I had a table top to glue up this weekend and was looking to build a jig to get better results adding biscuits to align the boards during glue up. I made a mistake on my last set of glue-ups and thought the boards were flush, but when I pulled them out of the clamps they were not even and required a lot of work to flatten.
I don’t like extra work and would rather use some common sense. There are a number of jigs on this site and in the trade mags that show how to fix the base of a biscuit joiner which allows you to clamp the work piece and and keep it from wandering during the cut. They also give you better more consistent results.
I did not have enough plywood to make the jig so a thought hit me.. why not just clamp the biscuit joiner to the table saw, use the hose I have for the blade dust collector and use the fence on the table saw in reverse to hold the workpiece in place. Worked great! here are some pictures since they are worth a thousand words.
Take a couple of clamps and clamp the biscuit joiner right up against the fence, use the fence to get it flush and parallel then tighten it down. Snug and not too tight, you could put some tape on the bottom if you like.
Move the fence back, slide in your first board and bring the fence snug against the joiner and clamp it down. Run your first slot, move the board to the next mark and run the other slots.. that’s it!
Just another shot of the setup.
In this case, all I wanted was three biscuits per board. one in the middle and one on each end to keep them lined up while they are clamped and glued. I usually draw lines across all the boards to locate the spot to cut the slots and make a circle where each biscuit goes.. this will help you remember not to cut a slot on the edge that will show. (yes I actually almost did this once)
Here is the glue up with two home made cauls to help keep it from bowing when clamped.
The result was a nice flat surface with little cleanup and short work with a cabinet scraper and hand plane.
-- Mike.... West Virginia. "Man is a tool using animal. Without tools he is nothing, with tools he is all.". T Carlyle