Anyone made a sen yet? I was unaware of this tool (which is basically a
draw knife for steel), but came across it when reading a borrowed book
on Japanese sword smithing.
The other type of draw knife I want to make is for scraping thin fullers.
I'm going to do a few other things as well, but I want to get the draw
knives made first :-)
Not being a blacksmith (just a high carbon steel metallurgy hobbist
and knife-knut) first thing that popped into my head was... how to
make a "metal-cutting draw knife" using a power hacksaw blade as the
They are too thin (and so flimsy) so some sort of thick piece of
steel would be needed to hold it. 900F silver solder could be used
which is the less obvious way to go about it?
Just thinking "out loud" not trying to change your plans, ok? :)
Alvin in AZ
ps- just shoot me if I try to blacksmith using coke or coal ok?
pps- I'll leave all that fun to you guys ;)
Looks like the plans are out the window today (it's raining a bit and I
can only work outside).
The idea is to use the same metal I use for the swords that I make... in
theory a H&T piece of metal will be able to cut the same un-H&T alloy.
I plan to make it kinda chunky, but having a sharp edge.
What do you like to make Alvin?
The posted DFogg thread is really cool, I like the idea of using an
old file... just drill it and put some stinkin handles on it? ;)
I'm a knife knut that got to reading about steel, as it relates to
knife edge holding and knife edge taking, the high carbon steel
metallurgy turned out to be my favorite part. :)
Metallurgy Theory and Practice by Dell K. Allen is by-far the best
written metallugy book for studying on your own and it's cheap as
Anyway that's what I'm into, that and working on my '75 F150. :)
Alvin in AZ
ps- not raining here! ;)
I don't know about them being to thin. Mine started life as 1/8 thick
1095. I haven't measured the final thickness but it was forged on so
lost some to scale and a little to grinding.
It takes off steel about as fast as a file but I find it has less of a
learning curve to get good with it.
The piece of metal I'll be starting out with is 6 mm (close to 1/4"),
and about 50 mm wide (close to 2"). I intend to edge pack the blade,
and compact the steel. H&T (almost sounds like T&A). Put some wooden
scales on it (a couple of cutlers rivets) and we're done, last step
sharpen and hone it.
I assume the difference being that the sen shaves off slivers and a file
Do you find that it needs to be re-sharpened on occasion, or has the
edge held up?
Cutler's rivets? Ick. <shiver>
Do -me- a favor ok? And at least once, try simple peened pins...
(somehow I can't really see you not having done this tho)
Like this old-worn-out I.Wilson skinner I got from a second hand
store... The tang is still covered with hammer marks. :) Iron pins
were used, back when, so the baby didn't turn green and stinky
etc... it's my kind of knife, simple as it can be, in every
direction. I used iron again after taking it apart.
The tang only goes back to the center pin. Made around WW1 they
didn't waste high carbon steel or money back then. ;)
The lower one is a 60's(?) carbon steel Dexter done the same way.
Except instead of having a tapered tang it had a modern factory
style square tang that I tapered and put hickory on. The I.Wilson
has beech (made in England).
I re-heat treated and cold treated both those... they are hard
enough to be used as a sen. :) 66+hrc, no kidding.
That's a power hacksaw blade, 4 of the holes were drilled with a
tungsten carbide tipped "glass and tile bit" then reamed to size
with an 1/8" solid carbide dremel bit. That hacksaw blade is about
65hrc and was used to saw railroad rail prob'ly 3 or 4 times, the
plain-ass looking wood was a saved piece of broken "spike maul"
handle (same handle as sledge hammer). So it's mostly made from
railroad junk. ;)
What I figured out is, 16 penny finishing nails are 11 gauge wire
at about .122" so fit real nice into a hole drilled from the 1/8"
common fractional bit. Unlike most pin material that needs reaming
with a numbered bit like a #30 or #29 to get the 1/8" rod to fit.
Numbered bits used to ream fractional holes aren't that big of an
investment but most nails don't size-up with drill bits like the 16d
finishing nails do.
I anneal the nails, they have some work hardening in them that when
removed, makes them very easy to work with.
Ok, so maybe that sizing-information is only good for the US, Canada
and Mexico? :/
Alvin in AZ
Aw cutlers rivets are fast... and I want to do other things, at the moment.
Usually it depends on what the customer wants, if the job calls for the
good ol' piece of brass rod, sure. Usually the customer hears a buzz
word and says "can I have X?"... who am I to say no?
My favorite way to attach fittings is by force i.e. cross/bolster slip
fit, grip slip fit, pommel slip fit then peen away... nice and tight.
Tight fittings makes large blades "sing"... you don't hear this with
small blades. If the fittings are loose you just hear a "clunk", as
opposed to a "piiiing".
P.S. Like your work :-)
Hadn't really thought about it before. :) The knives I made before
figuring out how to drill holes in 65hrc HSS, hold one of those
knives in your hand and rake your thumb over the edge sideways and
the blade rings to beat heck. :)
Hollow ground to about .015" helps make them have a ring no other
5 minute epoxy and didn't grind+roughen up the tang (as a test)
figured it'd last a year, lasted over 20. :)
Repaired, "20 ton" this time. ;)
It's the top one with a fresh-finishing 100 grit sanding job.
"hidden tang handle for HSS"
The first few handle slabs were grooved using a big-ass milling
machine and a .750" ;) wide cutter, these are from a router with
a 3/4" wide square groove cutter (used upside down and a "fence"
machine-screwed to the face-plate). The difference of working in
a machine shop and working as a signal maintainer outside. :)
Thanks <kicking dirt> since it's a hobby I get to decide what
fasteners to use? ;)
That's a 4oz ballpeen. :)
I have two 8oz that I actually use more.
Alvin in AZ
This is a story how mis-adventure is the mother of invention.
I was getting the shi... upset, with a piece of malee burl, a really
hard wood, but worth the effort. I was hand carving and getting
nowhere. There was sweat dripping in my eyes, and in frustration I
ripped off my goggles (which were fogging up).
The problem was I still holding onto the extremely sharp thin chisel.
The first thought was "I bet that's going to p*ss blood".
Surprisingly it didn't, the blade is thin and razor sharp, so there
isn't even a scar, of course it would have been a different story if I'd
poked myself 1/4" back and scewered my temple... I got lucky. I only
had to deal with the shock of doing it.
Anyway, determined "not" to become a statistic... I thought there has to
be a better and faster way to machine wood. I remembered that you can
modify a drill press to be a rudimentary wood lathe... so why not a
Off to the hardware store and a couple of packets of 1/4" shank router
bits later (I bought two packets because there was more variety). My
piece of handle material in a machine vice, put in a suitable router
bit. Adjusted the speed of the drill press to the fastest setting.
Moved the work up to the depth I wanted.
Before I switched on I was thinking "this is probably going to tear my
hand off!". So I switched on and carefully started my first cut... okay
things were going smoothly, I maintained that level of care until I had
finished the first cavity. The next scale was faster.
So gentlemen a drill press "can" be used as a wood mill :-)
P.S. Aw you should use a 4 lb demolition hammer ;-)
P.P.S. Oh, forgot to mention cutlers rivets look like cr*p if you don't
use a step drill.
I like stories. :)
My lastest-favorite wood working method is to use a brand spanking
new sanding disc on a little hand grinder.
The only thing I've found that'll cut the "end grain" on a new knife
handle (like it means business) and not burn or chip it.
Got a 10lb ;) and just bought an old 16lb head.
The 10lb worked fine re-arching the ~5/16" thick leaf springs but
wouldn't "move enough" the 5/8" thick overload spring and that's
the one I really wanted to modify the most.
Maybe this group won't think I'm nuts? ;)
...have you noticed how the "corner" of the new hammer heads (in
the last 30 years or so) are cut back (champhered?) too stinkin
While digging through my favorite used tool store's hammer heads, it
was so obvious the change that's been made over the last 50 years.
That's just something that's been bothering me for decades and 'til
now, been suffering in silence. ;)
The 16lb head is one of the good old-ones and isn't used-up neither.
And a certain size hole in the metal part for the cutler's rivets to
You can have my share of 'em. ;)
Alvin in AZ
ps- the re-arching job turned out real good, right at the maximum
change I wanted, not a lift, just a "put 31 years back in 'em"
pps- 25 miles on my new ring and pinion (not broke in yet by any
means) and my RTV smearing ability's not what I thought it
was, it leaks gear oil near the top, of all places :)
Just a thought, but I bet you could find a nice chunk of tool steel
from an old lathe bit and use that, instead of a power hacksaw blade.
I've found some large lathe bits for real cheap at local swap meets...
I think a parting blade would be about perfect for a sen.
What about a knife from a wood shop planer? Not sure how big you want,
the small 12" Delta blades are 12 inch long, by about an inch wide. I
have a hand chisel someone shaped out of a used planer knife that is
about 4 inch long. If you check carefully, you might pick a part of
the knife without the nicks ...
Questions to the sen senseis:
Is a sen always straight across, or can they have cocked handles like
Couldn't one just re-harden an old drawknife?
Why a 35 to 40 deg bevel? Wouldn't 85 to 90 degrees work better, and
Is there any back-bevel on those 40 degree edges?
Inquiring minds want to know...
I only had one example to go from so I don't know how the handles may be
Maybe you could re-harden a drawknife.
I started with 35-40 degrees. As I played with it I changed technique
and bevel angles to find what works well for me. I ended with a bevel of
about 70 degrees. I didn't put a back bevel on but I suppose someone
could try and report if it works .
At least this is my limited experience.
A similar tool except that it's intended medium is sword blades.
We're not talking heavy machining, just small shavings to even out the
However you can remove a lot of metal with these draw knives. You use
them by pushing them into the metal, as opposed to draw filing where you
P.S. When will the rain stop? I know we need it, but it usually
happens when I have a brain storm :-(
Things I definitely know about the sen.
* I know what the sen looks like (well the one the swordsmith in the
book uses anyway), and I can extrapolate the sizing based on the size of
the swordsmiths hands (being Japanese hands they are most likely smaller
* I know that it's made from the same metal as a sword (possibly an old
Things I don't know about the sen.
* The exact dimensions
* The exact alloy composition of the tool
What I intend to do.
* The sen illustrated in the book is a comparatively wide blade made
from quite thin metal. I will make my sen shorter and thicker, but
still having enough width to do the job. This way I only have to H&T a
smaller section of metal, and I will be able to use it on the narrower
sections commonly found in European blades. Having a shorter blade
means I'll be able to apply more force(if necessary) than a larger blade.
P.S. It's just got to stop raining long enough for me to do anything :-(
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