You need to grind the rake angle on the drill bit to a zero degree rake angle. The bit needs to scrap the material away, not slice it.
Go to varisairforce and scroll down and you can see a bit that has been ground. It also has a 60 degree point angle. That helps as well but takes some skill to grind by hand.
Go to sdplastics and you can see a drawing of how to grind the rake angle.
I taught Plastics Technology for 34 years so I did this a lot. Got paid good money to teach companies how to do this as well..
-- Bill - Mesquite, TX --- "Everything with a power cord eventually winds up in the trash.” John Sarge , timber framer and blacksmith instructor at Tillers International school
