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Drilling stainless steel

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Bangkok Mick:
I have just finished making a pen out of 316 S/S reinforcing bar. I used HSS drill bits 2mm followed by a 3mm to drill the 6mm bar for a ballpoint refill on my 7x14 Chinese mini lathe. I plan to make a few more to give as presents, can anyone suggest a better drill bit to hollow core the bar, approx. 50mm from each side, to make the work go easer.

Cheers Mick

Dawai:
Zen of drilling deep holes: forget where that book came from, mostly it was about sharpening a drill bit equally and applying the right forward cutting speed to the type metal, quality of bit, too much pressure and it went offcenter, drill bit not perfect and it went off center.
 I found a eye loupe with angles engraved in it to look at drill points, bought a carbine sharpener from HF, built a tool quorn according to NORM (he's here) and proceeded to mess up a few drill bits learning.  Then i graduated to a computer and camera microscrope, with a drill angle and center etched over the image coming in from the camera.. One side needs to be about half a shaving further back than the other side.
   Lemme look for that very special post on sharpening drills. Not sure where the book is, or went to. I am sure I loaned it to someone.

I HATE drilling stainless.. it is not really that tough, but curls up around the cutting edge like aluminum does, once it spins and the chips turn blue, you are done for. NO drill bit works.

Drilling electrical stainless panels.. now you are going to mock, laugh giggle till you try this.. I have taught 60 year old ironworkers, plumbers and steam fitters this trick. It was taught to me by a guy with not enough education or Iq to find his way to work some days..

center punch your hole, Stick a sharp drill bit on the punch, do not turn the drill on, just PUSH really hard and bump the trigger to like spin it a half turn.. again, again, again.. you got a curl, again.. you got a hole.. never really drills it, more like a rotary punch.. it never heats up and curls around the cutting edge.

Deep holes?? well I got this edm here I made for $10.. but it would take a month, too low of power..   

How about using SS instrument tube and rolling it onto a mandrel to shape it?? 5/16th (forget the mmee mee) is about perfect, what I used to make tattoo tubes with.. I silver soldered a animal hypodermic syringe needle into the end to hold my tattoo needle in the perfect spot..

Bangkok Mick:
Hi Dawai,

Thanks for your comprehensive reply. I have not had problems losing the center but it takes an age and have blunted a HSS bit and broken another in my efforts on the one pen so far. I guess I need to brush up on sharpening bits. I think computer and cameras are a bit beyond me at the moment.

I am using bored out solid S/S rebar as I am a civil engineer and this is what we use at work so thinking of making up a few theme pens for work mates or otherwise use tubes as you recommend.

Cheers Mick

David Jupp:
Cobalt HSS drills, ground with 135 degree point are sold as superior for use on stainless.  Could be worth a try.

75Plus:
Hi Mick,

I drill a lot of 316 stainless so I understand what you are up against. I find that Cobalt drills will last up to 10 times as long as HSS. The point angle also should be considered. While 140 degrees is optimum for stainless that point is not common. The 135 degree points are widely available and make a pretty good substitute.  The link below gives a lot of good information on drills and drilling.

http://www.mmsonline.com/articles/choose-the-best-drill-point-geometry

Joe

David was posting while I was typing.  :bugeye:

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