Things not to do: file knife and some stick tang lessons learned WIP

[daizee]

Hi All,
I haven't posted here in awhile, but I took a bunch of pix of this minor project, so it's show and tell time.
Mostly I do full-tang knives, and am pretty familiar with the requirements of my usual lineup. But I need stick-tang practice for some up-coming projects, so I've been doing occasional scrap knives and files with only modest finishing. For the n00bs: read the stickies on making a knife from a file. Summary: it's generally a bad idea for a lot of reasons. Buy some 1084. It's cheaper than your time! As '71Commando said to me during this project: "files live out their lives at the limit of useable hardness with a ton of stress risers conveniently pre-installed... recipe for disaster." And that's just one of many reasons to turn back...

I had an 8" Nicholson file, so I softened it in my little Atlas propane forge and ground some bevels on '71Commando's KMG:
At this point it was going to be a nice big boning knife. Not that I ever use a boning knife, but what the hell.

Here it is being sanded to 180 in Hefty Lefty's (lana-steel) Cha's Parker 3-1/2 vise. The knife board is a bit short for this one. Danger!

Finished up the sanding at home with my own Parker. Since this is a forge heat-treat, 180 is as high as it will go. I planned to leave it black anyway, and not bother with a polish.:

back to the forge to heat-treat. It went from the forge to warm canola. It came out of the oil rather curved, so I tried to straighten it during tempering:

Ooops....
I let the blade cool too much and got impatient. *SNAP*
Grr.... Well, the original blade was a little too long for my forge and its heat output. The back of the edge wasn't as hard as the rest of the blade, and it snapped in the transition area. The black blade section at the bottom is the remains, and I sketched out some alternative endings.

Here it is with the new tang. I softened it with a torch to get a pin hole through the end. Made it nice and springy near the shoulders. The tang is tapered from the spine to the edge, which will later cause fitting problems. The tang had to be straightened since it was right in the middle of the original curve. I was much more careful this time, used more heat, AND used a jig. No more snaping.
Some materials options are floating around.

With some advice from Hefty Lefty, I decided on ebony and oak for the handle. Here the ebony bolster is being filed to fit. This was one major learning point... The blade was only 3/32" thick at the spine, and the new tang was slightly thinner at the thickest point and tapered in all directions. Furthermore, my smallest fitting file is 3/32". Add to that the attempt to drill three aligned 3/32" holes on the drill press to hog out a slot, and you have the makings of a lousy fit.

Lesson 1: make sure your tang will be larger than your smallest fitting tool, to allow room for error and fit.
Lesson 2: wrongly tapered tangs suck
Lesson 3: a blade ground all the way back to the bolster with no ricasso won't cover the bolster slot completely.

Here it is all glued up. Drilling the hole through the handle and tang was another lesson, and the first time I've done this. I've been doing snug fit bolsters and sloppier-fit handle holes, but in this case the very thin tang was looser than normal. Not great, and without good jigging I drilled the pin hole off-center. This took some squaring up in the wood, and I almost ran out of room. Use oversize wood (and drill straight)! If skipping the cross-pin, I'd rather use a somewhat more square tang for simplicity.

Here it is all shaped up next to an earlier utility knife (note no cross-pin).

The ebony has some nice white grain in it:

I did a modified wa-style handle.

So after the rescue it turned into a neat little blade. Fun for an around-the-house user with a thin edge, and cutting well.

 

[Don Nguyen]

That's a nice little knife it turned into. I like the profile a lot with the size of the handle.

 

[elementfe]

That's a really cool series, thanks!
A lot can go wrong with knives made out of files, but one thing is that they aren't used hard, and if they are they break. In theory, file knives should fail a lot but they don't if made correctly. In my neighborhood I can sell every file knife or railroad spike "knife" I can make, so I go ahead and make them, use sane thermal cycling, and be sure to give the buyer all the usual caveats regarding recycled materials.

May I add a couple little points?
Lesson 4: As Stacy pointed out in my "Gumby D2" thread, Mf for carbon steel is 400F. If it's cooler than that, you won't straighten it.
Lesson 5: Be sure to have a forge long enough to heat treat the whole thing. Mine was built for blacksmithing work and basically cost diddly squat to build and peanuts to run. Long (23") and blown and stupid simple. Works great for welding.

 

[elementfe]

Double post

 

[daizee]

May I add a couple little points?
Lesson 4: As Stacy pointed out in my "Gumby D2" thread, Mf for carbon steel is 400F. If it's cooler than that, you won't straighten it.
Lesson 5: Be sure to have a forge long enough to heat treat the whole thing. Mine was built for blacksmithing work and basically cost diddly squat to build and peanuts to run. Long (23") and blown and stupid simple. Works great for welding.

Definitely good points!
In this case, I tried to straighten out of the tempering oven, but wasn't making headway and kept at it too long, letting it cool. Also, This is the longest blade I've put in that little forge, a mistake I won't make again. It certainly demonstrated the limits of my equipment.

 

[elementfe]

For my forge, I took a ten gallon LP tank, cut openings in the ends, put in a layer of Kaowool then a layer of...I can never remember the name of it, but it's a mineral wool that's reflective, unlike Kaowool, which, used alone, gives you a forge that doesn't get hot enough to weld. A few firebricks for the floor (some people use firebrick rubble, but I've done a world of welding in mine and it's still fine), smear some Plistix on the inside. Any kind of blower and a tube with a 90deg bend between where the propane dumps in and where it goes into the forge.
No jet needed, just a 1/8 copper tube with a valve on it- the propane just gets dumped into the tube and mixes on its way in.
It has a blower that would feed five forges, so it's always turned way down- that cost fifty bucks, but the rest was chump change.
If you have welding gear at all, I highly recommend the "stupid simple" route.