I have a couple of File Razors that are nearly ready for heat treat.
ATM they are hand sanded to 180 grit. What grit would you guys recommend sanding them to before they go in?
Thanks
Grant
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I have a couple of File Razors that are nearly ready for heat treat.
ATM they are hand sanded to 180 grit. What grit would you guys recommend sanding them to before they go in?
Thanks
Grant
180 is good, I useually sand to about 80 grit pre-heat-treat. and break all of the edges with and corners with a bit finer paper 150 grit.
Charlie
Hi Grant,
+1 on Charlie's recommendation - especially breaking the corners and edges a little. No sharp angles.
Also the grits between the USA and Aus are usually different scales. Doing carbon steel in oil, 180 is good. If i do high alloy i am sending to a heat treater with a vacuum system i go to at least 800.
Hope they come out great for you.
Adam
I take my hollow grind to 120 grit and the blade profile to at least 220 grit for carbon steel before HT.. Has always worked perfect for me.
+1 on trying to eliminate any sharp angles. All that steel moves around quite violently (and at the speed of sound strangely enough), any hard corner induces additional stress creating an opportunity for a crack.
Thats really interesting,can these movements be seen or measured? is it like a few thousands?Quote:
Originally Posted by Mike Blue
I'll let you be the judge: Japanese Swordsmith Komiya Kuniharu - YouTube
Admittedly this is happening in a long blade, lots of mass, but you can't miss what's going on with such a large object to see it all. Think of all this same movement happening in a little, very thin blade like a razor.
When you guys say take off sharp edges, to what extent are we talking? I'm starting to worry about my jimps now.
Would you consider them risky to quench.
They are not as deep as they look, probably 1mm deep on the deepest one. The groove kind of bends around to the side of the tang making them appear bigger
Attachment 101631
Attachment 101632
Thanks
Grant
Do not worry about the jimps. Jimps are an easier to cut on a pre heat treat blade I make most of my jimps pre heat treat. I have had very few razors that have had problems with the jimps during heat treat.
It is the nature of the beast, there will be some failures. I think the thing to do is push on and not worry about them.
Charlie
This weekend I HTed a slender kitchen knife. I clayed the spine to achieve a hamon (if was old file steel).Quote:
Originally Posted by Mike Blue
Before it went in, the profile of the knife was western (like a normal chef knife). After HT, the spine was arched like a tanto. That is quite a big deformation for a rather short blade. It surprised me.
So if you have sharp corners in your blade and a steep temperature gradient runs through that area, it could tear in.
Don't worry about the jimps. They run through the thick part of the tang which is structurally strong.Quote:
Originally Posted by baldy
Additionally, The tang gets cooled with the same temperature so there is no stress gradient like there can be between a thin edge and a thick spine.
As of this writing, of all the razors I've had a hand in heat treating, the jimps have not yet produced a stress riser. I have to say that a heavily file worked spine and some jimping has caused me to hold my breath at the critical moment. I can only remember one or two cracks and they were directly related to very acute angles.
It's possible to draw out the hardness of the tang after heat treatment, then file stuff in. Diamond files work pretty well on even the hard stuff, but it's a lot of hand work either way. Perhaps consider just enough of a cut to mark where you want the jimps, keep it shallow and radiused, then after heat treatment, cut in the sharp definition.
This kind of thing should be a point of discussion between the blade maker and the heat treater before the quench.
