Good drill bits

[Garandman]

Been using a variety of Harbor Fright and Home Depot purchased drill bits. Then had to drill some stainless fixtures and learned how poor they were.

What is a good fractional drill bit set, 1/64th to 1/2"? Do cobalt steel bits hol up better than Titanium nitride?

 

[Mendonsy]

Check with a local industrial supply to see what they have. Good sets like Chicago-Latrobe will be expensive.
Cobalt will generally hold up better than TIN. The secret to drilling stainless is slow speeds, high pressure, and lots of cutting oil to keep the bit cool.

 

[Snobdds]

I learned my lesson a long time ago with stainless steel...take it to the machine shop and have them punch the holes on an iron worker. So much less aggravation and frustration.

Nothing short of diamond tipped bits work on stainless, "efficiently".

 

[Tractor Seabee]

I found out that a small pilot hole helps drilling stainless. We always used liberal amounts of kerosene as a lubricant with both bits and hole saws. Even high grade bits have a hard time. Several holes and they are dull, hole saws are usually one time use if the stock is thick. A drill press with steady pressure woks better than hand held drill motors. I retired from the trade before plasma cutters were common. Does anyone have experience using that process on SS?

Ron

 

[Garandman]

I learned my lesson a long time ago with stainless steel...take it to the machine shop and have them punch the holes on an iron worker. So much less aggravation and frustration.

I got the pilot holes drilled (using a small drill press) and some of the larger ones. Think the speed was right, and used cutting fluid.

These are the bits I plan to buy unless anyone suggests something better.

29 Piece Cobalt M-35 Metal Index Drill Bit Set - Tools - IRWIN TOOLS

 

[fried1765]

I got the pilot holes drilled (using a small drill press) and some of the larger ones. Think the speed was right, and used cutting fluid.

These are the bits I plan to buy unless anyone suggests something better.

29 Piece Cobalt M-35 Metal Index Drill Bit Set - Tools - IRWIN TOOLS

The Irwin Cobalt M-35 sets are decent.
I have two sets, and they have held up well, though I only give them very occasional use.
You might want to also consider a "Drill Doctor", if you use your bits a lot.

 

[ArlyA]

Stainless is tough on bits. Oiling them helps and so does drilling slower. (less down force) Using Cobalt alloy bits may help but if it was me, I'd just assume that bits will be tore up doing this project. You didn't say the size holes your doing but pilots holes will certainly help as well.

 

[SpringHollow]

Maybe I have been lucky but I so far have not had problems drilling stainless using good American made drill bits, slow speed, high pressure, and cutting fluid. Fast speed and the bits are toast.

Ken

 

[SPYDERLK]

Maybe I have been lucky but I so far have not had problems drilling stainless using good American made drill bits, slow speed, high pressure, and cutting fluid. Fast speed and the bits are toast.

Ken

This is where Id focus. ^^^

Garandman, since you have a drill press [and therefore good control] the cobalts are an option. But quite expensive as a set. You may want to look at buying just the sizes you need:​

McMaster-Carr

They will generally have the best quality bits in all types. Standard black oxide coated HS steel is rated for Stainless​

Are your holes being made in sheet metal?

BTW, I have found that Chinese bits are soft. Even the TiN coated dull readily when drilling Gr8 steel, Whereas std American black oxide holds up.​

 

[downsizingnow48]

I get all my drill bits from McMaster Carr in the sizes and types needed.

 

[17 Oaks]

As per others X2.

Cobalt or HSS, cutting oil is your friend and cheap, slow speed...high pressure, not sure what high pressure is? That said apply pressure to insure a good drill is taking place but watch for heat buildup that can be your enemy in a hurry. Cutting fluid also helps keep it cool. To hot to touch is to hot...

 

[1965]

Drill bits meant for stainless steel are cut at a different, less an angle than regular steel bits.

 

[SpringHollow]

As per others X2.
.high pressure, not sure what high pressure is? That said apply pressure to insure a good drill is taking place but watch for heat buildup that can be your enemy in a hurry.

By high pressure, I mean enough force so that you are actually cutting into the metal making decent chips. I see way too many people basically letting the bit spin against the metal just work hardening the metal from the heat.

 

[woodlandfarms]

And what is slow speed in your guys books?

 

[Mendonsy]

Well ..... slow depends on what you are using to drill the hole, but in general the slower you can go the better. With my drill press I can get speeds down below 50 rpm, with a hand drill it is probably more like 150 rpm.

 

[SpringHollow]

The slower the better. 300 RPM I consider to be faster than what I desire.

 

[SPYDERLK]

And what is slow speed in your guys books?

With 1/4" -- 3-500rpm. With 1/2" -- 1 - 200. The point made that you be sure you are making steady progress is paramount. Never allow the bit to "rub" on the bottom of the hole. This not only dulls the bit but hardens the metal youre trying to cut.

BTW, pilot holes should be small. Just enuf to accept the larger drills web dimension. -- For example, 3/16 pilot or a little less would be right for 1/2"​

Otherwise you get chatter and grab effects.

 

[SpringHollow]

Look up Cole Drill. I have a couple of those. It is not hard to drill a 1" hole in 1" plate with one of those even though the drill bit is spun by hand.

 

[ruffdog]

Stick with HSS bits, and extra coatings are more for production uses. Basic steels can have 300-600 FPM cutting speed while a 304 stainless is 200-350 FPM. Aluminum is 1500-3000 FPM. Look to stay at the lower speeds with simple machines. Using a lube that fights friction is not good for working with SS (like motor oil). A high sulfur cutting oil would be better. As others have said: try to limit the time the drill "rubs" vs cutting....keep a chip load going. Basically, run the drill slower and keep the pressure on to keep the chips coming. When you release the pressure to break the chip, do it quickly, then, get cutting quick....no just spinning and rubbing.

 

[Big Barn]

I picked up this digital tachometer from ebay. Works surprisingly alright.