First knife HT/ Temper question

[Crood]

Is this ok? I am using 1080 steel, stock removal. I followed HT procedure listed on Sam Harper's site, Poor Folk Bows. Then I tempered it in a toaster oven at 400* for 1 hour, let it cool, repeated the cycle. The knife came out at blue, purple, red color that looks like an oil sheen on top of water. Is this ok?

[kbaknife]

To accurately answer your question would be a bit difficult.
Theoretically your procedure seems somewhat accurate at first glance.
But how hot you got - or not hot enough - before quenching in how much of what - we don't know.
Lots of knives have been tempered in toaster ovens.
Accurate success with that method is minimal.
The desired effect of tempering is best achieved with a consistent temperature.
The cyclic characteristic of toaster ovens makes them less than desirable. The huge variation of temps when heating and cooling is totally unpredictable from one oven to the next.
A correctly controlled furnace/oven will result, in most cases, in a soft straw color on the steel. We get concerned with colors like blue and purple because these often show up in temp ranges much higher than desired, like 500+.
But keep in mind those colors are also most reflective in the perfect world. Perfectly clean steel in a perfect environment, etc.
Some of those colors can show up simply be contamination.
The simplest test of your cutting edge can be accomplished with a file.
After hardening and tempering, does an off-the-shelf slightly used file slide off the cutting edge like it's filing a piece of glass with no bite?
Or does the file bite in?
So many variables.
Regardless, you tried. You've made more of a knife than most people are capable of or willing to do.

[Crood]

Thank you for your reply! I am sorry I dint know what all information you guys needed. I heated the blade in a coffee can forge. With propane. I had the entire blade glowing brute orange. I took it out and touched it to a rare earth magnet and it didn't stick. I put it back in the forge and got it to the glowing orange color again. I took it off of the direct heat and kept it at that bright orange. I timed it for 3 min. Came staring out into some warm vegetable oil. I held it in there moving in back an forth for about 30-45 seconds. Pulled it out sanded off the black scales (dipping in water frequently). I had to leave so it was about an hour before I started the tempering process. Like I said I brought it up to temp. (toaster oven knob SAID 400*) (I don't know how accurate that is.) After 2 cycles at one hour each I had the blue color. Should I just watch it next time? What is the typical progression of color? Tan,straw, blue...? If it was brought up too high what can I do to fix it? Start over with entire HT procedure?

[kbaknife]

With your existing equipment I would be inclined to agree that you've most likely got your knife as good as you can get it.
To improve things, you will need to gradually upgrade your tools and materials.

[gudspelr]

You've already got some good information from Karl. There are a couple things I'll add. First, if you're using a kitchen or toaster oven, invest in some thermometers. Just because a dial says it's a given temp doesn't mean it's actually right on. Also, I generally take some steel and put it in the oven to help act as a heat sink. I get the oven going and continue to monitor the temperature and tweak it until it's holding where I want it. THEN I get started on hardening the blade(s) I'm working on. I want the tempering oven at the right spot so I can quench the blade and get it right into the oven.

Another note from experience....after you've quenched and cleaned off a bit of the scale, do a quick file check like Karl mentioned. Be sure the file skates on the edge without biting in. I didn't do that one time and went through a lot more work before finding out I hadn't gotten where I needed to be for austenizing temp...I call it a learning experience now   . Keep it up and be sure to ask questions when they come up. Nothing like getting to use a knife you've made.

Jeremy

[Crood]

Thank you guys. It's nice having a place to pass on knowledge like this. How bad will it stink up my house to use my kitchen oven? When you say file across the knife edge. Do you mean what will be the blade? Or the side of the knife? I did this originally and it would leave scratches if I tried but it never "bit in" I guess. Like I said I'm so inexperienced I don't really understand the file test. I've got some mild steel I'll experiment with a file on it. I've ground a blade in and it's holding an edge pretty well I haven't given it a real test yet.

[kbaknife]

Try the file right directly on the cutting edge. If the file cuts and bites - the steel did not get hard.

Steel won't stink. Just clean any oil off.

[Bobby Urban]

X2 on getting thermometers in the toaster oven. Lots of nice knives have been created with your simple tools. Not like some of the stuff you see here but some of these guys have been doing this a long time and have accumulated some really nice tools. Needless to say there are also hacks like me that use what we have and toaster ovens are my go to tempering oven. Another thing to improve consistency along with a thermometer and some extra steel in with the blade is to fill s tray w sand and preheat that. Place your knife in there to temper. This will help offset some of the on off changes in toaster oven heat.