First heat treat, first screw up...

B

bkstabler

Joined
May 30, 2011
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So I finally ground out a decent looking knife that doesn't look like a prison shiv. Today I decided to heat treat it (1095), and in my haste, I forgot to drill my pin holes beforehand. I have a Craftsman drill press and cobalt drill bits. Will I ruin my bit if I try to drill it after its heat treated? Any suggestions? This sucks because after about 4 or 5 trial runs, I felt like I had a decent looking knife.
 
Either get a carbide 1/4' bit, or chew a hole through the tang with some cheap HF diamond bits ( $10 for a set of 20). A carbide ball burr will also do the job.

Read up on drilling a hole with a carbide bit before you do, or you will break it for sure.
 
I think you will need carbide bits; don't feel bad I did the same once. That knife sits on a bench as a reminder.
 
Did you quench the entire knife, or just the blade? If you left the tang soft, you should be able to drill through it.
 
Or you can cheat and use some really good epoxy. Then just pins in the scales......psssst...no on will know but you and it will never come off anyways :)
 
bladsmth said:
Either get a carbide 1/4' bit, or chew a hole through the tang with some cheap HF diamond bits ( $10 for a set of 20). A carbide ball burr will also do the job.

Read up on drilling a hole with a carbide bit before you do, or you will break it for sure.
Click to expand...

Thanks Stacy. So my Dewalt cobalt bit won't do the trick? I'll run and pick up some tungsten carbide bits tomorrow
 
Since it's 1095 you can use a torch to carefully draw back the handle then just drill normally. Put the edge in a shallow pan of water then play a torch over the handle until it goes through the colors then starts to turn gray again. That should leave it soft enough to drill with regular bits.
 
+1 to the torch. I've found that if I clamp the blade in my vise, the vise acts as a heat sink and you can heat the tang up with no ill effects. Take it up to dull red, let it cool, you should be able to drill it.
 
Jason Magruder said:
Since it's 1095 you can use a torch to carefully draw back the handle then just drill normally. Put the edge in a shallow pan of water then play a torch over the handle until it goes through the colors then starts to turn gray again. That should leave it soft enough to drill with regular bits.
Click to expand...

that is exactly what I would do. you dont even need to take it through all the colors, once you get it blue your cobalt bits will go right through it. just run your press slow and put something on the bit to cool it.
 
Yes, drawing the tang soft is a good system. Since the OP didn't seem to have much experience, I went with the simplest method. Adding another heat treatment can be fraught with problems for those who don't fully understand the principals.

FWIW;
Cobalt, TiN , and all the similar drill bits are nice, but are still nothing but tool steel bits with either a different alloy, or just a coating. They only drill annealed steel. For hardened steel, and stainless steel, you need carbide.
Carbide bits are usually referred to as "Solid Carbide" and are way harder than regular bits. They are also very brittle and have to be used on a drill press with the work clamped tightly. Lubrication is a good idea with any drill bit. The speed you drill at can ruin a bit in a second. Bookmark a chart with the speeds for different types and sizes of bits and the metals they drill.
In a pinch, a new carbide tipped ( masonry) bit will drill a hole in a hardened tang.
 
Thanks for all of the advice everyone, but now it appears I have a new problem. I got a carbide tipped masonry bit (Lowes didn't have solid carbide), but the bit was so long that it wobbled and bent all over the place when I tried to drill. So I said screw it and decided to try my cobalt bit... It drilled straight through it no problem, lol. So now I'm thinking I did a shitty job heat treating. I heated the blade (1095) to non-magnetic in a brake-drum coal forge, but I didn't get it to the canola oil quench until about 6 seconds later. I took it inside and threw it in the preheated oven at 400f for 1 hour. Any idea where I went wrong? Should I have gotten it from the forge to quench faster?
 
Yeah, 1095 needs to get into the quench immediately. I believe it's something like one or two seconds max in order to get past the pearlite nose. Some of the more knowledgeable guys on here can give a more accurate number but I know that six seconds is way too slow to reach full hardness.

With just a forge and canola oil you will get much better and more consistent results with 1084 or 5160. It might be worth your while to order some and save the 1095 for when you've got more experience.
 
As with any first HT, there are usually a cocktail of problems. Lets take them one at a time.;

Metal choice - Use 1084 or 5160 for simpler Ht with no temperature control.
Quenchant - Use canola for 1084 and 5160, but commercial fast quenchants will be better for 1095.
Timing - 1084 will miss the pearlite nose and convert into martensite with a canola quench if it goes into the oil withing a few seconds of leaving the forge fire. 1095 has to drop from 1450F to below 1000F in less than one second ( once it enters the oil), so it needs a fast oil and must get from the forge to the oil without delay. 5160 will almost allow you to take a drink of coffee and then stick it in the oil after you take it from the forge.
Tempering - Go from the quench tank after the blade has sat there until it is cool, directly to the tempering oven at 300F. Wipe it off and carefully wash it in the sink, but don't do any banging, bending, or file testing until it comes out of the oven. After the first temper, test the edge with a file. If it is hard, do the second temper. If not....re-do the HT.
What should be hard? - The edge should be hard in all quenches. The spine may vary in hardness ,depending on the steel type and the quenchant. The tang may not be hardened at all, depending on how you heated the blade and how you quenched it. Often the blade is held by the tang while heating and the tang is not stuck fully into the oil. This will almost guarantee a softer tang. This is not a bad thing.
 
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