Randell Warren

My Seax attempt

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Finished the forge work on this today, quenched fine and baked it at 450 for an hour. Ended up tannish with purple areas, little confused because it's my first time heat treating (I made stock removal knives in the past from finished metals)

Are the colors right for a functional knife or should I try again. Just concerned that the purple is in some random spots. The edge is purple too. Wish I could keep it that color.

Image is post quench, pre-treat. I was just giddy it didn't explode or warp!

 

20170906_182316.jpg

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Looking at the picture its primarily 440 with the cutting edge and spots (maybe thin areas?) 540. I read up on the threads but can't seem to grasp of it's bad or not.

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If you had your oven set at 450°, you think it looks like 440°. Ok, close, but how will an oven set at 450° get something to the 540° range? Even on thin parts. Isn't that why we use ovens. Set it and forget it?

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Frosty   

You need to buy an oven thermometer, you oven may not have an accurate thermostat. Another thing to remember especially for a gas oven, the thermostat keeps an AVERAGE temperature so it will  range above and below the set temp. Electric ovens keep a more even temp but even then the elements are on only about 20% of the time once it's to temp. 

That means it gets the oven hot enough it won't drop below the minimum temp for about 10 minutes (in our oven) so it gets the temp well above the setting so it takes a while to cool to the low side restart. A way to help even out the temp is to place your blade in a pan of sand, the added thermal mass takes longer to heat and cool so it'll average closer to the setting but GET AN OVEN THERMOMETER!

So yeah, I'm not a bit surprised the thin places on your blade show 540f. temper colors when the oven was set for 450f. Purple to blue is good for the spine and I like straw for the edge on a work knife say a skinner, pale straw for a light duty slicer say a pocket knife. I'd shoot for a dark straw for a heavy chopper like a broken back Seax.

Frosty The Lucky.

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Hrmm. Backwards result from what I tried to achieve then. So should I return to the forge for a requench? Would a different quenching medium change the heat treat result? I used oil, but I could use water or maybe even mix up some brine.

I could probably anneal it and work it with the file to try and even the thickness.

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JHCC   
7 hours ago, Frosty said:

You need to buy an oven thermometer, you oven may not have an accurate thermostat. Another thing to remember especially for a gas oven, the thermostat keeps an AVERAGE temperature so it will  range above and below the set temp. Electric ovens keep a more even temp but even then the elements are on only about 20% of the time once it's to temp. 

That means it gets the oven hot enough it won't drop below the minimum temp for about 10 minutes (in our oven) so it gets the temp well above the setting so it takes a while to cool to the low side restart. A way to help even out the temp is to place your blade in a pan of sand, the added thermal mass takes longer to heat and cool so it'll average closer to the setting but GET AN OVEN THERMOMETER!

The thermal mass of the pan of sand will keep the temperature around the blade more consistent. You can also add some firebrick inside the oven to increase the overall thermal mass and thus moderate the temperature swings. Also, if you have an oven with a convection setting, don't use it; those often will automatically go to a lower actual temperature to compensate for the more aggressive heating from the moving hot air.

There's a post around here somewhere about someone who modified a flea market toaster oven with a thick layer of insulation to help keep the temperature constant.

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I like the toaster oven too.  Big ovens are prone to hot spots. Also, just to add to the fun, the oxide layer gets thicker the longer it's in there, so for longer or repeated tempering cycles, the color may not match exactly what you see on the guide.  

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The proper tempering temperature for a blade depends totally on the ALLOY used as well as what it's intended to do and personal preference!

Anyone telling you there is *one* correct colour for tempering blades could fertilize the back 40 all by their lonesome.

Now folks usually give answers based on what alloy they generally use; but if you are not using the same alloy you may want to do it differently.

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What I meant was you have to make sure the blade is clean from the oil, and free of finger prints before tempering, or it can throw off the temper colors.

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Buzzkill   

Even the finish can affect the temper colors from what I've seen.  I had 2 pieces from the same starting stock where one was a rough finish (around 80 grit) and the other somewhere around 400 grit which I tempered at the same time and they did not have the same colors on the blades afterwards.

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11 minutes ago, Buzzkill said:

Even the finish can affect the temper colors from what I've seen.  I had 2 pieces from the same starting stock where one was a rough finish (around 80 grit) and the other somewhere around 400 grit which I tempered at the same time and they did not have the same colors on the blades afterwards.

I've found that too. I learned pretty quickly to always clean blades up perfectly post quenching/pre tempering And to have them to the same grit every time.

That's if you want them nice an' shiny lol.

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What medium you use to quench will not affect the tempering colors. The colors are an indication of how hot you are tempering and how much hardness is being removed versus how hard the steel is. Sometimes, you will do an edge quench and get a slightly darker color on the edge, because the edge is thinner. This means that a little bit more hardness has been tempered out of  the edge that the rest of the blade. However, the edge is still harder than the spine, because it started way harder prior to tempering.

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Awesome, thanks all. I'll try the pan of sand after I redo it this weekend. I was straightening the edge and ended up working some soft spots. 

A question for someone who knows more than I, I want to lay a thin layer of copper or brass over the spine for looks, should I notch the start of the handle and set it in flush or build the handle up to cover the end? I left the handle a little bigger than it needs to be because I want sure about that.

As for finishing it before baking, it's important this one looks rough. It's the aesthetic I'm after. Filing that away for future reference though.

 

20170907_110055.jpg

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1 hour ago, Randell Warren said:

A question for someone who knows more than I, I want to lay a thin layer of copper or brass over the spine for looks, should I notch the start of the handle and set it in flush or build the handle up to cover the end? I left the handle a little bigger than it needs to be because I want sure about that.

I'm not completely sure what you are trying to accomplish with this, perhaps a sketch is in order?

  1. If you are planning on putting scales on the side of your handle and want to have copper or brass showing in between the two sides of the scales I would recommend you look into frame handles with a hidden tang.  In that case you will have to cut down your tang width quite a bit to fit the frame around it, and that will likely be a problem with the large hole in the middle of the tang. 
  2. Another possibility would be to simply plate the edges of your existing spine/tang with brass rod using a torch (brazing).  I would do this before hardening and tempering if possible, and if you are careful with the final heat treatment to just heat the blade the brass on the handle should be fine as it does not melt till 1650 deg. F.
  3. Wire inlay is another possibility, but without the ability to cut a groove in the edge of the spine/tang I think it would be fairly weak just held by glue between your scales.
  4. Another interesting option would be to make a set of scales that have wood outer layers and a thin sheet of annealed copper or brass added as a liner between the scales and the tang.  If this liner is left a little proud of the surface it can be carefully hammered down to fill any gaps between the tang and scales and leave a nice color accent in the handle.
  5. A final option would be to electroform the copper or brass (to date I've only done copper, but I know that it is possible with silver and gold, so maybe worth investigating). to the area you want to have that accent.  This might be the best option, as it can be done cold so as not to ruin your blade heat treatment.  Needless to say you will have to have some sort of resist to keep the plating only in the area you want to see it.

Good luck, I look forward to seeing the finished knife.

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Solder the piece of copper to the spine using stay-brite using a propane torch and with the edge of the blade standing in a pan of water---a couple of small C clamps can hold it  edge in and spine away.  Like all soldering make sure that the area to be joined is smooth and clean!  Dress it with a sharp fine file after and put the handle on like a full tang knife or like those kitchen knives that show the tang on top but not on the bottom.

Notches on tangs/blades are often stress risers and so not a good thing.

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27 minutes ago, ThomasPowers said:

Solder the piece of copper to the spine using stay-brite using a propane torch and with the edge of the blade standing in a pan of water---a couple of small C clamps can hold it  edge in and spine away.  Like all soldering make sure that the area to be joined is smooth and clean!  Dress it with a sharp fine file after and put the handle on like a full tang knife or like those kitchen knives that show the tang on top but not on the bottom.

Notches on tangs/blades are often stress risers and so not a good thing.

I think Thomas has a better idea of what you are trying to accomplish.  I got carried away with the concept of "thin layer" and didn't have a good mental picture of the final product.  His method seems much easier and cheaper  :D

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idea comes from a bowie knife my dad had that looked like the one attached. Sorry if my descriptive skills were lacking, im not sure how to describe it best, It just appears in my head and wont go away.

bowie.jpg

On 9/7/2017 at 0:32 AM, Frosty said:

You need to buy an oven thermometer /-/ GET AN OVEN THERMOMETER!

Frosty The Lucky.

Yessir. Done and done. I was also told later the stove heats erratically (not my stove). definitely going with my own stove and a pan of sand this next go. I have nearly a ton of store-bought sand leftover from some masonry work on my parent's house, will that work?

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No you described it well, I just missed the boat.  Based on the sketch and photo I recommend following Thomas's plan with the solder.  I'm not familiar with Stay bright solder, but am sure it will do the trick.  Personally I would be inclined to use jeweler's extra EZ solder and a microtorch, but that is just what I am familiar with.  Don't forget to clean and flux.  You may be able to find the brass c-channel section at a good hobby store.  A tight fit around the spine will work best.

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Yes the sand will work, the brass back on a Bowie was supposed to be used for catching an opponents blade edge on in a fight---it would bite in allowing you more control over their blade.  Some hobby stores sell small brass channel stock that might work.  I think I would taper the sides before soldering as it will be more difficult afterwards.  Some viking era blades did have ornamental nonferrous work on them.

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