AndrewB

Rebar Knives

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 I  was just digging through one of my old tool boxes out in my shed.  Needless to say I found myself some re bar and a piece of 3/8 inch steel.  Commonly found in welding shops (3/8 inch steel).  Now I know I could make a blade out of the 3/8 inch.  But before I waste that, the re bar that I have.  It is in small 1 foot sections.  I have about 4 or 5 pieces of it.  So I figure that would be enough to get me started on certain projects.  But I know Id like to start practicing with bladesmithing.  How ever I have watched several you tube videos, with individuals making re bar knives.  Some of them actually turned out pretty decently.  But I've also read that making a re bar knife can be a bit troublesome because of the carbon level or something like that, please correct me if I'm wrong.  How ever I figure since I have the material it would be a good place to practice with. Maybe even if a blade possibly turns out from the re bar it could be used as a working blade if I temper it and harden it correctly.  Any thoughts or suggestions on this?

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Andrew does practicing with mud pies increase your skills as a Baker?   As knife alloys work differently than mild steel---which is what your welding steel is most likely---or A-36; once you have the basics down I'd go with a steel that will make a decent knife. Talk with a local Mechanic and get a scrapped coil spring. Cut down both sides of a diameter and you will get up to 20 or so ( pieces each one will allow you to practice temperature control, hammer control, moving a stiffer metal alloy and then you can practice heat treating and if you have any beginner's luck you will end up with a knife and not a shiv...Once you learn that alloy you can add different ones to your skill set!

Now for a quick test on if scrap will make a decent blade, heat it up till a magnet won't stick to it and quench it in several gallons of water.  Then WEARING PPE try to break the quenched end: if it shattered going into the water, probably a good alloy but try quenching in warm vegetable oil. If it did't shatter, test it with a sharp file.  If it slides on it without cutting then probably a good alloy and a water or oil quench. (when you thin steels down to blade thickness they sometimes go one quench type easier, water to oil, oil to air.)  If it bends or breaks only after heavy hammering on it or just bends  it's not a good alloy for a blade. MOST scrap steel is not good for a blade!

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I drive by a plant that makes it on a regular basis so I know what's in it---whatever is in their scrap pile!

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As I said the re bar would just be a practice mode.  It wouldn't be functional to much.  If it is functional then I guess I got lucky.

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Most of the 1/2” stuff you get at the big box stores here gets real hard, even in to air hardening, as we have a shefeild plant in north eastern OK that makes ”T” posts from used rail ( they also make rail spikes) I suspect that a large percentage of it comes from them (or Mexico which turns out some hard stuff that the Mexicans like for shoes) 

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And as I say: "Practicing making mud pies does not train you much in making real pies".  Since you should be able to get steels that work for blades for free WHY PRACTICE ON SOMETHING THAT DOESN'T WORK OR REACT LIKE THE STUFF YOU WANT TO BE USING?

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Not to be too contrary here TP, but does that mean you think using clay or play-doh to emulate how hot steel moves between hammer and anvil is useless?  I don't disagree with you that it's best to practice with the alloy you plan to use for final projects, but at the same time I do think there is value in practicing general concepts even if not on the identical alloy.  Just my 2 cents.

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Using the playdoh does not give you the illusion of the feel of moving metal  any particular way, but you can do lay outs.   Just mentally, the problem in using other metals one thinks that if they can do it this way with the rebar then they can with the alloy steels and that is not true. nor are proper temperatures  as to when to start  hitting and when its is not safe to hit,  one gets bad habits because the mild steels and rebars  have different temperature ranges  to work

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It's really the reasoning I object to; generally I see "I I can't afford to use free steel that's a correct alloy; so I have to use free stuff that's the wrong alloy"  (Ranks right up there with the "I can't afford $20 more to use the correct lining for a forge but I can afford to spend many times that in wasted fuel costs." )

And the part about making your bad habits ingrained before you go to higher carbon steels is very very true. I've even seen it in very good ornamental smiths when they made a HC tool at a demo as SOFA once. They treated the HC like it was mild and it had a crack that I saw when they handed it around.  I pointed this out and they said it was good enough to use---and fell apart on the second hit. This works the other way around too. It takes an act of will for me to heat real wrought iron to the heat it needs as all my habits keep yelling "it's going to BURN!" (I can get around this somewhat by telling myself I'm going for a weld...)

Personally I think they should be learning the basics of forging on mild steel NOT doing BSOs or shivs and move up to bladesmithing when they are not making zero day errors.

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The other problem is when I advocate that,  I get reamed for being mean. usually by people that are clueless about tool steels, but it still  bothers me

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I appreciate the answers.  I think it's good to add those things to the oft-repeated mantra "rebar doesn't make good knives." 

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4 hours ago, Steve Sells said:

Using the playdoh does not give you the illusion of the feel of moving metal  any particular way, but you can do lay outs.   Just mentally, the problem in using other metals one thinks that if they can do it this way with the rebar then they can with the alloy steels and that is not true. nor are proper temperatures  as to when to start  hitting and when its is not safe to hit,  one gets bad habits because the mild steels and rebars  have different temperature ranges  to work

So what is this your saying Steve, I shouldn't bother with re bar at all?

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The only good uses for rebar that I've found are projects that use the texture (e.g., snakes) or that are purely utilitarian (such as a hammer rack or shelf support) where function is all and appearance is irrelevant. Forging out the surface texture is a waste of time and energy, and using poor-quality steel in place of good material is counterproductive. 

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21 minutes ago, Steve Sells said:

rebar is only good for reinforcing  concrete

With trepidation, I disagree. I welded up a bunch of bits of rebar for the foot pedal on my treadle hammer, and the texture is great for keeping my foot from sliding around.

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Okay so what if I decide to hammer out a small knife out of re bar and test to see if it works if it does work I guess that means I can post pics of it and boast a bit then huh.

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Well, what do you mean by "if it works"?  

You can beat rebar into a basic knife shape, and you can put a sharp edge on it.  That doesn't make it good knife blade material.   Some rebar will not harden when quenched and some will get quite hard.  You never know until you test it.   Remember, bronze, bone, iron, and stone (among other things) have been used over the years for cutting edges.  However, if you want a knife that will take and hold a good cutting edge without breaking when it's dropped then you want a steel with known properties and documented heat treating specifications.

There's no doubt that a person can heat rebar, pound it into a knife-like shape, and put a sharp edge on it.  None of that will allow you to make the claim that it "worked."

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1 hour ago, AndrewB said:

Okay so what if I decide to hammer out a small knife out of re bar and test to see if it works if it does work I guess that means I can post pics of it and boast a bit then huh.

By all mean. When you post pictures, however, be sure to post a video with edge retention and flex tests.

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If you need a good set of tests the Journeyman tests for the American Bladesmith Society would be a good choice.

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On 2/16/2018 at 3:00 AM, AndrewB said:

As I said the re bar would just be a practice mode.  It wouldn't be functional to much.  If it is functional then I guess I got lucky.

If you are going to practice, practice right.  Perfect practice makes perfect work.  Why waste your time and fire on crap? You don't see a baseball player practicing his swing with a broomstick do you?  Or a bowler practicing his game with a basketball?  Same thing.  But hey I'm just an old guy with an opinion.

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I must have missed it some how or need it explained in a simpler way. If you are using proper technique, how is using re-bar to practice making blade shapes a bad thing? 

Is init the purpose of practice to better hone your basic skills. Are you guys saying it is better to not practice at all because you don't have what you want to make a quality knife?or that you will just have to learn everything over again because of the difference in steel. That sounds a lot like, don't waist your time learning to black smith before knife smithing because the types of steel used are different. I know that is not what you should do.

 Wouldn't it be wise to practice making a point, drawing out, forging an edge etc. and become more familiar on how to us your tools the horn or edge of your anvil in making the knife shape you want before you go an mess-up the good stuff? Yeah different steels react and should be treated in deferent ways and he will have to learn how each works,(Is init a given that different thing react differently).

I literally watched a smith hammer molding clay into the exact shape of what he made with steel. As an example showing how they are similar. As well as being good practice in hammer control. How is that not a good practice technique?

FREE STEEL!!!!! Yeah okay. Everyone knows there is no such thing as free.

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The point is, steel -- even decent quality blade steel -- is the least expensive part of making blades. Far more valuable is the TIME that you will invest in forging, grinding, finishing, sharpening, and putting a handle on your knife. (You'll also spend more money on sandpaper than you ever will on steel.) Even as a beginner, your time is too valuable to waste on rebar, especially when good knife steel is just a few bucks and a few internet clicks away.

Practicing on clay is valuable, but it's not quite the same thing as forging hot steel. It will teach you some valuable lessons about how metal flows under the hammer, but it won't give you the muscle memory that actually working steel will. That only comes from time at the anvil, which -- again -- is best invested with decent raw material.

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