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Author Topic: Drill bits - sharp vs dull  (Read 3938 times)

qstick777

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Drill bits - sharp vs dull
« on: August 24, 2007, 07:27:34 AM »
How do you know when your bits are getting dull?

I have a set of bits with unknown "mileage" - other than the 10-15 balls I've drilled myself, I have no clue how many times they have been used.  How will I know if a bit needs to be resharpened?

Is there a secret to drilling an existing hole bigger?  Previously I would just take a bigger bit, center it on the smaller hole and just drill away (creating a larger hole to plug, or when drilling out a slug).  Never had any problem using my existing bits, but.....

I just bought a new 1 1/4" bit and when I tried to drill into an existing hole, the bit started chipping away at the ball - scared the crap out of me!  Same thing happened when I tried to drill out a slug.  Doesn't do any of that when I drill a fresh hole with the bit.....is that normal?
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solid9

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Re: Drill bits - sharp vs dull
« Reply #1 on: August 24, 2007, 09:20:30 PM »

 What is the speed of your drill press?

justdale

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Re: Drill bits - sharp vs dull
« Reply #2 on: August 24, 2007, 09:32:13 PM »
Our 31/32 is by far the busiest drill bit we use, you can feel the bit when it starts getting dull. You can feel the bit drag a little and bump a little.
The speed of the press indeed dictates how quickly the drill bitwill lose its ability

qstick777

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Re: Drill bits - sharp vs dull
« Reply #3 on: August 26, 2007, 01:20:42 AM »
Not sure of the drill speed.  It's a Rockwell 15-080 - from an old K-mart drilling setup.  The belt is set up on the second from the bottom pulley (on both pulleys).

I thought the drill had a chart to tell the speed, but I don't see it - don't know if it fell off, might be in a box with the rest of the stuff it came with (and I just can't seem to find at the moment).

The motor itself says 1725 rpm, but for some reason I want to say it is setup to run at either 375 or 525 rpm.

Maybe somebody else knows more about the drill? If not I may breakdown and buy the manual on ebay for $20 (would probably be a good idea for the future anyways).
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