Rebar crossbow??

[SubterraneanFireForge]

Hi I’m new to this forum and pretty new to blacksmithing as well. 

a crossbow is something I wanted to make sense I started forging. 
I was wondering how rebar would work for this application.

I Know a leaf spring or other spring steel would work better but right now I have rebar and Im probably going to try it anyway and at least make a wall hanger or a crossbow shaped piece of steel.

if anyone has advice on quenching ,tempering, annealing demotions ,forging, grinding ect I’d appreciate it. 
 

[arkie]

Rebar is not a suitable type of steel for a crossbow.  You would be better served using one of your aforementioned steels in your query.  It would indeed be a CSPS using rebar.

Happy forging!

[Steve Sells]

using rebar for the spring? I hope your life and medical insurance is paid up, also I doubt it will take the heat treat in the first place

[Frosty]

Workable as a cast lead airplane.

Frosty The Lucky.

[BillyBones]

Here is where it needs to be said, Fill out the header. Let us know where in this great big world you are located. 

I and probably the majority of us on this forum have a pile of leaf springs. If you are close to me i would tell you to come on over and take one. 

[George N. M.]

Welcome aboard from 7500' in SE Wyoming.  Glad to have you.

As everyone else has said, rebar is unsuitable for the prod of a cross bow because it does not have enough carbon content to be able to successfully heat treat to make it springy.  You could make the stock/tiller of the cross bow from rebar but it would be, IMO, mud ugly.

Steel prods for cross bows are  under a LOT of tension when drawn/spanned.  It they fail there will be a LOT of sharp bits of steel flying around close to you eyes and face.  Even though I have been blacksmithing for 45 years I would be hesitant about forging and heat treating a cross bow prod that I was comfortable and comfident of its safety and strength.

You can build a model cross bow that will never shoot anything out of anything from paper on up.

"By hammer and hand all arts do stand."

[Irondragon Forge ClayWorks]

Welcome from the Ozark mountains.

If you were to put your general location in your profile, like suggested in the Read This First thread, it would show up with every post and we wouldn't have to dunn ya for it because a lot of answers require knowing where in the world you are located. No sense in me telling you to stop by my forge and pick up some steel that would work for a crossbow if you are in another part of the world.

I can't control the wind, all I can do is adjust my sail’s.
Semper Paratus

 

[SubterraneanFireForge]

Wow so many replies! Thanks!

it seems like waiting to stumble across a better piece of steel is the way to go. 

Just curious for others projects can you ad notice able amounts of carbon to rebar by case harden or oil hardening it?

that’s a generous offer Billybones I live in New York home of tons of rebar.

[arkie]

Sub....

Rebar is rebar...often characterized as being the "sausage of steels".  Rebar is best used in concrete.  No, it won't help rebar by trying to carbonize it.

Visit your local car repair shop, spring manufacturer/installer, scrap metal/recycle yard and get some real steel from car parts such as leaf and coil spring, suspension parts, etc. and give the rebar a rest.  If you're needing a specific steel, there are some retailers who sell for specific uses such as blade work, etc.  It DOES, however, make good tent stakes since the ribs make it a bit harder to pull out of the ground than smooth rod.

Rebar is marginal when it comes to a "practice" steel.  It varies quite a bit in composition, being a steel "sausage" and does not forge uniformly.

Happy forging!

[Frosty]

Sub: Please put your cursor on your AVATAR, name, etc. and click. Select "edit profile" button in the upper right of the screen that appears, click on it and put your general location in the header. 

Telling the forum members where you live in ONE posts won't do you one bit of good. Heck you might live on the same street as a member who has a bucket of leaf spring and can show you how to work it. IF THEY KNOW WHERE YOU LIVE.

There is a reason there is so much rebar in the scrap stream. It isn't good for much of anything but reinforcing concrete. It's lousy for learning blacksmithing for a couple reasons. First as has been said several times already in this thread, it is NOT consistent. Meaning the steel it's made from hasn't been produced with a need for a particular carbon or anything else content so long as it takes at least x amount of pull to break and x amount of bend strength. That's it, nobody cares what's in it so long as it's strong enough. Sometimes it can vary markedly in a relatively short distance along the same bar.

The other thing that makes it poor stock in a smithy is the texturing. Rebar's texture is intended to make concrete bond to it well. PERIOD. If you want to forge something you have to spend a lot of time and effort either planishing ( forging it smooth) or grinding it all off. There are only a few things a smith might want a rebar texture on a forged product. 

To be honest I can forge a concrete bonding texture in a piece a lot faster and easier than having to deal with rebar.

Frosty The Lucky.

[Julianb]

Hello,

and please be careful with steel that came from used car springs in parts with such a vital function, like the arm of a crossbow. You do not want a previously damaged piece of steel fail in exactly the wrong moment. Stress-related microfractures don't repair themselves by reforging the spring.

Cheers and good luck!

Julian

[Steve Sells]

In answer to your questing about carbonizing steel, Yes I can do it, can you? maybe, maybe not but it costs more than buying the correct steel in the first place

[George N. M.]

Case hardening would not work because the carbon only penetrates a very small distance into the metal.  To pentrate into the full thickness of a piece of rebar you would need a large furnace and the ability to hold it at a high temperature in a controlled atmosphere for quite some time, probably at least several days if not longer.

Basically, forget rebar as material except for "junk" projects.  In 45 years of blacksmithing I have used rebar only a handful of times.

"By hammer and hand all arts do stand."

[mcostello]

I friction sawed a piece of rebar and it was 2 distinct colors, one side steel colored and the other side dark grey like cast iron. It had a clean line between the two. Someone did not even stir the melt up. Might make good pegs, might split into two pieces also.

[Frosty]

I just got back from a trip to town and have remembered a place I used salvaged rebar to good effect. In fact it's perfect. 

A neighbor was building a log cabin when I was still living y "moved to Alaska live in a cabin in the woods," phase. It seemed pretty mandatory for young folks moving to Alaska in the 70s. Anyway "pinning" the corners was pretty necessary for the type log joints they'd chosen. Saddle or A and B notches were too much work so they made "butt and Pass" corners. They'd gotten maybe 2 courses when they bumped a wall, sheared a wooden peg and realized we don't have wood good enough to pin logs. 

Soooo, I collected a bunch of scrap 1/2" rebar at the Talkeetna land fill and we pinned the logs with rebar about 1/16" smaller than the holes. The only way to drive them in with a sledge hammer was to lubricate them so we lubed them with Bondo. The bad part was when one of the guys got the idea to roll little sausages of bondo and drop them in the holes. When the rebar bottomed in the hole bondo tended to squirt out the top of the hole which was . . . un-good.

Were I do do it now I'd buy a stick or two of galvanized rebar and thin the bondo with a little acetone so it'd carry into the logs. But . . . . ME build a log cabin now?     

Frosty The Lucky.

[George N. M.]

Old rebar, e.g. from a demolished building, the older the better, tends to be of better quality.  Or at least more consistent quality along the length.  You still have the issue of the ribbed texture though.  I did salvage a piece of smooth wrought iron rebar from the demolition of an early 1900s building.  I have seen old rebar which was smooth with chisel marks on it to improve the bond with the concrete.

"By hammer and hand all arts do stand."

[SubterraneanFireForge]

George after what u said I took some bolts and nails I had gotten from a demolished building and sawed and snapped them and they looked like wood!!

I had wrought iron right under my nose!

Sorry if this is redundant but will quenching in oil ad carbon to construction grade steel mild steel or wrought iron?

Thanks for all the feedback. 

[LeeJustice]

The heating of those steels to quench will actually cause some decarburization.  So, the quench in oil to add carbon would be a net loss to begin with.  And really no carbon from the oil would go into solution with the metals.  Processes that can add carbon to the metal's microstructure would be one like pack carburization.  There are also carburizing compounds like cherry red, which uses a torch, I think to make the carbon transfer to the SURFACE.  All these methods result in only surface hardening, known as case hardening.

[Frosty]

Sorry no. Lee laid the reasons out well. An oil quench adding carbon to steel is an old myth, probably started by folks as a gimmick to sell their stuff. 

Once you've become reasonably well skilled at forge welding adding the wrought to forge welded billets makes for good high contrast when etched. If used for knife furniture it can be etched to bring out it's natural grain structure. 

Carburizing wrought to high carbon would take many hours held optimum temp per inch of depth, in a sealed container packed in charcoal or better carbon source. Even for nails it isn't a trivial undertaking. 

Frosty The Lucky.

[Steve Sells]

try researching Blister steel

[TWISTEDWILLOW]

Rebar is really good for bending and welding and reinforcing lawnmower decks after people have beat them to pieces but that’s the only “Good” use I’ve found for it other then it’s intended purpose, 

it makes a good handle for brush fire rakes too! 

there’s so much free an cheap steel to be found that’s better suited for forging projects then rebar 

For a project thats going to be hand held under pressure holding a projectile though…

I would honestly recommend buying a piece of new material that you know the Exact composition and heat treatment for 

that way you have a higher chance of success in your project and probably safer since you will know the treatment requirements for the steel

that would really smart if you used some found metal and it snapped off and wacked ya about the third time you put it under pressure

[Shainarue]

I know you've already gotten a lot of feedback here but I wanted to throw my feedback in since it's different from the others, lol

On 12/17/2023 at 10:08 AM, SubterraneanFireForge said:

probably going to try it anyway and at least make a wall hanger or a crossbow shaped piece of steel.

If it's truly just for decoration and it will never be under pressure - and if you think the texture of the rebar would look cool - and if this project is what you're passionate about - then go for it! Making something that excites you is the whole point of this hobby, in my opinion. Some people really like the industrial look that rebar imparts to everyday objects so if that's what you're going for then I think you should try it. 

For decoration, you wouldn't need to worry about heat treating or springiness. Just get it to the shape you like, add some design elements that make you proud, and hang it on your wall as your first successful blacksmithing project!

That said, every time I work with rebar I cuss up a storm. That stuff is a pain in my keister. But the one stone snail I made looks really cool so that one was worth it, lol

[Irondragon Forge ClayWorks]

59 minutes ago, Shainarue said:

I think you should try it. 

Well said.

I can't control the wind, all I can do is adjust my sail’s.
Semper Paratus

 

[Mike BR]

I've made a couple of settings of "silver"ware from stainless rebar.  I have to say the handles look sharp with the fire scale polished off the tops of the ridges.