Use of Router bits

Robert is right but for timber look for helical cutters. An upcut bit will clear material out of a slot or hole, a downcut will shear off any bits of furry grain at the edge of a pocket and compress the chippings in the slot. They are usually solid carbide so will be more expensive and brittle (tough, stays sharp longer but if you bash them they will break) I have run cnc carving machinery for 25 years, 90% of my cutters are helical bull nose for relief carving and a mixture of helical and standard tct for milling and surfacing. Dont use old blunt cutters, they will burn, strain your motor and make a mess. Woodcarvers sign off with “stay sharp”