Best method to drill 1300 3/4" holes in stainless

fightingrobots · Oct 5, 2017

I need to drill/machine 1300, 3/4" holes in 3/8" thick, 304 stainless. What are your recommendations for tooling to do this as quickly as possible? Center drill / drill with 3/4" drill bit? Do Annular cutters make sense for this?

I like annular cutters but removing the slug may eliminate any time savings.

Tolerances are not tight as the application is for a construction project so this could be done on a Bridgeport, Lagun CNC knee mill or drill press.

Appreciate any insights you may have. Thanks.

Ries · Oct 5, 2017

you cant punch em? thats the preferred method, using an ironworker.
I have drilled tens of thousands of holes in stainless, and for 3/8" thick, I would consider it a tossup between a 3/4" silver and deming, and an annular cutter. I think the annular would be faster, but if you are good at hand sharpening, or have a fancy drill bit sharpener, and a powerful enough drill press or mill, you should be able to run the 3/4" twist drill without a pilot hole.

or, send em out to be water jet, plasma cut, or laser cut...

fightingrobots · Oct 5, 2017

Thanks for the quick reply. We did a test run in our iron worker since this is 2" flatbar and it bent the flat bar.

I'm already waiting for a quote to waterjet.

litlerob1 · Oct 5, 2017

Indexable 3/4" drill? I don't like either of the options posted. TBH Ive never used a hole saw for Stainless though. What grade and condition is the material?

R

Tyrone Shoelaces · Oct 5, 2017

Sub contract the job out.

Regards Tyrone.

Madis Reivik · Oct 5, 2017

I would do it on beefy drill press with controlled feed. And with HSS Co tools, couple drills, heavy feed and frequent drill touchup on grinder.

Mtndew · Oct 5, 2017

Sandvik Indexable Corodrill.

Illinoyance · Oct 5, 2017

fightingrobots said:
Thanks for the quick reply. We did a test run in our iron worker since this is 2" flatbar and it bent the flat bar.

I'm already waiting for a quote to waterjet.

I am betting the stripper is bending the stock as the punch is withdrawn. Can you modify the stripper to prevent bending?

twin staged · Oct 5, 2017

What make is the iron worker? I would give them a call or someplace like Cleveland punch and die and ask for their advice on the setup.

Glug · Oct 5, 2017

fightingrobots said:
I need to drill/machine 1300, 3/4" holes in 3/8" thick, 304 stainless.

This is my drill press. There are many like it, but this one is mine. It is my life. I must master it as I must master my life. Without me my drill press is useless. Without my drill press, I am useless. I must guide my drill press true. I must drill straighter than the competitor who is trying to drill me. I must drill him before he drills me. I will. My drill press and I know that what counts in the shop is not the bits we break, the noise of our tooling, or the smoke we make. We know that it is the cash that counts. We will drill.

My drill press is human, even as I am human, because it is my life. Thus, I will learn it as a brother. I will learn its weaknesses, its strengths, its parts, its accessories, its spindle and its table. I will keep my drill press clean and ready, even as I am clean and ready. We will become part of each other.

Before God I swear this creed. My drill press and I are the defenders of my shop. We are the masters of our material. We are the saviors of my pay.

So be it, until victory is America's and there is no enemy.

Ries · Oct 5, 2017

if the ironworker bends the bar, you unbend the bar.
straightening metal is what you need to learn in your first year fabricating- its not rocket science.
dont you have a vise?

as mentioned above, correct punch and die sizing for the material and hole size, plus a correctly adjusted stripper will help.
But really- getting flat bar straight is really easy. Its bent at the center line of the hole. You put it in the vise with that line aligned with the edge of the jaw, and you pull it a little. With 3/8" thick you can even do it by hand. Or use a cheater pipe, or a big crescent wrench. We have a 24" Proto crescent wrench hanging right on the floor vise, and it gets used for this every day.

an ironworker will do this job cheaper and faster than any drill press. And with decent gaging, just as accurately.

fightingrobots · Oct 5, 2017

Ries said:
if the ironworker bends the bar, you unbend the bar.
straightening metal is what you need to learn in your first year fabricating- its not rocket science.
dont you have a vise?

as mentioned above, correct punch and die sizing for the material and hole size, plus a correctly adjusted stripper will help.
But really- getting flat bar straight is really easy. Its bent at the center line of the hole. You put it in the vise with that line aligned with the edge of the jaw, and you pull it a little. With 3/8" thick you can even do it by hand. Or use a cheater pipe, or a big crescent wrench. We have a 24" Proto crescent wrench hanging right on the floor vise, and it gets used for this every day.

an ironworker will do this job cheaper and faster than any drill press. And with decent gaging, just as accurately.

Agree that it isn't difficult to bend but there are 9 holes in a 42" length bar and that is a lot of time correcting over 140 parts.

adama · Oct 5, 2017

FYI if forced to use flat i would stack drill em with a stub length hss cobalt drill bit. IMHO its going to cost way to much in annular cutters. You want a drill with power feed and enough balls to do it with out a pilot even if you are using a pilot.

My prefered option would be to just buy them in laser cut, laser's eat 3/8" stainless like most kids eat candy! At 42" long they should easily come out of std sized 8x4 sheets efficiently. The 4kw+ Mitsubishi lasers can leave a really clean edge too on stainless at that thickness, at very little additional cutting costs.

Mitsubishi Laser HVII-series SUS34 t1mm Brilliant Cutting - YouTube

Add in the far nicer finished parts cut from sheet not the typical horrible flat bar that takes ages to get to a good finish!

litlerob1 · Oct 5, 2017

Glug said:
This is my drill press. There are many like it, but this one is mine. It is my life. I must master it as I must master my life. Without me my drill press is useless. Without my drill press, I am useless. I must guide my drill press true. I must drill straighter than the competitor who is trying to drill me. I must drill him before he drills me. I will. My drill press and I know that what counts in the shop is not the bits we break, the noise of our tooling, or the smoke we make. We know that it is the cash that counts. We will drill.

My drill press is human, even as I am human, because it is my life. Thus, I will learn it as a brother. I will learn its weaknesses, its strengths, its parts, its accessories, its spindle and its table. I will keep my drill press clean and ready, even as I am clean and ready. We will become part of each other.

Before God I swear this creed. My drill press and I are the defenders of my shop. We are the masters of our material. We are the saviors of my pay.

So be it, until victory is America's and there is no enemy.

Holy hell psycho!! I hope you and your Drill press have long and happy Marriage.

Mcgyver · Oct 5, 2017

litlerob1 said:
Holy hell psycho!! I hope you and your Drill press have long and happy Marriage.

you didn't get it was a take off of the riflemans creed? Know your machine and how to use it and so forth.

Piss on the drill press creed.....i'm with outsource to water jet

fightingrobots · Oct 5, 2017

I like outsourced water/laserjet too but cost from my vendor was too high.

I talked to Scotchman and they told me to go with a larger clearance die set to minimize bending of the bar.

Thanks to all for suggestions.

litlerob1 · Oct 5, 2017

Mcgyver said:
you didn't get it was a take off of the riflemans creed? Know your machine and how to use it and so forth.

That was a little beyond "knowing your machine and how to use it". I just work in Manufacturing, I don't know about like Brainwashing and stuff.

Monarchist · Oct 5, 2017

fightingrobots said:
Agree that it isn't difficult to bend but there are 9 holes in a 42" length bar and that is a lot of time correcting over 140 parts.

Well... if you want to get 'er DONE, and make yer numbers at low per-hole cost and high throughput w/o exotic technology, you don't need a # 5 MT, 7.5 HP 2 or 3 inch hole capable Alzmetall AB5/S with coolant. One of its lesser #4 MT or even # 3 MT siblings can do 3/4" holes just fine.

Back to "sub it out", though.

Cheap enough way to make LOTS of holes, but not many folks traffic in "heavy" drillpressen - or even mediums - these days.

azmachining · Oct 5, 2017

From the sounds of your parts and their requirements the iron worker is what I would use, sounds like you need a new punch and die. But back to your original question of best way to drill, I would probably throw them in the VMC with a solid carbide 3/4" diameter 135 degree split point screw machine length drill bit. If I had to use a drill press I probably would use our big radial arm auto feed.
That drill isn't cheap, but it should get you through it. I can regrind a drill quite well and since your hole specs are very loose I would get that drill in high speed or cobalt. If you want to farm it out let me know, I'd be happy to quote, I like drilling and punching holes, and stainless I especially enjoy.

azmachining · Oct 5, 2017

Forgot to mention, since you might not know, but with the drill bit I mentioned above due to the drill point angle you wouldn't have to center drill or spot, well maybe spot if your using a drill press depending on how you do it.

Best method to drill 1300 3/4" holes in stainless

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