Spiral up cut as drill bit

[Kyle Stapleton]

Can I us a .25" up in my air drill to drill holes?
I found my brad tip bits are too long and need to order short ones.

[scottp55]

Kyle, don't know answer to your question, but temp fix? Inside profile with spiral ramp with bit 50-80% of hole diameter? Use scrap and watch chips(usually I'm too conservative at first and the bit gets warm until I go more aggressive).

[Kyle Stapleton]

.25 bit for .25 hole no room for inside profile.

[srwtlc]

If it's a plunge end, it should work ok, just slow down the Z feed as it won't be spinning as fast as it would be in the spindle. It won't give you as clean of an entry as a brad point bit. Chuck it into a hand drill and see how much effort there is to drill with it. If it feels like it will only go so far with minimal effort, then it's not going to plunge well.

Look into some RH boring machine bits. They're scoring/brad point and short. They have a flat on the shank, but if you chuck them up carefully so the flat isn't under the jaws, they work nice.

[scottp55]

Does bit actually measure out .25"? How deep holes? What wood? Doesn't take much clearance(used a .117" (Onsrud 1/8") for a few hundred .125" holes until new bit came in once and didn't get warm). Peck drill for short term temp fix? profile/spiral faster. Good luck.

[Regnar]

If you have time I would order Screw-Machine Length drill bits. These are shorter than Jobbers and most of the time don't require a pilot hole. I have never understood or liked Jobber bits.

http://www.mcmaster.com/#screw-machine-drill-bits/=rnce0h

[Kyle Stapleton]

Could I just take the up cut and put a point on it will a drill doctor?

[srwtlc]

Got a diamond wheel in that Drill Doctor?!! It would be easier to cut the back end off the brad point bit you have with a cut off wheel (keep it cooled).

[gundog]

When I do 1/4" holes in plastic I bore them with an 1/8" bit. I have drilled holes with a 2 flute center cutting up cut bit in the past but I had problems with the plastic I cut wrapping around the bit and then creating problems. With wood it would probably work but either pocketing or inside profiling with a ramped spiral would be about as fast as peck drilling.

Mike

[ssflyer]

Yeah, you can do it, Kyle. I have. The issue is the way the controller works. Normally when it gets to the bottom of the hole, it slows way down for the change in direction - which can actually start a fire if you use vacuum for hold down. When I've done it, I set my plunge rate to be equal to my feed rate, about 1-2"/sec. - and I still watch carefully...

I just did a big media center job with 1/4" adjustable shelf holes, with a 1/4" spiral bit. I actually called it a 0.251" hole with a spiral ramp. I don't think that actually worked, but the holes were perfect...

BTW - I used my spindle turned down to ~3000 rpm - I don't have an air drill.

[Simops]

BTW - I used my spindle turned down to ~3000 rpm - I don't have an air drill.

Mmm.....the lowest I can dial in my spindle is 6K......am I missing something here? Using Ver 3:6:44

Cheers

[Kyle Stapleton]

Well it worked, but you could see a little runout when the flat tip first hit the ply.
Can't wait till my short brad point comes.