Drill bits for 1/4" steel?

[JEDI]

BLACK & DECKER 20-Piece High-Speed Steel General Purpose Drill Bit Set

http://www.lowes.com/pd_200005-70-71...7C0&facetInfo=

to go thru steel, i've read you need high speed bits.

Will these do?

 

[IronWing]

Yep. But maybe not very many times. I'm sold on HSS Thunderbit drill bits.

 

[marvdmartian]

See the little pictures, where it says MATERIALS? Yes, those will work for steel. That's what the little I-beam picture portrays. :hmm:

 

[PottedMeat]

if you're doing a lot of drilling and need only one size i'd just get a single cobalt bit - they're not that much more than a HSS and you can get them individually at lowes/hd

 

[highland145]

 

[JEDI]

if you're doing a lot of drilling and need only one size i'd just get a single cobalt bit - they're not that much more than a HSS and you can get them individually at lowes/hd

cobolt better than titanium?

 

[IronWing]

Magnum Hole Shooter FTW!

I find that they tend to slip in the chuck more than other bits and on high carbon steel they tend to act more than a bit like lipstick.

 

[SooperDave]

cobolt better than titanium?

Yes. Titanium is a coating that flakes off or comes off when sharpened. Another vote for cobalt.

 

[PottedMeat]

cobolt better than titanium?

yeah

'titanium' means titanium nitride coated high speed steel bits, they're better than uncoated, but eventually it will come off

i've seen 'cobalt' bits that when you look at the label it's cobalt coated - i'd avoid those

 

[highland145]

Magnum Hole Shooter FTW!

I find that they tend to slip in the chuck more than other bits and on high carbon steel they tend to act more than a bit like lipstick.

Yeah, you can't use them very well in the chuck. I believe they'd work much better with a hammer and nail set. Maybe the OP can try that.:whiste:

 

[Triumph]

Yes those will work but they won't last super long. If you want one hole, or ten even, they will work fine.

Use lubrication (any oil will be ok), make a good mark with a center punch, drill pilot hole, drill final hole. Slower speeds on steel.

If you wanted a good home user drill bit set that will last a long time, you'd need something like this. It's the low end of professional but better than a $20 set you are going to get at Sears or Home Depot.

 

[DrPizza]

Another vote for an individual cobalt bit. My first introduction to cobalt bits was when I asked at the hardware store what to use to cut through some thick angle iron. 1/4" also, iirc; it went through it like butter. Since then, when I need a bit that I don't have, I just go out and get a cobalt bit.

 

[overst33r]

cubic boron nitride or bust!

 

[Fenixgoon]

See the little pictures, where it says MATERIALS? Yes, those will work for steel. That's what the little I-beam picture portrays. :hmm:

most HSS bits are cobalt/nickel/tungsten/iron/carbon, IIRC. not super high alloy stuff, but enough to develop extreme hardness. TiN is also pretty common on the tip of the drill bit.

in addition to HSS bits, just make sure you have plenty of lubricant to keep the drill bit cool and take your time. you'll get through to the other side (eventually) but you will need to patient.

 

[iGas]

Yes those will go though 1/4" mild steel. However, they wouldn't last much more than one or two holes.

 

[DayLaPaul]

It's only 1/4". You can probably use an old rusty garage sale bit and it would still do the job.

 

[stargazr]

Yes those will go though 1/4" mild steel. However, they wouldn't last much more than one or two holes.

Really? What will happen?

 

[JEDI]

Yes those will go though 1/4" mild steel. However, they wouldn't last much more than one or two holes.

best bang for the buck bits that last more than 2 holes?
cobolt?

 

[Fenixgoon]

Really? What will happen?

you heat the tool bit, it tempers and loses strength/hardness, and eventually breaks.

 

[stargazr]

you heat the tool bit, it tempers and loses strength/hardness, and eventually breaks.

I doubt he'll get it that hot.

"High-speed tool steels have in common the ability to maintain high hardness at elevated temperatures: typically, 52 HRC at 540 °C (1000 °F) and 48 HRC at 595 °C (1100 °F). Thus, as the term high-speed implies, these steels are primarily used for cutting tools that generate considerable heat during highspeed machining of steels and other metals. In addition to excellent hot hardness, sometimes referred to as red hardness because of the ability of the highspeed steels to resist softening even when red hot, the high-speed steels possess a number of unique alloying and processing features. These features include sufficient alloy and carbon content to provide excess alloy carbides in heat-treated tools, hardening at temperatures close to or at their melting points, hardening with fine austenitic grain sizes, deep hardening by cooling in still air, and prominent secondary hardening during tempering."


The Materials Information Society


http://www.asminternational.org/por...toid=ccd394be27de9110VgnVCM100000701e010aRCRD

 

[Lemon law]

I see almost no one on this thread has a background as a a machinist or toolmaker. Or understand anything about speeds and feeds. Or what constitutes a cutting tool material.

But there is little difference between High Speed Steel Bits and their cousins that have extra cobalt. But if you have a 1/4 inch electric drill, and are drilling a 1/4" hole in mild steel, there is a very big chance that you are ruining your drill bit edge by using too high an RPM. HSS steel bits with extra cobalt are only marginally more heat resistant. But can run at 3x the RPM as equally hard plain carbon steel drills.

The other sin of the amateur is to use a hand held drill and no consistent feed. As a result the drill edge dulls by skating on the surface without cutting as the user changes the orientation of the drill to off drilling axis.

Drilling is best accomplished on a drill press, hand or machine fed, and a person knows what they are doing can get hundreds of holes in mild steel out of one HSS tool bit before it even needs sharpening. Especially if a spot drill is used to start the hole. Or at a minimum a center punch.

And how the drill is ground depends on the material, aluminum tolerates much higher RPM and rake angles than mild steel. But beware of too much rake in brass, the rake itself can pull the drill into a too soft material causing itself to bite off more than it can chew.

And the smart person with only a drill and a hand held electrical drill will use a drill guide made out of even wood to start the drill into the hole in metal. Just C clamp a wood backing on both sides, and you can start a straight hole much better. If you don't exceed 80 feet a minute speed and get a thin but continuous spiral chip out of both drill flutes, you will know its about right. Back off the feed pressure if you your chip starts turning blue. If even tiny thin chips are still blue, you are using way too fast a speed.

 

[overst33r]

sheesh. he just wants to drill a few simple holes, not start a business doing it... not saying you're incorrect, but talk about over-complication...

 

[Triumph]

I see almost no one on this thread has a background as a a machinist or toolmaker. Or understand anything about speeds and feeds. Or what constitutes a cutting tool material.

But there is little difference between High Speed Steel Bits and their cousins that have extra cobalt. But if you have a 1/4 inch electric drill, and are drilling a 1/4" hole in mild steel, there is a very big chance that you are ruining your drill bit edge by using too high an RPM. HSS steel bits with extra cobalt are only marginally more heat resistant. But can run at 3x the RPM as equally hard plain carbon steel drills.

The other sin of the amateur is to use a hand held drill and no consistent feed. As a result the drill edge dulls by skating on the surface without cutting as the user changes the orientation of the drill to off drilling axis.

Drilling is best accomplished on a drill press, hand or machine fed, and a person knows what they are doing can get hundreds of holes in mild steel out of one HSS tool bit before it even needs sharpening. Especially if a spot drill is used to start the hole. Or at a minimum a center punch.

And how the drill is ground depends on the material, aluminum tolerates much higher RPM and rake angles than mild steel. But beware of too much rake in brass, the rake itself can pull the drill into a too soft material causing itself to bite off more than it can chew.

And the smart person with only a drill and a hand held electrical drill will use a drill guide made out of even wood to start the drill into the hole in metal. Just C clamp a wood backing on both sides, and you can start a straight hole much better. If you don't exceed 80 feet a minute speed and get a thin but continuous spiral chip out of both drill flutes, you will know its about right. Back off the feed pressure if you your chip starts turning blue. If even tiny thin chips are still blue, you are using way too fast a speed.

Actually I do, and I realized that it didn't matter too much because the guy is not running a machine shop, he just wants to put a hole in something for a stupid home job.

 

[Jaepheth]

http://www.ebay.com/itm/29-pc-M42-S..._Automotive_Tools&vxp=mtr&hash=item5642760d04

 

[iGas]

best bang for the buck bits that last more than 2 holes?
cobolt?

You can buy the only bit that you need, and perhaps buy 2 bits just in case you break one at the local shop (not expensive under 1/2" and can be up to around $10 each for size up to 3/4"). Buy a drill bit set if you are intended to do some more drilling in the near future, other wise it is pointless to have a set of drill bits.

Cobalt Jobber Drill Bit 1/4" x 4" -- $3.50 each.