Thread: Router bit choices

I personally use the standard router bits for wood (Straight 2 flute carbide tipped bits) but I'm mostly machining structural particle board (Yellow tongue) for holding parts, cuts clean every time.

Good question, I'm also interested having recently acquired a cnc machine.

My machine runs a Porter Cable router so I only have the capacity to use 1/4" and 1/2" bits.

I have bought some v-bits, and have a pretty good selection of router bits: spirals, twin flutes, up cut, down cut etc.

Are there any must have bits for a cnc?

Should I be trying to source different collet sizes to enable me to use a wider range of cutters?

Plywood comes in a variety of types and qualities. The poorer ones will splinter whatever bit you use, the high quality ones should cut perfectly with the right bits.

Spirals will generally leave a better cut on one side than the other, as the bit shear cuts using the core to support the face on the non eject side. An up cut will cut clean on the lower side but may raise fibers on the upper side, a down cut will give a clean cut on the top side but may raise fibres on the lower side. The lower should be supported by the sacraficial board below it, but unless it is refaced after every cut, there will be points of poor support and fibres will be raised.

The compromise solution is a compression bit, with an up spiral at the tip and down spiral above, so the shear direction is toward the core for both faces. However there are issues there as well, including limited sizes (1/4in minimum), height of the transition point typically about 5/16in so not much use for 1/4in sheet, and cost.

To isolate whether the issue is the bit or the material, do some test runs on MDF sheet, if you cannot get smooth cuts with that, it is a bit issue, good cuts on MDF but poor cuts on ply suggest a poor material selection.

The MDF cut pretty smooth. Looks like I need to come off the wallet a little bit on the plywood.

Thanks for the help