Convert full tang to hidden after heat treat.

timos-

timos-

Knifemaker / Craftsman / Service Provider
Joined
Oct 22, 2012
Messages
2,210
Hi all,
Quick question, but first here is the situation.
I have several 3/32 thick 1095 blades I am prepping for Heat treat. I am using them mostly to get my heat treat batch up to 20+ blades.
The blanks are all full tang. I may want to convert a couple to hidden tang after being heat treated.
Would it work to grind off the unneeded material allowing the steel to get real hot, thus making it soft enough to drill? How quickly would I start to ruin the blades hardness?

thanks,
tim
 
Tim, I'm curious about why you would wait until after HT to decide to drill the holes? Drilling extra holes in a full tang knife isn't a problem in most cases, so why not just put the holes in for both full and hidden tang and avoid the need to "soften" the tang.
 
Good point Tryppyr. I have actually done this but what I have found is that despite thinking ahead and drilling lots of holes I always seem to want to drill a hole exactly where I did not. Basically, It would be nice to have the option.
 
Well, in answer to your initial question, I have only done this twice before, and I didn't feel compelled to drill any more holes after the conversion. The conversion process is simple, as long as you don't over complicate it. You can protect the blade by wrapping it in a wet cloth or by mounting it in a vise correctly to act as a heat sink.
 
You can use a carbide drill to cut the hole. If you don't need a precision cut, a masonary bit will work. You can also use a pencil torch to temper down small areas of the tang. This will make it a little easier to drill. If you can get the small area red hot and then slowly cool it you might anneal it enough to use a regular drill on it.
 
I'm missing something here.

If you haven't sent them to be hardened yet... why are you planning on converting them afterward? Why not do it NOW??? :confused: It seems like you're planning on making things harder on yourself.


Don't plan to use heat from grinding to do a localized temper... there's very little control with that.

You can use a torch and do a localized temper on a hidden tang. I do it with damn near every knife I make. There's a full description in my sig line thread. In that thread I did it with an oxy/acet torch, but you can easily do it with a propane torch. When using a propane torch, I put a soft firebrick behind the tang so the heat stays there... it makes the job much faster.
 
Tryprr and Bo T, thanks for those suggestions. Good to know it would be a slow cool that would result in the steel being annealed.
Nick, Its not that I am planning to convert them afterwards. I just want to know whats involved If I need to. I know its a bit silly but I can be pretty fickle with a knifes design. I am only sending in this one batch for HT this year so I like to try and keep my creative options open and still have a hardened blade I can finish up real quick. And thanks for the link in your sig. While Ive seen and learned from many of your threads for some reason I overlooked that one.
Thanks for the responses all.
 
If the holes are small, or not drilled yet, grinding the blade down after HT isn't all that hard with a 36 grit belt. The concern is if there are holes in the full tang that will interfere with getting the hidden tang small enough.
 
Hold the blade in water, heat tang to dull red with a torch three times, allowing to cool to black In between. It will drill just fine. It's a poor mans spheroidizing anneal. Thats how I do it.
 
Okay, I can understand that. It seems like you'd be best off to just go ahead and make a couple of them hidden tangs now, when it's easier to do. ;) :)


Ceramic belts will eat any steel, hard or soft, and good ones will do it without building up a bunch of heat (so long as you're careful).


You don't actually have to heat a tang to a red heat to be able to drill it. I'm not saying you shouldn't! Do whatever works for you in your shop! :) But heating the tang all the way to red would make me a bit nervous. I heat to blue, and the go a bit past that, to where the oxides go from that pretty blue to a silvery color, cool it off, sand off the oxides/color, and repeat two more times.

I just did this very thing on the Joe Paranee project blade's tang last night (fully hardened 52100), and it allowed me to drill with a 1/8" Cobalt bit, and then opened it up to size with a freshly sharpened HSS bit. :)
 
I hope I'm not hyjacking this thread, but it might be educational for others as well.
I might not be nervous cause I don't know any better. What should I be nervous about? My understanding is the steel is still in its martinsite state after doing this, is this correct? Even if it goes to perlite, would that be so bad? Not getting defensive, just want to understand this better.
 
Not hijacking at all, just taking it to the next level. I am wondering these things too. How does the steel start to change?
 
Hi, I have purchased some Damascus blades that were already ground and heat treated and etched. The blades were super hard so I gripped the blade in a vise with some leather and clamped little vise grip pliers all around the tang and heated the spots with a torch where I wanted to drill holes. I used tungsten carbide bits and was successful.

I would drill all the holes I might need before heat treat on the blades that I grind and decide which holes to use when making bolsters and scales.
 
If you're not confident in what a blade can do, or what purpose it will serve, it's not ready for HT.
 
You must log in or register to reply here.
Back
Top