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bobbybeef
08-17-2005, 07:06 PM
Tried drilling a hole in a 3/16"stainless steel cover yesterday and the drill was not up to the task and the metal has hardened. Can this stuff be annealed by heating? how far does the hardening effect extend from the failed to drill site? I am a bit leary about using one of my beautiful titanium covered drill set on this stuff. since the piece is a cover I can move along a bit and drill another hole if the hardening is not too bad. Grateful for any and all guidance.
bobbybeef.

C. Tate
08-17-2005, 08:43 PM
Do not apply heat!!!!! Use carbide drill if you have one. Otherwise use new drill and run slow with lots of coolant (waterbased if you have it plain water if you don't) push past hard spot and resharpen drill after you break through. When machining nickel based stainless feed harder than you would for steel and keep it cool. Run drill slower also.

mochinist
08-17-2005, 09:07 PM
316 and 304 sure is fun arent they. Anyways if you hardened it real good as I suppose you did, you need to get thru it with a carbide endmill or drill as c tate suggested.

As for being scared to use your precious titanium drill bits I say be a man, did you buy them to stare at or drill holes with. Make sure your drills are sharp(just because they are new doesn't mean they are sharp either, harbor freight drills and the like are just as likely to be dull as they are to be sharp)if the one you want to use is not sharp, sharpen it. Next turn your rpms way down, I would say to around 400 rpm for a 1/4 drill(dont know what size you are using). Now start drilling, you need to feed it hard and never I repeat never let the drill dwell, so feed hard and then clear your chip. If you are drilling a deep hole you may need to sharpen your drill before you finish, if it is just sheet you might check the drill every few holes and resharpen as needed. Oh yeah use waterbased coolant too, douche that sucker and keep it cool, use a squirt bottle if you dont have flood.

P.S. I know most of you guys are home shop machinist and cheap scrap metal is a bargain when you have to pay out of your own pocket for it, but when it comes to stainless you will save your self alot of headaches and worn out tools if you pay the extra money and the project permits 303 type stainless. It works almost like cold rolled steel if not better and you would really have to try to work harden it.

Your Old Dog
08-17-2005, 09:25 PM
Bobbybeef, it's perfectly okay to use those titanium babies. Just do it on a Sunday. That's the only day of the week I take mine out. The rest of the week they just sit in the "Shrine of Titanium" in the East corner of the shop!! Got a big day coming up this Sunday. Gonna break those babies out and turn some "R's" with'em! http://bbs.homeshopmachinist.net//biggrin.gif I got mine from an old school teacher who only used'em on Sundays.

Keep us posted.

WJHartson
08-17-2005, 09:36 PM
I use cobalt drill with a 135* split point low rpm 300 or so and keep it feeding with coolent. When it get hot it gets hard. If you really want to have some fun try pipe threads in stainless. Still trying to figure out the best way for that.

Joe

bobbybeef
08-18-2005, 01:58 AM
Thank you guys,
The cobalt with 350 revs and some squirted on water did the job.
Thank god I didnt have to use the TITANIUM. They are just too pretty to use. I go all goey just looking at them.
the set I have is 113 pieces in a case with an individual compartment for each drill. It really is the nicest outfit that has ever graced the shop. well the space in the garage between the car and the wall.
303 stainless I have not run into it yet does it have a special content to make it malleable. how is it on corrosion. The stuff I do is mainly around a very small winery so effects on foodstuffs are very important.
Again thank you all.
bobby.