Tips for drilling through steel plates?

[icehorse]

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]

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.

 

[rcsracing]

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.

 

[icehorse]

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]

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.

 

[lynnmor]

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.

 

[DustyRusty]

Get an acetylene torch. It is a lot faster and doesn't ever grab and twist your wrist.

 

[m-m-m-myKubota]

I've drilled several 1" holes in 1" thick steel using a hole saw and a lot of cutting oil.

 

[fried1765]

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!

 

[hodge]

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.

 

[BruceP]

• 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

 

[skeets]

Good bits are a must and oil, right speed,, bigger slower lots of on line chart

 

[The Evil Twin]

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.

 

[chim]

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.

 

[JimmyJazz]

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.

 

[Steamer Pete]

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.

 

[The Evil Twin]

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.

 

[Bugzilla46310]

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.

 

[Oil pan 4]

Use cutting paste.

 

[mikester]

If you are drilling large holes ie. 3/4 a core drill and a drill press or mag drill will be your friend.