Drilling holes in steel

[jenkinsph]

You let other people use your drilling gear???
Brave man.

It is part of being in business, just another risk that is why we pay for workmen's comp here.

 

[the old grind]

I'll add to what CalG and other seasoned hand-wheel spinners said (ie: one pilot >web thickness) and to mention that carbide drill bits will self-destruct in a hand drill.

Guys, avoid 'lube' oils!! WD-40 is ok for alum, but what you want is to cool the tool not demand the cutting edge work through a true lubricant. Any liquid will cool the cut ok but you'll have to apply more feed pressure with good lube oils.

The best thing for drilling/tapping steel is still rendered pork fat, and the reason is about the very low surface tension and specific heat of organic fats. When in doubt use water by trickle or by helper with a spray bottle, esp when drilling 'bed rail', lest it work harden on you. (.. low rpm and lots of pressure)

I'm only retired from occasionally using CNC grinders and from being paid, not from sharpening, and I miss all that GM production tooling on my 'in' bench. :melodramatic:

 

[rScotty]

A pilot 1/3 the size of the final hole works OK for me.

I thought I had always picked pilot drills by eyeball, but when I take a look at what I'm using I tend to start with 1/8" because it is rigid enough and a common size. And then I go up so that each succeeding hole is starting in a pilot hole about half the new bit's diameter. Like several have said, I've also noticed that using too large of a pilot will chip the edge of the larger drill bits, where using too small of a pilot just causes them to heat up and dulls the edge.
Does anyone else use a Drill Doctor to sharpen bits??
rScotty

 

[Big Barn]

I thought I had always picked pilot drills by eyeball, but when I take a look at what I'm using I tend to start with 1/8" because it is rigid enough and a common size. And then I go up so that each succeeding hole is starting in a pilot hole about half the new bit's diameter. Like several have said, I've also noticed that using too large of a pilot will chip the edge of the larger drill bits, where using too small of a pilot just causes them to heat up and dulls the edge.
Does anyone else use a Drill Doctor to sharpen bits??
rScotty

I'll touch up larger bits on the belt grinder, but use the Drill Doctor about once a year when I have a "bunch" of drill bits to sharpen.

Terry

 

[CincyFlyer]

I thought I had always picked pilot drills by eyeball, but when I take a look at what I'm using I tend to start with 1/8" because it is rigid enough and a common size. And then I go up so that each succeeding hole is starting in a pilot hole about half the new bit's diameter. Like several have said, I've also noticed that using too large of a pilot will chip the edge of the larger drill bits, where using too small of a pilot just causes them to heat up and dulls the edge.
Does anyone else use a Drill Doctor to sharpen bits??
rScotty

I was given a Drill Doctor as a gift. It took a little while to learn to use it effectively, but once you have the technique, it's a wonderful thing.

 

[the old grind]

Sharpeners that use diamond-coated wheels work well, they just don't do high volume work w/o 'eating' wheels.

Learn to use one of these, and become adept at drill sharpening with bench grinder or belt sander.


(I'm using a Lisle 92000 (discontinued ), and am continually seeking parts for it ...)

 

[Big Barn]

...the old grind. Now I understand your username

I would love to come across a used Lisle 92000...

 

[jwmorris]

For a 5/8" hole in what thickness of what kind of steel and what tool are you using to turn the bit?

Nothing is faster than a punch. A hole saw or step drill is good for thin sheet steel. A MFD or MSP is faster than drilling multiple holes most often (also requiring less thrust and producing less heat than a regular drill bit) and if you are doing it in steps you don't want them to be too close or they try and grab, that's where you are getting bit damage from.

 

[GaryM]

OK, I'll say upfront that I was never a machinist, though my Granddad was. I've had good luck drilling larger holes, up to say 3/4" - 7/8" with the stepped Unibits. No, not for 3/4" thick material, but up to 1/4" or so. They also work well for enlarging existing holes. Because they only have one cutting edge they self center and leave a nice round hole.

 

[EddieWalker]

Interesting information on how the pros drill holes. As a guy who just needs a hole drilled in a piece of metal every now and then in metal that is rarely more then an 1/8 of an inch thick, I just hit it with a center punch, then drill with the size bit I want the hole to be. Do it once and be done with it. I sharpen my bits on my grinder, and if it doesn't start cutting right away, I touch up the bit, then drill the hole.

If it's really thick metal, or if I need a really big hole, I use my cutting torch.