How I make knives

Daniel Fairly Knives

Daniel Fairly Knives

Full Time Knifemaker
Moderator
Joined
Jan 9, 2011
Messages
16,030
I'll go in to this a little bit more but here are the basic facts.

I start off with a big bar of steel, chop it into knife sized lengths and get to grinding.

I plan on using templates soon so I can make some consistent models but right now I just go to grinding... no scribed lines or anything, it is all in my head. I'm not too great at drawing so I just skip that step. :D Every knife is a little different.

I use a KMG grinder to rough grind my outline.

I'll then lay out my holes and drill them out, starting with a pilot bit and then the final size. I then chamfer every hole to keep stresses in the steel to a minimum. I usually do this step before any scratch removal on the flats.

After that I grind the steel flat by hand also on the KMG if I need to, if the steel was not precision ground first I have to get it dead flat and grind off any scale, decarburization or "bark." At this point I have a silhouette or profile of the knife.

I'll start grinding in the bevels either flat, hollow or convex, this part takes a while. I usually run through about 6 stages of belts on the grinder before heat treat taking the knife to a 400 or 600 grit or better finish.. This can easily take all day on one knife.

Once I'm happy with everything and have all smooth edges, no burrs, all chamfered holes and a smooth scratch free finish I clean the knives off and get ready for heat treat.

heat treat next... I skipped a bunch of small details but this is a lot of the process, there is lots of hand sanding also involved to get everything just right.
 
Once I have a good looking knife with an edge about as thick as a dime I am ready for heat treat. Every steel is different so I mainly work with O1 and 5160, you have to learn the characteristics of each steel to get them right. The heat treat is relatively simple, I like to set up a lawn chair, get some tunes going and babysit the kiln. The important part is to stay relaxed and focused, you don't want to quench unevenly, slowly, or drop a piece of 1500F steel on your foot.

I put the knives in the kiln edge down in a holder that keeps them straight and make sure they are not near a heating element. I make sure my programming on the kiln is correct then turn it on, I don't do anything but wait at this point, everything is digitally controlled. The knives and kiln are both at room temp when I get everything going, I don't want to shock the steel by putting it in a hot kiln.

The kiln takes a minute to ramp up so I go heat up my quench oil to 130F or so while gets to temp. I also turn on my oven so the heat is nice and even for tempering.

This only takes a second so I go chill again at the kiln or work on other projects.

I let the knives ramp up to preheat temp then hold them at that temp for 5 minutes, then the kiln ramps up to quenching temperature. The O1 has to soak for 10 minutes at temp, the 5160 for 5. At this point the knives are around 1500F for 01 and 1525F for 5160. Hot.

At this point I am very careful to make sure everything is laid out perfectly, you don't want to make a mistake during quench. I put on the glasses, welding gloves and get the pliers. I have my kiln and quench oil on the floor, I feel it is safer that way.

The quench is simple, just get the knife out of the kiln as fast as possible then I quench horizontally leaving the spine and handle out of the oil. I use an up and down motion but no side to side. At around a 30 count I plunge the rest of the knife in the oil until it is relatively cool, around 150-200F. I then water cool or set on a fire brick spine down, the steel is hardened at this point so it is a matter of preference.

The differential hardening process can lead to some small oil fires, it adds excitement to the process. If the flare up lasts any time I will put it out by pushing the knife a little deeper in the oil, this usually works... you don't want a big oil, it can stress the steel a little bit but mostly is just sketchy!


After the knives are cool enough to hold in the hand I scrub them off to remove any scale and oil that I can. After that they go in my preheated temper oven, for a 2.5 hour or longer temper. Long temper times are good especially if the steel is thick. I then cool the knives by turning off the oven or water cooling, it just depends. Then they go in for another 2.5hour temper, sometimes I test them between tempering for hardness but after a while you can tell by the temp and resulting oxide color. I temper different knives with different temperatures depending on the desired outcome, for example an O1 slicer might be a fair bit harder than a 5160 chopper.

OK, There is more to it but I have to get to work!
 
I found 3 grammatical errors and 1 spelling. You receive a B+ on this report. thank you come again :D
 
Great post! There is alot more to it than most people think, huh Daniel!
 
At this point the knives are coated with scale and funk from the kiln, it is time for the post heat treat grinding.

I grab a fresh 300m or 160m gator belt and start grinding. At this point I basically re grind the whole knife. I run through about five stages of gator belts then I start finishing with a cork belted loaded with compound. I also get the knife somewhat sharp at this point by cutting in a micro bevel if it is a flat or hollow grind, if it is convex I try to work it to a zero edge which has no final microbevel. Each knife is different...

You can never heat up the knife at this point so every couple of passes I cool the knife by dunking it in water.

During this time I'm also checking the knife for flatness, I like to get everything 100% flat so the scales fit perfectly. I like to flatten before I cut in my last bevel grinds as they look sharper and crisper that way. These last couple of steps can take from an hour to a couple of days depending on the knife.

Once I'm 100% satisfied with the grinding it is time to etch my signature. I clean the whole knife with soap and water then final clean it with acetone. Time for gloves, no oil can be present. I get my stencil all lined up and flat by scotch taping it to the knife then etch away. I etch for a couple of minutes then switch my machine to mark and mark for 30 seconds or so to blacken my etch. After that I neutralize the etch with some stuff I got from the etch company and make sure it looks clean. I then finish the knife a little more as the etch usually looks a little blurry around the edges until I do so.

I cut and debur some pins or tubes or get whatever scale fasteners I am going to use ready. I also get out my rock saw and cut the G10 or micarta to rough size. Most handle material needs to be surface ground so I clean it up on my grinders flat platen then on a piece of glass with sandpaper attached. I also use the glass and paper to make sure the knife is perfectly flat at the flattening stage. I rough up the scales and tang where the glue will be applied but leave everything else untouched. When everything looks good I clean it up again with soap and water then acetone and I'm ready for glue up.

If I am cord wrapping the knife I will do that at this point, I get the wrap right then hold it in place with Star-bond cynoacrylate. After that I weigh out and mix up some West System 105/207 epoxy and soak the handle. To soak it I use a toothbrush and apply the epoxy, it sucks into place by capillary action. I use a cardboard box and stab the knives into place or hang them with tape until they dry. I usually do 2 coats to saturate the cord, with some wraps I do one coat as it looks nice that way and is very strong.

Handle glue up. I mix up some West System G-Flex epoxy and get to work. Everything has been fitted multiple times at this point so I wear gloves, work on a clean area and everything usually goes smoothly. I apply the g-flex to everything including the entire tube or pin. The knife gets clamped up and is left to cure for at least 3 days before I do any more work on it. I know of no stronger way to glue a handle, the G-Flex is incredible stuff.

Cure time...
 
Last edited:
You must log in or register to reply here.
Back
Top