What Happened With This Hamon?

[ScarFoot]

I’m new to making knives and not sure what happened with this hamon. I had the clay 0.5”-0.75” from the edge but the hamon line is right at the edge. The pictures show what it looked like after the first few cleaning passes post quench and temper. You can see a faint line where I thought the hamon should be. Any thoughts? I’m not going to lie I don’t remember if it’s 1075 or 1084. I just grabbed a piece and started grinding.

 

[Joshua Fisher]

Clay was either too thick or too close to the edge, or you didn’t let it soak long enough at your hardening temp. Couple different variables that can cause the hamon to be lower than your actual clay line.

 

[Stacy E. Apelt - Bladesmith]

Several possibilities:
Too high a hardening temperature (most likely cause)
Clay too thick (probable cause)
Clay too close to edge (probably not the cause)
Too much manganese in the steel (always get an analysis report when buying steel)

 

[ScarFoot]

Thanks for the feedback. I have an actual oven I’m using that holds temp. I put the blank in when I started the oven and I left it in there for 15-20 minutes after it reached temp then quenched in Parks 50 I had heated to the 130-140 degree range. I’m thinking I may have had the oven too hot. I got my oven from my dad and he said it runs a little cool so I set it at 1590 hoping it would be in the low to mid 1500’s. I’m trying to figure out a way to get an alternate temp indication so I can confirm where it actually is. I didn’t think they clay was too thick (maybe 1/4”) but I’m just judging from pictures I’ve seen online. I did work to even it out and get it a consistent thickness everywhere.

My second question is, do I need to fix it, scrap it , or go with it? I’m just at the tinkering phase of my knife making journey so I’m trying to learn as much as I can right now when I mess something up.

 

[Gene Kimmi]

Parks 50 should not be heated unless it is below 50 degrees. It should be used at room temperature. The max working temperature for it is 120 degrees.

 

[A.McPherson]

Generally, you want to put your blade in once the oven has stabilized at temp for 10-20 mins, then start the timer after it gets back up to temp.

That way, the oven doesn't overheat your blade on the way up to temp.

 

[ScarFoot]

Parks 50 should not be heated unless it is below 50 degrees. It should be used at room temperature. The max working temperature for it is 120 degrees.

See the info I’ve found has been all over the place on that. It was about 100 degrees outside so my oil was pushing 105-110 at ambient temps in the quench tank. I won’t heat it next time.

 

[ScarFoot]

Generally, you want to put your blade in once the oven has stabilized at temp for 10-20 mins, then start the timer after it gets back up to temp.

That way, the oven doesn't overheat your blade on the way up to temp.

Thanks for the tip. I was concerned about the over heat but wasn’t sure which would pose the greater risk between letting it heat slowly or opening the door and letting it get back to temp that way. With that in mind I had it on the slowest ramp rate which took about 45 minutes to get to full temp but I don’t know how “hard” it works to ramp. I can certainly see what your saying about overheat being a possibility. Thinking through it now I can see an advantage in putting the blanks in at full temp because they will still be coming up to temp while the oven is trying to catch back up.
I’m going to try to get some thermocouples or something going to see what the temp is doing during ramp up and how far it’s off from set point at holding temp. It’s some type of little lab oven that can be programmed to ramp and soak at various temps and set times. I just need to confirm the accuracy.

 

[Taz]

Get a K type thermocouple and some sort of reader to display the temperature. It will really let you know what is going on inside the oven! Ovens run hot to get up to temp and a longer soak will lead to more scale and maybe decarb too, plus you don't know what the temp really is when it is heating up. I let my kiln get to temp, open the door and put the blades in, get back to temp, then start the timer.

 

[Keith Nix]

Let your oven soak at temp for at least 30 minutes to allow it to stabilize before inserting the first blade. I do batches of 10-20 blades. The first run it takes the oven 3-4 minutes to get back to temp. An hour later that's down to less than 2.

 

[ScarFoot]

Let your oven soak at temp for at least 30 minutes to allow it to stabilize before inserting the first blade. I do batches of 10-20 blades. The first run it takes the oven 3-4 minutes to get back to temp. An hour later that's down to less than 2.

I’ll try that on the next run. I can only get 3-5 blades in my oven at a time in its current configuration without stacking them on each other. I’m thinking about making a slotted “rack” out of a fire brick to set them in and keep them separate so I can fit more.

 

[ScarFoot]

Get a K type thermocouple and some sort of reader to display the temperature. It will really let you know what is going on inside the oven! Ovens run hot to get up to temp and a longer soak will lead to more scale and maybe decarb too, plus you don't know what the temp really is when it is heating up. I let my kiln get to temp, open the door and put the blades in, get back to temp, then start the timer.

I was shopping K types earlier today. I’ll have some before my next oven run.

 

[Bunker Hill Blades]

I didn’t think they clay was too thick (maybe 1/4”) but I’m just judging from pictures I’ve seen online. I did work to even it out and get it a consistent thickness everywhere.

I’m no expert, but 1/4” is way to thick.

 

[ScarFoot]

I’m no expert, but 1/4” is way to thick.

I’m clearly no expert either lol. I’m enjoying the learning process though. I get a little better every time I stumble through making one. This is only my 6th knife like object so I have a long way to go.

 

[Stuart Davenport Knives]

Just to reiterate, Parks 50 should not be heated much beyond room temp. I keep mine in the garage where the ambient temp in south Texas gets in the upper 90s. There is a recommended range of temps from Maxim oil, I wish they would print it on the label, but they don't. I just checked mine. According to the Maxim oil website who sells the stuff, the recommended range is 75°F-120°F. So I just leave mine in the garage. In the winter, I pull the bucket inside and drag it out when needed for the quench.

If using something like canola, warm it up to ~130°F, but not P50.

I think you tried the hamon on your 1084 steel. Too much manganese for a good hamon.

 

[ScarFoot]

Just to reiterate, Parks 50 should not be heated much beyond room temp. I keep mine in the garage where the ambient temp in south Texas gets in the upper 90s. There is a recommended range of temps from Maxim oil, I wish they would print it on the label, but they don't. I just checked mine. According to the Maxim oil website who sells the stuff, the recommended range is 75°F-120°F. So I just leave mine in the garage. In the winter, I pull the bucket inside and drag it out when needed for the quench.

If using something like canola, warm it up to ~130°F, but not P50.

I think you tried the hamon on your 1084 steel. Too much manganese for a good hamon.

Good info on the P50. My Garage doesn’t stay quite that warm in the winter either. I’ll just drain it back into the jugs and stick it in the basement when it gets cold. I’m in Alabama so our ambient temps are probably simIlar.
It may well have been 1084. I know I had a few pieces of it on the shelf. I’m just throwing stuff at the wall to see what sticks at this point.

 

[ScarFoot]

Just etched this one this evening and am pretty pleased with it. I probably had the clay too thick on it as well but at least the line isn’t at the edge. It’s 1075. Haven’t quite figured out how I want the handle to look yet.

 

[Stacy E. Apelt - Bladesmith]

Too hot and wrong quench temp.
The parks at 130-140° was the biggest issue - Use it at 50-90°
Low 1500's° was too hot - 1080 quenches at 1475°, and even a little lower when seeking an active hamon.

Go ahead and re-do the quench with thinner cay, unheated #50, and 1465° as the oven temp.