Best drillbit for steel

[woodlandfarms]

I am confused on all these different types if bits for steel and woos and plastic. I need to get a 5/8 hole through 3/8 steel. I kinda get the stepping up but I really don't get cobalt vs titanium vs neobonium or whatever the latest flavor is.

And who is the higher quality manufacturers?

 

[Shield Arc]

The last 10 or 12-years I've been buying those cheap drill bit sets from ebay, or where ever I can get them. Some of the bits have to be re-sharpened tho.:confused3:

 

[k0ua]

Is this just "mild steel" also known as A36 or 36000 psi steel? If so, you will not need cobalt or TI bits, but they would not hurt except your pocketbook. Just regular HSS (High speed Steel) bits will work OK. A 5/8 hole in 3/8 materiel is a pretty good sized hole. I sometimes use hole saws for holes that big and bigger. What ever you use, I sure hope you have a good drill press (not some hand drill) turning at low speed with plenty of lube.

 

[k0ua]

I can't remember if you recently bought a plasma, but if you did you can cut that kind of hole with a plasma too. Just depends on how accurate you need that 5/8 hole to be.

 

[downsizingnow48]

For a 5/8 hole in steel these days I would use an annular cutter. I think they used to be just for magnetic drills. But adapters are available so they can be held in drill presses, lathes. Some annular cutters are designed for hand held drills too. They cut fast and leave a smooth accurate hole.

 

[kennyd]

For anything over 1/2" size, I tend to use hole saws-especially if I can do it in the drill press/mill. But you need to go SLOW and use cutting oil.

 

[George2615]

Sharp ones.
Seriously, I buy most of mine from Graingers. But I do have a larger set (up to 1") from Harbor freight. The ones with the reduced shank to use in a 1/2" drill. I recently drilled some 1" holes thru 1/2" steel starting with a 1/4" and stepping up as I went. The hardest part is once you get to the larger bits using a 500 rpm drill and the drill bit catches it will twist the drill right out of your hands. I hand sharpen all my bits sized 1/4" and up. Anything smaller I just buy new. I use high speed steel, cobalt, or titanium. Mostly cheap bits but I keep them sharpened.

 

[Big Barn]

For a 5/8 hole in steel these days I would use an annular cutter. I think they used to be just for magnetic drills. But adapters are available so they can be held in drill presses, lathes. Some annular cutters are designed for hand held drills too. They cut fast and leave a smooth accurate hole.

I went this route, but only recently. Wish I had done it years ago. Drilling holes is actually enjoyable now.



1" annular cutter with 1 1/2" cutting depth with shank adapter. (In my case MT 3)



3/4" Rota Cut sheet metal cutter with 3/16" cutting depth. The kit comes with arbors for hand held or drill press.

Terry

 

[whistlepig]

High speed steel bits for mild steel. Cobalt for stainless steel. Cobalt is very brittle and chips easily. Titanium nitride is just a coating. Works great until the coating wears off. And that doesn't take long. When the titanium nitride wears off it's just another high speed drill bit. Carbide tipped for cast iron and concrete.

 

[whistlepig]

Cleveland makes the best drill bits. Not cheap but they are the best.

 

[newbury]

Cobalt bits and chainsaw oil if the piece being cut is not horizontal. That way the oil sort of sticks around.

/edit - and DEFINITELY as larry below points out GO SLOW, heat is bad.

 

[SPYDERLK]

Stepping up sizes in small steps can cause trouble because the drill bits have a tendency to catch. You get a LOT of benefit from just a small pilot hole to help the larger point penetrate. ... For 5/8 in mild steel I use a pilot no larger than 1/4 and then go straight to the final size. If you have the means, spin the big bit slowly. ... 200 rpm or less.
larry

 

[flusher]

I am confused on all these different types if bits for steel and woos and plastic. I need to get a 5/8 hole through 3/8 steel. I kinda get the stepping up but I really don't get cobalt vs titanium vs neobonium or whatever the latest flavor is.

And who is the higher quality manufacturers?

I have several 5/8" cobalt twist drills that I use successfully on steel plate like the stuff your drilling. My drill press is a Rigid floor model from Home Depot (1/2" chuck).

For larger holes I use Milwaukee bi-metal hole saws (the ones painted white at your hardware store). They work fine. Just be sure to clamp the work piece securely to the drill press table and use a lot of cutting fluid.

Good luck

 

[LD1]

Stepping up sizes in small steps can cause trouble because the drill bits have a tendency to catch. You get a LOT of benefit from just a small pilot hole to help the larger point penetrate. ... For 5/8 in mild steel I use a pilot no larger than 1/4 and then go straight to the final size. If you have the means, spin the big bit slowly. ... 200 rpm or less.
larry

Beat me to it.

When you step bits up, you are only cutting with a small portion of the bit (the outer tip). AND the way bits are made, the further out you go, the more angle of attack they have. So it tries even harder to bite in. And usually results in grabbing and twisting the drill out of your hand, chipping the tips of the edge, and if using a S&D bit (reduced shank), it is likely to bend the bit.

Most Bits over 1/2" are NOT split point bits. Rather they are Chisel tip. Use a pilot only as big as the chisel. (usually around 1/4"). This will give the best results.

Ditto on Cleveland being good bits. Chicago-Latrobe (C-L), Precision twist drill (PTD), Hertel, and Morse are also good bits. There are more, but these are mainly what you see in any metal working or machine shop.

 

[woodlandfarms]

I know people talk about Hole Saws but for me they have not been successful. They cut, but when they where out there is no recourse on sharpening. What am I missing with the use of a hole saw?

 

[k0ua]

I know people talk about Hole Saws but for me they have not been successful. They cut, but when they where out there is no recourse on sharpening. What am I missing with the use of a hole saw?

Oh, I think you are right, but the trick is to buy very good quality ones to start with so they last longer, and to spin them slowly and with lotsa lube so they last longer. I have a Bosch set the wife bought me a long time ago, and I have used them quite a bit, and they are all still good. By the way that gift beat the heck out of a bunch of ties or something like that.

 

[downsizingnow48]

I use bimetal hole saws for holes larger than 1". Get a good brand, use lots of cutting oil, and turn at a slow speed (150-200rpm). In mild steel it will last a fair while. Pull it out of the cut and clean out the chips frequently, otherwise the blade gets too hot, because it does not eject chips very well when fully into the steel. For sharpening, it is just like a hand saw bent into a circle and can in principle be sharpened the same way. But that is tedious and not easy to do well.

For holes 7/16 to 1 1/16 I use the previously mentioned annular cutters (high speed steel). Big Barn showed them in a drill press. See below for lathe.

 

[Big Barn]

I know people talk about Hole Saws but for me they have not been successful. They cut, but when they where out there is no recourse on sharpening. What am I missing with the use of a hole saw?

Like the other members mentioned, use quality hole saws and lower speeds. Use your compressor to direct a stream of air to keep saw cooler and to help clear chips.

Terry

 

[LD1]

I too am in the camp of not having much luck with hole saws. Especially for a measly 5/8" hole. And especially in thicker stuff.

No way would I want to use a hole saw in 1/2" + material. Especially for holes under 1" diameter. But then again, I have always had access to good drillpresses, mills, lathes, mag drills, etc.

The OP is talking a 5/8" hole in 3/8" steel. Not sure bout a hole saw, but a with a 1/4" pilot and a good 5/8" twist drill, should take no more than about 20 seconds to make a hole.

 

[nc redneck]

I have had good luck with a drill doctor on 1/4 inch and above bits. Are they as good as new NO. Will they cut steel yes, and do a good job. If you you use them in a drill press I doubt you can tell they have been sharpened. I buy smaller bits in 10 pack from Amazon or Ebay.
I no longer want to buy a new drill bit set 1/8 to 1/2 every time I go to store. Trying to use up some of the 100s I have.
If I have a stainless steel project I do buy new dewalt bits.
I do not have the ability or training to sharpen on bench grinder as some have here. Oil and slow speed are your best bet.