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Plywood chip out with dado blades

moggymatt

Any good ideas on how to minimize chip out on prefinished plywood when using the dado blade? I'd like my edges to come out as good as Norms.

ChrisNeilan

Use a strip of painter's tape over the cut line. It helps...

GeorgeM

moggymatt wroteAny good ideas on how to minimize chip out on prefinished plywood when using the dado blade? I'd like my edges to come out as good as Norms.

In addition to using tape, you could pre-score the cutting line.

Gene Howe

My dado set is a Tenryu and used to cut huge bat wings. I intended to use the set for box joints and the bat wings were a no-no. I sent it out to have the two outside blades re-formed to eliminate them. I'm not sure what the sharpening service did exactly but, when I got them back not only did it produce absolutely flat bottomed dadoes, but there was no tear out in hardwood or plywood.

Possibly, if you describe your tear out problem to a good sharpening service, they might be able to sharpen the set to a configuration that would at least minimize the tear out.

algale

Did you view this Sawdust Session? http://www.shopsmithacademy.com/SS_Archives/SS112/SS112_Dadoes_&_Rabbets.htm

Fast-forward to about the 19 minute mark to get to the discussion you will be interested in. Hint: he scores the sides of the dado using a square and a utility knife before cutting it.

masonsailor2

The tape and scoring method are about the only two methods I know of. The scoring method works the best but with both methods you will need a zero clearance insert for the dado blade. Get the dado blade adjusted to the width you need and then create the ZCI so the insert fits the dado blade exactly.

Paul

charlese

How about first dadoing a very shallow cut - only through the face veneer. This will work on some plywoods as the thickness of plys differ between types of boards.

Tape combined with a VERY light first cut has worked for me. :)

I've tried scoring, but always manage to slip the knife of the square. :mad:

anmius

I've had good luck with all of the above (tape, scoring, shallow cut) plus a good sharp plywood blade.

wa2crk

I have stopped using the dado blade and now prefer using a router with the appropriate cutter and a home made guide

Bill V

benush26

wa2crk wroteI have stopped using the dado blade and now prefer using a router with the appropriate cutter and a home made guide

Bill V

Me, too.

However, the majority of my dado cuts are in larger pieces.

I feel more comfortable and in better control when I pass the router bit through (aka blade over) the material where I can see the cut rather than passing the material over the dado blades where I cannot see the cut.

I was helping a friend build some tall books shelves. We bought American Eagle "plywood dado" router bits which worked like a charm. Frankly they were a bit pricey at more than $60 for the set. Where they really shined was making the stopped dado!! We put the two uprights flat, side by side and lightly clamped them so the wouldn't shift. laid out the interior shelf locations, started a plunge cut on one side (the stopped portion) made the cut across both pieces, stopping short on the other side. For the top and bottom simple through dados. Everything fit well, glue up was nice!! :D

Sorry, not a solution to the current dado blade dilemma :o but a thought for future projects.

Be well,

Ben

PS. In the past I have used both tape or an exacto knife to precut. I preferred the ease of the tape. Plus too often the blade would stray! :o :rolleyes: - yup operator error!

moggymatt

Gene Howe wroteMy dado set is a Tenryu and used to cut huge bat wings. I intended to use the set for box joints and the bat wings were a no-no. I sent it out to have the two outside blades re-formed to eliminate them. I'm not sure what the sharpening service did exactly but, when I got them back not only did it produce absolutely flat bottomed dadoes, but there was no tear out in hardwood or plywood.

Possibly, if you describe your tear out problem to a good sharpening service, they might be able to sharpen the set to a configuration that would at least minimize the tear out.

Gene, any chance we can get an image of what those reground blades look like? I'll have a chance soon to try my hand at saw blade sharpening when I aquire my father in laws foley-belsaw equipment. When that happens I'll start playing with yard sale finds.

in the mean time I'll give all the great suggestions a try.