11-28-2001, 12:17 PM
I've finished the 'flat grinding', read filing and filing and filing. I'm down to a decent profile and an edge thickness of .050". What do I do next? Should I polish it and then harden it and finish the blade after hardening or do I take the blade down to almost finished edge??
FYI I am doing this with a file and sandpaper, no grinders…
11-28-2001, 12:38 PM
What type of steel are you working with and how are going to heat treat it?
11-28-2001, 02:11 PM
I was planning on heat treating it from some directions on knifemaking 101. I was going to use an oxy-propane torch and quench it in oil (don't know what kind yet). I also have indirect access to appropriate equipment at our schools machine shop.
11-28-2001, 08:43 PM
When you heat it up with the torch, oxygen will cause a hard scale to form on the steel. After heat treating you will have to remove this scale then temper the blade and then continue your polishing to a final finish.
I would recommend you take the knife down to a 120 grit finish and be sure you have removed all file marks prior to heat treat. Make sure the blade is symetrical, if your grind is not even on both sides it can/will warp. After heat treat, clean it up. The clean-up will be difficult as the scale is as hard or harder than most files (some people soak in vinegar overnight to remove scale). You have to get down to clean metal before tempering so you can see the colors created during tempering. After tempering you can take the blade to final finish and do your handle work, etc......
You may want to go to Ed Caffrey's forum and read there. There is a lot of heat treat info. Also, Ron from Little Hen Knives uses a lot of O-1 and he may be able to assist you through the heat treat process.
Little Hen Knives
11-28-2001, 09:27 PM
here is how I do it.
- make a mixture of 1/3 borax, 2/3 water bring to boil and dip blade in and let dry.
- heat up forge
-heat blade up to non magnetic and then a count of 5
- instantly quench in vegetable oil at 135F( edgedown, horizontally ) leave in oil till you can handle it with the bare fingers.
- temper immediately at 350F for 3, one hour cycles
- steel come out at about 58 to 59 rockwell
this is my simple heat treat, I will heat treat bigger blades with clay, basically involves covering the blade with clay where you don`t want it to get hard (use the same hardening and tempering sequence) it gives a nice hardening line or "Hamon". For knives that will see hard use I heat treat and temper the same way as above but after the last tempering cycle is done I put the blade edge in wet sand (covering the part you want to stay hard) then heating the spine gently with a propane torch till the spine turns bright blue ( spring temper ) almost all the way down to the sand.
The heat treat part can be done with a propane torch if it is a small blade or acetalene if it is bigger, I also hear map gas works good for the average size hunting knife.
The Borax and water mixture stops the scaling, if done right the scale or black crud should flake off upon quenching leaving a dull grey steel ( no scale )
Hope this helps you, if you need anything else feel free to email me.
11-29-2001, 07:46 AM
Well, thanks for all the info...I'll let you know how I did.