Help with dealing with hardened blades when squaring shoulders.

[groy87]

Hello all,

I am having some issues with squaring the shoulders on the knife blades I have on hand and I have to think there is a simple solution to this.

I purchase all of my blades premade and they come in hardened. This makes squaring the shoulders of the blade problematic and quite time consuming. I have recently gone through 4 files on the last 3x blades I worked on. Now I don't mind replacing files when needed but averaging about 1-2 files per blade I can see this becoming an expensive issue later on.

I am now on the list for one of bruce's file guide and I am looking for alternatives to making squaring the shoulders of the blades a more efficient and cost effective process moving forward. As it stands I see 2x options that will work with my budget and available shop space:

1.) Buy a torch and anneal the tang to soften the metal then square the shoulders with the files. I am concerned about ruining the hardening of the blade in the process. (I've seen a few threads on this already)
2.) Buy a small 1x 30 or 1x 42 sander and use that with bruce's guide to true the shoulders. This setup could also help with stock removal on the handle but I haven't seen many positive reviews for this belt sander setup.

Ideally I would like to buy a 2x 72" system but I currently don't have the space for a larger setup like that.

What has worked best for those out there when it comes to this step on knife making? Any input on this would be greatly appreciated.

 

[bodog]

.....

 

[Bo T]

If I understand you, it seems that fitting the guard/bolster to the shoulders is easier than squaring the hardened blade to fit the guard/bolster?

 

[Bill DeShivs]

There is a reason they aren't squared.

 

[groy87]

If I understand you, it seems that fitting the guard/bolster to the shoulders is easier than squaring the hardened blade to fit the guard/bolster?

My goal is to square up the shoulders of the blade in order to get a good fit to the brass or nickle silver bolster. The edges of the blade that would meet the bolsters have a slight slant across the thickness/width of the blade shoulder. This will cause a gap when fitting the bolster to the blade. I would rather square the shoulders to make the fit up easier than having to wack away at the assembly to essentially embed the blade into the bolster lol. My problem is that with the blades coming in hardened I am chewing through files faster than I would like and I'm wondering if there is a simple solution to make the squaring process easier.

I have seen several cased where scandanavian knife smiths will use a softer material like stabilized wood or antler as the bolster and simply route out the material with a dremel from the bolster to fit to the blade. In most cases this looks great but I am more partial to a metal bolster so some adjustments need to be made to the blade to get the tight fit that I want.

 

[Stacy E. Apelt - Bladesmith]

I have never seen pre-made blades with off square shoulders. If they are at a slight angle, that is because the guard was meant to be at a slight angle. If they curve, just file the slot ends in the guard in a curve to fit. Also, only the very ends of the slot have to seat flush on the shoulders. The slot can flare out to be 90% of the shoulder width to accommodate the curves.

That said, all you need is a diamond sharpening stone or a small belt grinder to change them. Use the diamond plate like a file. A coarse Lansky stone or equivalent works perfect.


Just to make one thing clear, the transition from tang to the shoulders should be curved, not at a 90° angle.

 

[groy87]

Sorry if I was being unclear. I've attached an image below of what I am dealing with. I am keeping the general slant of the junction and the radius of where the tang meets the blade. I am just trying to true up the slight misalignments that will show up as gaps later on.

 

[john april]

i use a dremel with a tungsten carbide tip (# 9901) to gnaw away hardened steel. you could get it close with the dremel, and smooth the rest with a file.

 

[groy87]

i use a dremel with a tungsten carbide tip (# 9901) to gnaw away hardened steel. you could get it close with the dremel, and smooth the rest with a file.

Thanks for the recommendation. That worked great on the smaller blade in the picture above.

 

[S.Alexander]

Softening the tang and shoulders is easier than you would think (with carbon steels).

Hold the blade under water with pliers or tongs, with just the tang and shoulders outside of the water. Heat the exposed metal until the steel turns blue/purple. Let it sit cool for 30 seconds or so, then dunk in water. Repeat one more time.

This will put the hardness of the tang and shoulders much lower than a file. The water will protect the temper on the edge.

I use that method, along with a carbide file guide and grinder, but a file would work as well.

 

[Willie71]

I have a set of small diamond files for small adjustments. I got them at Lee Valkey. The easiest us using my Bruce Bump carbide guide on the belt grinder. This would work even on a 1x30 grinder. Dictum sells files that will cut hardened steel too. Several options. :thumbup: