We have gotten a lot of questions about how to tell carbide drill bits from steel drill bits and all other types of drill bits…and the answer is not always that easy. Let’s break down the different types of drill bits that you could come across not only in machine shops but in everyday applications and even your garage!
What are Carbide Bits?
These are the “best of” drill bits because of not only their value but their longevity. These will have a very slight magnetic pull to them, but should not stick to a magnet. They will have a darker dull grey color and will be very dense when compared to other types of drill bits, even compared to M2 or other tool steel. Carbide is known for holding the cutting edge both on the drill bits and also finish the cut much better than other methods…thus the reasons that machine shops love it.
How Hard is Carbide?
Great question! Maybe some of you remember the Moh Scale of Hardness from your 8th-grade science class. If you do remember it, you will remember that it goes from 0 to 10 with 0 equaling something like talc (chalk) and 10 equaling a Diamond. Well, carbide comes in around a 9-9.5 and that just shows how strong and hard of an alloy that it really is.
Carbide is one of the holy grails for scrappers, and to find it means that you will get a big cash in, but the problem is that you cannot just stumble upon it. Carbide is generally found in the machining industry and over the years prices have always been very strong…especially when compared to aluminum or brass.
Carbide generally only has one grading but could have the prices decreased due to a few different factors.
- Carbide with brazing – This means that the carbide could have some type of copper or zinc coating on it and because it will be combined with other metals, it will be devalued.
- Carbide with steel – This could but something like a road milling bit where only the carbide tip is attached to a piece of steel. These are used when chewing up old asphalt for repaving projects as well as used to cut through stones in quarry’s and when digging foundations.
- Tantalum Carbide – While very rare, there are applications known to use carbide mixed with some level of Tantalum to increase the amount of heat that the metal can take in.
Tool Steel Vs. Regular Steel Bits
Tool steel will generally have a few different things going for it versus the normal over-the-counter drill bit.
Compare M2 Drill bits to a regular black oxide steel drill bit from your basic hardware store is like comparing prescription painkillers to an over the counter painkiller like Advil. Both will get the job done, but the one that will work better is probably the prescription one with a higher dosage…just like the M2 drill bit with a higher amount of carbon steel that has a higher heating point overall.
Tool steel will have a higher scrap value as well and should have small markings on the bit to tell you what grade of steel or drill bit that it is.
Coatings on Drill Bits
Many bits may be coated or have tips of a better metal then the majority of the bit itself…and some will ask if that means that it is worth more. For example, there is a drill bit that may be coated or tipped with titanium, and while that may be sexy on the packaging, the scrap value will not be increased by it.
How to Really Know Grading
It is not always easy to look at drill bits (especially if you are new to this) and know what the grade is or how to sell it. Look at this list of different types of High-Speed Steel that you could have:
- M1, M7, M10, M30, M33, M34, M42, M43, M46, M47, M2, M3, M4, M6, M14, M35, M36, M41, M44, M45.
The question isn’t where to start…but who to sell and will that scrap yard know the difference in pricing on these different grades.
Overall tool steel and carbide should be more cut and dry, but that is not the case. Looking at them the easiest way to know whether it is a high-speed steel or a carbide product will be the magnet test. If you use a magnet that has a hard stick and immediately pulls the bit up…chances are that that is NOT a carbide. Carbide will only have a slight pull so you really have to be careful to get the right one.
The Rust Factor
Carbide does not rust. That is the entire thing you have to remember…so if there is any rust on the bits or tips that is a tell-tale sign that the bit or tip is actually steel. That will be a tell-tale sign that you do or do not have carbide.
Let us know if you have any other questions or other tips that we could add and share with other scrappers!