brian robertson Posted March 5, 2012 Share Posted March 5, 2012 Recently forged 6 blades for hoof knives using 1/8"x3/4" A2. This is the third series of these blades over approx 5 yrs. The heat treat went well on 4 of the 6 blades. I don't think I did anything different from the past. On the other 2 blades the tangs are way to hard to drill for the pins. Any hope of spot annealing the tangs? Will this thin stock take a do over and perform well? Write it off as "the gods were angry"? Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted March 5, 2012 Share Posted March 5, 2012 A carbide bit will drill with no problem. If you try one remember that when the tip pops throiught the backside of the tang it will almost always break.. Unless you have the tang firmly clamped to a piece of mild steel so the hole continues into the mild. If I were to make those blades i woiuld take a pair of tongs and carefull fit them to the tang sot the hold it evenly on each surface. then I woiuld hold the tongs tight while I quenched. The tongs will suck some of the heat ouit and slow the contact with oil so that the tang may stay unhardened as compared to the blade. i anneal steel lby heatging to critical and sticking in vermiculite. This stock I put in with a thicker piece of steel heated to same temp to slow the rate of temp drop. With a blade shaped like you have that would be tough Quote Link to comment Share on other sites More sharing options...
brian robertson Posted March 5, 2012 Author Share Posted March 5, 2012 This A2 is an "air hardening only" steel in thin cross sections. These 2 tangs are so hard, they ate my 9/64th carbide bit and spit it back out,barely putting a mark on it. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted March 5, 2012 Share Posted March 5, 2012 Did you attempt spheroid annealing? see here... http://www.iforgeiron.com/forum/56-knife-stickies-here/ Quote Link to comment Share on other sites More sharing options...
brian robertson Posted March 5, 2012 Author Share Posted March 5, 2012 I'm trying to do a salvage procedure if possible. The heat treat on the blade portion on these 2 are right on the money. I'm looking for a trick to anneal only the tangs. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted March 6, 2012 Share Posted March 6, 2012 drill or punch while hot ? Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted March 6, 2012 Share Posted March 6, 2012 I use small carbide drills to drill heat trreat stainless steels that test at 61 on rockwell c scale. The heat treat specs for A 2 say if you temper at 350 you will get a rockwell C of 62,,I can drill that. If you did not temper that is your problem. if you wish take a new chain saw file and try and file the tang. If youi cannot it is way too hard to use as you may get a fracture. I bend my hoof knives in use, I would not use a blade that hard. If yoiu did temper and the file will cut it then methinks you have a bit of less than wot you need. Basically if you did not pay alot for that bit it is likely not a goodun... Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted March 6, 2012 Share Posted March 6, 2012 You can try Rich's suggestion by fitting a pair of tongs to the handle then heating them to orange and clamping across the handles where you want the holes. Let cool naturally and you should have a soft band across the handle. BTW, A2 will easily get to 62 Rc in thin sections, which is probably what you are experiencing. Quote Link to comment Share on other sites More sharing options...
brian robertson Posted March 6, 2012 Author Share Posted March 6, 2012 I wish I could put my finger on what I did wrong with these 2 out of the 6. I didn't mark them so I don't know if these 2 are the first,last,middle or apart. What's weird is that the blade portions ground and polished exactly like the other 4. Not too hard, not soft. I suppose I could always epoxy them in their handles. Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted March 6, 2012 Share Posted March 6, 2012 I still wonder about how hard they are on each of the blades and how you heat treated them.... Quote Link to comment Share on other sites More sharing options...
pkrankow Posted March 6, 2012 Share Posted March 6, 2012 Instead of annealing, can you draw the temper back quite far safely? That may soften the material enough to drill. Phil Quote Link to comment Share on other sites More sharing options...
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