Drill Press For Metal Work Versus Wood Work

depends what diameter drill your spinning, but metal drilling needs to go slower than wood. bigger drills, more slower, once you go past 1/2" dia. drilling in metal, you really need to slow down. Drill presses made for woodworking are generally unsuitable for holes in metal larger than 1/4" dia, unless you like sharpening & replacing drill bits alot.

That is great information. What are the specific characteristics I should call out? 1/4 to 1/2 inch diameters would be a very typical range for us.

Drilling "thick" stainless, you have no chance in hell with a drill press that runs at woodworking speeds. You'll burn every bit even at the low speed end. Also, you have little chance with 1/4" bits in "thick" stainless unless you have a pretty rigid drill press that can run at very moderate metalworking speeds. Somebody here will know the specific RPM, but it's 'way down there.

A drill press that will cover the appropriate speeds for both is a not very common. My floor model 50-year-old Walker-Turner, which is belt-driven, will just do it, but it's because I have the intermediate pulley ("third wheel") option for it. It's just barely rigid enough for drilling stainless with a

1/4" bit, partly because I had a lot of experience drilling many hundreds -- probably thousands -- of stainless pieces when I worked in a shop. It requires some practice to keep adequate pressure on the bit without springing the whole affair or slipping the belt, unless the drill press is a heavy industrial model. If you don't keep adequate pressure (feed pressure, that is) on it, you'll work-harden the stainless, burn the bit, and make it extremely difficult to get the hole re-started.

The best bet in a commercial setting is to have one drill press appropriate for each task. In fact, I prefer drilling thick stainless in a Bridgeport or other mill.

-- Ed Huntress

My Delta woodworking drill press goes down to 250 rpm. Home Depot item from about 1996, with a 3-pulley system and 1720 rpm motor.

For a half inch drill bit in stainless you want a drill press that will go as slow as 300 rpm. Most better quality woodworking drill presses can go that slow. A gearbox driven drill press gets very expensive but for half inch and less you could get by with a vee belt driven drill press. 1/3 horsepower motor would be on the weak side.. look for an honest half horsepower motor. Randy

You've got the rpm covered. How does it do in thick stainless with a 0.25" bit?

-- Ed Huntress

I meant to ask, how does it do in stainless with a 0.5" bit? That's really pushing it in thick stock, with a woodworking drill press. My Walker-Turner won't do it, even though it has the right rpm. I have squeaked through with

3/8" bits, after drilling an 1/8" pilot hole. But that's not the way to go for commercial work.

-- Ed Huntress

I've managed into 304 stainless. Also 7/8" in hot rolled 1018 steel.

It is really handy to have T-slots milled into the table so that you can mount a vise or jigs to it. Wood doesn't tend to spin as much as metal when drilling, and it causes less damage when it does, so that feature is often overlooked on the woodworking DPs, where the work is easily held by hand.

Dig up the recommended cutting speed in surface feet per minute, for the materials you are cutting, and the drill materials you are using, and start from there.

Too fast cooks drills, too slow cost you time.

Some materials are just nicer to work with, too, and are less picky about speeds and feeds. 304 is not one of those, for example.

Cheers Trevor Jones

Can you point to a good source for this information? I'd like to do better than my normal "hmm, this drill is about so big, guess I'll run in second notch this time".

one:

This info is available in the American Machinist's Handbook. My copy is over 40 years old.

Machinerys Handbook may have it, also.

Or try a text book from a technical college on machine tool operation.

IIRC this topic was discussed in this forum not too long ago (last year?) try searching for it.

If you get stuck re-state your question here and we will see what we can do.

Wolfgang

Thanks! Exactly what I was looking for.

For cutting 1/4 inch stainless (let's say 300 series) which of the bit types should we be preferring:

- high speed steel

- uncoated carbide

- coated carbide

If it matters, then let's assume that the application is drilling 1/4 inch diameter holes in the 300 series stainless plates that are about 1/4 inch thick.

I'd buy a quality machine - one that can change spindle speed from metal rates - slow to those of faster wood rates. Some wood is slow. But when using it as a shaper and and such - it is fast.

The 1/4" Stainless is not a trivial task. Make sure you have ample clamping ability to hold the work tight. A catch can whip a sheet or bar and really spoil a day of someone.

A nice large flat table and an adjustable speed - belts are ok - you say once a month change the belts for a job. Cheaper than electronics, but not as handy.

Mart> Should a drill press used for drilling holes through 1/4 inch stainless

High Speed Steel.

Working stainless is not the "nearly impossible" task that some people seem to think it is. I've been machining stainless since the 1950's using high speed steel tooling with no problems.

There are two areas you need to address in machining stainless - cutting speed, and feed rate. As a general statement you want the proper cutting speed (RPM), or a little slower, and the highest feed that the tool will handle.

For a 1/4"HSS drill, look up the cutting speed for HSS and the stainless alloy you are using.

300 series 50 - 70 FPM. Using the lower speed the drill RPM will be: 50 X ((12/(Pi X D)) 50 X (12/(3.1416 X 0.25)) = 763 RPM - set the drill press for that speed or slower

Now use as high a pressure on the drill press handles that the drill bit will stand. The chips will come off the work as spirals and may be a light brown; if they are dark brown or blue slow the RPM.

As the drill starts to break through the bottom you should be able to feel it and lighten up on the pressure just a bit. If you can't feel the drop in pressure just use a piece of wood as a backing block until you get the feel.

When people refer to stainless as being hard it is rather that stainless work hardens very rapidly. Letting your drill spin without cutting for just a second results in a work hardened surface that the drill can no longer cut.

The thing you want to remember above all else is "keep the speed low and the feed high" and you'll find that drilling stainless is no more difficult then drilling mild steel.

Bruce-in-Bangkok (Note:displayed e-mail address is a spam trap)

On Tue, 30 Oct 2007 22:40:12 -0400,

"T>depends what diameter drill your spinning, but metal drilling needs to go

I have a cheapo YingTong drill press, 2MT, 16mm chuck, 16 speeds. I only run it at 200 ? rpm ( lowest speed), no matter what size drill bit, 3mm to 25mm in steel or wood, 6mm to 70mm in Forstner bits (wood) or up to 150mm holesaw in steel or wood. I am just too lazy to change the belt on the pulleys. Works for me. Most important is to check runout on the chuck, mine is negligible.

Alan

I've got it on one of my sites... All very conservative numbers with coolant factored in.

Stainless really should never be drilled without coolant.... Unless you can spin at 2 RPM. :)

Regards, Joe Agro, Jr. (800) 871-5022

01.908.542.0244 Automatic / Pneumatic Drills: Spindle Drills: V8013-R