Drilling holes in steel

[CincyFlyer]

I bought these drills for my present project to drill for bushings mounted in box tubing with 1/4" wall. Works well with less torque needed to turn them. Bought these in 1 3/8" down to 7/8" sizes very satisfied with the results after using these to drill holes in tubing and flat bar. These will cut up to 1" deep but other depths are available.

This is the 1" size.

Annular bits combined with a magnetic drill base is the perfect setup for "field work", or things that cannot go under the drill press. 1" holes in 3/8" plate are nothing. Kind of pricey, however (with a good drill and bit set running $1K), unless you go with the Chinese versions.

 

[jenkinsph]

Annular bits combined with a magnetic drill base is the perfect setup for "field work", or things that cannot go under the drill press. 1" holes in 3/8" plate are nothing. Kind of pricey, however (with a good drill and bit set running $1K), unless you go with the Chinese versions.

I like magnetic base drills and have used them for drilling flanges on large tanks years ago. Good heavy duty models were about $2500 at the time, have these come down in price? I probably have more in drill bits than $1000.

 

[Big Barn]

Another good option is purchasing an arbor adapter for your drill press to accommodate using annular cutters.

An appropriate adapter is under $50 and Made in USA annular cutters are always available economically on eBay.



Terry

 

[Big Barn]

I like magnetic base drills and have used them for drilling flanges on large tanks years ago. Good heavy duty models were about $2500 at the time, have these come down in price? I probably have more in drill bits than $1000.

You can get a GOOD heavy duty one for way less these days. If Steve (BukitCase) sees this he will prolly post links for the best Hougen deals.

Terry

 

[CADplans]

IMHO,, drill bit life, when drilling large holes,,, is totally controlled by the feed rate of the bit.
(this is assuming you are using the correct rotational speed)

With power feed controlling the rate at which the drill bit progresses bit life is tremendous.

I can drill hundreds of holes with one drill bit, no dulling occurs.

Drill the same hole size, with the same drill press, using hand feed,,,
you are lucky to get a dozen holes before the drill bit is chipped, dull and useless.

The coolant is mostly used to allow higher drilling speed.

The more rigid the drill press, the greater the possible feed rate.

This drill press drills 3/4" holes in steel at a feed rate of .006" per revolution.

If the hole gets larger than this,, I usually use a small pilot hole.
The pilot hole reduces the horsepower needed to drill large holes.

 

[oosik]

If I'm drilling with a hand held drill - I always start with a pilot hole for any hole larger than around 3/8". If I'm using my adjustable feed drill press - I will only start with a pilot hole if the material is 1/2" or thicker. And no matter what I drill - SLOW is the only way to go - with lots of lube oil.

 

[D2Cat]

If you're drilling a hole 3/4" and up, it's easy for the drill bit to chatter. The drill speed needs to be <200 RPM, and the piece being drilled needs to be anchored securely.

 

[Mace Canute]

Here's an interesting and informative read about drill geometry.

DRILL POINT GEOMETRY by JOSEPH MAZOFF

 

[LD1]

Yes, creeping up on a hole is foolish as mentioned. And I too have no clue where the nonsense came from.

Anyone with any machine-tools background or education knows this.

"most" drill bits under 1/2" have 2 grind angles. Called a split-point bit. They are self centering and require no pilot at all.

Most drill bits OVER 1/2" have a single grind angle and the result is whats called a chisel point. To make drilling easier and allow metal to cut instead of mash and deform out of the way, a single pilot hole equal to the thickness of the chisel point is all that is required.

If someone in my shop is drilling a 3/4" or 1" hole and creeping up on it with 6 or 7 different drill bits....they are quickly banned from the drills and mill.

 

[mark in portugal]

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