Need advice on a HT method for this blade.

K

KyKaMo

Joined
Mar 31, 2012
Messages
23
Hey,

I got a couple questions. I will be making a sword with a buddy in a week. What our goal is, is to make a blade that can cut nicely through some pop bottle and such and maybe chop wood and use like a machete. i need to order the steel. All i have available to me right now is 1/4" thick 1075 or 3/16" thick 1084. I am confused about the performance difference between the two steels.

How much difference in performance would there be if i through hardened either one to 55 rhc? Casuse if minimal, i would rather go for the 3/16 size for less weight.

My other question is about a HT method and performance for which ever steel we decide is best. What i would really like to do is temper for 58 rhc and then soft back drawn the spine to 55 (maybe less???). Is this a bad idea? Whats the performance difference between through hardened at 55 rhc and diff. tempered at 58 and 55 rhc?

Thanks
 
1075 and 1084 are very similar, they should have nearly identical heat treatments, and their performance should be indistinguishable.
Through hardened at 55 Rc will give an edge of 55 Rc, diff tempering at 58 and 55 Rc will give an edge of 58 Rc which will hold an edge longer, but would not be as tough. keep in mind though that diff tempering is usually done on knives, it may be difficult to do such a process on a long blade.
 
When asking advice on a project ,it is best to give us some info. Planned sizes will change the answers a lot.

A sword can be 1" wide and 40" long, or 2.5" wide and 16" long. It can be 3/16" thick or 3/8" thick.

For a bush chopper, a 16" by 2" blade in 1/4" steel will work well for a first attempt. Look at some of the Bolo shaped chopper/machete blades for ideas. Forget any fancy hooks, saw teeth, or doo-dads. Just a straight blade with a square or rounded tip and solid back are what you want. A full flat grind, or slightly convex bevel are the best starter choices. Leave the edge at .040 before HT. Tapering the blade (distal taper) will make it lighter feeling and add better control. If you make the blade flare toward the tip, as in most Bolo machetes, don't make the ricasso less than 1.5". You want a good 6" handle. Again, forget the fancy stuff, and go for a plain palm grip shape. Finger choils, and large bird-head butts are not going to make for a better camp sword/chopper. A guard is not really useful on a camp sword. A metal bolster is nice, but not necessary, either. Canvas Micarta can't be beat for low price and durability on a chopper. All the suppliers sell it in many colors, including camo. A simple kydex or concealex sheath will really finish this project off, but that may be a bit above your level. Noting wrong with an Neatsfoot oiled leather sheath.

For best results,use a simple carbon steel ( 1075 or 1084) and do a basic HT with a oil quench ( canola or parks #50). Your fire pit will work, but you will be far better off using a forge, or even better with an oven. Sending the blade to Peters for HT might be a good alternative to the fire pit. It will come back at exactly Rc 57-58 if that is what you ask for.
Either way, have it fully hardened and then draw the temper to Rc57-58. If doing it yourself, do it in your kitchen oven by tempering twice at 450F for two hours each time.

To draw the spine -
First clean the blade off a bit with 120 grit paper to make the surface shiny metal. You need to watch the colors change as you draw the temper. You will finish the blade later, but for now, just make the surface metallic.
Take a shallow baking pan and put 1/4" to 3/8" of water in it. Use a torch to draw the spine to a blue color, while keeping the edge rocking back and forth under the water. Start at the tang, just above the ricasso. The temper colors will roll down the bevels toward the water, and should stop near the surface. As the straw color ( sort of yellowish/bronzy/brown) gets near the water surface, move the flame down the spine.
Go slow and walk the colors down the bevels, and move down the spine in a smooth process. Don't rush it, and use just enough heat to do the job. This isn't the place for a cutting flame. A brazing or Presto-lite torch is perfect, and a simple propane plumbers torch will work fine.
This will give you a softer and tough spine and bevel, with a hard and sharp edge. Once the entire spine length is drawn to within 1-2" of the tip, just lay the blade over in the pan to cool it off.Don't lift it from the pan until the blade is cooled off. Wrap the blade in a wet cloth, and draw the tang with the torch, starting from the butt. Work down the tang, and when the yellow/brownish color gets to the ricasso, dunk the tang in a bucket of water to stop the temper from going any farther. This will help prevent the blade from snapping at the tang in rough use.

The above should give you a blade that will cut well and do simple chopping, too. The edge angle should be kept a bit high, to avoid chipping. Start with 30° ( 15° per side) and see how that works. Re-sharpen to a different angle as your testing indicates.
 
Great answers guys thanks.

We were planning to make something less wide and longer than a machete. we wanted to make a simple wakizashi type blade but straight (so basically a hollywood ninja-to). It would be 1" wide, 20-22" long blade and OA length around 30" and 3/16" thick. Sorry for not mentioning earlier. I realize this is not a perfered design for machete work, but would the soft back draw method provide a blade that could? Or, from experience, is there a better method that would?(like a through harden to 55?)

Thanks
 
I'm going to be Uncle Stacy for a minute:

You are bouncing all over the place and haven't made a knife yet. Slow down, read a lot more, make some drawings and plans, post them here, and get some critique and help.
As you are going right now you will either burn out or fail and give up.

A wakizashi isn't a starter project for anyone. Make a few drop point hunters in a simple steel, and then decide where you need to improve, and where you wish to go.
Save differential hardening, clay coated blades, complex HT,swords, and all that for later...there is lots of time.

Now, in the mean time, please read the stickies. There is a ton of info in them. The Count ( 123456789) usually makes his newbie post, but what it contains is the bulk of the stickies. He is a Cannuk,too.

There are several makers in Alberta, and if one is near you it would be a good idea to go see him. Alberta is a huge place, so i don't know if that will work, but if it does, take advantage of it.

Alberta has a nice summer to work in. IIRC, summer up there is July 22 through Aug 14. The rest is winter. Winter is a good time for hand filing and sanding, and making plans :)
 
I appreciate what your saying and am glad your just trying to look out for, but i already have made a couple knives. I even made the knife that cut my wedding cake :) . I do not think i'm any where near a pro or expert, but have made functional knives with proper HT. Mine are still ugly, but am proud that they function better than the cheap stainless 30$ ones ive bought. I have even "sucessfully" (havnt tested it by bending it but did succeed by not letting the heat run into the edge) diff temp. a chopper and skinner i made too. This summer i hope to get better equipment so i can do more and my buddy is proud of me and really wants to try and make a simple sword just for novelty sakes, so thats why i am just wondering what the best HT would be for what we will use it for. Both in theory and by our expert experience. Then we will have fun in trying our luck with our first sword, just like i have already tryied my luck with my first knives a year ago :)

This is the only picture of any of my knives so far.

KamekoKyleWedding-586.jpg
 
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