quote:

Originally posted by MikeinNC:
What’s the deal with the stepped drill bit...I’ve seen them a lot on tv shows but never seen anyone use one in real life....

If you're talking about the step bits that are shaped like a big cone, they are for drilling large holes in sheet metal. They work very well for that.

^^^^
That's the answer.

But it won't drill angle iron that is bent to the left.

IIRC WD40 is primarily fish oil. Generally any lube is better than no lube.

Squealing and smoke are not good signs. Squealing means it is dull. Smoke is often an indicator of too much speed.

If there is one BIG mistake that is made it is too much speed. When drilling with a good, sharp bit you should see chips immediately and they should not be turning pretty colors.

Drill bits with a pretty blue on the cutting end means they have been run too fast, have overheated/lost their temper and are now pretty useless for metals.

Drills can be resharpened, by hand with some kind of grinder or (better) belt sander. Heat is the enemy here. A standard bench grinder running 1725 rpm will burn the cutting edge that you are trying to sharpen. Belt sanders typically don’t run so fast, so the drill can be easier to sharpen without the heat.

As a teacher I have demonstrated that it is possible to sharpen drills on the following:

Bench grinder, belt sander (1”,4”,6” hand held, stationary), disc grinder (4.5”, 9”, hand held and bench) and drum sander as well as things like a “Drill Doctor”

Yes, sharpening a coated (gold) bit grinds the coating off. Even so, once sharp it will continue to make holes successfully.

Final note - grinding or sharpening bits on a machine that is connected to a wood dust collection system is a REALLY BAD IDEA. It introduces hot sparks into an explosive forced air system. Think flowing flames through all that ducting to a yet bigger tank at the end, full of flammable dust.

What is the proper way to keep a drill bit lubricated and cooled while drilling?

quote:

Originally posted by Tommydogg:
What is the proper way to keep a drill bit lubricated and cooled while drilling?

Squirt can/pump oiler.

quote:

Originally posted by henryaz:

quote:

Originally posted by Tommydogg:
What is the proper way to keep a drill bit lubricated and cooled while drilling?

Squirt can/pump oiler.

What I've always done was drill about 20 to 30 seconds, stop, squirt, drill, repeat. Is this the way your supposed to do it?

quote:

Originally posted by Chris42:
IIRC WD40 is primarily fish oil. Generally any lube is better than no lube.

WD40 uses mineral oil as a base and CO2 as propellant, a few simple hydrocarbons common in kerosene and diesel fuel, and a couple of other things.

https://www.wired.com/2009/04/st-whatsinside-6/

I stand corrected about the fish oil.

As far as “How much lubricant and when?” - Industry using computer controlled machines typically have “flood” systems. These literally flood the part being cut with coolant/lubricant from before the first chip is made until after the cutting is complete. The flooding also flows chips away from the part, helping to prevent clogging of chips in holes.

For home? Ideally start cutting through a drop of lube, add as needed to keep hole wet. Smoke being made? More lube.

quote:

Originally posted by Tommydogg:
What I've always done was drill about 20 to 30 seconds, stop, squirt, drill, repeat. Is this the way your supposed to do it?

I usually judge by how the drilling is going. If it's no longer making shavings, starts to smoke, or becomes harder to make progress, squirt time. Also, if the workpiece is laying flat, the oil tends to stick around more than if you're drilling on an angle.

WD-40 isn't a lube, and it burns off too quickly when used for cutting/drilling. It's still better than nothing.

OK, I know I'm going to get a whacking for even mentioning this, but...

I found out that drilling stainless steel can be next to impossible unless you use bacon grease as your cutting "oil".(yeah, go ahead, yuck it up)

It may work with what you are trying to do.
I had a project for a friend on which I could only get a little dimple drilled into the surface. Fourteen holes in all.
Dulled 3-4 bits before seeking a remedy. Found out about bacon grease, hand sharpened a bit, and the drilling went like a miracle through all fourteen holes without resharpening.
Mind you, the bit I resharpened had the coating removed and still did the trick.

I also found out that old timers also used butter milk to drill hard copper back in the day.
Don't ask me for footnotes or hard evidence,just trust me on this

Nope. No whacking here.

Bacon fat/lard has a higher flash and smoke point than way oil, or many of other mineral fluids used to cut. The cutting fluids mixed with water are the exception on the heat component and they cool better, allowing for better cutting and longer contact during work, and the cooling allows the oil to lubricate by keeping the working temp much lower than oils alone.

WD-40, as mentioned has a very low flash point, and as Arc stated, it will "burn off/evaporate" very quickly, and is not a good cutting oil, nor well as a coolant unless applied almost continually.

So, no surprise the short cutting duration using back grease works as well as you state.

Buttermilk would be closer to water miscible cutting fluid with the fat (oil) mixed with milk (water).

One thing not mentioned was work hardening, and that can make drilling a chore by rendering hard spots at the point of drilling, and the burnishing and polishing the cutting edge. The cutting bit will look fine, but it will have lost its edge just enough to frustrate you.

So, have a BLT and make happy holes.

maybe just send it too PHPaul, and be done with it

Chip load is key when hand drilling. Don't baby it especially in mild steel, it will work harden. I have a feeling you are work hardening your angle iron, any high speed steel drill should go right through it. You want to keep a lot of cutting pressure on the drill so you get a bigger chip and remove heat with the chip. Light cuts tend to dwell and cause heat which in turn will work harden mild steel fast.

Don't be afraid to push your drill hard.

quote:

Originally posted by FenderBender:
I see no reason not to use tungsten carbide bits exclusively.

a) expensive
b) snap like brittle twigs without a very ridgid set up

quote:

Originally posted by isthatasiginyourpocket:
Chip load is key when hand drilling. Don't baby it especially in mild steel, it will work harden. I have a feeling you are work hardening your angle iron, any high speed steel drill should go right through it. You want to keep a lot of cutting pressure on the drill so you get a bigger chip and remove heat with the chip. Light cuts tend to dwell and cause heat which in turn will work harden mild steel fast.

Don't be afraid to push your drill hard.

That is interesting, I'll bet I may have done that. Thanks for the Tip ! I'm shopping for m42 cobalt drill bits, jobber length, a small set, but they only seem to come in larger sets, which are lotsa dollars. I only need a small set, like a dozen or so, but m42 grade. Will keep looking.

All these crazy fluids for drilling. Why not just some good old fashioned cutting fluid?

https://www.amazon.com/Forney-...721&s=gateway&sr=8-3