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View Full Version : Which bits? Auger, carbide or spur-point?


rass
Mar 19, 2007, 01:08 PM
Have been doing the research but really I'm getting more confused:

I am dealing with the following project/prospects:(A) Drilling into really hard wood (South American 'Greenheart' and Purple Heart'). Tried using ordinary twist bits which I was assured would be adequate and the lumber simply ignored the bits! Just succeeded in dull bits.
(B) Drilling into concrete block and,'cast' concrete (conventional mixture of stone,sand and cement). I understand that I need carbide bits in this case.

My question is, should I simply invest in all carbide bits and would they be appropriate for hard-wood drilling?
Moreover, one article claimed that wood augers exert a pulling action on the drill and therefore are not suitable for hand-held power drills.

Whatever is the correct type for each application, I'm looking for 3mm to 10mm @ 12"plus.
Using a Makita 3/8th.

Thank you for your kind assistance.

ballengerb1
Mar 19, 2007, 01:24 PM
Augers should be done only with a bit and brace (handheld twist) A masonery bit (not just carbide) will not drill hard woods very well. They drill concrete by chipping little bits at a time and shatter the masonary. A high quality twist bit will cut Purple Heart but you must use a slow RPM, high speed will heat the bit and cause it to turn blue, loss its temper.

biggsie
Jun 9, 2007, 08:07 PM
Hello

I really like 2 fluted step bit... Works on metal,great on wood!!

IRWIN Unibit by IRWIN Industrial Tools (http://www.irwin.com/irwin/consumer/jhtml/unibit/unibit.jhtml?source=google&gclid=CI6y2-HH0IwCFSMKGgod_lHauA)

May have masonry bit, or use Milwaukee hammer drill, with water flush and ease drilling