I want to bore out the hole in a adapter that is on a Homelite engine between carb and engine. The material is kinda of a hard looking plastic. The hole is about 1/2 inch now and has to be about 1/8 inch bigger. Is it best to drill...grind ....or use a end mill and feed the end mill real slow. Only got one chance to do it, without cracking it out? Any Ideas???? Thanks Capt,n