How to avoid splintering with dado
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Two students, Jeremy Cowles, Scott Burden and I were experimenting with dado cuts while working on some custom-made kitchen cabinets in our shop last week. We accidentally discovered a very productive technique. Looking at some of the initial cuts, I couldn’t help but notice the splintering of wood on each side. The scoring method we attempted only resulted in splintering up the score. Our taping method failed as well. That’s when I had an idea. We made one shallow cut across the grain which only shaved off the first veneer, then made our full depth cut of the dado. It was amazing how clean of a cut we now had with only a small bit of extra work. There was no splintering whatsoever. The fixed shelves came together beautifully with the sides of our oak cabinets. The pieces came together without one splintered blemish. We were so happy with the results that we wanted to share the idea with everyone. This is a sure-fire way to prevent splintering and I believe it would interest all artisans that take pride in a job well done. My students and I thank you for your time and we hope to have made the joy of woodworking that much more satisfying for your readers.
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Sincerely,
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John Shelburne
Carpenty Instructor
Replies
A sharper or better dado set would also help. I have a Forrest and have zero splintering on solid wood, and next to zero on plywood. Forrest will sharpen any brand, by the way.
Thanks for the tip, JW. I suspect many responders will be curious as to what other steps were taken to minimize splintering. In my case, other than "what kind of dado were you using?" (per Steve above), I'd be curious if you tried a zero-clearance insert also.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Sounds like you may be cutting your dadoes with a table saw. Many of us use a router for crossgrain dadoes and the table saw for rabbets and ploughs. Every commercial shop I've work in uses a panel router for crosscut dadoes. Very often, some hand routers are permanently set up for back and faceframe rabbets. A little hair will still be raised but it only takes one swipe with a sanding block to eliminate it. Quality of the plywood and sharpness of the bit play a big role. A single cabinet with a partition and fixed shelf can have nine crossgrain dadoes and it's not unusual for a kitchen to have 20 or 30 cabinets. Since this is a labor intensive business and time is money, not many shops can stay in business doing things twice.
Cutting dadoes on a table saw is not a very good way to cut the joint. Any crossgrain movement on the plywood will leave tell tale marks. Since the plywood comes to us nicely sanded and ready for finish, you want to avoid marking it and making extra work. There is also a safety factor. If the work moves sideways at all during the cut, the thickness of the dado blades can bind in the cut. You can't do stopped dadoes with a saw very well and many cabinet jobs require them. Replace the round base plate on your router with a square one that will follow a straight edge. Your time, and quality of cut will improve and you will also have a more versatile way of cutting small or long narrow pieces. The action of a saw blade will often cause tearout with crossgrain cuts. Not to menntion the difficulty in keeping large pieces tight to the table for consistent depth of cut.
Beat it to fit / Paint it to match
Thanks Jw- I appreciated your input, just the way you wrote it-
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