Re: Making a closed tranfer port open
For fast cutting there are 'double cut' bits & they come in all shapes & several diameters. Don't waste your money on anything other than carbide bits. The others get trashed real quick. Search rotary file carbide bits & the like. Unfortunately they're not cheap. But well worth it. Also keep them lubricated when you're using them. I use a very small plastic lid or cap to put some oil in & just dip the bit into it every minute or so. (real often) They will last a real long time if you don't abuse them.