Hole drilling problems

T

TroyO

Joined
Mar 20, 2001
Messages
71
I was drilling some holes in ATS-34 and started getting some chattering. I was using 3 in 1 oil, and the problem was much worse with large bits. I had the drill press on it's slowest setting, and the end result is it gouged and pretty much ruined my 9/16" drill bit. I don't think the bit got that hot, the oil was smoking a little but not dramatically.

Any ideas what went wrong? Was it because the bits are dirt assed cheap, or maybe there is sonething wrong with the drill press? Is there something I am missing as far as drilling method?

I also now have a pretty funky half drilled hole in my blade handle, will that screw up heat treeating?
 
It could be several things, or a combination.

First, a dull bit is useless when drilling a tough material like stainless. A dull bit can also work-harden the material to the point that even a sharp bit won't cut. Try drilling from the opposite side. secondly, make sure that the material has been annealed, otherwise you'll have to use a carbide bit on high speed flooded with coolant. Take care, Carbide bits have a habit of shattering if you aren't careful! In the absence of a proper coolant like cool tool use water. A water drip can be set up on your press easily using small copper tubing, compression fittings, a small ball valve and a coffee can.
I don't know what kind of press you have but, some of the smaller ones aren't slow enough, even on the slowest speed.
Good drill bits are worth their weight in gold!


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A Paladin in Hell
 
Oh darn! one other thing. A chattering drill usually means it was sharpened improperly, i.e. unevenly. An uneven drill will cut oversize too. This is a real pain if you want snug holes for pins.
 
The drill runs at 620 RPM on slow speed, if I remember. The ATS-34 is annealed. It started drilling OK, so I am more likely to believe that I screwed something up, hehe.

I am going to stop by the store after work today and grab some bits to see if I can recover this mess. This time, no cheapies.
wink.gif
 
Pay the extra juice and get cobalt ones, but if the steel is hardened from the dull bit, the cobalt won't go through either. The suggestion of drilling from the other side is a good one. Good luck.
 
I bought lots of drill bits before someone told me about cobalt bits. They are worth the extra money! Be sure to go slow and flood the spot with coolant. Tap Magic works good. Bruce B
 
toxicavenger,
When you get a chance, drop me an email. I see you are from my home town.
 
as said above...buy cobalt drill bits...
It will also help a LOT if you start small and work up to the large size....say start with 1/8....then 3/16.......222.....250 etc.. If you stick some sizes in between it doesnt hurt...this way your large bits will last a lot longer...and they are the ones that cost a lot more.

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http://www.mayoknives.com
John 1:14
Love is Stronger than Death!
 
I should add...when I need to put some big holes in...like 1/2"...I clamp them in my mill and use an endmill.
 
I think it was a combination of work hardening and cheap drill bits that got me. The hole would start out removing nice size chips/threads of material which got finer and finer untill there was no more progress. I drilled through the back side and got about the same distance and it did it again.

I did finally get it all the way through by stepping up drill sizes.

Ohh well, guess it's time to go to the "Tom Mayo School of Advanced Precision Hole Drilling" since I obviously can't get it right myself.
wink.gif


Luckily they are just large weight reducing holes in the handle, so although they are hideously ugly they will be hidden. As long as it doesn't bugger up Paul Bos's heat treating it should be fine.

Thanks for all the help, everyone!

Troy
 
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