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Whats harder than a Cobalt bit
Im drilling spring steel 1inch thick and the new Cobalt bit doesnt faze it :CRY:whats next ?
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You sure you have a cobalt bit?? Start off with 1/8" bit and work your way up to 1"
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yup, start with a small bit and spin it pretty fast (drilling hardened bolts use fastest setting on bench press) and use a lube made for drilling, has higher sulfur content.
this thread is useless without pics!! |
Carbide is the next step. But, it is extremely expensive. Use oil--high sulfur is best.
David :):):) |
Thanks David thats what im looking for high sulfer need to get some.This thread is good for me,I did start small got all my 3/8 holes done got half way though on a 1/2 and it stopped bought a drill doctor no help, cobalt bit@ 17.$ still nothing high sulfur good info thanks for the input,carbide is next :)
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We sometimes use the old 90 weight diff oils as well for nasty milling. We have a really special milling oil we use for cutting stainless here in the shop, but we buy it by the 55 gallon drum and I don't know where to get small quantities.
As for carbide, we routinely mill out broken taps with carbide end mills. You have to have a very rigid set up, peck extremely slowly, and spin the end mill quite fast for it to work. Spinning the end mill fast is counter intuitive, but it is the only way we have had any luck. For those who are interested, we use an rpm of 3000-4000, peck of 0.010" and a feed of 1 inch/minute. I have milled out 1 1/2 inches of hardened tap many, many times this way. When you are done, it is pretty cool because you mill out the center of the tap and the teeth of the tap just fall out. We use junk end mills for the tap removal that you would never believe would cut anything. But they do. They are completely fried when we are done. But we do save the part. David :):):) |
Carbide and a can of "cool tool", you might get your 1/8 drill through.
Are you sure it isn't case hardened? Take a stone grinder and grind 1/2 in the area you are trying to drill. You might have to take it in a bit, but case hardened is very hard for the first 1/16 to 1/8, then it is a little easier. Just my $0.02 worth. :D :D |
I guess thats what is so strange im half way through this peice of 1inch and everything has come to a halt,it's a swaybar I just want to put a bolt through the end.:CRY:
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After wasting my time burning up $20 worth of Cobalt bits trying to drill spring steel, I took it to a machine shop and they drilled it for free.
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Not all swaybars are spring steel. Many of them are simply 4340 shaped and then hardened. Since hardened steel is just about as hard to drill as spring steel you might try this trick to drill it.
Heat the area you are trying ti drill with a torch until it is a dull red hot. Be careful not to heat more of the bar than necessary. If this is a heat treated bar, the heat will take the temper out of the area you heat and you will be able to drill it easily. I've done this a couple times on parts on my roadster during the build and it worked perfectly. Yeah, I hate going through expensive bits too. Another option is to not use a bolt, use one of those half round cradle type connectors for your sway bar that clamps to the bar and has an attachment part on it. No holes needed in the sway bar. Bob |
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But think about the satisfaction of doing the job himself that Bill would miss out on by having a machine shop do it for free.:) |
An old trick is to use a Masonry bit and sharpen it like a regular drill bit. These have a piece of tungsten carbide braised into the end. I've used them in the past to drill hard stuff.
Cheers |
If all the above fail, bring to a die shop and have them EDM the piece for you.
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Clever Mike. Thanks for the tip.
Chaplain, what is EDM? |
EDM is electrical discharge machining. Using either a wire or carbon rod (the rod can be a custom shape) the machine esentially burns a shape into a part. It is capable of very close tolerances in very hard material. Check this link out.
http://www.engineersedge.com/edm.shtml |
What size carbide drill do you need? You are drilling 1" thick material. Give me the drill size and I'll just send you one for nothing. If you need more than one size, let me know and I'll see if I have some of those lying around also. I work for a company that manufactures carbide all over the world. I have tons of drills, facemills, turning tools etc. lying in my garage.
You should be able to drill this with ease. More than likely, you are not putting enough feed on the drill and you are work hardening the material before you drill it. This shouldn't be hard at all. I use WD-40 at home. Just drill a little bit, then pull the drill up and spray some WD-40 in the hole. |
I was going to suggest the same. It sounds like it has work hardened on you. You may have to temper it locally like Bob said or go with the carbide. Make sure when you start an operation like this to keep enough pressure on it to take out a chip. If you stop feeding and let it spin at one depth it work hardens and yes it becomes hard to work.
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