Just a note on those Chinese TBN's Leo mentioned...1/8" shank, and only a .25mmR tip, and I've made 2 MASSIVE operator errors with them without them breaking:)
First I drove it into a solid Sugar Maple block full depth using an offset toolpath, and the toolpath was zeroed to the spoilboard, and I zeroed to top of material
THEN, in Walnut I zeroed to top of material, moved ZZ up and was cutting a few lines(not using a roughing toolpath), dropping the Z down in steps... and had a static "Burp" that lost all positions in a "Wolf" carving(the digger closest to the wolves) and it plunged and started carving .5" deep at 2IPS in X,Y,Z!...reset and then tried again and MISSED a decimal point
Amazed the bit survived all that and is still cutting beautifully.
Rugged little suckers
Oh, static was my grounding wire inside hose had a connection come loose while I was cleaning behind machine...NOT a usual occurrence!