Can't weld a drill bit ?

admin

I need one of those long drill bits for running wires, but I need one that doesn't seem to exist.  I want one that is 36" and 1/4".  So I decided, why can't I just make one.  So I got a 36" 3/16" dia rod from HD and a regular 1/4" high speed steel drill bit.  I tacked the bit onto the rod, but when I went to adjust the bit SLIGHTLY, I found the tack weld was not flexible, and cracked, and was very brittle.  I was using my Lincoln SP135 with flux core wire (and the correct polarity).  The weld would break off of the bit.  It seemed to penetrate the bit but then would just break off.  What is the problem?Thanks
Reply:Most likely Heat is your problem...  being w/ flux cored ...to my knowledge ..those bits are not a mild steelI would consider a different aproach weld it like you own it
Reply:That's pretty long for a 1/4" drill. Something tells me that's too long to be practical. Are you using the ones twisted for wood or steel?Anyway that brittleness is pretty typical for welding those bits, even the shank portion, and I doubt T-11 or T-gs is the wire for the job. Your best bet is to use two of the long bits, make your cuts and welds a distance away from the actual twist portion and heat them up to where you start to see or suspect a dull red then lay it in there.
Reply:You can buy the flux bits 6' long just cut one down Me!
Reply:You may want to look for drill bit shaft extensions. They do exist, most are for bits that have a 1/4" hex on the back of the bit. You can just buy a long bit if you look at an electrical wholesale shop. They have them up to 5 ft. long. As for drill bits and welding them, they are a grade of tool steel, not mild or chromo. So, you would have better luck tigging it, but it will still be brittle. Your best bet is to nickel braze it. But, really?? Just get the long bit.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Originally Posted by RojodiabloYour best bet is to nickel braze it.
Reply:Originally Posted by lewrayMost likely Heat is your problem...  being w/ flux cored ...to my knowledge ..those bits are not a mild steelI would consider a different aproach
Reply:That's some hardened steel on those drill bits.  It's most likely AR Tool steel and will need to be preheated and require a different filler material than used for mild steel not to mention preheating and post heating.On something that small in diameter I wouldn't even know how to do it correctly.Buy extensions.
Reply:Originally Posted by SandyThat's pretty long for a 1/4" drill. Something tells me that's too long to be practical. Are you using the ones twisted for wood or steel?Anyway that brittleness is pretty typical for welding those bits, even the shank portion, and I doubt T-11 or T-gs is the wire for the job. Your best bet is to use two of the long bits, make your cuts and welds a distance away from the actual twist portion and heat them up to where you start to see or suspect a dull red then lay it in there.
Reply:try to tig it.  I have done that on a few bits and made them work in metal.  They wernt the straightest things ever but they held.I didnt add any filler, just cranked the amps and burnt it in.Have we all gone mad?
Reply:Originally Posted by MigionCould I heat treat the bit to solve the problem?  I don't care if I lose the hardness since I just want to drill through wood.
Reply:I have a 1/4" homemade extended bit in my toolbox.  I'll have to look at it to see if it was brazed or welded.  I would think that you would have to take the heat treat out of the shaft end of the bit to weld it.  You want the flute to remain as hard as possible, but in a pinch...anything will do.  I fashioned a long bit out of a coathanger once and it got the hole bored with some finesse and strategic support.Hobart 140 Handler w/ gasHyperTherm Powermax 380 Plasmaoxy/acetylene
Reply:Originally Posted by Me!Even that will be brittle, tried it a few time on hex keys with no luck the always snapped off.To solve your problem:http://www.lashen.com/vendors/BES/Fish_Bits.asp
Reply:I have had fair luck brazing rod to drill bits. I grind a flat bevel on one side of the butt of a bit and flip it 180* and do the same, also do the same for the rod.  Set it up in an angle iron with a window cut in it, braze it up with a torch, carefully grind or file off the excess brass.It will not take a beating, but with care, will get the job done.Just my  opinion, not from a book, just from the road.Howes Welding Inc.www.howesweldinginc.com
Reply:I have made up quite a few long drills. We used to make them up to 8 feet long to drill out the elements in flail mowers when reconditioning them.The method is to drill out the shank of the drill bit and turn down the end of the bright mild shafting you are using as an extension. Then silver braze it with the top silver content. The stuff we used to use was sold as Easy Flo but in Australia it is sold by the silver content and I have found that the highest silver content is the same stuff. You have to get the flux on it first and when it is hot enough blob a small bit of rod on it and chase it round with the flame, the capillary action will draw it down into the join. You want a good fit by the way, about .002" is plenty and at least 1/2 inch long on a 1/2 inch drill so I guess you would be looking at the the same length as the diameter.Oh yeah, lay it in some angle for support and to keep it straight. Plus once it is machined don't put your fingers on the surface to be brazed and machine it dry, no coolants as they contaminate.CliveLast edited by clive; 10-08-2007 at 10:42 PM.
Reply:Friction/rotary welding would be the modern way, providing you had 2 compatible metals.
Reply:I was thinking you might could anneal the shank first then try to weld it?DewayneDixieland WeldingMM350PLincoln 100Some torchesOther misc. tools
Reply:Originally Posted by cliveI have made up quite a few long drills. We used to make them up to 8 feet long to drill out the elements in flail mowers when reconditioning them.The method is to drill out the shank of the drill bit and turn down the end of the bright mild shafting you are using as an extension. Then silver braze it with the top silver content. The stuff we used to use was sold as Easy Flo but in Australia it is sold by the silver content and I have found that the highest silver content is the same stuff. You have to get the flux on it first and when it is hot enough blob a small bit of rod on it and chase it round with the flame, the capillary action will draw it down into the join. You want a good fit by the way, about .002" is plenty and at least 1/2 inch long on a 1/2 inch drill so I guess you would be looking at the the same length as the diameter.Oh yeah, lay it in some angle for support and to keep it straight. Plus once it is machined don't put your fingers on the surface to be brazed and machine it dry, no coolants as they contaminate.Clive
Reply:Originally Posted by cliveThe method is to drill out the shank of the drill bit
Reply:Originally Posted by littlefuzzI was thinking you might could anneal the shank first then try to weld it?
Reply:Originally Posted by MigionWhat do you use to drill out a drill bit?
Reply:The shank is relatively soft. But you have to do it in a lathe, otherwise it will be all over the place.Clive
Reply:I knew about the lathe part.  I just figured the shank is as hard as the cutting end.I annealed the shank of my bit tonight but I didn't get a chance to try welding it.  Hopefully I will get to that tomorrow and I will report back.  I will MIG it.  I don't have a TIG but that's a good idea although I don't know why that would work better.
Reply:Originally Posted by MigionI knew about the lathe part.  I just figured the shank is as hard as the cutting end.I annealed the shank of my bit tonight but I didn't get a chance to try welding it.  Hopefully I will get to that tomorrow and I will report back.  I will MIG it.  I don't have a TIG but that's a good idea although I don't know why that would work better.
Reply:I have welded a few drill bits to about the same size steel rod before and have not had any problems like you mention. I did clean and bevel the end of the rod pretty good prior to welding and also made sure I had a good gap between the end of the rod and the drill bit. Made two using this method in the last few months and both of them worked great. I made sure I had the bit good and straight with the rod prior to welding them together.I have used Clive's method and it is the BEST method.  If you do weld the joint make sure to normalize/anneal the joint afterwards.  Heat the location to red and allow to slowly cool in still air.  The slower the cooling rate the better.
Reply:I welded it last night, after annealing the shank the night before.  It seemed to weld good.  After, I was able to straighten it a little and it did not crack as before.  The idea to anneal it again after welding sounds good.  I have not tried the bit yet.  Hopefully tonight I will give it a try and see if it is actually useful and the weld holds.  I will report back.
Reply:most of the bits i ahve run across (the cheaper, HSS bits) are only case,or shell hardened. they are not heat treated all theway through. i don't know if it woudl work, but you coudl try grinding part of the shank down in order to get to the softer metal.good luckAndy
Reply:oops... sorry, i didn't read the post before my last.
Reply:The post heat is more important than preheating on such a small part.  The weld is not the critical part.  It is the heat affected zone right at the boundary between weld bead and parent metal.  If all welders learned to harden and temper a piece of carbon steel they would have a better understanding how cooling rates affect hardness and built in weld/forging stress.
Reply:I tried it tonight, drilled a couple of holes.  One through the ceiling into the attic and one through the floor into the basement.  Worked like a charm.  It actually worked a lot better than I thought it would.  When you have a bit 3 feet long if you are not through just keep drilling you will get there!  Anyway now I can send 1 million spam e-mails with the subject "Want a longer dr1ll b1t?"...  OK that's a joke.
Reply:Originally Posted by MigionI need one of those long drill bits for running wires, but I need one that doesn't seem to exist.  I want one that is 36" and 1/4".  So I decided, why can't I just make one.  So I got a 36" 3/16" dia rod from HD and a regular 1/4" high speed steel drill bit.  I tacked the bit onto the rod, but when I went to adjust the bit SLIGHTLY, I found the tack weld was not flexible, and cracked, and was very brittle.  I was using my Lincoln SP135 with flux core wire (and the correct polarity).  The weld would break off of the bit.  It seemed to penetrate the bit but then would just break off.  What is the problem?Thanks
Reply:I have taken Rex triple A Hi speed tool bits and tigged them onto mild steel for boring bars countless times using 70-S2 for filler..No special treatment from a to zWeld like anything else and carry on..Drill bits are Hi speed steel correct?Same thing applies.....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.