When I'm testing a piece to see what the grain looks like, I heat treat it exactly as I'm going to heat treat the blades.  One process step different can make a difference in the final results.

To me, good grain has a velvety look to it.  You should not be able to see any individual grains.

That's what I was shooting for here, but this is the first piece that I've done in my kiln.

I don't trust the electronics right out of the box but I'm not sure how to verify what the PID says.

I set it for 1500° and quenched it like I plan on doing in the future, but I think the kiln is hotter than that.

I'm getting ready to do one with the kiln set at 1400 now to see if it's better.

I should break the piece as quenched, correct?

Thanks for the help!

We'll, no more tests for today. The SSR seems to have failed closed, so it's basically just running wide open. Lol

Gotta love cheap electronics. I could have helped it die though, as it's just mounted to a piece of wood without a heat sink and it does get quite warm. I figured it wouldn't get too hot as it's rated for 40amps and it's only drawing 14.

We'll see if it works after it cools down and maybe I get lucky and I can just buy a heat sink. If not I'll be sure to get one with the new SSR.

Yes, break as quenched.

Table salt melts at 1474*. I've heard of people using it to check the accuracy of their kiln.

That's interesting, as it's much closer to the range where most of the work gets done vs icd water of boiling water.

I'll have to look into that.

I need to learn more about tuning the PID controller also. It was working beautifully with the bate metal thermocouple but since I put the ceramic insulated one in it seem to overshoot the temp by a lot.  I'm 80% sure that it's because the thermocouple has more mass(insulation) that it's slower to read the temperature (by the time the thermocouple hits the target temp the rest of the oven is past the temp).

I'm not sure exactly which parameter is the one to fiddle with to fix that. I think it's the "integral" but I'm not 100% sure. There's a bit of info out there but a lot of it is above my head.

I got the new SSR wired in (and mounted to a heat sink this time). I set the temp offset by using my probe thermometer from the kitchen(only at 175c because I didn't want to nuke my thermometer)

Today I've been hardening chunks of 1084 starting at 798c and dropping by 10° and then breaking them.

Here's where I stopped for the night. I think I'm getting close.

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ETA: here's the first blade I tried hardening in the kiln. Attached File

Here's the first one from today, at 10°c under the last one. (758°c indicated temp)

Getting better, but compared to a broken file it's still a little bit grainy.

The first one I hardened in the kiln is on top of the current test piece.

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I'm also noticing that the pieces seem to get more difficult to break as the grains get smaller, which I'm assuming is a good thing.

So, here's what happened between the last post and now.
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Starting with the kiln set to the prescribed temp I quenched a chunk of the steel and when it got to room temp I'd check it with a file, then clamp it in the vise and break it with a hammer.  Then I'd drop 10° on the kiln and do it again.  All the way until the file started to bite a little bit. The file started to cut on the one at (indicated)700°c.  718° had the best looking grain.  Here's a pic of that one.

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I'm going to stick with 718°c(as indicated on the PID) for this 1084.

Next I'll have to come up with a good way to test the temper temps.  The only ways I can think of involve using up a lot of steel, so any help with ideas for that would be awesome.

I suppose I could try making a bigger knife and start on the hard end of things and brass rod test the edge and go through a temper cycle at higher temps between tests and hopefully go from chipping the edge off to bending the edge over and then pick a spot in the middle.

Thanks again for any help or encouragement.

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Actually trying a blade in here after verifying the temp by breaking another piece.

@ksred , I saw your picture of heat treating a batch and I want to thank you. I've been reaching into the kiln to grab knives off of the bottom with a pair of pliers. I never thought about hanging them from rods in the top of the kiln. My only question is, what are those rods called?  I've been looking for them but everything I find is metal rods for firing beads.

Thanks for any help with finding them.

 The white rods are a ceramic rod that came with the kiln.  The pins the knives are hanging on are .160" stainless pins that came with it also.

 I would imagine Jen-Ken would sell the ceramic rods as replacements.

Awesome!  Thanks again. I'll look into getting some from there.

I didn't realize that you had a purpose built HT oven. I thought it was a repurposed pottery kiln, based on the shape.

Did you have to do a bunch of testing when you first got the oven to establish proper temps for your steel or was it pretty dialed in from the factory?

I'm starting to get frustrated with this.

Before I hardened the knife yesterday I hardened another piece of the same steel, just to make sure that everything was going to work as it had been.  The piece that I hardened and broke looked great, just like the test pieces I'd done at the same temp, so I tossed the blade in the oven, let the temp recover and sit for a couple of minutes at my target temp and then quenched the blade.

I was a little suspect because of the way the surface of the blade looked.

I went ahead and tempered it one time last night anyway.  This morning after much thought, I decided to break the tip off of the blade and look at it and it was sandy looking again. It was quite difficult to break though, requiring a few good smacks with a hammer and punch.

Here's a pic of the surface of the blade and the test piece that I was trying to duplicate the HT on.  The test piece (and the ones for the next 40° hotter) are smooth and only have some cooked on oil.  The blade has what looks like pitting on it.
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And here's a pic of the broken ends. The small one is the blade, the large one is the test piece.
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I'm assuming that if the grain looks good before the temper, it will stay that way after it?


Now that I think about it a little bit, maybe the small pieces have the time to cool down between the kiln and the quench and the blade has more mass so it carries more heat to the quench?

At this point I'm beginning to kick myself for not buying a "real" HT oven, but I'm not sure if I would be having the same issues with one of those too. The down side is that I wouldn't have it yet, due to the quarantines. If I buy a paragon or evenheat, are they ready to roll right out of the box?(plug it in, set it to the recommended temp for the steel and it's dead on)


I want to get back to actually making knives, but now that I know that my knives up to this point all have questionable heat treats, and I have a tool that has potential to solve that issue, I can't make more until I get this figured out.  I even have 4 heat treated blades that are ready to be ground that I don't want to waste time on before I fix the HT.

To anyone following along, sorry for venting.  It's just getting very frustrating.

Well, this definitely isn't knives, or metal. Lol

I'm on standby until my thermocouple wire shows up, so we do what we have to. Lol

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I'll paraphrase something that an instructor at vocational school told me because I can't remember exactly what he said (sorry Wayne).  When you are repairing something people shouldn't be able to tell that you touched it, with the exception of the problem being solved.

That is one of two things that really stuck with me from school that I try to live by.

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Ok. Back on knife stuff.

It's looking like I got the thermocouple/PID/kiln situation working.

I'm currently attempting to normalize a blade that I had heated and broken using the schedule that kuraki suggested in my GD thread about the kiln. (1650 for 10 min, then 1500 for 5 minutes 3 times, then 1500 for 5 minutes and quench)

I'm hoping that I've turned the corner and I can start getting better results than I was with my forge.

And here's what happened when I broke it.

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It still looks a little powdery to me, but nothing like it was before. (this piece had been hardened and broken before)

I followed the HT "recipe" from the supplier for this steel and hardened a couple of coupons.

I broke one and I'm going to try to get the other one tested locally.

I think I'm on the right track(finally)
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No dice on getting my sample coupons tested locally.

I've let myself get into a funk over the kiln project. I had to force myself to get back to work. I think it's been since April since I've really worked on a Knife.

I have three blade blanks that I hardened in my forge plus one new one (I'm excited about the new one. It's an evolution on what has been my EDC fixed blade) that I'm going to start thermal cycling and re heat treat using the same "recipe" that I did on my last test pieces.

This one was a twin to the "whale gutter" that I messed up on the swedge/harpoon part.  I decided to just grind the top off and make a skinner.  The primary bevels were already ground so I didn't want to risk ruining it by redoing the heat treat.

I got handles roughed out of black richlite and it'll have one copper pin and a copper lanyard tube.

It was tougher than I thought it would be to get back after it, but I'm glad I've taken a step.

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Search eBay or Amazon for hardness testing files.  Cost is around $50.  The files will give you a range of hardness within about 5 c.

Pay attention to soak times.  Find the formula for your steel and thickness.

Have you thought about getting a secondary temp probe?  

Temper in a toaster oven immediately after your part has cooled.  Don't leave the door open to your HT oven.  Rapid cooling will shorten the life of your heating coils.

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I decided to play with etching and then stone washing.

I think I'm going to shake it around some more to try to break up some of those long scratches.

Still no idea why I get the different flat and shiny areas in the etch though. I degrease with acetone or brake cleaner then wash with hot soapy water and then straight into the ferric, without touching it with my hands.

All done with this one, except for a sheath.

3/32" 1084  Etched and stonewashed with richlite scales and copper pin and lanyard tube. 3 1/4" blade, 7 5/8" oal.  .020" on the cutting edge before I sharpened it.

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I'm hoping to get to undress a pig or two with this one in a couple of weeks.

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I'm making more knives. I wasn't really feeling it when I started working on this last one, but the monkey is back since I finished it.

I'm 99% sure that I'm going to buy a set of hardness testing chisels from one of the makers at dragons breath forge (I think @kuraki told me to get some of these several weeks ago.  I'm hard headed though. Lol).

I'm still not 100% positive about the hardness I'm going to be achieving on this batch, but I'm pretty sure the kiln is reasonably accurate in it's readings now, so I'll just follow the HT recipe that the supplier calls for and hope for the best. I figure It should be at least as good as the ones I was austenitizing in my forge.

ETA: I just ordered the chisels

MAIL CALL!

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Here's my half set (58-64 HRC) of hardness files from Matt Parkinson at dragons breath forge.

After a little bit of playing around, it seems that most of the knives I've made are too hard. (63-64) so I'm thinking that my temper temps haven't been high enough.  I'll probably start tempering in my kiln instead of the oven in the kitchen, so hopefully that works better.

The little test piece in the picture is one that I did in my kiln using the recommended thermal cycling and austenitizing temps and times from the supplier. It skates the 64 Hrc chisel and the HT info says that it should be 64-65 as quenched, so I'm thinking that my kiln/PID problems are solved.

I'm still quenching in peanut oil, but it's looking like for this 1084 it's working fine for now. I do plan on buying some real quenching oil at some point in the not too distant future though.

Have you been chipping the blades that are "too hard"?

If not, why not run them a harder? Better edge retention?

The only one that I had an issue with was spot. I broke the tip off once, but it's ground pretty thin and I was using it to pry stuff apart when the belt in my dryer broke.

I'm pretty easy on stuff most of the time though. I have batonned most of the fixed blades I've made and kept without issue though.

I'm not sure if running them a couple of points harder than I "should" will help with edge retention or not. I suppose it's something to play around with now that I have some more repeatability in my processes.

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Starting another batch. The two on the left are twins to knives I've done before (I almost always do two of a design) that I re heat treated and the one on the right used to be a twin to the one I made with the blue and tan handles, but I changed the handle and blade proportions a bit. The one second from the right is the one I'm most excited about. It's my second "evolution" of the knife I've been carrying.

I'm pretty happy with how these came through the heat treat and temper processes. Having the hardness testing chisels allowed me to test the as quenched hardness (dead on with what the "recipe" called for (64 HRC) and the tempered hardness, which came out at 61 HRC after two cycles at 400°, which is what is called for.  I hadn't had any failures to speak of up to this point, but I didn't like not knowing how things went.

I posted in the edc thread but I figured I'd ask in here too, just in case.

Does anyone have any tips or tricks for grinding near the tip on a dagger or bayonette  grind?  I wanted to try that grind on this blade, but not have a false edge on the top (follow the black line), but my brain broke when I got out near the tip and I couldn't figure out how to grind the edge the same thickness as the back end of the blade without the grind line climbing towards the edge.  Is a second edge or swedge required to bring the center line back down?

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Thanks for any help.

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I think grinding the primary bevels in is my favorite part of knifemaking.

Looks to me like you're good at it!

Thank you. I'm trying.

Have you considered heat treating in molten salt? That is the way to go if you are concerned about grain growth due to overheating or oversoaking.  You can probably make one for less than $500, including a nice digital thermometer for a k-type thermocouple.

I've seen it. I haven't really considered it though. There's just something about having a vat of lava in my garage that doesn't sit well with me. Lol

It's really cool though, like Sous vide for Knife blades. As I understand it, you don't have to worry about overheating thin areas and decarb isn't an issue because of the oxygen free environment.

True.  I always do it outside.  A 1-inch diameter bar will reach bath temperature in 4 minutes.  I would like to have a kiln, but the cost coupled with the uncertainty as to exactly when the load reaches the kiln temperature are kind of off-putting.

I'm $150 into my kiln setup.

I was going to buy a real heat treat oven but the deal on the kiln came up so I figured I'd give it a try.

I'll probably end up upgrading at some point as this one is pretty slow to heat after 1500° or so.

If I haven't mentioned it before, I love these clamps. You can put a surprising amount of force on parts without them pushing the material around. And you can install or remove them one handed.

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I hate when this happens. The stencil had been sitting on my work bench for six weeks or so, so I don't know if that had anything to do with the holes in it or if they were defects in the tape.

Luckily this Knife is for me so it doesn't matter too much but it's still frustrating. If this one was for someone else, the only thing I could think of to "fix" the messed up etching is to either attempt to remove the same amount of material from the flats on both sides or turn the primary bevels into a full height flat grind and then etch again.


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Going ahead with the build.

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ETA: holey crap, the top pic did not want to post correctly. I uploaded it once, it was inverted so I flipped it upside down in my phone and posted that. Still upside down. I ended up posting it upside down, downloading it to my phone, flipping it back right side up and posting it again. Wtf is that about?  Lol

Anyone else looking at that will just think character mark.

Thanks.

I wouldn't be happy with it if it was on a Knife I paid for though.

@ksred ,

Thanks again for this tip.

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The blobs on the blade are the mostly cured squeeze out from the front of the scales.

Got scales roughed out for the other one.

Seems like a good enough place to stop for the night.

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This guy's about done. I still need to sharpen it and make a sheath. I'm thinking this one will get leather unless someone can convince me otherwise.
I'm pretty happy with everything except the spots around my mark. I'll have to try to spot that ahead of time moving forward.

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Nice

I happened upon a cool opportunity to learn (even though it means more work to get this one right).

This blade was hardened the first time in my forge and tempered twice in my kitchen oven, then thermal cycled per the suppliers instructions, then hardened in my kiln and then tempered twice in the kiln.  

I wanted to etch and stonewash it.  Here it is after a quick etch.
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@kuraki had mentioned in another of my threads that decarb stays white when it's etched.

I took this opportunity to poke around on the blade with my hardness chisels. The parts that etched black or dark grey test at 61hrc(60 chisel skates, 62 bites in) like it's supposed to but the 58hrc chisel easily bites into the white (decarb) spots.

I'm a little tired from a whole day at work followed by standing at the grinder (and having a bad grinding day) for a couple of hours, so this might not be as interesting to anyone else looking as it was to me.

What is the etching compound?

It's ferric chloride.(PCB etchant)

I'm still having a hard time getting a nice even black that doesn't wipe off.  I think I might try diluting it with some distilled water and letting it go longer. I've been sticking the blades in the FC for about 15-20 seconds and then rinsing with water and repeating that a couple of times to get them to darken up a bit better but they still end up kind of blotchy. (It's extra bad in the pic because it's got some WD-40 on it to keep it from rusting overnight)

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Here's where we're stopping for today. Got handles(black richlite) shaped and sanded to 600 grit and the blade sanded to 320 and etched(to include my mark, without any extra bs this time!).

Tomorrow should see it getting stonewashed and then glued up with a copper pin and lanyard tube.

A sheath comes after that and then it's outta here.

You can get temperature-indicating crayons from McMaster.  They melt at specific temperatures.  You can get pyrometric cones fron other places, too.

Today I'm taking a couple of minutes to build a chain breaker for cutting 8 series forklift chain.

It's not really a chain breaker, more a guide so I can drive the rivets out with my air hammer.

First, some measurements, maths and scribbling.

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Drill the holes out and then transfer the holes to a piece of scrap that will become the top plate/guide for this contraption.

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In retrospect, I could have tacked the plate onto the square tube and laid everything out and drilled the holes all at once and had a slightly easier time.

Maybe I'll do that if I make another one of these.