I know that cobalts are for hardened steel. what about carbide?

what's harder to cut through, concrete or a grade 5 bolt? 6? 7? 8?

thanks!!

For concrete you should be using masonry drill bits on a hammer drill.
They'll have a special carbide tip.

A concrete bit doesnt drill through the material like its going through steel. It chips away small pieces and screws them out of the hole with the spiral part of the bit. I have used cheapo canadian tires bits for years and never had a problem. The only difference between a mastercrap bit and a hilti bit is how fast it drills through usually.

Also, be sure to use a hammer drill not a regular drill.

are the tips usually different (the angles used) between concrete and other materials?

found some info:

What Is The Difference Between Carbide And Diamond Bits?

Carbide bits have flutes cut into them that provide the cutting power. The more the flutes the finer the cut. A carbide bit cuts like a potato peeler leaving the surface smooth while filing it down.

A diamond bit is a shank that adhesive is applied to and it is then rolled into diamond material that dries on the shank. The diamond particles file the nails as a hand file would by scratching the surface and ultimately filing it down. The diamond particles may wear down but never looses it sharpness

from wiki:

Materials for bit construction
Titanium nitride coated twist bit
Titanium nitride coated twist bit

Many different materials are used for or on drill bits, depending on the required application.

[edit] Steels

Soft low carbon steel bits are used only in wood, as they do not hold an edge well and require frequent sharpening. Working with hardwoods can cause a noticeable reduction in lifespan. They are inexpensive when compared to other tools with a longer life.

high Carbon steel bits are made from high carbon steel and are an improvement on plain steel due to the hardening and tempering capabilities of the material. These bits can be used on wood or metal, however they have a low tolerance to excessive heat which causes them to lose their temper, resulting in a soft cutting edge.

High speed steel (HSS) is a form of tool steel where the bits are much more resistant to the effect of heat. They can be used to drill in metal, hardwood, and most other materials at greater cutting speeds than carbon steel bits and have largely replaced them in commercial applications.

Cobalt steel alloys are variations on high speed steel which have more cobalt in them. Their main advantage is that they hold their hardness at much higher temperatures, so they are used to drill stainless steel and other hard materials. The main disadvantage of cobalt steels is that they are more brittle than standard HSS.

[edit] Exotic materials

The material referred to as Tungsten carbide is extremely hard, and can drill in virtually all materials while holding an edge longer than other bits. However, due to its high cost and brittleness, it is more frequently used only in smaller pieces screwed or brazed onto the tip of the bit. It is becoming common in job shops to use solid carbide drills, and in certain industries, most notably PCB drills, it has been commonplace for a long time.

Polycrystalline diamond (PCD) is among the hardest of all tool materials and is therefore extremely wear resistant. The material consists of a layer of diamond particles, typically about 0.5 mm (0.019") thick, bonded as a sintered mass to a tungsten carbide support. Bits are fabricated using this material by either brazing small segments to the tip of the tool to form the cutting edges, or by sintering PCD into a vein in the tungsten carbide "nib". The nib can later be brazed to a carbide shaft and ground to complex geometries that cause braze failure in the smaller "segments".

PCD bits are typically used in the automotive, aerospace, and other industries to drill abrasive aluminum alloys, carbon fiber reinforced plastics and other abrasive materials, or in applications where machine downtime is undesirable.

[edit] Coatings

Black oxide is an inexpensive black coating. A black oxide coating provides heat resistance and lubricity, as well as corrosion resistance. These result in a longer drill life than the typical uncoated high-speed steel drill.

Titanium nitride (TiN) is a very hard ceramic material, and when used to coat a high-speed steel bit (usually twist bits), can extend the cutting life by three or more times. A titanium nitride bit cannot properly be sharpened, as the new edge will not have the coating, and will not have any of the benefits the coating provided.

Titanium aluminum nitride (TiAN) is another coating frequently used. It is considered superior to TiN and can extend tool life five or more times.

Titanium carbon nitride (TiCN) is another coating and is also superior to TiN.

Diamond powder is used as an abrasive, most often for cutting tile, stone, and other very hard materials. Large amounts of heat are generated, and diamond coated bits often have to be water cooled to prevent damage to the bit or the workpiece.

Zirconium nitride has also been used as a drill bit coating for some Craftsman tools.

there was a guy at a local hardware store that had told me to go get carbide bits at brafasco. when I arrived there, they told me that carbide are for concrete drilling only. Wiki seems to state that carbide bits are harder, but doens't mention anything about a specific material. it will drill through anything that is softer than itself.

Masonry bits with a carbide tip in a hammer drill are for brick and concrete. They are too brittle to be used effectively in steel, and as they come, they are too "dull" to be used in steel. I HAVE reground masonry bits to use in steel (you can only grind them on a diamond wheel or on a silicone carbide [green] wheel), but they are not ideal. If you are trying to drill out hardened steel, there are better ways..but most require a machine shop, not hand held tools.

The coatings on regular drills are a bit of a "gimmick". I won't go so far as to say they are useless, but a good quality HSS drill bit with NO coating is about 100 times better than a "chinese HSS" drill bit with any or all of the fancy coatings. They DO make a difference if you are using the drill bit in a high volume production application and pushing it to its limits. On the Canadian Tire drill bits, it just makes them look pretty

I've been using cobalt bits from brafasco and they have been giving me some penetration, but it is time consuming. I have gotten cobalt bits from Sears and they didn't cut (or file) like the ones I have now.

is there such a thing as a bit made from carbide, not coated with it?

what do machine shops use?

For concrete drilling it's all about the tip...
Look up TCT "tungsten carbide tip".
If you're not using a hammer drill and a masonry bit, you're doing it wrong
If you are using those, make sure the drill is set to hammer mode.

I have a hammer drill.

I am drilling hardened steel. (i think it's steel, can't be iron)

cobalt bit. would a carbide bit be better?

is there such a thing as a bit made entirely out of carbide and is it suitable for hardened steel?

what do they drill iron with?

Depends on how hard the steel is that you are drilling. In steel, you should NOT use the hammer feature of the drill. Maybe a better description of what it is you are trying to do would help.

Cast Iron can be drilled with pretty much any HSS drill.

TO answer your question, you CAN buy drills that are entirely made of carbide. They are EXPENSIVE, and I would NOT recommend using one in a hand drill. I would bet dollars to donuts you will break a very expensive drill.

If the steel is REALLY hard, there is NO WAY you will drill it. It CAN be cut with other methods, but...again, in a shop. Can the piece you are trying to drill be brought to my shop?

Yes, more info on what you're doing please. The whole time I thought you were just trying to run a cable into your house

In any case, it may help to start with a small drill bit and work your way up.

are bits made entirely of carbide more brittle than other metals?

There is a broken bolt on the front subframe (crossmember?)that needs to be removed. It welded itself to the subframe due to loose front end components with far too much play.

I've considered removing the subframe and taking it to someone better equipped to drill hardened steel (grade 7) but I'd figure I just keep at it for a little longer since I am slowly making progress
Besides, i assumed that because the subframe is awkwardly shaped, I figured it would be too difficult to mount on some type of drill press, but then again, I don't know what they would use for this.
not to mention the time to remove and replace without anything else snapping. (which I doubt)

It's just a headache and a waste of time, but I did enjoy learning about bit materials.

I plan on using a helicoil sleeve with loctite, and torque to spec. Maybe go he extra mile and have it tacked in place.

I'd like to try a carbite tip with a diamond point, but where would I get one?? are they easier to brake than cobalt ones?

I lost a couple of bolts & threads, and now my cross-member is welded on at the back (through the bolt holes).
Being a 1G FWD it's not something I ever have to remove, so no problem. Not sure about your 2G though.

I can almost GUARANTEE you will break a carbide bit. They are MUCH more brittle than a regular bit...about 100 times more brittle. I have no idea how hard grade 7 would be. Hardness is measured on the Rockwell C scale. Up to almost 50 Rockwell you can drill with a decent quality HSS or Cobalt drill bit. Personally, I don't find the Cobalt drills that much better than a good HSS drill, but in your case it might be enough to make the difference. Get a GOOD QUALITY drill from an industrial supplier, NOT a home depot or Canadian Tire drill. I would recommend either Nachi or Guhring....then you KNOW you have a good drill. You also have to run the drill at the right speed so that you are CUTTING the metal and not just rubbing it. Most electric drills run too fast for drilling a decent size hole in metal. You can put a bit of oil on the tip every little bit to help also. YOu should see actual chips coming off the drill, not just smoke. Finally, the drill CAN be resharpened, and if the metal you are cutting is fairly hard, and the drill running a little too fast, you will probably have to resharpen every few minutes..