Big drill bits

[TimberHole]

A pilot is not going to Waller out a pilot hole of the proper size. A magnetic drill or a drill press doesn’t even require the pilot.

 

[ArlyA]

I have access to a Bridgeport I use for my serious hole drilling. I use pilot holes on it.

 

[LittleBill21]

53 minute mark

Container building roof metal work - YouTube

yes this is more expensive, but drilling 1/2 myself this is prolly the way i would go as well if i need a bunch done.

here is the drill he's using

https://amzn.to/2MUt5vZ

 

[CADplans]

The drill bit is mostly not the issue, the drilling technique is the issue,,,

I have a power feed drill press, I can drill 1 1/2" holes, no problem

This pic shows the result of power feed,, continuous chips.

Without power feed, the pressure is intermittent, the metal being drilled will "work harden" the hardened steel quickly dulls the drill bit.

You can tell poor technique from the chips, little flakes means the pressure on the drill bit constantly is changing.
You can make continuous chips with a manual drill press, but, only when using small drill bits.

Using power feed, I have drilled hundreds of large diameter holes oven the last 15 years with this drill press, without needing to sharpen, or replace a drill bit.

Proper coolant helps also,,,

 

[repete]

I have the original version of that drill,

It's from the B&D Professional line of tools, made by Elu. Elu made some of the BEST power tools ever made, not sure who makes the current line?

I bought mine, after blowing the tranny on a Milwaukee Hole Hawg, and going on the job having a plumber telling me he had two Hole Hawgs with blown trannys on his bench in his shop.

My industrial tool dealer, told me the Elu was a MUCH better drill, so I bought one, and that was back on in the early 80's, I have nothing but good things to say about this drill.

For bigger holes, I try to use a drill press as much as possible,

but I realize that's not always possible. Also, when drilling, get your self a can of "Tap Magic", that stull really is magic!! Step drilling and Tap Magic IS the way to go!!

SR

That is exactly the B&D I have. When I am boring a 3 and 9/16" self feed bit over my head on a ladder I LOVE the clutch.

 

[Oldpath05]

If you have an inch hole and need a 1.5 hole a pilot bit isn稚 going to do you any good

You might be able to tack weld a steel plate behind the 1" hole for the pilot bit to stay centered for a lager hole, theoretically........

 

[TractorGuy]

Another vote for hole saws. Quality large bits are expensive and easily burned up. Once they over heat and work harden the metal it won't cut no matter what you do. I just messed up several bits trying to bore a 7/8" hole in some hot roll bar stock. I had two pieces of 1/2" welded together for one inch thick. A new Milwaukee hole saw walked right through it.

 

[Industrial Toys]

I like hole saws too, but the tolerence usually suffers.

I consider much of my work butcher engineering, but if the final result is pretty good, who cares how you got there?

The difference in drillbit quality from one make to another cannot be over stated. That pretty much applies to any cutting tool.

 

[radios1]

Another vote for hole saws. Quality large bits are expensive and easily burned up. Once they over heat and work harden the metal it won't cut no matter what you do. I just messed up several bits trying to bore a 7/8" hole in some hot roll bar stock. I had two pieces of 1/2" welded together for one inch thick. A new Milwaukee hole saw walked right through it.

that what happens when the rotational speed is too fast!. if you go slow enough in speed, even work hardened metal can be drilled through!.

 

[fried1765]

that what happens when the rotational speed is too fast!. if you go slow enough in speed, even work hardened metal can be drilled through!.

A quality cobalt bit, slow speed, and oil, will drill through most anything.

 

[ArlyA]

I agree. Cobalt is a good HSS product and I buy tools made from it. In particular countersink tools.

A quality cobalt bit, slow speed, and oil, will drill through most anything.

 

[denchen]

Large drill bit, verses rotary cutter. I think it may depend on how many holes you have to drill. In the factory I used to work in, it might have been 200, two and a quarter inch holes in plate, half inch thick, every day. Many other holes would also have to have been drilled. A small pilot was drilled, about a quarter of an inch then the 2 1/4 went straight through, slow speed, power feed, alkaloid oil/ water mix to cool. The oil water mix looks like milk. This was all done on a big radial drill. No way would it be possible to hold a hand drill with this amount of torque. Now if I wanted to drill the same size hole at home, then a rotary cutter would do the job, but a lot slower, with a good power drill. The drill bits we used were normal good quality bits, nothing fancy like cobalt, and were sharpened when I got around to it about once every 3 - 4 weeks or if someone done something daft and one got chipped. I don`t think a rotary cutter would last long in our working environment. The other way of making holes in our factory was simply to punch them out cold. The square holes in the hard tips of power harrows for the bolts, were made this way

 

[Oldpath05]

Maybe a good quality drilling lube will make big drill bits last longer, something like this>> Anchorlube G-771, water/soap based metalworking lubricant

 

[radios1]

Large drill bit, verses rotary cutter. I think it may depend on how many holes you have to drill. In the factory I used to work in, it might have been 200, two and a quarter inch holes in plate, half inch thick, every day. Many other holes would also have to have been drilled. A small pilot was drilled, about a quarter of an inch then the 2 1/4 went straight through, slow speed, power feed, alkaloid oil/ water mix to cool. The oil water mix looks like milk. This was all done on a big radial drill. No way would it be possible to hold a hand drill with this amount of torque. Now if I wanted to drill the same size hole at home, then a rotary cutter would do the job, but a lot slower, with a good power drill. The drill bits we used were normal good quality bits, nothing fancy like cobalt, and were sharpened when I got around to it about once every 3 - 4 weeks or if someone done something daft and one got chipped. I don`t think a rotary cutter would last long in our working environment. The other way of making holes in our factory was simply to punch them out cold. The square holes in the hard tips of power harrows for the bolts, were made this way

for production, this is used. https://www.mscdirect.com/product/details/88425228

 

[BukitCase]

Wow, at $400 per size (not including the machine to use it) I'm kinda glad I got my mag drill when overtime was still an option - I went with a larger drill so I could drill larger holes easier, have about $2200 TOTAL (including 3 vises, xy table, etc) invested INCLUDING cutters from 7/16" up to 1-1/2" (the size of all the pins in my backhoe except 1) - most cutters up to 1" are $30-40 (the cost of a decent twist drill that size)

These days, if you don't need much bigger than 1" holes there are drills that'll do it for around $400.

Here's my setup

https://www.tractorbynet.com/forums...-table-build-6.html?highlight=mag+drill+table

I've added a few more cutters since this pic - - need to come up with a bigger "index" - if you only buy cutters as needed, the "onesie-twosies" aren't as painful as getting every size would be...

I do quite a bit of stuff using 1/4" wall square tube; I have over 100 holes on some of my bits, they're all still as sharp as new.

The part that ALWAYS makes me smile - a 5/8" hole in 1/4" steel takes me 20 SECONDS - NOT a misprint; no pilot hole, just do it. Anything I can't do on the table I can usually find a way to clamp a piece of steel to it (if it's not big enough by itself to just hold the drill to it and turn on the magnets)

For stuff that even the mag drill can't get to, the Blair rotobroach kit can drill down to 1/4" holes with a HAND HELD drill. (as long as you don't get TOO wobbly holding it; they CAN be broken, DAMHIKT )

I know, not for everybody; but worth considering if you see a lot of bigger holes in your future... Steve

 

[TractorGuy]

I like hole saws too, but the tolerence usually suffers.

I consider much of my work butcher engineering, but if the final result is pretty good, who cares how you got there?

The difference in drillbit quality from one make to another cannot be over stated. That pretty much applies to any cutting tool.

I've got an old 5/8 bit that cuts the old Chrysler symbol. It's always been a mystery how a round bit does that.

 

[Industrial Toys]

I sold my Van Dugen (sp?) mag drill to a friend because his didn't have variable speed and mine did. I sold it because I could not afford or justify the angular cutters.

Now, for impressive holes, I go to my other friend who works with a 40 (or so) foot long tubing laser!

 

[k0ua]

I tend to use hole saws for anything 3/4" and above.

Are you drilling free handed or with a press?

Same here. Go slow, lube, clear chips. Do't burn up the holesaw. It is a lot easier on the drill too.

 

[Industrial Toys]

I unfortunately destroyed a 6" Millwalkee hold saw on a stainless electrical cabinet. Even used SS cutting fluid and went slow!

 

[k0ua]

By hand makes my wrists hurt. I'm always concerned with the drill hanging and making pretzels out of wrists. Size like that really needs to be done with a drill press if possible, which it isn't always.

I have some experience with a huge 5/8 slow speed drill. You know the good old metal cased kind built back about when I was born, and a 5/8'' bit in it. So drilling a 3 inch steel pipe. and when it broke thru on the back side, it just about broke both wrists before I could get off of the trigger. It started to wrap up my hands, cord and me. Wasn't fun.