Drill bits - Page 2 - Electrician Talk - Professional Electrical Contractors Forum

Amish Electrician · 07-16-2012, 10:14 AM

Your first concern is the drill point - you want 'split-point' bits. When you look at the bit from the end, you see something like a 'bow tie,' rather than the "S" you see on an ordinary bit.

The next thing you need is some cutting oil. I find the foaming stuff from a spray can to work best for our situations. Carry a rag and wipeup your mess.

"Feed and speed" matters. Spin slow and push hard.

Brands? The DeWalt pilot points are very good. The bits sold by parts houses - often Triumph or Vermont American - are quite good.

I've had better luck with HSS bits than with the more expensive Cobalt bits. The cobalt bits may be 'better' bits, but they are also easier to break.

As for the self-tapping screws .... you need the drill point to be somewhat longer than the thickness of the metal you're drilling, or you'll break them off in the hole. I tend to use a 1/8 bit for a pilot hole, than finish the hole with one of those screws.

Center-punching your holes is a help; look for a substantial spring-loaded punch. No hammer needed!

Bbsound · 07-16-2012, 11:19 AM

Quote:

Originally Posted by bubb_tubbs

I know what you were referring to.

The customer specified bolts - no teck screws were permitted because the rear could be seen.

Tapped with centre punch, piloted with oiled 1/4" bit, drilled out with oiled 1/2" bit.

I'd love a mag drill but I don't control the ordering. You'd have to convince the owner: I'm talking about personal drill bits here.

Your company needs to be buying consumables like bits, hole saws, flashlight batteries, etc.

Aegis · 07-16-2012, 12:25 PM

We use tech screw but with the longer tap. The cutting threads of the tech screw has to be as long as the steel is thick otherwise the head blows off with my impact drill lol

chewy · 07-16-2012, 01:38 PM

Quote:

Originally Posted by Amish Electrician

Your first concern is the drill point - you want 'split-point' bits. When you look at the bit from the end, you see something like a 'bow tie,' rather than the "S" you see on an ordinary bit.

The next thing you need is some cutting oil. I find the foaming stuff from a spray can to work best for our situations. Carry a rag and wipeup your mess.

"Feed and speed" matters. Spin slow and push hard.

Brands? The DeWalt pilot points are very good. The bits sold by parts houses - often Triumph or Vermont American - are quite good.

I've had better luck with HSS bits than with the more expensive Cobalt bits. The cobalt bits may be 'better' bits, but they are also easier to break.

As for the self-tapping screws .... you need the drill point to be somewhat longer than the thickness of the metal you're drilling, or you'll break them off in the hole. I tend to use a 1/8 bit for a pilot hole, than finish the hole with one of those screws.

Center-punching your holes is a help; look for a substantial spring-loaded punch. No hammer needed!

A self drilling tek makes a good centre punch, automatic centre punches go for about $150 to $200 here so Im cool with the hammer method.

Amish Electrician · 07-16-2012, 05:11 PM

Balderdash! A center punch- not a hole punch!

It's a tool that fits in your pocket, about 1/2" diameter and maybe 5" long. The really nich ones have strong springs and carbide points. A common manufacturer is "General."

To use, you place the point where you want the hole's center to be, push on it until it makes a snapping sound, and -viola!- there's a little dimple in the steel to catch the drill bit.

chewy · 07-16-2012, 05:22 PM

Yeah I know what you mean but they are really expensive for decent ones like Facom and Starett over here.

Wirenuting · 07-16-2012, 05:22 PM

Quote:

Originally Posted by Amish Electrician

Balderdash! A center punch- not a hole punch!

It's a tool that fits in your pocket, about 1/2" diameter and maybe 5" long. The really nich ones have strong springs and carbide points. A common manufacturer is "General."

To use, you place the point where you want the hole's center to be, push on it until it makes a snapping sound, and -viola!- there's a little dimple in the steel to catch the drill bit.

I carry one of them and use it all the time.

Now Chewy is down-under. You could get rich shipping a few to him at Hmmm,, $45 a piece.
LoL

bubb_tubbs · 07-16-2012, 05:32 PM

Quote:

Originally Posted by Amish Electrician

Balderdash! A center punch- not a hole punch!

It's a tool that fits in your pocket, about 1/2" diameter and maybe 5" long. The really nich ones have strong springs and carbide points. A common manufacturer is "General."

To use, you place the point where you want the hole's center to be, push on it until it makes a snapping sound, and -viola!- there's a little dimple in the steel to catch the drill bit.

Yeah, my spring-loaded one was only $10.

I do use oil, low speed and the centre punch though.

Frasbee · 07-16-2012, 05:39 PM

I agree with Amish. Cobalt is more brittle and more expensive. If it catches on a large chunk, you're at a greater risk of snapping the bit.

You're better off using cheaper bits with a proper technique for the material.

LARMGUY · 07-16-2012, 08:55 PM

I bought a set of industrial grade drill bits 5 years ago for $100 and keep them sharpened with a Drill Doctor. Haven't bought a drill bit since unless some dumbazz breaks one.

chewy · 07-17-2012, 05:11 AM

Quote:

Originally Posted by Frasbee

I agree with Amish. Cobalt is more brittle and more expensive. If it catches on a large chunk, you're at a greater risk of snapping the bit.

You're better off using cheaper bits with a proper technique for the material.

Cobalt bits were the only way I was able to drill through welds on the deck of my brothers ute, we were using self drilling screws but they werent cutting the mustard on the welded spots.

jeffmoss26 · 07-17-2012, 11:28 AM

I just get bits from the tool crib at work...usually cobalt bits.

bubb_tubbs · 07-17-2012, 12:31 PM

Tool crib - what a novel idea...

These guys won't even buy drywall anchors (lots of them use 1/4" blues in sheetrock!)

MechanicalDVR · 07-17-2012, 02:00 PM

If you were using 3/8" bolts it seems a waste of time to drill 1/2" holes. I'd drill the proper size hole and it wouldn't be with drill bits I provide.

coon88 · 07-17-2012, 05:39 PM

Quote:

Originally Posted by wcord

I'm not talking about tapping the holes.
These are what we use. No fumbling with nuts etc.

Those are tek point screw...try the 5 points for the harder items

8V71 · 07-17-2012, 06:09 PM

Quote:

Originally Posted by MechanicalDVR

If you were using 3/8" bolts it seems a waste of time to drill 1/2" holes. I'd drill the proper size hole and it wouldn't be with drill bits I provide.

I was wondering why such big holes but I figured he has a reason.

chewy · 07-17-2012, 06:56 PM

Quote:

Originally Posted by 8V71

I was wondering why such big holes but I figured he has a reason.

No spud?

bubb_tubbs · 07-17-2012, 07:16 PM

1/2" because it's the size of the bit they provided.