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Thread: Hacksaw blade for a whittling knife

  1. #1
    Sharp Shooter

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    Default Hacksaw blade for a whittling knife

    I had been doing some wood carving with a Leatherman Crater and quickly discovered everything a carving knife should NOT be.
    So I made a handle from meranti dowel and shaped it to be comfortable for both push and pull cuts. I took a piece of bimetal blade and ground down the teeth with a small angle grinder.
    There was still some of that waviness on the edge which I tried to straighten out with a hammer and steel chisel.
    I then ground a cutting edge, trying to not push the very edge back from where the tooth gullet had been. The idea was to end up with a high speed steel edge that would not require frequent sharpening.
    I was unable to completely iron out all the waves which resulted in an edge bevel of varying width. It might also have resulted in areas not quite as sharp as the rest. It sharpened up to at least on par with the Crater though and retained its "carvability" for much longer. That might just be because of how thin it is rather than actual edge retention.
    The blade is obviously quite flexible which has its uses for carving but it makes it tricky to keep an even pressure along the length for sharpening.

    Is there any merit in my reasoning behind a durable HSS edge? Does the HSS even extend back past the tooth gullet?
    If so, can anyone tell me how wide the actual piece of HSS is? If there is enough HSS meat left I can grind the edge a little further back and out of the wavy area.
    It was so quick and easy I am considering doing the same with a sabre saw blade.
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  2. #2
    Sharp Shooter

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    Nice distraction while waiting out a storm.


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  3. #3
    Sharp Shooter
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    William the HSS hardening of the blade might be limited to the teeth. The harder steel is the more brittle it becomes so it might make sense to leave the teeth area fully hardened and temper the back of the blade back to less hardness to prevent it 'snapping' when slightly twisted under tension. The total blade will be of the same steel. Chances are though that you might be removing some of the hardness when doing shaping with an angle grinder due to overheating. You could try correcting this when grinding is done by heating the steel to 'cherry red' or ontil a magnet won't stick to it and then dipping/quenching it in water. A camping gas or kitchen gas burner could be used to accomplish this since it's a relatively small piece of metal to heat. A crude way of heat treatment without accurate thermometer but you'll end up with equal hardness all over the blade. It might be too hard then which would leave it brittle. To prevent this you could try quenching only the working edge of your chisel after heating. Have fun experimenting.
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  4. #4
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    Quote Originally Posted by DvdM View Post
    William the HSS hardening of the blade might be limited to the teeth. The harder steel is the more brittle it becomes so it might make sense to leave the teeth area fully hardened and temper the back of the blade back to less hardness to prevent it 'snapping' when slightly twisted under tension. The total blade will be of the same steel. Chances are though that you might be removing some of the hardness when doing shaping with an angle grinder due to overheating. You could try correcting this when grinding is done by heating the steel to 'cherry red' or ontil a magnet won't stick to it and then dipping/quenching it in water. A camping gas or kitchen gas burner could be used to accomplish this since it's a relatively small piece of metal to heat. A crude way of heat treatment without accurate thermometer but you'll end up with equal hardness all over the blade. It might be too hard then which would leave it brittle. To prevent this you could try quenching only the working edge of your chisel after heating. Have fun experimenting.
    As I understand it, bi-metal blades already have a tougher back while a strip of HSS is electron-beam welded on (butt-weld, I guess) to form the cutting edge.
    I have since discovered that bandsaw blades use the same technology, and googling it produced more useful pictures. Turns out the HSS strip is so narrow that after cutting the teeth literally only the tooth tip retains a piece. The gullet runs right into the back alloy.
    Maybe fine-tooth hacksaw blades have some HSS left behind the gullet, I will have to look into it further. I know Irwin makes utility knife blades with HSS edges.
    Last edited by William; 21-07-19 at 15:11.
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  5. #5
    Sharp Shooter
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    You had me curious so I took an Eclipse hacksaw blade to the knife grinder. I put a cutting edge on the backside and ground the teeth away on the cutting side without overheating it, hardness the same on both sides. Can be that only the teeth tips are super hardened. I guess the rest of the blade's hardness to be at least in excess of 60HRC, 58HRC being the average for a working knife. Tested the sharpened Eclipse on a leg of parma ham, slices like a razor but the blade is just too thin to yield a sturdy knife for accurate slicing.
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  6. #6
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    Thanks for checking.
    Was that specifically the bi-metal blade? Because they still make the standard plain high carbon blades as well.

    I tried to find the weld seam by heating a short stub with a torch to see if there is any difference in oxidation colours. Nada. Not that there was guaranteed to be any difference, but worth a try.

    My blade is 0.6mm thick, so I might have saved myself the trouble and just used a hobby scalpel at 0.5mm thick. And l would have learned nothing in the process...
    Still want to try the sabre saw blade though, it has more practical width and thickness and hopefully less waviness on the cutting edge.
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  7. #7
    Sharp Shooter
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    It is a 32tpi 'flexible' Eclipse, nothing high-end, suspect it is a normal high carbon blade without hi-tech electron beam welds. Or you could go the lazyman's route when doing wood carving like me and invest in a Dremel or generic Dremel with a few tungsten carbide carving bits
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  8. #8
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    I have since picked up a small Okapi with a stainless steel blade. Not sure what grade it is but it sharpens easily without the Leatherman's tendency to chip.
    The stock edge bevel angle was very large and would never have provided the necessary "bite" for carving. So I took a file to it and gave it a completely new angle. Until my Opinels had arrived it was actually the sharpest tool in the shed.
    The handle is small and narrow but proportionally long for the blade, making it surprisingly comfortable in all kinds of whittling/carving grips. I dropped it on day one, damaging the tip, hence the mini sheep's foot shape.
    It is sturdy enough to harvest 50mm tarwood sapplings and yet the tip is capable of carving really fine detail. I only revert to the hacksaw knife when some blade flex is desirable. The Crater has been relegated to the occasional use for making deep, stabbing gouges, only because of its chunky blade and locking mechanism.


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  9. #9
    Sharp Shooter

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    The Opinel No. 9 immediately got some patina treatment with mustard, vinegar and lemon juice.
    Sharpness as-bought is nothing extraordinary, it still needs some stropping. But that little No.6 is in a league of its own...









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  10. #10
    The Oom From T.J.O.P.S
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    Very nice, cannot wait to see when done with #9
    Have you ever held a Opinel #13?
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  11. #11
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    Quote Originally Posted by AYOBA! View Post
    Very nice, cannot wait to see when done with #9
    Have you ever held a Opinel #13?
    That thing is a beast, more like a folding broadsword than a knife!
    Apparently they were originally made only as a window display models for marketing. Until people started insisting on buying them.

    I don't have much more planned for the #9. I did consider a handle of local hardwoods while keeping the classic shape, but the light beech colour is as much part of the Opinel history as everything else.
    If I ever get myself a #2 or #3 I'll make a large comfy handle for it, recess the blade a little deeper into the handle, add a second rivet and turn it into a fixed blade whittling machine.
    I have asked the Morakniv agent to bring in a few blade blanks with the classic Scandi grind. They will each need handles anyway so I will wait to see how they turn out before mess with the Opinel.
    That said, it is dead easy to swap the Opinel blade back and forth between different handles.
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