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.