Sharpening large drill bits

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Although we have a Drill Doctor I pretty much sharpen my drill bits by hand on a belt sander.  It only sharpens up to 3/4 anyway(and I often use bits larger than 1").  I am currently drilling 13/16 holes in some c-channel and the bit keeps chipping.  My guess is it's getting brittle from the heat and quenching of sharpening.  Does anyone have any suggestions on how to keep this from happening.  I'm sure that there's some of you that sharpen bits like I do that have overcome this issue.
Reply:use less pressure and a finer belt when grinding, take less metal off so it doesnt get as hot and quench before its hot enough to sizzle.
Reply:Proper angle and relief makes a big difference.A guide...Here.I use two large nuts welded together as a angle check. The angle should be 59, with the nuts it's 60...close enough. The next big thing is the relief.Also, stop grinding before the bit turns color. Small removal and quenching often should help.Semper FiJesus may have been a Carpenter, but his dad was a Millwright" A grinder and a can of paint, will make a welder what he aint' "I've done so much, with so little, for so long, that now I can do anything with nothing!
Reply:Don't heat and quench.  Grind slower or dip them in water often to keep the temperature down.  If it's sizzling in the water (above 212F) you got it too hot.  Repairing a chipped bit may take quite a bit of grinding (and time since you need to keep it cool), but after the bit is in shape it shouldn't take much grinding for a quick sharpen.Dynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:Hmm I learned how to sharpen drill bits from a machinist years ago. I have never quenched one and I have never had a problem with chipping unless I got my angle too steep and the bit was too aggressive. If I had that happen I reduced my angle closer to the factory degree and the chipping ended. I suggest you have your angle too steep and that you need to bring it back to what ever angle was originally cut on the bit when you bought it. If you have a new one laying around use that as a guide and you can easily fix your problem.
Reply:The slightest bit of chatter will take the edge off any drill in no time flat..Steady pressure and make sure NOTHING IS MOVING on ya..Wax is good lube for this also......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:A belt sander will sharpen a bit very quickly but doesn't heat up the bit as fast as a grinding wheel will.If you drill a pilot hole keep it small as possible.  Drilling a large pilot hole makes drilling easier but puts all the load on the outer cutting edge and your bit will chip very easily.In thick material, if you do make a pilot hole, don't quite drill all the way through and put some cutting lube or oil in it."The reason we are here is that we are not all there"SA 200Idealarc TM 300 300MM 200MM 25130a SpoolgunPrecision Tig 375Invertec V350 ProSC-32 CS 12 Wire FeederOxweld/Purox O/AArcAirHypertherm Powermax 85LN25
Reply:if its turning blue your getting it to hot.. just go slow, take your time.. also,the only time i dip a bit in coolant to cool it is when i'm rough grinding...  when i go to finish grinding i do not dip it...also another little trick is to take a polishing stone, or a piece of sandpaper will work, and break the sharp edge very slightly. basically just get the small burr off thats left from grinding..  if its the tip thats chipping you need to thin the web more.Last edited by brucer; 09-23-2011 at 05:43 PM.tackleexperts.comwww.necessityjigs.comhttps://www.facebook.com/groups/mach...dingequipment/
Reply:I wanna say thanks for everyones replys.  It was the corners and cutting edges that were chipping off in pretty good size pieces.  I got it under control now.  It was a little of all of the above.  And to be honest I knew I was doing it wrong.  It was just one of those days when your head's not on straight and you need someone (you guys) to say:  "Hey dumby, you know better, Now stop it!"  After you stop, take a breathe and think about what you're doing instead of just trying to get through it, it starts to come together.  Thanks again guys.
Reply:Originally Posted by ironmangquse less pressure and a finer belt when grinding, take less metal off so it doesnt get as hot and quench before its hot enough to sizzle.
Reply:Has anyone here bilt a bit sharpener?
Reply:Originally Posted by Old DougHas anyone here bilt a bit sharpener?
Reply:No one has a wet grinder ?http://www.harborfreight.com/8-inch-...der-35098.htmlAbout the only way to really keep the bit cool and grind at a reasonable rate at the same time...Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:sears sells a craftsman wet sander for under $75 new, which I consider pretty good.Dynasty 200DXPassport plus w/ spoolmate 100victor 315c oxy/(act and prop)Miller digital elitemilwaukee power tools
Reply:I looked up the oliver of adrian 510 very inpreseve.
Reply:Originally Posted by Old DougI looked up the oliver of adrian 510 very inpreseve.
Reply:Grant, I am putting all my drill bits into one of those $10 all you can stuff into them usps mailing boxes and shipping them to you... I need them back by the weekend...I know you can do it... LOLWeldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:we had one of these sterling drill sharpeners at a mold shop i worked at.. it worked real well on drills from about 1/8" to 3"..  i've seen a couple at auctions and i should have bought one of them, but i let it go, one those kick yourself in the rear things..tackleexperts.comwww.necessityjigs.comhttps://www.facebook.com/groups/mach...dingequipment/
Reply:That appears to have all the bells and whistles one would ever need and in a compact space... how much do they typically go for.... like the ones you passed up ?Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:the one i passed on went for $500, it wasnt near that pretty either.tackleexperts.comwww.necessityjigs.comhttps://www.facebook.com/groups/mach...dingequipment/
Reply:Originally Posted by GBMGrant, I am putting all my drill bits into one of those $10 all you can stuff into them usps mailing boxes and shipping them to you... I need them back by the weekend...I know you can do it... LOL