Tips for drilling through steel plates?

icehorse

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L3901, FEL, box blade, tedder rake, mini round baler, rotary cutter
Aug 10, 2022
53
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98261
Until I get a LOT better at welding, it seems like I can kludge together a lot of useful stuff, if I can drill holes (from 1/4" to maybe 3/4") in steel plates (up to maybe 3/8" thick). So far so good?

I have a Dewalt DCH133 rotary hammer drill that so far I've used only to drill holes in concrete. But it looks like I can also use this tool to drill holes in steel?

Any tips? Good bits? pilot holes? coolants?
 

Pawnee

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L2501
Jul 1, 2021
209
181
43
Ontario Canada
Use cutting oil.
Definitely a pilot hole. And up by reasonable amounts 'til you get one size below the finished size. The last bit through should make a nicer hole that way.
Some steels will harden if the drill rubs rather than cuts and then you are in for a nasty slog. So start with sharp bits.
No hammer drill but you can usually turn the hammer part off.
 
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rcsracing

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LX3310, brush hog, box blade, pallet forks, front blade
Jan 22, 2022
22
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Pittsburgh, PA
Agreed - Hammer drill mode will not make for a fun experience. Also, there are some charts available online for cutting speeds - bigger drill bit, slower speed.
 
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icehorse

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L3901, FEL, box blade, tedder rake, mini round baler, rotary cutter
Aug 10, 2022
53
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8
98261
Awesome, thanks. Yes, my drill has a "rotary drilling" setting.

Another dumb question: If you have - let's say - 1/4" bolts, do you drill a 1/4" hole, or maybe a nudge bigger hole (like 5/16" or 9/32") ?
 

lynnmor

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B2601-1
May 3, 2021
830
574
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Red Lion
Awesome, thanks. Yes, my drill has a "rotary drilling" setting.

Another dumb question: If you have - let's say - 1/4" bolts, do you drill a 1/4" hole, or maybe a nudge bigger hole (like 5/16" or 9/32") ?
Usually 9/32, use 17/64 if you want a better fit.
 
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lynnmor

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B2601-1
May 3, 2021
830
574
93
Red Lion
The hardness and type of steel will dictate the quality of drill you will need. Cobalt drills will cut fairly hard material but they cost more. Drilling a pilot hole is a good idea since the center of a drill actually chisels the steel. Be careful with going larger in steps, too much of a step will require pushing harder then as you break thru that hard push may grab. Allowing just a small amount can also be a problem, especially when using a hand drill, since the drill can "corkscrew" pulling it in.

Running the drill at the correct RPM is important, download a speed chart or calculator, search for them online and find one that you can understand.
 
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DustyRusty

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BX23S
Nov 8, 2015
2,774
1,806
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Get an acetylene torch. It is a lot faster and doesn't ever grab and twist your wrist.
 
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fried1765

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Kubota L48 TLB, Ford 1920 FEL, Ford 8N, SCAG Liberty Z, Gravely Pro.
Nov 14, 2019
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Eastham, Ma
Until I get a LOT better at welding, it seems like I can kludge together a lot of useful stuff, if I can drill holes (from 1/4" to maybe 3/4") in steel plates (up to maybe 3/8" thick). So far so good?

I have a Dewalt DCH133 rotary hammer drill that so far I've used only to drill holes in concrete. But it looks like I can also use this tool to drill holes in steel?

Any tips? Good bits? pilot holes? coolants?
Variable (low) speed drill press, and cutting oil!
 
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hodge

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John Deere 790
Nov 19, 2010
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You don't have to drill a larger hole. If you have a 1/4" bolt, you can drill a 1/4" hole. Then, you will have a net fit. A slightly larger hole, in the right circumstance, will lead to wallowing. There's no need.

No exaggeration, I drill 30,000+ holes a year through steel, 1/4" to 1", hot and cold rolled. I don't know much, but I do know this subject.
 
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BruceP

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G5200H
Aug 7, 2016
753
277
63
Richmond, Vermont, USA
  • Properly sharpened bits.
  • cutting oil
  • MagDrill
  • Proper RPMs (larger diameter means SLOWER RPM...torquey MagDrill)
  • DO NOT allow drill to 'rub'. (either CUT or NOT CUT) Work-hardening is a real thing
    • Some steels will work-harden if the bit 'rubs'
    • The work will get so hard it cannot be cut by a drill.... then you have problems
  • 'peck' at the work to break the chips
 
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skeets

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BX 2360 /B2601
Oct 2, 2009
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Good bits are a must and oil, right speed,, bigger slower lots of on line chart
 
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The Evil Twin

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L2501
Jul 19, 2022
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Virginia
Curls tell you the RPM is good once the bit is sunk in the metal.
Transmission fluid can make a good cutting oil in a pinch.
 
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chim

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L4240HSTC with FEL, Ford 1210
Jan 19, 2013
1,278
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Near Lancaster, PA, USA
I've been reading up on lubes, and decided to head for the welding supply store and get a stick lube. The metal shop used that lube on the Hougen and Jancy annular cutters for years with great results. I was out in the shop one day when they spent all day drilling I beams and the cutter was like new at the end of the day.

Drilling has generally been a part of fab work that I haven't enjoyed very much over the years. I can definitely say I know the pain. Just recently I bought a Vevor MD40 mag drill, and was gifted a hefty drill press in the course of three days. Pretty well covered now. Only test drove the drill press but used the mag drill with both the annular cutters and the Jacobs chuck on small projects already.

Not making this move years ago was a mistake. For one example, the bucket in the picture has five 1/2" bolts holding the angle on top and the wear edge has 13. That took 36 decent-sized holes (18 plain hole and 18 tapped). All were drilled with a good cordless drill.

I posted about the drills the other day, and the picture below is from today. The 2x2x1/4" galvanized square tube needed a 3/8" hole drilled straight through. I had already made a base plate for the mag drill that can be clamped or tacked onto whatever needs drilled. It has a hole in one end that can be positioned over the target, or it can be flipped around so the drilling is done off the end.
 

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JimmyJazz

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B2601
Aug 8, 2020
967
543
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Pittsburgh, Pa
When I ordered my vicious Piranha tooth bar for my loader bucket they provided (sold) me a fancy stepped drill bit the likes of which I had never experienced before. It made short work of drilling those 2 holes in the bucket. $20 for the bit = $10 per hole. I hope to use it again someday. Worked amazingly well. Maybe look into the stepped bits now that your confidence is bolstered. Welding is harder than it looks. Good luck.
 
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Steamer Pete

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LX2610
Mar 29, 2021
28
21
3
Holland, MI
1) Pilot hole is recommended on any hole larger than 3/8" if drilling with a hand drill. 2) cutting oil. 3) Good quality drlll bits. 4) Understand what a good sharpened edge looks like. Learn to dress the edge by hand, or find a drill bit sharpener. 5) Learn the feel of the feed thru the metal. As it starts to come thru the other side, really cut back the feed to finely cut thru, rather than plunge thru. 6) speed is NOT your friend drilling steel. Roughly - 1/8" - 1000 rpm, 3/8" - 600 rpm, 3/4" - 300 rpm.
 
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The Evil Twin

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L2501
Jul 19, 2022
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Virginia
When I ordered my vicious Piranha tooth bar for my loader bucket they provided (sold) me a fancy stepped drill bit the likes of which I had never experienced before. It made short work of drilling those 2 holes in the bucket. $20 for the bit = $10 per hole. I hope to use it again someday. Worked amazingly well. Maybe look into the stepped bits now that your confidence is bolstered. Welding is harder than it looks. Good luck.
Step bits (or Uni-bits as we call them in the trade) are the bees knees for a lot of jobs. You'll come to find more uses for that bit in the future. The best part about them is that they won't "corkscrew" when you punch through to the other side. They aren't suited well for wood or thicker metal since the hole will be tapered like the bit. You can hit it from the other side to clean it up if it's not too thick.
 
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Bugzilla46310

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2022 BX2680 198? AC 916H
May 22, 2022
106
96
28
Demotte, IN
Bought a couple of the cheap carbide tip hole saws off of Amazon for a project I was doing in stainless. 1” and 1-3/8”. Tired of getting 2 holes out of a good bimetallic hole saw in stainless. Was amazed how well they drilled. Will definitely get more sizes as the projects demand.