jeepsr4ever
01-30-2004, 04:05 PM
High speed steel is good for anything from wood to titanium, why titanium you ask...its beacuse the high speed steel takes te heat where carbide will cause work hardening and snap a drill very fast if the piece gets warm. Their are alot fo variables on this one but high speed steel is a great general purpose steel for drilling/milling
Cobalt~ cobalt is a very tough material but extremely brittle and when mixed with HSS it creates a very tough drill second only to carbide good for everything from wood to harder steels
Carbide~ there are many different types of carbide with micrograin carbide being the toughest and couple this with coarbonitrate titanium and other titanium coatings and you have a very formidable drill that is capable of drilling most any material, Concrete drills use carbide tips and hardened steel bodies with the carbide brazed on the body, this provides a very tough drill that can take the pounding and not chip out. Carbide drills are usually 3 times heavier than HSS
Diamond~ Diamond is used for cutting concrete and for holding tight tolerances in high speed machining of aluminum and softer metals, When i was at 3M they actually invented a machine that makes industrial grade diamonds, it was so efficient that GE asked them to stop producing diamonds. The Machine that looks like a alien bomb still sits in a dusty room to this day at 3M's center in Oakdale MN. Diamond or diabide is coated onto drills and adds a very thin layer of diamond buildup that last a long time in abrasive conditions. Diabide cannot take heat and the coating crumbles off when cutting harder metals.....its kind of a bummer we can use diamond on our cutters but cant cut anything hard. Also industrial diamonds are used on concrete blades and are visible by little black dots and raised dots on the blade.
Drills come in many different sizes and qualities with chinese drills leading the pack of cheap disposable drills that dont hold an edge very long, so is true for carbide and cobalt drills, you get what you pay for..usually if you go to JandLindustrial.com theylists all their tools as either import or domestic. Machinists know the difference between import and domestic tooling` Import tooling wears out too fast but is a great substitute when setting up a production job where you may break a tool or 2.
Also drill technology has come a long way, companies likeAllied offer a psade drill that takes a insert made out of micrograin carbide and coated for the application. these drills are sweet but arent for your average consumer. Here is a little info if you are going to sharpen your own drills at home
1. 118 degrees is your standard drill tip angle
2. 135 degrees is usually used on a split point drill where you are not using a center drill to start the hole.
3. Keep in mind the relief on the top of the drill and on the side!!
4. Drills usually are only sharpened 8-10 times in a machine shop as the inner web gets thicker and is tapered the drill looses alot of efficiency
5. Drills are also prone to the side flutes wearing, it is possible to resharpen a drill and it may look good but not leave a good finish in thehole or leave a galled or reduced diameter.
6. Remeber that you can sharpen a drill back to spec but if you spin the drill in your chuck youve probly damaged the shank and the drill will not hold a on center rotation with a damaged shank.
good luck with your drills guys and if your hand drilling with a old drill make sure your bracing yourself or slow down at the end of the hole
Cobalt~ cobalt is a very tough material but extremely brittle and when mixed with HSS it creates a very tough drill second only to carbide good for everything from wood to harder steels
Carbide~ there are many different types of carbide with micrograin carbide being the toughest and couple this with coarbonitrate titanium and other titanium coatings and you have a very formidable drill that is capable of drilling most any material, Concrete drills use carbide tips and hardened steel bodies with the carbide brazed on the body, this provides a very tough drill that can take the pounding and not chip out. Carbide drills are usually 3 times heavier than HSS
Diamond~ Diamond is used for cutting concrete and for holding tight tolerances in high speed machining of aluminum and softer metals, When i was at 3M they actually invented a machine that makes industrial grade diamonds, it was so efficient that GE asked them to stop producing diamonds. The Machine that looks like a alien bomb still sits in a dusty room to this day at 3M's center in Oakdale MN. Diamond or diabide is coated onto drills and adds a very thin layer of diamond buildup that last a long time in abrasive conditions. Diabide cannot take heat and the coating crumbles off when cutting harder metals.....its kind of a bummer we can use diamond on our cutters but cant cut anything hard. Also industrial diamonds are used on concrete blades and are visible by little black dots and raised dots on the blade.
Drills come in many different sizes and qualities with chinese drills leading the pack of cheap disposable drills that dont hold an edge very long, so is true for carbide and cobalt drills, you get what you pay for..usually if you go to JandLindustrial.com theylists all their tools as either import or domestic. Machinists know the difference between import and domestic tooling` Import tooling wears out too fast but is a great substitute when setting up a production job where you may break a tool or 2.
Also drill technology has come a long way, companies likeAllied offer a psade drill that takes a insert made out of micrograin carbide and coated for the application. these drills are sweet but arent for your average consumer. Here is a little info if you are going to sharpen your own drills at home
1. 118 degrees is your standard drill tip angle
2. 135 degrees is usually used on a split point drill where you are not using a center drill to start the hole.
3. Keep in mind the relief on the top of the drill and on the side!!
4. Drills usually are only sharpened 8-10 times in a machine shop as the inner web gets thicker and is tapered the drill looses alot of efficiency
5. Drills are also prone to the side flutes wearing, it is possible to resharpen a drill and it may look good but not leave a good finish in thehole or leave a galled or reduced diameter.
6. Remeber that you can sharpen a drill back to spec but if you spin the drill in your chuck youve probly damaged the shank and the drill will not hold a on center rotation with a damaged shank.
good luck with your drills guys and if your hand drilling with a old drill make sure your bracing yourself or slow down at the end of the hole
