Leaf Spring Axe

[Will Robisch]

I am going to try to make a fold over leaf spring axe. I have heard that it is VERY difficult to forge weld leaf springs, however on another topic on the forum a guy mentions using a mixture of charcoal and borax and using it as a flux, he called it "Alaska Flux."

https://www.iforgeiron.com/topic/44538-how-to-forge-weld-leaf-spring/

I was wondering if it actually works, and if not are there any other tips on how to weld forge leaf springs.

[Irondragon Forge ClayWorks]

If Teenylittlemetalguy says it works, you can take that to the bank, in other words yes it works. There are about as many flux recipes that work as there are blacksmiths. The main secret is get the metal really clean (no rust or crud) before starting the weld.

[Will Robisch]

Ok I will try it, thank you for the response.

[Latticino]

I recommend better than really clean.  Grind the surfaces you plan on welding together to full bright to remove any surface mill scale or oxides and flux those surfaces as soon as they are heated.  I think more aggressive fluxes than Alaskan flux may be needed for success with the higher chromium alloys, but don't have a formula for you.  One trick that works is to put a piece of shim stock of high carbon (say 1075) between the two layers of leaf spring, as the spring will weld to that more easily.  The other thing I've done is to use the spring as a kind of extended bit (that goes from edge right up to the eye), and just use mild steel for the eye.

Good luck.

[JHCC]

Like this?

[Will Robisch]

No, I was thinking the whole thing Spring steel folded over.

I do have some High carbon that I could put in between the two pieces to get it to forge weld better if you think that would work.

[ThomasPowers]

I picked up some old hand saws at the scrapyard just for that purpose; high carbon low alloy---(old!) steels for a shim between spring that can be a more difficult weld.

[Will Robisch]

Ok, thanks I will try your suggestions next weekend.

[BillyBones]

I have made better than a dozen axes from leaf spring this past year. Yes it is a pain to weld but once you get the technique down it gets much easier. Do not get lax in that technique though. Do it the same way with as much attention to the details as the first one. Here is one i made a while back ago. I will start by necking down the center of the spring some before folding, that helps with the eye profile. Also after i have it done i fire up the old stick welder and run a bead in the blade side of the eye. That will take out the sharp "V" shape to get more of a gentle curve, more of a "U" shape. 

Edit: Done as in the welding and shaping, weld before heat treating. Just to clarify.

 

Edited April 12, 2021 by BillyBones
clarification

[Will Robisch]

@BillyBones, did you have a shim in between the steels, did you use a certain flux, or did you just weld it as is?

[Latticino]

4 hours ago, JHCC said:

Like this?

John,

Yes, I did something similar on this one using wrought and 5160 (but left the wrought proud for the visual effect):

[BillyBones]

Latticino, nice ax.

Will, mostly no shim but i have used them on a couple that were stubborn. I use Borax with some metal filings thrown in. Not much, i keep my Borax in a .50 cal can, about a table spoon of filings in half a can of Borax. 

The worst part of making the ax is the heat radiating off such a large surface. You definitely want a long handled spoon for your flux.

Be prepared for failure. Even though i have done a bunch of these i still have quite a few in the scrap pile.  

[teenylittlemetalguy]

16 hours ago, Irondragon ForgeClay Works said:

If Teenylittlemetalguy says it works, you can take that to the bank, in other words yes it works.  

You made my day, thank you!

I have to agree with everyone here, clean surfaces are really important.  People do weld it without the powdered charcoal, I have it in mine to help insure a reducing environment at the joint.  Having a poor atmosphere in a gas forge for welding is very common and it is very critical with leaf spring. 

Good luck with your project! 

 

[Will Robisch]

Today was the day I tried to forge weld it, I got my propane forge and put the steel in and heated up as hot as I could, I put flux on, I put it back in, then I took it out and started lightly tapping it and then hit it slightly harder, however no matter how hard I tried it did not forge weld, it just kept seperating, I had a saw blade as a shim and everything but still did not work, any more advice? I think the saw blade might have been m2.

This is what it looks like after trying to forge.

[Steven NY]

Hello,

Have you used your propane forge to forge weld before? It is hard to tell from the picture but I am thinking that the metal was not hot enough to forge weld. I use a coal forge when forge welding, and have developed an eye for what the metal should look like to know it is at the right temperature. I have heard that metal in a gas forge does not develop the same "Wet" look it does in a coal forge. I am sure some of the gas forge people on the forum can give you details of what they look for. Your metal does not look overly pitted like it was burned, but is is hard to tell from the photo. The scaling does not look very heavy either. So my guess is more heat, but again my propane forge experience with forge welding is none existent. 

Good luck, keep trying,

W

[Frosty]

I hope you have more material, that's getting mighty thin.

Next time when you have it all clean and shined up give the joint surfaces a dusting of flux then wrap it with wire, tack weld, etc. closed. THEN put it in the forge, bring it to a temp flux begins to melt, I put a little on a the piece so I can see it melt. When the flux melts and spreads bring it out and flux it. Then return it to the forge, bring to welding heat and set the welds. 

Brush vigorously, reflux, return to the fire heat and set. 

If it doesn't set do NOT keep trying! if necessary open the joint and clean it again.

The chrome in spring steel oxidizes almost instantly and forms a hard shell that has a higher melting temp and is resistant to chemicals like the borax in forge welding fluxes. Why people clean spring steel, shine it even then bring it to orange heat where you can watch scale form on steel almost instantly before fluxing it escapes me. I rarely have trouble with forge welds but I never bring steel to orange before fluxing. 

One of the main things flux does is form an airproof barrier on the steel. Applying enough it can carry inclusions and scale out of the joint when you hit it just means you either didn't clean it well enough or oxide is forming in the closed joint. 

Its easier to find a reducing atmosphere in a coal forge and welding spring steel is much easier. So, if all you have is a propane forge and you think it's oxidizing then flux before you put your weld in the fire and if you put a little charcoal in your forge it will scavenge free oxy making a reducing atmosphere.

Frosty The Lucky.

[ThomasPowers]

You may remember that when I mentioned using a saw blade as a shim I referenced OLD plain steel ones; I use scrapped hand saw blades that may be from the 1920's and 30's!  M2 is a high alloy HSS and is considered suitable for welding only for folks like Hrisoulas!

[Will Robisch]

Thank you, do you have any recommendations on how to clean the inside of the joint easier as well, I am having trouble getting it super clean, the hottest I could get it in the forge was a bright orange to yellow color, I tried it in a coal forge as well but the coal forge was to small and did not get it nearly as hot as the propane. Thank you for the advice I am 14 and just trying to learn.

[Frosty]

When you fold it leave the joint open enough to use a file and sand paper between the sides. Leave the stock as thick as possible, you shape it AFTER it's welded and more thickness will stay hot longer. 

Once you've cleaned and shined the joint surfaces, wipe them with some light oil like 3 in One and dust it with flux. To close the joint carefully heat ONLY the far side of the eye enough you can close the join. 

Warm it, brush and flux it then bring to welding temp and set the weld.

Not scarfing the ends might effect things but if it's actually detrimental I cut the bad off. 

The light oil does a few things for the weld: first it makes the flux stick where you want it, secondly it helps keep oxy off the surface and lastly it scavenges oxy as it burns. All good things for forge welding.

How about a pic of your propane forge, we aught to be able to get more than low yellow for you.

Frosty The Lucky.

[JHCC]

Bright orange to yellow probably isn’t hot enough. Have you done other forge welds before? 

[Will Robisch]

Yes, I have forge welded a 1095 and 15n20 damascus billet, but it was fairly small.

 

[JHCC]

In this same forge?

[Will Robisch]

Yes in the same forge as in the back ground here.

 

The steel in this image was not the welding heat I used, it was to big to fit in to the forge at this point so I just barely got it hot enough to bend the rest of the way.

[Latticino]

In the photo the forge doesn't look nearly hot enough for welding.  You will likely need doors, at least, and it is hard to tell about your burner design.  Where did you get your forge?

Also, just to reiterate what I originally said (as well as others following my post): I recommend you grind the steel faces to be welded completely clean, then flux as soon as they get heated to a dull red.  Not just before bending, not after bending, just as soon as you heat it past dull red for the first time after you grind it clean.  You will likely have to reflux it several times during the bending process, unless you can speed up some and get it bent in one heat.  Once the sides are close to each other, try brushing vigorously then squeezing together with a vise.  Flux and heat it up to screaming hot in your forge before bringing it to the anvil.  Have hammer in hand and tap the joint closed as soon as the steel touches the anvil.  Just a few quick taps to set the weld, then back into the forge.

Butterfly style axe forging isn't a beginner project, so don't get frustrated.  This may take a couple of tries.

[JHCC]

Will Robisch, Latticino is not just one of our resident gas forge experts, but also quite skilled in making butterfly-style axes (indeed, he taught me). He's worth listening to.