Greetings all!

I can't seem to make my drill bits last more than a hole or two when drilling steel. I usually have to drill lagre holes between 3/8" and 1", and go through bits like crazy.

Is there a trick or "proper" method to drilling large holes in thick hard steel?

Thanks in advance.

Kevin K.

 

Use pilot holes, and lots of cutting oil. Take your time, and you should notice a difference.

 

Very slow speeds. Most drills and drill presses seem to be set up for drilling wood. Use the slowest speed possible on your drill press or motor.

 

Drilled too many 5/8" holes in 1/2" steel beams and flatbeds: 180 rpm, cutting oil (30W will do too), use firm steady pressure so that the cut steel ribbon 'curls' off of the bit, not chips. Can get ~150 holes out of a sharp HSS bit on a decent press. Titanium Nitride, TiN, bits last >3x as long but cost more.

 

Thanks for the tips.

So, when I have to drill a 3/4" hole, should I just start with a 1/8" hole and go right to the 3/4"? Or, should I go 1/8", 3/8", 5/8", then 3/4"?

Also, most of the bits I buy are the cheap ones. I'm using a hand drill as opposed to a press, so what type of bits should I be getting?

Thanks again.

Kevin K.

 

Whew, hope you don't have many 3/4" holes to drill by hand in steel, ya' gonna' get sore. . .
A heavy handdrill with lottsa' torque, 12-15amps, at slow RPM less than 300rpm- 180rpm better- I'd start with a 1/4" bit first it will let the point of the 3/4" bit cut directly into the steel cavity. Important to hold straight (perpendicular), no wobbling to save the bit & your strength, sit on the drill top handlebar if you can. If the work is vertical I've strapped myself to it to get a better purchase. Ya may want to go 1/4", 1/2", then 3/4", depends on you & the drill.
'Cheap' HSS bits are ok if your cutting mild steel, forget it in hard steel gotta use TiN or Carbide bits.

 

FWIW - RexB knows what he is talking about.

There is no question he has drilled ~plenty~ of those $*&#$ holes.

I was going to recommend a torch. I have drilled plenty of them too

 

I have used a torch to spot anneal steel for easier drilling -hehe.

 

kjkozak2:

If you're "going through drill bits like crazy", and you do a lot of drilling, I suggest you buy yourself a thing called "The Drill Doctor", with the special chuck to handle drill diameters up to 1" (the standard unit handles up to 1/2"). The regular Drill Doctor runs about $100.00.

This device allows you to resharpen your drill bits, and is very easy to use. It'll sharpen regular points, split points, and masonary bits regardless of composition (HHS, carbide, titanium, etc). I used to buy new bits whenever one got dull, but not anymore! As long as there's any fluting left, you can sharpen that sucker BETTER than new because you can increase the rake angle beyond standard if you want. It took me several tries to get the technique down right, but once you understand what you're doing you can resharpen a bit in just a minute. Amazing how much money this will save you, and you always have very sharp bits available. No other bit sharpener even comes close to this device - and it saves so much
aggrevation and frustration.

I recently had occasion to do some volunteer work constructing some rather large playground equipment (it took 50 volunteers/day for over a week), and was told in advance that priority items to bring along were 1/4" & 3/8" "peashooters" and bit sizes (if I had any). I took along my battery operated drill, and about a dozen freshly-sharpened bits of each size (had PLENTY I'd replaced over the years but never fert right in throwing away). Saw guys pushing their guts out trying to drill, their bit just a-chattering & squealing away trying to punch the holes in the pipe-type uprights (you know the scene), and them cussin' & swearing under their breath. I'd hand them a bit of mine, and they couldn't believe how it cut - very fast and smooth with very little pressure. Many commented they'd NEVER used bits like mine, and asked what the secret was. My bits were the talk of everyone who used one.

One doofuss snapped two bits when he "broke through" the pipe wall and twisted the drill sideways like a pry bar in the hole. At the end of the day, I just took the bits home, ground the flute end flat on my bench grinder, and resharpened it on the Drill Doctor. One broke about 1/2" from the non-fluted shank and I was able to recover the piece that broke off. I sharpened what was left on the shank, as well as both ends of the piece that broke off. Made three bits out of one, and used those the next day at the playground too! The "double-ended bit" raised a few eyebrows, I must say.

Yes, drilling technique is important - relatively slow speed and lubrication if you're honkin' through big thick stuff with a larger diameter bit. I used to drill pilot holes, too, but once I started using the the Drill Doctor, I find I don't need to. I only need to centerpunch to start the hole where I want it. And if I can grind a splitpoint just right on a resharpened drill, most of the time I don't even need to centerpunch.

You can buy the Drill Doctor at Home Depot, Sears, etc. Makes for a real nice Christmas present, too. That's how I got mine (after I asked Santa for it in my annual letter)!

There's a thread on this board entitled "Tools you can't live without" or something to that effect. In this business, the Drill Doctor may not may not be #1 in my book, but it's darn close to it!

 

A big 10-4 to Traderjoe and the Drill Doctor. It makes for much easier drilling in any steel. I have use of the small unit so I can't do the split point, but my Doctor will be the bigger unit when I get my own( my Dad is letting me use his!).
Forgot to mention the cutting oil, buy some actual cutting oil and use it!! It makes the bits last longer and cut smoother and faster.

 

Actual cutting oil works much better than motor oil (has additives that inhibit cutting). If you look around here you may even run across a user that will send you a sample of some very good cutting oil...

 

I bought the Drill Doctor thinking it would end my dull bit problem. Sharpened 3 or 4 bits before I realized it ruined all of them. Flattened them out with no cut edge. It's too easy to use to screw it up, but what did I do?

Back to the bench grinder...

 

I saw a very impressing infomercial yesterday on the Drill Doctor and have just about convinced myself that buying one would be cost effective given the number of my drill bits that my son and son-in-law are going through with their new interest in metal welding and fabrication. I'm trying to decide if I need to go top of the line to handle both the 118 degree "standard" and the 135 degree "high performance" bits, or can I save a few bucks and get one of the more basic units (I'm not even sure whether I have any 135 degree bits). Any thoughts?

Pat Corbin

 

Ya know, I had a similar type device in my hands this weekend, but just couldn't justify the $50 for it. It's going on my x-mas list though.

Kevin K.

 

if you take you time, you can sharpen bits on a bench grinder just as good, and you can even add the split points. i'm the third generation in my family to run the family machine shop, so i do a fair amount of drilling, from 1/16 to 1 1/2 solid drills, and 4" cores.

alot of "cheap" drills have too much rake ground on them for drilling steel, they will chatter, grab, and break or dull the cutting edge.

like everyone else says, don't turn it too fast ( if your chips are turning blue, it's too fast) step up you holes(makes life alot easier with a hand drill) and you can use cutting oil, if you so desire, it will increase your bit life.