Advice in Drilling into a Stainless Steel Wall

I have been tasked with drilling a number of 1/2" diameter holes into a 1/2" thick stainless steel wall. Any recommendations about how to go
about this?
Thanks in advance.
Andrew
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.50 cal. BMG
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drill fast and hard!- a bit at a time- dont let the bit or ss get hot (i presume you are unable to put this on a drill press)
Andrew wrote:

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Fast?? No way! Slow speed, as much pressure as you can provide. You may want to drill a 1/8" starter hole, then move to a Unibit of the corrct size, certainly better if the stainless is thinner guage. Greg
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Oops! Missed the 1/2" thick part! Pilot hole about the size of the web of a 1/2" drill bit, slow speed, and lots of pressure. If you spin the drill bit in stainless it will work harden so be sure to be making chips all the time. Greg
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right you are!! went i said fast i guess i meant get into it fast ...don't drill slowly
Greg O wrote:
</pre> <blockquote type="cite"> <pre wrap="">drill fast and hard!- a bit at a time- dont let the bit or ss get hot (i presume you are unable to put this on a drill press)
</pre> </blockquote> <pre wrap=""><!----> Fast?? No way! Slow speed, as much pressure as you can provide. You may want to drill a 1/8" starter hole, then move to a Unibit of the corrct size, certainly better if the stainless is thinner guage. Greg
</pre> </blockquote> <br> </body> </html>
--------------030508060603010909060601--
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Moderate speed and LOTS of pressure. Maybe rig some sort of lever action on a very securely anchored frame but keep the chips flying no matter what. If you get whimpy in the middle of the hole it will work harden and burn up every bit you have.
Andrew wrote:

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New bit, slow, LOTS of pressure. I have a 1/2" drill with a 200 rpm speed, works really well. I rig up some sort of lever or bar so I apply way more pressure than normal. If not, get the huskiest memeber of the football team to lay some muscle into it. You have to keep chips coming off ALL the time. Relax and let it spin for a couple of seconds will dull the bit and work harden the steel. Then even a new bit will have trouble getting started.
Get a high quality TiN coated bit. No hardware store junk. No Harbor Freight junk.
Your later post says non magnetic, likely a 300 series alloy. What is the application so we can guess at what the alloy might be?
Andrew wrote:

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New bit, slow, LOTS of pressure. I have a 1/2" drill with a 200 rpm speed, works really well. I rig up some sort of lever or bar so I apply way more pressure than normal. If not, get the huskiest memeber of the football team to lay some muscle into it. You have to keep chips coming off ALL the time. Relax and let it spin for a couple of seconds will dull the bit and work harden the steel. Then even a new bit will have trouble getting started.
Get a high quality TiN coated bit. No hardware store junk. No Harbor Freight junk.
Your later post says non magnetic, likely a 300 series alloy. What is the application so we can guess at what the alloy might be?
Andrew wrote:

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Do you already have the tool or does the job warrant an investment in a new hand drill? If so, I'd recommend Metabo. I have a BE1020. It has electronic speed control for high torque at low RPM. Also, all Metabo drills have safety clutches such that if the tool grabs, it will clutch out instead of injuring your wrist/arm/shoulder.
Use a slow speed. Try and get a drill with both high and low gears. Ideally, you want to be able to adjust your speed via some type of dial (either on the drill body or the switch) so that you don't have to lessen your grip to reduce your RPM's. This is important. Make sure that the bit is cutting smoothly. If you get chatter, reduce your RPM's and push harder.
Predrill the holes with something like a 1/8" bit. I haven't had to machine stainless in a while but I remember it being gummy. Watch for the breakthrough. If the drill has a side handle, _use it_. This will keep your wrist/arm from being injured.
Use cutting fluid like Cool Tool.
Regards,
Robin

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Hey Andrew,
Geez, I hope you don't have very many to do. Not a fun job. Horizontal is hard work. And Stainless is a very FAST and EASY work-hardening material.
"New" stainless is quite a soft material and cuts quite well, UNTIL you let the drill spin, and then you got trouble. It turns to GLASS HARD in the snap of a finger!!
Anyway, DO NOT center punch if you can help it. That can start the work-hardening. Make a jig to position the drill bit. Use a larger drill motor than necessary so that it doesn't accidentally get too high on the RPM's. Preferably at least a VS 1/2" drill motor. Drill with two or three smaller sizes first, using spotting length bits if you have them, and a good tapping/cutting fluid, and once you touch the turning drill bit against the stainless start pushing VERY firmly, and at no time allow the drill bit to spin. If you screw up and do let it spin, even for a split second, then take that bit out and throw it away and then get the next larger drill bit and hope you will still be OK.
I have used a levered 2 X 4 to push against the back of the drill motor to good effect. Get a bit of practice on something else first.
Take care.
Brian Lawson, Bothwell, Ontario.
ps.. How many holes?? And where did you find a 1/2" thicK Stainless Steel wall?!?! XXXXXXXXXXXXXXXXXXXXXXXX
On 17 May 2004 10:06:29 -0700, snipped-for-privacy@mit.edu (Andrew) wrote:

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The funny thing about work hardening, and crappy materials in general, is that years ago Dad used to run "the old sailing ships" (turret, then later NC lathes) when he started out at Woodward's. Well he says he never had any trouble whatsoever doing stainless, inconel, etc. jobs.
Tim
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You tryin to make a withdrawal of some sort... ;-)

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Getting ready to go to work and do some more of this myself, but I've got to go 1/2 Dia. x 2" deep.
My personal observations of 300 SS: IF at all possible, try to avoid doing this with a hand drill. Around 65 SFPM with coolant, about 45 SFPM with oil, and feed it just as hard as you reasonably can. Even your center drill will cause a work hardened surface, so I try to avoid step drilling, and only dimple(with centerdrill) for centering. If you do have to step drill, use the smallest drill possible (around the diameter of your larger drill web thickness) to avoid isolating too much heat on the corners of your larger drill. Using a split point may get you around step drilling. I typically do deep holes where breaking the chip is required, but, avoid it as much as possible.
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