Noob question, but why do I need five of these bits? It seems like you could get all the increments with one or two.

You don't "need" any of these bits. Both, my...another family member and I purchased these as the touting of cobalt, titanium, and High Speed Steel bits made us both believe they were a steal of a steel deal. Boy we couldn't have been more wrong! These are absolute garbage. AGAIN THESE ARE ABSOLUTE GARBAGE BITS. I've got a free pocket knife from a gas station that drills better. Shavings from the first time we used these bits were put in the MassSpec at his showed NO cobalt at all present. For those that don't know a mass spectrometer gives you a breakdown of the molecules and elements present in a sample. Upon my complaining to the seller, I was told well.... "They're only cobalt colored and aren't intended for use on steel or hard metal alloys." You buy a cobalt %containing bits to handle the higher frictional heats encounters when cutting/drilling tougher steel alloys, stainless, or even just wanting your High Speed Steel bits to last longer. It's so your bit doesn't take damage and be destroyed or worse yet damage the piece you're drilling (especially when you're using tapping fluid too to lubricate the cutting edges reducing that friction and subsequent damaging heat) and M42 is the highest grade of cobalt bits I have & that I know of / have used. You buy titanium bits from M7 (high molybdenum for toughness) to M35 (HSS with a 5% titanium component) or the king of titanium bits and heat dissipation (HSS with 8% titanium) so your bits won't be damaged to the point they're unable to be used again. These high end bits you pay for ones made right. There are proper recipies the boundaries mix up molten of all the components from the iron and nickel of base steel, to adding molybdenum for toughness, cobalt for thermal resilience, titanium coatings to reduce friction, and many many more components in a bakery for steel. These bits are beyond poorly made and are NOT good moreless decent bits. So I'll reiterate fro my own and others experience, THESE ARE JUNK AND YOU DONT "NEED" THEM.....well unless you need to drill holes in pure Gallium at ambient temperatures above 30°C. And just a FYI I have 1/8" M42 aircraft legnth bits that'll drill through a 10" hardened steel block and a 1.0" M42 bit that could just about drill aluminum foil without tearing it. Size has nothing to do with quality. Small bits for small sheets and big bits for big sheets is a cop out answer to make the customer think they're the problem in how they're using the bits. The bits are crap and the Seller sends different answers to different people. They're garbage bits from cheap garbage metal (I hesitate to even call them true steel)

Are these bits titanium or cobalt? The product description shows both titanium & cobalt.

You don't "need" any of these bits. Both, my...another family member and I purchased these as the touting of cobalt, titanium, and High Speed Steel bits made us both believe they were a steal of a steel deal. Boy we couldn't have been more wrong! Destroyed 1st use at slow speed off the speed chart and using tapping fluid to lubricate. These are absolute garbage. AGAIN THESE ARE ABSOLUTE GARBAGE BITS. I've got a free pocket knife from a gas station that drills better. Shavings from the first time we used these bits were put in the MassSpec at his showed NO cobalt at all present. For those that don't know a mass spectrometer gives you a breakdown of the molecules and elements present in a sample. Upon my complaining to the seller, I was told well.... "They're only cobalt colored and aren't intended for use on steel or hard metal alloys." You buy a cobalt %containing bits to handle the higher frictional heats encounters when cutting/drilling tougher steel alloys, stainless, or even just wanting your High Speed Steel bits to last longer. It's so your bit doesn't take damage and be destroyed or worse yet damage the piece you're drilling (especially when you're using tapping fluid too to lubricate the cutting edges reducing that friction and subsequent damaging heat) and M42 is the highest grade of cobalt bits I have & that I know of / have used. You buy titanium bits from M7 (high molybdenum for toughness) to M35 (HSS with a 5% titanium component) or the king of titanium bits and heat dissipation (HSS with 8% titanium) so your bits won't be damaged to the point they're unable to be used again. These high end bits you pay for ones made right. There are proper recipies the boundaries mix up molten of all the components from the iron and nickel of base steel, to adding molybdenum for toughness, cobalt for thermal resilience, titanium coatings to reduce friction, and many many more components in a bakery for steel. These bits are beyond poorly made and are NOT good moreless decent bits. So I'll reiterate fro my own and others experience, THESE ARE JUNK AND YOU DONT "NEED" THEM.....well unless you need to drill holes in pure Gallium at ambient temperatures above 30°C. And just a FYI I have 1/8" M42 aircraft legnth bits that'll drill through a 10" hardened steel block and a 1.0" M42 bit that could just about drill aluminum foil without tearing it. Size has nothing to do with quality. Small bits for small sheets and big bits for big sheets is a cop out answer to make the customer think they're the problem in how they're using the bits. The bits are crap and the Seller sends different answers to different people. They're garbage bits from cheap garbage metal (I hesitate to even call them true steel) see less

How good is the quality?

You don't "need" any of these bits. Both, my...another family member and I purchased these as the touting of cobalt, titanium, and High Speed Steel bits made us both believe they were a steal of a steel deal. Boy we couldn't have been more wrong! They were destroyed the first time used. Following the slow speed on the charts for the 2 steels and using tapping fluid to lubricate. These are absolute garbage. AGAIN THESE ARE ABSOLUTE GARBAGE BITS. I've got a free pocket knife from a gas station that drills better. Shavings from the first time we used these bits were put in the MassSpec at his showed NO cobalt at all present. For those that don't know a mass spectrometer gives you a breakdown of the molecules and elements present in a sample. Upon my complaining to the seller, I was told well.... "They're only cobalt colored and aren't intended for use on steel or hard metal alloys." You buy a cobalt %containing bits to handle the higher frictional heats encounters when cutting/drilling tougher steel alloys, stainless, or even just wanting your High Speed Steel bits to last longer. It's so your bit doesn't take damage and be destroyed or worse yet damage the piece you're drilling (especially when you're using tapping fluid too to lubricate the cutting edges reducing that friction and subsequent damaging heat) and M42 is the highest grade of cobalt bits I have & that I know of / have used. You buy titanium bits from M7 (high molybdenum for toughness) to M35 (HSS with a 5% titanium component) or the king of titanium bits and heat dissipation (HSS with 8% titanium) so your bits won't be damaged to the point they're unable to be used again. These high end bits you pay for ones made right. There are proper recipies the boundaries mix up molten of all the components from the iron and nickel of base steel, to adding molybdenum for toughness, cobalt for thermal resilience, titanium coatings to reduce friction, and many many more components in a bakery for steel. These bits are beyond poorly made and are NOT good moreless decent bits. So I'll reiterate fro my own and others experience, THESE ARE JUNK AND YOU DONT "NEED" THEM.....well unless you need to drill holes in pure Gallium at ambient temperatures above 30°C. And just a FYI I have 1/8" M42 aircraft legnth bits that'll drill through a 10" hardened steel block and a 1.0" M42 bit that could just about drill aluminum foil without tearing it. Size has nothing to do with quality. Small bits for small sheets and big bits for big sheets is a cop out answer to make the customer think they're the problem in how they're using the bits. The bits are crap and the Seller sends different answers to different people. They're garbage bits from cheap garbage metal (I hesitate to even call them true steel) see less

Would this work on hardened steel?

You don't "need" any of these bits. Both, my...another family member and I purchased these as the touting of cobalt, titanium, and High Speed Steel bits made us both believe they were a steal of a steel deal. Boy we couldn't have been more wrong! They were destroyed the first time we used them; at slow speed following the reccomend speed charts for the metal with a cobalt bit, and using tapping fluid to lubricate the whole time. I returned my set and wish we hadn't thrown out the messed up ones. We had to buy all new material with the damage these bits did not cutting correctly coming off center and edges disentigrating. These are absolute garbage. AGAIN THESE ARE ABSOLUTE GARBAGE BITS. I've got a free pocket knife from a gas station that drills better. Shavings from the first time we used these bits were put in the MassSpec at his showed NO cobalt at all present. For those that don't know a mass spectrometer gives you a breakdown of the molecules and elements present in a sample. Upon my complaining to the seller, I was told well.... "They're only cobalt colored and aren't intended for use on steel or hard metal alloys." You buy a cobalt %containing bits to handle the higher frictional heats encounters when cutting/drilling tougher steel alloys, stainless, or even just wanting your High Speed Steel bits to last longer. It's so your bit doesn't take damage and be destroyed or worse yet damage the piece you're drilling (especially when you're using tapping fluid too to lubricate the cutting edges reducing that friction and subsequent damaging heat) and M42 is the highest grade of cobalt bits I have & that I know of / have used. You buy titanium bits from M7 (high molybdenum for toughness) to M35 (HSS with a 5% titanium component) or the king of titanium bits and heat dissipation (HSS with 8% titanium) so your bits won't be damaged to the point they're unable to be used again. These high end bits you pay for ones made right. There are proper recipies the boundaries mix up molten of all the components from the iron and nickel of base steel, to adding molybdenum for toughness, cobalt for thermal resilience, titanium coatings to reduce friction, and many many more components in a bakery for steel. These bits are beyond poorly made and are NOT good moreless decent bits. So I'll reiterate fro my own and others experience, THESE ARE JUNK AND YOU DONT "NEED" THEM.....well unless you need to drill holes in pure Gallium at ambient temperatures above 30°C. And just a FYI I have 1/8" M42 aircraft legnth bits that'll drill through a 10" hardened steel block and a 1.0" M42 bit that could just about drill aluminum foil without tearing it. Size has nothing to do with quality. Small bits for small sheets and big bits for big sheets is a cop out answer to make the customer think they're the problem in how they're using the bits. The bits are crap and the Seller sends different answers to different people. They're garbage bits from cheap garbage metal (I hesitate to even call them true steel) see less

Manufacturer	CO-Z
Part Number	CO-Z SDB-0000
Item Weight	1.14 pounds
Product Dimensions	4.33 x 1.57 x 6.1 inches
Country of Origin	China
Item model number	CO-Z SDB-0000
Is Discontinued By Manufacturer	No
Color	Dark Bronze
Style	5PCS HSS Titanium, 50 sizes
Finish	Titanium
Material	High Speed Steel, Titanium, Cobalt
Item Package Quantity	1
Measurement System	Inch
Batteries Included?	No
Batteries Required?	No

ZELCAN Step Drill Bits, HSS 5PCS Titanium Step Drill Bit Set, 50 Sizes in 5 High Speed Steel Unibit Drill Bits Set for Sheet Metal with Aluminum Case, Multiple Hole Stepped Up Bits for DIY Lovers

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