I recently bought my first biscuit joiner, a used Porter-Cable. The
previous owner had apparently set the depth too shallow because when
dry-fitting boards the biscuits bottom out before the joint closes.
I increased the depth with the fine adjustment for my first test joint
so the joint closes when dry fitting. But when I added glue to the slots
I started to wonder if I ought to cut a little deeper yet to give more
space for the glue.
How can I set the depth to the ideal, or am I worrying about something
that's not critical?
Cut a test slot, insert a biscuit, using a sharp pencil make a line on the
biscuit on top of the wood, remove the biscuit, turn over and reinsert, draw
another line, remove the biscuit, the lines should match. Adjust the depth
until the lines match. You can set the depth so the biscuit is just a hair
deep for ease of assembly.
Radial Arm Saw Forum: http://forums.delphiforums.com/woodbutcher/start
There's usually a rotating cam, but there's also a screw adjust in the
If you buy a cheap biscuiter then it's worth checking this, as they're
often inaccurate. I've recommended Screwfix's Ferm biscuiter to a few
people as a really cheap but usable machine, and then had them report
problems with it. Fixing this adjustment solved the problem.
I am sure someone here would probably make some cuts and measure it for you.
I could do that in a day or to if you need me to. In the mean time, my
Porter Cable biscuit cutter is still set up in the factory default setting.
I think it cuts 1/16 - 1/8" extra depth (For a size 20). This is handy as it
allows for almost 1/2" of missalignment of the two slots (length-wise, not
thickness-wise) and still allows the joint to come together. You wouldn't
want to get too carried away on this extra depth becasue at some point the
biscuit won't be centered properly (located more in one baord than the
other) and you will loose joint strength. I think the 1/16" - 1/8" is about
right though, in my opinion.
Joe In Denver
My Woodworking Website:
You're right, it should be just a little deeper than the width of a
biscuit. What I've seen recommended is to cut a slot, seat a biscuit
in it, and draw a line across it with a sharp pencil where it crosses
the top of the slot. Pull the biscuit out of the slot and reverse it
and put it back in. If the line ""just" disappears into the slot the
depth is good.
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