Squaring shoulders for hidden tang.

A

alexmin

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Nov 16, 2005
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I am making my first hidden tang knife. It's already HTed it but shoulders are not perfectly square. Should I anneal shoulders(steel is O1) with a torch first and then square them with a file or there is some other way of doing this? I am concern that I might ruin heat treating even if I wrap blade in wet blanket since cutting edge is only 1/4" from shoulders.
BTW I do have a jig to keep file perpendicular to the shoulder.

Thanks,
Alex
 
What I would do is a soft back draw. Place the edge of the blade point down and at an agle in water so that about 1/2 of the lower cutting edge is submerged leaving the end of the tange and shoulders just out of the water. Heat with a tourch to a blue, let it cool and do a couple more times cleaning the oxidation color off between heats. The water will protect your edge and give the spine and tange a springyness to boot. I almost never do a full quench and instead like to leave the tange and part of the spine soft. I try to leave the gaurd shoulders soft, but sometimes get the lower hard and have to spot soften it with the above methoud. You only need about 1/8" of the lower shoulder out of the water, I asume your not taking more than a few thousanths off? If the color starts moving toward the edge closer than you like just dip the shoulder further in the water to stop the temper. As long as you keep the temp down to a blue and not a red or orange it'll be OK.
 
Put the filing jig on and grind them flush. Or a diamond file will clean them up also.
 
A diamond stone (coarse grit) will trim it up just fine.Use a jig to see what is off.
Stacy
 
alexmin said:
I was thinking about that but didn't want to gauge the jig.
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Put a piece of masking tape or two over the closed jig, then slit along the join with a razor blade. Proceed. When you start filing the tape, stop.

I do like Bruce says with the grinder with one side of my jig. Periodically i dress them up either on the grinder or surface grinder. The other side I keep pretty.
 
I did as you recommended: put some tape on my jig and tried to ground square shoulders. Here is the problem I have. My pyroceram platen has 1/8" rounded edges so I can't get really close to the shoulder. Where shoulder plunge is suppose to start I have beginning of 1/8" curve.
 
Alex,

Just my two cents, but I anneal the tang, shoulders, and spine with a torch; cooling it in water as soon as I get the color change I want in the sections I'm heating. If you want, you can even submerge the edge in water while you are using the torch. I then use my filing jig and square up the shoulders with a file.
 
I even made a holder where I suspend the knife by the tang point down in a PVC tube of water. Fill the tube full and just leave out of the water what you want to draw back.
The heat will stop at the water level.
 
alexmin said:
I did as you recommended: put some tape on my jig and tried to ground square shoulders. Here is the problem I have. My pyroceram platen has 1/8" rounded edges so I can't get really close to the shoulder. Where shoulder plunge is suppose to start I have beginning of 1/8" curve.
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Actually, having a radius there is structurally sound. Some makers leave the curve there on purpose, and file a corresponding curve in the guard slot using needle files.

It sounds like you are at the point of needing a diamond file or two. Stones will work, too, like Brent mentioned.
 
Am I the only one who does the shoulders before heat treating? :confused: It sure makes life simple and I have never had to redo one after heat treatment.
 
No, you're not alone. I always do. I only mention the above because sometimes I need to bend the tang a little or maybe soften the tang for threading purposes.
Actually, with a temp controlled oven, I take my knives to full finish before HT.
About all you have to do after that is a little clean up of quench muck and the very outside of the blade, and it's done!
 
Fox said:
Am I the only one who does the shoulders before heat treating? :confused: It sure makes life simple and I have never had to redo one after heat treatment.
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No, you're just one of the smart ones. In truth, I never thought of that. Dooh!
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Guys,

does anyone file tang on all four sides, so bolster sits on four shoulders. This way it'll be easier to avoid gap on between bolster and sides of a blade.
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Hidden tangs in carbon steel are darn near all I do anymore.

If I do a fully hardened O1 or 52100 blade, I wait until everything is ground at at a dirty 600x hand rubbed finish. By dirty, I mean it's nothing but 600X scratches, but I don't care if they are all uniform yet.

I put a 5 gallon bucket of water on my bench-top. I hold the blade in my fingers, point down over the bucket. I hold the blade right next to the ricasso. I almost always employ a short ricasso, I just prefer the look. So it's not a long shot from the edge to the tang.

Heat with the torch until it starts getting my fingers hot, then gently lower the blade into the water, right to the guard shoulder area. Yes, this means you'll be dipping your hand in the water... but hang onto that blade!

I usually only have to do this a couple times.

I go over the tang at the same time so that I can easily drill a hole in the handle later.

Next I take 600X paper with a steel sanding block and sand off the oxidation. You want to do AS LITTLE SANDING as possible after you cut those shoulders, because you will round them off. Even if you don't think you are, you will very quickly round them off. This will cause a dip where the guard butts up against the shoulders.

Next-

Cut the shoulders with the jig and a good file. Do not stop filing until you can take a surface ground piece of steel and run it onto the file guide and over the blade shoulders without feeling a bump.

When you're done filing, you'll have a slight bur around the shoulders. Use a hard block (I use finely surface ground steel) to sand that off.

Proceed with guard fitting.

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