Newb tip: Japanese sen, if you have an old file laying around make one.

B

b_rogers

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Sep 25, 2011
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After seeing the sen mentioned a lot when reading about Japanese blades, I decided to make a sen-like blade out of a worn out half round file. Basically i ground off the file teeth on the flat area and part of the round to make a extreme angled sharp bevel. Make sure you cool it frequently or it won't hold its edge.

WOW! This thing spits hot ribbons and chips once you get the hang of it. Sometimes I see smoke coming off the edge, just crazy.

As with draw filing you have be careful of downward pressure or you will create a divot. After it "digs" in it will really start to cut. Watch out for chatter or you will end up with serrations instead of a nice flat surface. It takes a little while to get it, so grab a piece of scrap and practice. I did the mune of a W2 tanto really quick compared to filing alone. You will still need to file and sand, but this thing will remove metal FAST. I start out with short pulls to get started, then long light pressure pulls to keep it all even. Once the sen wears in a little it also seems to cut better, maybe its just I'm getting better at it.

If you have an old file and a few minutes, whip one up!

Brent
 
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Also, I'm thinking eye protection may be good when using these. The draw stroke can send a shower of chips right at your face.
 
Very cool, like a drawknife but for steel. :eek:

My first time hearing of them.
 
I have been lagging in making one of these. I think it was Don Fogg's forum that had a bunch of info and some pics. Looks like a handy tool.


-Xander
 
I made one once but it didn't work so well, so I'm looking forward to your pics.
 
This is just a makeshift one..A real one would be hollow ground on the flat and each side would have a cutting edge for push/pull action. That way its riding on a 1 or 2 degree bevel even when pressed flat. I don't have a way to hollow grind so I just did mine like a spokeshave or drawknife. If i find the drawings ill post them..

image-29.jpg


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Results, with some sanding and a few pulls of the file..BTW that triangle file is my favorite for draw filing, very stiff and using the odd angled sides can move metal quick too
image-30.jpg
 
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I've been meaning to make a Sen and after spending the yesterday hand lapping what I'd thought was a fairly flat blade, and your thread, it's the kick in the butt to do it. It's just been one of those backburner items I've just put off making--hm, with those "easy" buttons, I wonder if anyone makes a "get around to it" switch.

I've been using this on spines, clips, and mid-width flat grinds:
383415_409910012353000_255573364453333_1622847_1774236191_n.jpg


A jeweler friend made me it after he sat listening to me talk about needing a sen and griping about those little low spots and gouges you don't spot hand sanding a tang until you're up to about 600...leaving you to drop back to 120. -_-; The scraper is about 65rc--I'll ask him this week when I see him what steel he used--the three cutting faces are at 15*, 20*, and 45*. It's made final clean up a cinch, but the full length edge (he didn't know any better and I should have been better in describing a Sen to him) and short length make working bevels and flats a pain--literally if I don't wear gloves.

However when I get a free second this week I'll be following your example and making a proper one.

I like how you used a half-round, it looks like a better relief angle for scraping, and the hemisphere cross section ought to sit better in the hand.
I assume (hate that) you held it to the platen at about 45* for the cutting face and 20-25* for the under relief using an 80grit and then just worked up to about 400grit?
 
Ed Braun said:
I've been meaning to make a Sen and after spending the yesterday hand lapping what I'd thought was a fairly flat blade, and your thread, it's the kick in the butt to do it. It's just been one of those backburner items I've just put off making--hm, with those "easy" buttons, I wonder if anyone makes a "get around to it" switch.

I've been using this on spines, clips, and mid-width flat grinds:
383415_409910012353000_255573364453333_1622847_1774236191_n.jpg


A jeweler friend made me it after he sat listening to me talk about needing a sen and griping about those little low spots and gouges you don't spot hand sanding a tang until you're up to about 600...leaving you to drop back to 120. -_-; The scraper is about 65rc--I'll ask him this week when I see him what steel he used--the three cutting faces are at 15*, 20*, and 45*. It's made final clean up a cinch, but the full length edge (he didn't know any better and I should have been better in describing a Sen to him) and short length make working bevels and flats a pain--literally if I don't wear gloves.

However when I get a free second this week I'll be following your example and making a proper one.

I like how you used a half-round, it looks like a better relief angle for scraping, and the hemisphere cross section ought to sit better in the hand.
I assume (hate that) you held it to the platen at about 45* for the cutting face and 20-25* for the under relief using an 80grit and then just worked up to about 400grit?
Click to expand...

That tool looks handy too! I really only did a slight angle on the bottom face, maybe 5 deg. and just followed the curve of the file for the other angle..I will forge one or two of these with the hollow and without next time I order some steel from Aldo, I'm out of everything but 1084

Its a cool little tool for sure, won't replace a file but can save some filing time.

Heres some good info
http://forums.dfoggknives.com/index.php?showtopic=2741
 
An old broken knife bolted to some flat stock works great too, leave it very hard and square off the edge.
 
Very cool. I have heard of people using steel as "simple" as 5160 to make a sen, so I guess that it doesn't have to be screaming hard, just a fair bit harder than what you are trying to scrape. The advantage of using a decent worn out file is that it is going to be harder than woodpeckers lips to begin with. The interesting question is how long will it last because you know that steel like W2 doesn't always reach full hardness all the way to the center.
 
Ed, I have to call you on that tool. It wasn't made by your friend.

It is a standard jeweler's 3 sided scraper/burnisher.
You buy them anywhere jewelers tools are sold. That one is probably made by Mohawk or Smith. They cost less than $10.
I have several, as do most jewelers, and they are used sort of like a mini-sen to draw shave metal, round edges, and clean out inside ring castings. They wouldn't last too long on steel, though.
 
bladsmth said:
Ed, I have to call you on that tool. It wasn't made by your friend.

It is a standard jeweler's 3 sided scraper/burnisher.
You buy them anywhere jewelers tools are sold. That one is probably made by Mohawk or Smith. They cost less than $10.
I have several, as do most jewelers, and they are used sort of like a mini-sen to draw shave metal, round edges, and clean out inside ring castings. They wouldn't last too long on steel, though.
Click to expand...

Son of a...Thank you Apelt Sensei...I just went and searched out both those names, and hanging my head in shame on this...but he charged me 20 dollars...I understand caveat emptor, but this just pisses me off. I owe you a definite thank you on this one, sir, of those things that irk me, being fooled is one thing; being fooled and making a fool of myself in the same swoop is an altogether different Pandora's Box.
 
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