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Knife Making Discussions A place to discuss issues related to all aspects of the custom knifemaking community. |
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#1
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drilling rpm
hi all, what rpm would you suggest i drill my titanium and SS at? im using carbide bits and drilling 3/16 and 1/8 holes.
thanks bill __________________ Cowards die many times before their deaths; the valiant never taste death but once. --Shakespeare: Julius Caesar |
#2
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With carbide, spindle speed is less important then if you were using high speed steel. You can run an 1/8 drill at 2000 revs without a problem. 3/16 you'd be safe between 1500 -1800. Just listen to your drill. If she starts screaming at ya, back off the revs. Use a lube, itl' make your tooling last longer.
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#3
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it seems like none of my bits last that long. how many holes are most people usually able to make with on bit. it seems like after a few holes i start drilling stop signs instead of holes.
bill __________________ Cowards die many times before their deaths; the valiant never taste death but once. --Shakespeare: Julius Caesar |
#4
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I run my drill at 250 rpms no matter what type of drill bit I'm using, no matter how large or small the hole, no matter what material I'm drilling AND I use a lubricant. This speed is far below what conventional wisdom suggests, especially for carbide drills but my drills last a long time and they rarely ever break. When they do break or jam it is not nearly as spectacular as it would be at a higher speed.
My preference is to use screw machine length (short and stubby) cobalt drills rather than carbide for normal drilling. I use carbide only when drilling hardened steel. Cobalt is much cheaper and much tougher (they don't chip like carbide can) ...... |
#5
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Ray is right, there is no reason to run carbide tooling on Ti or stainless. I have one carbide drill for drilling my detent hole in folder blades, and I do use carbide reams when doing my pivot and stop holes. Other than that, high speed works fine. I find Ti actually machines better with high speed steel. Just be carefull when drilling, keep your tooling cool with a lube, Ti work hardens something silly. There's a good use for your cabide drill, busting through a work hardened hole!
Rock on |
#6
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the hardware stores sells drill bits for like 1.25 and the others for 4 something is the cheap ones high speed then. seems like with them i get two holes and thats it. do you always drill pilot holes and work your way up?
bill __________________ Cowards die many times before their deaths; the valiant never taste death but once. --Shakespeare: Julius Caesar |
#7
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Always center drill every hole you plan to drill. Spend the money and order morse brand twist drills.
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#8
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are the ones in the hardware store usually not twist drills, and where can i get the morse bits
thanks bill __________________ Cowards die many times before their deaths; the valiant never taste death but once. --Shakespeare: Julius Caesar |
#9
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I don't know what you're buying at the hardware store, but usually they stock imported crap. If you go to home depot or lowes for for tooling like drills, taps, dies, stuff like that, your buying China made junk. If you get one good hole you're doing good. You need to find an industrial supply store or get a Mc Master Caar or Msc catalog and order yourself some good american made tooling. Some names to remember are Morse, Niagra, American twist drill, they'll usually specify domestic or imported. A twist drill is a standard drill you use everyday. It's just a pet peve of mine to call it a drill "bit". It's not a bit, it's a drill. The devise that turns the drill is a drill motor, drill press, or mill or anything else that provides power to the tool. I don't want to sound like a dick, but I'm a tool maker, and when an apprentice comes to me and asks for a 1 1/4 inch drill bit, it drives me nuts. You don't drill holes with bits, you turn material in a lathe and fly cut on a mill with tool bits. Ok, I'm done whining to you guys, buy a good twist drill, run it at 700 revs or so for SS, use coolant or lube, and peck drill your hole. Keep your drill lubed and free of chips with short quick pecks of the quill and you'll be good to go.
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#10
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I find that a lot of people don't really drill holes with the best efficiency.
First, rpm is based on two things, material and diameter of cutter. Machinists use a shorthand formula to calculate the base rpm. It's (4*cutting speed)/diameter. There is a more accurate formula, but that required a more accurate machine to hit the rpms. Let's say that you're going to use an 1/8 inch HSS drill and drill a hole into mild steel. A good cutting speed is 90. Using the equation, that would be (4*90)/.125, or 2880 rpms. The machinist handbook has a base cutting speed for just about any material that you'll probably ever need. Carbide gets run a little bit faster. Let's say it's the same material, but this time it's a 1/8 inch carbide drill. Same formula, but different cutting speed, 500 this time. So the rpm works out to be (4*500)/.125 or 16000 rpm! Stainless, hardened steels, tools steels, copper, titanium, etc... all have their own base cutting speed. When it comes to coolant, the basic rule is to always use it if possible. With carbide, you only use it if you're able to flood it during use. Otherwise it's better to use it dry. Cutters, whether drills, end mills, counterbores, or whatever, work best when loaded correctly. Running it too slow won't be real efficient, and running it too fast usually work hardens the material and dulls the cutter. When drilling by hand, you need to feel how fast to feed it. The equation for that, is rpm * chip load per tooth * number of teeth. By hand, it means the faster the rpm, the faster you can feed it. Machinists will use this to program their speed and feeds. Center drilling is important if you're concerned about location. If you just need a hole about this size about this spot, I wouldn't worry about it. If you are worried about location, I'd center drill and then drill ream. If I wanted a hole that measured .125, I'd center drill it first. Then I'd drill through with a 0.093 diameter drill. Then I'd finish it with either a 0.123 or 0.124 drill. It leaves about 0.015 per side to load the final drill. It will also prevent the drill from wandering as much due to the point. Why not use a 0.125 drill? It won't make a 0.125 hole. It will make something bigger, possibly 0.126, possibly 0.130, possible bigger. If a 0.125 drill made a 0.125 hole, the drill would get stuck. Jamie (who spent too much time tonight at work fixing parts because some of this stuff wasn't done) __________________ Jamie Boley Polar Bear Forge - Custom Blades www.polarbearforge.com jamie@polarbearforge.com |
#11
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Jeremy & Jamie,
Thank you both. Awesome information. Copied and saved for future reference. -Ben M. |
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