how much prep before heat treating

[cedarfluteman]

Ok I am using 1084 steel. I profiled my knife and drilled pin holes for my handle. Now my question is how much prep is needed before I heat treat? I will grind the blade in after heat treating but so far I made sure the blade was nice and flat and I sanded it with 220 grit. Is this good enough or do I need to do more? And should I leave the grind lines from the sand paper going from tip to hilt or back of blade to edge of the blade?

[Ray Rogers]

You should be sure that there are no sharp angles on the profile. For instance, no sharp 90 degree corners where the tang meets the blade in a stick tang design. Any such angle should be rounded out with a small round file to prevent a possible crack.

220 grit is fine and the sanding marks don't matter much, you'll have to remove them after HT no matter which way they run. Bottom line: don't over think it, just no sharp angles or deep scratches. Since you plan to grind after HT you can clean up after HT too...

[Eli Jensen]

Depends what kind of finish you want. It doesn't matter to much cause you'll have to re-sand it after HT anyways. I personally like horizontal handle to tip. Sounds like your good to go.

[cedarfluteman]

don't over think it

Thanks for the advice Ray. That don't over think it! I'll take that as a compliment. I've never been accused of that before.

[cedarfluteman]

OK I heated the blade to non magnetic and dunked her in the oil. Took it out cleaned it up and checked it with a file and it seems to be hard. The file don't bite. Now I think I have a toaster oven some place. I hear 400 degrees for an hour is what is needed. Is there any other way to do this like protecting the edge some way and heating the rest of the knife with a torch?

[Ray Rogers]

There's lots of ways to do it but now isn't the time to be asking about it. The blade should be allowed to cool to "warm to the touch" while still in the oil. After that, it should go immediately into the tempering oven - the longer you wait, the better chance that the blade will crack.

You can draw the back with a torch but that should be done after the tempering since just drawing the back would leave the edge as hard as it was quenched (a bad thing). Unless this is a large camp knife type of thing then drawing the back may not serve much purpose.

400 degrees for an hour, cool to room temp in open air, then repeat at least once more . Clean a spot on the blade before you start tempering, after tempering the spot should be straw yellow. If it isn't, raise the temp 25 degrees and try again ....

[cedarfluteman]

[QUOTE=Ray Rogers;434568]There's lots of ways to do it but now isn't the time to be asking about it. The blade should be allowed to cool to "warm to the touch" while still in the oil. After that, it should go immediately into the tempering oven - the longer you wait, the better chance that the blade will crack.

Now that I've waited to long before tempering should I start over and reheat treat the knife?

[Eli Jensen]

No. Either it hasn't cracked and you should temper it now. Or it has cracked and there is nothing you can do except thrown it away.

[Ray Rogers]

You haven't waited too long unless it cracked. Of course, the crack could be microscopic right now and not show up for days or longer. If that should the the case then re-heat treating it now won't help. Just get to tempering and, unless you see obvious damage afterwards, then go ahead and finish the knife. Use it for testing like you've probably seen me squawking about in other recent threads. For the future, just remember that heat treating is a timed process. Different steels have different tolerances but a good rule of thumb is, once you start you continue straight through until all the steps are completed. Most any steel should get into tempering or cryo (if required) as quickly as possible after quenching. Again, different strokes for different steels but that's a good rule to follow. With 1084 we don't want to wait any longer than we have to but since you plan to grind after HT and thus have not yet introduced new stresses into the steel you could still be OK. Just git 'er done and see what you get. Either way you'll learn something ....

[Ed Tipton]

cedarfluteman...In all probability, your knife will never again go through anything as stressful in it's entire lifetime as it did during the quench cycle. During the quench, the amount of stress that the blade is subjected to is tremendous, and that is why it is so common for blades to either crack or warp during that part of the process. It is during the quench that blade is at it's most vulnerable when it is literally as hard as glass and without any temper...and full of stress. If you allow it to remain in this condition for an extended period of time without entering into the tempering phase, the internal stresses can overwhelm the steel and result in a crack even when it is just sitting innocently on your workbench. This is why it is important to get the blade into the tempering cycle ASAP after the quench....to help relieve those internal stresses. Of course, it may not crack or warp, but why chance it? Better to be safe, and be prepared to temper it immediately. This is where thinking your entire process through pays off big time. Going directly from the quench tank into the toaster oven will save you time, money, and frustration.
The sequence should be :quench...test with file....clean off scale (make shiney enough to see tempering oxidation colors)...put into toaster oven. From the quench tank to the toaster oven should not take more than 1-2 minutes.

[cedarfluteman]

Thanks for all the replies. I tried to find as much info as possible and tried to watch you tubes on heat treating but, I just didn't know the time was so critical. Live and learn. You got to start somewhere I guess.

[Crex]

Cedar
All the above advice is valid and important. Don't beat yourself up too much, it's easy to get excited about a new adventure and get ahead of yourself. You did do good in selecting a beginner friendly steel, 1084 is more forgiving than most.
You've nothing to lose at this point by going back and reheattreating from the start.
Couple of points:
> When you heat the steel to nonmagnetic you are still several degrees below critical temp. You need to at least hold it at this temp + for a few minutes to allow the entire piece of steel to reach the same temp before quenching.
> Your oil should be prewarmed to 110 to 120 degrees for better quench results.
> You should already have your tempering oven preheated to your target temp. Toaster ovens are notorious for bad temp settings, place an auxillary temp guage in the oven and go by it, not the dials.
If you can't get the toaster oven setup right for some reason, in an "emergency" situation you can put the blade blank in your household oven at 350 to draw a preliminary temper and releive the stress factor temporarily until you get your toaster set. Make sure you clean all the oil off before putting in the oven!!!! Momma won't like it!
This is all based on the recommendation that you heed the previous thread advice and think ahead.

There are as many ways to skin a cat as there are folks skinning them and I do not wish to impede anyone elses' advice, but I would recommend pre grinding the blade blank to coarse dimensions of your intended bevels, etc. before heattreating. The steel will grind/file more easily in the annealed state. Finish grind after heattreating. Be sure to follow Ray's advice on sharp corners and angles.

[Ray Rogers]

I think I need to expand just a little on part of what Crex said. He said hold the steel at non-magnetic+ for a few minutes to be sure the blade is evenly heated. That is technically correct but in the context of Cedar's experience he will likely get a very bad result if he tries that since he is using a forge and he's new to the whole process. With an electric furnace it would be easy to hold the temp about 50 F above non-magnetic for as long as you want but a forge requires extreme diligence and skill to keep the steel at that temp for several minutes. I believe that Cedar would interpret that instruction to mean 'get the steel to non-magnetic and then leave it in the forge for a couple more minutes just to be sure' and we know that would result in the steel being far over heated for the quench. Even if he didn't take the meaning that way he still won't be able to hold that temp for several minutes and the result will be over heating his steel.

So, I would suggest that Crex's instruction be modified to get the steel heated evenly to non-magnetic, wait a few seconds longer to gain about 50 degrees and then quench immediately in warm oil....

[cedarfluteman]

Originally Posted by Ray Rogers

I think I need to expand just a little on part of what Crex said. He said hold the steel at non-magnetic+ for a few minutes to be sure the blade is evenly heated. That is technically correct but in the context of Cedar's experience he will likely get a very bad result if he tries that since he is using a forge and he's new to the whole process. With an electric furnace it would be easy to hold the temp about 50 F above non-magnetic for as long as you want but a forge requires extreme diligence and skill to keep the steel at that temp for several minutes. I believe that Cedar would interpret that instruction to mean 'get the steel to non-magnetic and then leave it in the forge for a couple more minutes just to be sure' and we know that would result in the steel being far over heated for the quench. Even if he didn't take the meaning that way he still won't be able to hold that temp for several minutes and the result will be over heating his steel.

So, I would suggest that Crex's instruction be modified to get the steel heated evenly to non-magnetic, wait a few seconds longer to gain about 50 degrees and then quench immediately in warm oil....

So what happens if the metal is overheated? Does it just melt or what?

[cedarfluteman]

I finished the knife after I tempered it at 400 degrees for a little over an hour. I didn't notice any cracks or anything bad. However it don't seem to get a super sharp edge when sharpened. To sharpen I use a 220 grit belt and slow speed. I take it down till I see a slight burr show up on both passes then lightly buff the burr off with a hard buffing wheel with compound on it. Is there a better way? Or did I just mess things up by not doing things quite right with the heat treating? Knowledge is a wonderful thing. Wish I had more of it!