenons
and/or half-housed are the only way to make plywood
joinery like this work, IMHO. The plywood thickness
is indeterminate by 0.050", and the router bit is only
accurate to maybe 0.020", in my experience.
1. Rip some 3/4" scrap to exactly fill the dado, but just a little thick.
Glue it in. Sand smooth.
2. Go ahead and install your shelf. Use both glue and screws to hold it in
place. Heck, use some biscuits, too. Fill the very slight gap with wood
filler. It will disappear when you paint.
First, they do make router bits sized to match the actual size of 3/4"
plywood. But I'm sure you know that by now... :)
In addition to the other suggestions mentioned, I have one other possible
solution. Use thicker plywood for the cross piece, or glue a couple of thin
sheets together, then rabbet the ends so they fit the dado properly.
One final idea, save the miscut board for a future project, and prepare a
new sheet with the properly sized dados.
If you decide to shim the dado with a veneer strip, do it on the
bottom where it will show less. On most shelves, it will never be
seen unless it is above eye level. In that case put the shim on the
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