6mm Router Bits Buying Guide
Cutters can come in a number of different shank diameters, the common imperial sizes are 1/4 “ and 1/2”, whilst in metric they are 6mm, 8mm, and 12mm. It is important that the shank diameter is correct for your router collet.
Usually this is fairly obvious, you can’t get an 8mm shank in a 6mm collet, but it is possible to fit a 6mm cutter in a 1/4” collet. This is not safe, 1/4” is 6.35mm and the extra 0.35 can mean the cutter is not held properly in the collet, this could be dangerous to you or your work piece.
Clean off the resin build up on cutters either using a proprietary cleaner or an oven cleaner (cheaper), Also make sure the shank and collet are clean before inserting the cutter. Vibration leads to a bad cut and any dirt on either can cause this. Vibration can also be caused by uneven sharpening.
If a cutter is blunt it can be touched up a little with a diamond slip stone but be careful to apply the same number of strokes to each cutter to ensure balance. Dress the front face not the outer face, dressing the outer face will change the profile or diameter of the cutter. Touching up only works a few times after that you can either get more costly cutters sharpened professionally or just dispose of the cheaper ones and buy new.