Lets talk drill bits

[l_bilyk]

Okay i know the basics. I think

HSS - general purpose, wood
Titanium coated - general purpose, less heat buildup
Zirc - similar to titanoum, but more durable
cobalt penetrated - general purpose metal
cobalt - best for stainless steel etc.

Did i miss anything? Do you have recommendations as far as brand names go?

 

[dink]

Hi-molybdenum Steel

This handles Stainless & Hard steel
Wood
Plastic

 

[Uncle Buck]

Best brands are, Greenfield, Cleveland and I think Triumph is also a good brand.

 

[dink]

Actually it really doesnt matter as long as they aren't made in China....unless your getting into very job specific style bit

 

[bmwpower]

Which ones need to be used with cutting oil?

 

[OldCarGuy]

Drilling coolant

When drilling into most metals it is best to use water mixed with soluble oil. The mixture looks like milk and will cool the drill bit and work better than oil. Plus the heat produced will cause oil to give off a lot of undesirable smoke.

 

[bmwpower]

When drilling into most metals it is best to use water mixed with soluble oil. The mixture looks like milk and will cool the drill bit and work better than oil. Plus the heat produced will cause oil to give off a lot of undesirable smoke.

Hmmm... I would think you wouldn't want water as the water will boil at a lower temperature than the oil.

 

[dink]

Water will work fine as long as its hitting the bit fine....because air is going through the water as it hits the bit and that helps keep the water cool

 

[kartracer55]

I dont know where this whole "you can only drill steel with cobalt" myth came from. You can drill steel with regular old HSS bits, they simply wont retain thier cutting edge as long as cobalt will.

Whats more important than the material of the bit is being able to sharpen it, be it by hand or drill doctor. This way, you can buy an expensive set of HSS bits that cover a full range for 200$ instead of thier coblat counterparts for 500$ because you know how to sharpen them.

What are you looking for? Just good general purpose bits that can handle steel? Go with DeWalt cobalt bits. If your looking for production or super precision, go with a more expensive set. Im partial to Chicago Latrobe because I can get them locally. You can have the best drill bits in the world but it doesnt mean sh....**** if you dont match the speed to the bit and use cutting oil on materials needed.

Jim

 

[OldCarGuy]

Mist coolant

A spray mist coolant system works rather well when production drilling as well as milling and will not cause a flood all over the floor. http://www.discount-tools.com/catalogs/gen/1037.pdf However for most work I just use a home pump spray bottle filled with water coolant.

 

[REFLEXX]

gents,

I use drills every day. My faves are PTD (Precision Twist Drill) 135 degree, split point, stubby length, cobalt drills.

Stubby length drills are shorter and therefore more rigid. The do not need a center drill when used in a mill or drill press. The 135 degree angle makes them very effective on alum and steel.

I have a set of numbers, fractions and letters. I use them 90% of the time.

If you're looking for drills to use in a hand drill, at odd angles, into the frames of cars or in a "fab" environment, then any good American Made drills will work. I've seen enough Chinese piece-o-chit drills break or not even spin true!!!

Certain things you should not compromise.

AND always wear your safety glasses, it's $3 insurance against blindness and high medical bills.

 

[Elroy]

gents,

I use drills every day..........( and so does Elroy)...........

Stubby length drills are shorter and therefore more rigid. The do not need a center drill when used in a mill or drill press. The 135 degree angle makes them very effective on alum and steel.

Elroy was wondering if geometry was ever going to be mentioned. Steel is very important no doubt but so is the geometry of the edge and flutes. A stub drill as pointed out, is also more rigid. THAT has a big influence on productivity.

As far a fluids go: Elroy prefers "Tap Magic" especially on Stainless. AND when you do drill Stainless, make sure you cut from the get go with a sharp tool. If it work hardens you'll never get it drilled regardless of what kind of fluid your using.

AND always wear your safety glasses, it's $3 insurance against blindness and high medical bills.

AND that is the best advise!

 

[REFLEXX]

Elroy,

I'll also add that faster is NOT better when drilling. Steady, but good pressure. Nice size chips, not dust, not foot long pigtails.

and don't ever grab a long, stringy chip to clear it out of the way. I drove a buddy to the hospital for slicing three fingers to the bone. Use pliers and stop the damn machine.

I use water soluable oil, AKA "milk" as mentioned above.

For tapping it's Alumtap for alum (obviously), for steels it s Moly Dee.

 

[MXtras]

I have always said that when drilling, the attention should be to make a good chip - the hole is the by-product.

Using "coolant" is almost unneccessary. If the chip is formed properly and the speed and feed are good, the chip will take most of the heat with it. Coolant will help keep the heat from building in your part or in the tooling on long tool cycles. Cutting fluid helps reduce friction, but not where the cutting is occuring - it helps lubricate the chip in the flutes and provides a barrier to keep the hot chip from transfering heat to the flute. - think about it - how is any cutting fluid going to reach under the chip to actually get to the cutting edge? It doesn't. It lubricates the land areas and face of the flutes and the keeps the chip moving along.

I rarely use either coolant or oil for drilling steel. I will use fluid for drilling aluminum to keep the AL from galling in the flutes. I always use a sharp drill. The drill should not be hot after drilling a hole most of the time - if it has adequate clearance and is sharp, it will be slightly warm from chip friction, but it should not be hot. If so it is either dull, has inadequate clearance, you are spinning it too fast or you are feeding too aggressively. There are a lot of situations that will cause a drill to get hot - I know - but generally speaking it should remain handleable after drilling - without coolant.

Go as slow as you can to make a curly, silver chip. If the chip is blue or black, back off on the pressure. If it is not curly or stringy, back off on the RPM or increase pressure. If the drill is squealing, back WAY off the RPM, sharpen the drill properly or get someone else to make the hole for you.

Make the chip and the hole will be there.

Scott

 

[l_bilyk]

I dont know where this whole "you can only drill steel with cobalt" myth came from. You can drill steel with regular old HSS bits, they simply wont retain thier cutting edge as long as cobalt will.

Whats more important than the material of the bit is being able to sharpen it, be it by hand or drill doctor. This way, you can buy an expensive set of HSS bits that cover a full range for 200$ instead of thier coblat counterparts for 500$ because you know how to sharpen them.

What are you looking for? Just good general purpose bits that can handle steel? Go with DeWalt cobalt bits. If your looking for production or super precision, go with a more expensive set. Im partial to Chicago Latrobe because I can get them locally. You can have the best drill bits in the world but it doesnt mean sh....**** if you dont match the speed to the bit and use cutting oil on materials needed.

Jim

I think i'd like to buy one of those big sets with all the in-between sizes for the odd time that i have to tap something

 

[eschoendorff]

I have always said that when drilling, the attention should be to make a good chip - the hole is the by-product.

Using "coolant" is almost unneccessary. If the chip is formed properly and the speed and feed are good, the chip will take most of the heat with it. Coolant will help keep the heat from building in your part or in the tooling on long tool cycles. Cutting fluid helps reduce friction, but not where the cutting is occuring - it helps lubricate the chip in the flutes and provides a barrier to keep the hot chip from transfering heat to the flute. - think about it - how is any cutting fluid going to reach under the chip to actually get to the cutting edge? It doesn't. It lubricates the land areas and face of the flutes and the keeps the chip moving along.

I rarely use either coolant or oil for drilling steel. I will use fluid for drilling aluminum to keep the AL from galling in the flutes. I always use a sharp drill. The drill should not be hot after drilling a hole most of the time - if it has adequate clearance and is sharp, it will be slightly warm from chip friction, but it should not be hot. If so it is either dull, has inadequate clearance, you are spinning it too fast or you are feeding too aggressively. There are a lot of situations that will cause a drill to get hot - I know - but generally speaking it should remain handleable after drilling - without coolant.

Go as slow as you can to make a curly, silver chip. If the chip is blue or black, back off on the pressure. If it is not curly or stringy, back off on the RPM or increase pressure. If the drill is squealing, back WAY off the RPM, sharpen the drill properly or get someone else to make the hole for you.

Make the chip and the hole will be there.

Scott

I wish someone would've told me that a long time ago! Great write up!!!!!

 

[zeebad1]

These are guaranteed for life.

http://www.irwin.com/irwin/consumer...B3MCQHUBSCHPQKA4QHQJCK?prodId=IrwinProd440048

and they work very well too. I just sent in 8 bits that were not broken, but dull, and will receive replacements in about 2 weeks - NO CHARGE! I have doubles of most of the sizes so I'm not without bits while being replaced.