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Hello, I want to cut some 4mm wide flat bottomed grooves across a 60mm wide board.
What is the best type of blade geometry to do this, one that slices the grain cleanly?
ATB blades, although they slice the timber nicely in a cross cut, do not give a flat bottom
FTG and TCG blades are designed for ripping, not crosscutting, but do leave a flat bottom to a groove
Do you have a router, if so I would use same with a suitable cutter, and router square
You need the small, high ATB teeth to get a crisp clean edge. If you want to use the table saw then finishing the bottom of the groove with a router plane would be the easiest option. As China has suggested a router with a spiral downcut bit will give you the result you want. Have a look at the finish using different bits in the attached pic's.
get yourself a router plane.
Use any blade you want to cut your grooves, then finish the cut with the router plane.
Perfectly flat bottoms at exactly the right depth
And by the way a TCG blade does NOT cut a flat bottomed groove. :no:
I recently purchased a combination blade, it has a pattern of 4 ATB ground teeth with every fifth tooth a flat grind. I used it for the first time on the weekend to make some shaker style doors out of spotted gum with marine ply inserts. The blade cut very nicely with no chip out cutting across the grain and cut 15mm deep grooves along the grain with ease. The finish is not perfect but is more than good enough for the grooves and tenons I was making.
In in case you ask, it was a 60 tooth 315mm diameter contractor grade blade from Axminster.
Cheers Andrew