The 60-minute knife.
Jason Cutter aka Dr Kwong Yeang
Bladesmith, Part-time Knifemaker, Australia
Jason Cutter Bladeart
Originally posted on on BladeForums and the USN
I undertook this project for the heck of it. When forumite 2 knife
suggested we show our “60-minute knives” some makers were skeptical if it
could be done. Here, I show that it CAN be
done ! The knife is just a small working knife with synthetic handles & an
machined satin finish. But it is fully funtional and will give pretty good
cutting performance. The finished knife even has a full tapered tang & a
filed thumb traction groove !
I hope I am not coming across as a show-off... just having some fun here.
I spent +++time planning, considering a range of options in my mind & on paper, before even attempting it. I also had to consider my method of taking the photos. I had to develop a zen-like state that required complete focus & zero distractions. Turned the cell phone off, etc. I’d organized all my materials & equipment & even did some mental trial-runs. Some of the techniques were visualized down to the absolute detail, including the foot steps I would take as I pressed the camera button to get back to the grinder, etc.
Honestly, the entire project took me 68minutes to finish. However, considering the time it took to set up the camera for each shot, I feel that I would have completed the knife in under 60minutes. That’s why when the stopwatch buzzed at the 60minute mark, I kept going & felt I had enough time to do some further hand sanding & to file in a single traction groove (see the last frame).
I was very fortunate that I made no obvious mistakes, & didn’t need to perform any corrections. This is very rare. In addition, virtually all the photos I took turned out & seemed to be on the mark. This is even more rare !! So everything really worked out in my favour this one time !! I don’t pretend that I can actually reproduce this feat. Thinking about my usual knives, I figure to achieve the same result, I’d usually spend twice as long working on the knife, so this is not my usual way of making a knife.
BUT… there is ONE major catch.
The technique shown is one of a number of traditional blacksmithing heat treatment methods. I DO NOT regard this as necessarily the most reliable or accurate method of tempering a blade. It was chosen simply because it was the ”most reliable” QUICKEST way to temper such a small knife, that I could think of. I have done this before & I know it works.
My usual method of tempering an O1 carbons steel blade is to temper at 385-390F for 60minutes x 3times. This tempering process alone takes at least 6hours. I guess on a long shot, we could technically ignore this time as I am not being hands-on & simply waiting for the purposes of the “60-minute knife” test.
Nonetheless, in making this “60-minute-knife” the outcome of the bare-bones heat treatment was successful. The blade passed the brass rod edge flex test & any concern about the accuracy of the tempering process was dismissed.
On close inspection, the machined satin finish is on par with any other working-grade knife I have made recently. I do this intentionally to reduce costs & to encourage customers to use such knives. The fit & tolerances are equivalent to that of my full-house custom pieces. In other words, I have chosen time-saving techniques, & NOT quality-skimping techniques.
To ensure that I would end up with a knife equal to my other knives I would proudly sell, I planned that the knife shown at the very end, actually has scales & pins that are removable. The pins could be tapped out & the blade put through my usual tempering process to assure quality, then re-assembled.
TIME & EFFICIENCY - DISCLAIMER.
Another thing to say is that, if one were to set up a so-called “production line” style of making knives, eg.- grinding 20 blades, then heat treat 20 blades, then finish 20 blades, then attach 20 handles, etc. one might find it more likely to approach the TRUE “60-minute knife” mark. This can be put down to achieving peak efficiency (which is different for every maker). A good example of improved use of time, is that it takes the same amount of time to heat treat 20 blades as it does 1 blade. This is especially true with stainless & high alloy air-hardening steels. Well, provided one has an oven large enough… It is of course very dependent on the type of knife one is wanting to make.
The 60-minute mark is not recommended, nor is it necessary, to be regarded a good knifemaker. I think that patience is one of the very best virtues a knifemaker can develop. While it is always good to challenge one’s limits & abilities, a knifemaker, should only compete with one’s self, & not with others. In order to make a good knife (& there is no point in making a lesser knife…), a maker should simply take as long as he or she needs.
HERE WE GO.
Note each of these frames, A., B., C., etc. denotes an approximate timeframe of about 5minutes, +/- 1minute.
MAKING THE BLADE BLANK
A. CUTTING THE STEEL.
1. I mark the rough blade stock I want, on 1/8th " thick O1 tool steel plate
2., 3. I use a mounted cut off saw with a 0.6mm abrasive disc to cut out the steel I want. This is one of the most effective time saving pieces of equipment for rough profiling barstock. I highly recommend it to knifemakers.
4. Here I have a bar of O1 steel, about 6-1/2inches long, 1/8th " thick & tapered to account for the shape I will create later.
B. PROFILING THE BLADE
1. I set up the worktable on my Hardy Wangemann belt grinder with the flat platen.
2. I grind the profile by hand, using an old 50grit 3M “Gold” Cubitron belt.
3. Here we have the profiled knife. Note that I profile the shape without any drawings or scribed marks. I generally don’t work with templates & like to form the profiles on the run. After profiling, I flat grind each entire side of the blank to flatten it & remove any burrs from the heavy stock removal of profiling.
C. DRILLING HOLES
1. Center punch the location of the handle holes.
2. Drilling on a drill press with cobalt HSS bits & plenty of tooling oil. The rivet holes are 1/8thinch, & the other 2 including the lanyard hole are 1/4inch. I then countersink each hole & the lightening hole is heavily drilled with the countersink to remove more material.
3. The result. We are ready to grind bevels now.
SETTING UP THE HANDLES
H. PREPARING THE HANDLE MATERIALS
1. Hacksawing the 416SS pin stock & 303SS lanyard tubing. Honestly, I set up this photo. I already have a quantity of 1inch & 3/4inch long pin stock I hacksawed & deburred. What did I say about efficiency ? It all about preparation.
2. Mark the approximate handle shape on some 1/8th " thick Jade green G10 plate & bandsaw them to rough shape.
3. We are ready to work the handle.
J. PREPARING THE HANDLE SCALES
1. Clamp one side of the handle material to the tang with some vise grips. Drill the corresponding rivet & lanyard holes on the drill press. (1/8thinch & 1/4inch respectively). Repeat on the other side. One could get worked up about the taper in the tang & how to account for that, but with such thin dimensions & the fact that G10 is quite flexible, not bothering about the tapers etc., seems to make minimal to no difference to the way the handle is fitted up.
2. Apply both sides for a quick test fit & to determine how the leading edge of the handles will look. I mark with some magic marker.
3. I remove the handle scales & position them back together with the rivets & lanyard tubing. Bandsaw the required shape in. Grind if necessary with an 80grit or 120grit belt & finish the leading edges with a medium 3M Scothbrite belt.
4. The scales are ready for attaching to the blade.
FINISHING THE HANDLES
K. CREATING THE HANDLES
1. Apply the handle scales & pin in place. Wrap blade well with paper & duct tape. Please note - the handles & pins are NOT glued in place & but sit pretty tight. They can be tapped out with a punch for further heat treatment of the blade, & to epoxy the scales in place. In this picture, I have ground the rivets & lanyard tubing flush with the handle. You MUST keep the metal parts cool to prevent the G10 from burning.
2., 3. I’ve ground the handle flush with the tang with 80grit, then 120grit & chamfered the edges of the handle. All the contours on the knife are designed to incorporate natural profiles that exist on my grinder’s contact wheels. I touch up the handle & the metal parts with a Coarse 3M Scothbrite belt (maroon), followed by the final finish with a Medium belt (blue). Chamfer the inside edges of the lanyard tubing with a countersink.
4. This is the finished knife at the 60minute mark. The stopwatch has just beeped as the picture
was taken. The marks on the blade is NOT a hamon, just my grubby fingerprints.
L. FURTHER FINISHING
1., 2. I felt I could give myself a bit more time & did some hand finishing on the handles. The metal parts need no further treatment… Note I am still wearing a respirator & long sleeves. You can see how dusty and fine the G10 is; not good stuff for the lungs.
3. I use a 5/32inch chainsaw file to cut in a thumb traction groove in the spine where the steel is not hardened. Clean it up with some 240grit W&D paper wrapped around the file. I use an old 240grit ceramic belt to grind in a convex edge to create a burr & the knife is now complete. rass rod flex test shows good flex on the edge & return to true without deformation or chipping.
Jason Cutter aka Dr Kwong Yeang
Bladesmith, Part-time Knifemaker, Australia
Jason Cutter Bladeart
Many thanks to the good Doctor for this article - GB