Can I make my knife good?

[jsandvad]

In February I went on a knife making course at Isasmedjan, and made the knife shown in my profile picture. It was my very first attempt in knife making, and I don't really plan to start making my own knives, but was curious about the craft of forging knives. It was a great experience, Jonas is a great teacher and an exceptional knife maker, and with a bit of help from Jonas I ended up bringing home a sharp, knife-shaped object.

I would love this to be my daily workhorse, but unfortunately it just doesn't cut very well. It's fine on tomatoes, but on carrots it needs too much force, and the carrot is wedged rather than cut. So, I guess it needs some thinning. I have been working on it with sandpaper using those cork bricks to hold it, but so far hasn't done the trick. Comparing with my favourite knife, the Birgersson short gyuto, it is a bit chunky.

I will spare you my terrible, out of focus choil shots, but I think it is safe to say that the main issue is my knife is still way too thick behind the edge. So, now on to plan B: My lowest grit stone was a Naniwa pro 600, so now I bought an Atoma 140 and a Suehiro Debado 320 grit and will give it another go tomorrow with the thinning (it was already my most expensive knife by far, it will be Kamon expensive before I'm done )
Will keep a journal in here on progress. Any advice very welcome!

 

[deltaplex]

I wish you luck! I don't know that I'd shoot for quite as thin as the Birgersson grind, but even relatively close to that will be a very good cutter. If you'd share a choil shot (here or in DM) I could give you how long I think it would take to get to where you want to be on it.

 

[jsandvad]

I wish you luck! I don't know that I'd shoot for quite as thin as the Birgersson grind, but even relatively close to that will be a very good cutter. If you'd share a choil shot (here or in DM) I could give you how long I think it would take to get to where you want to be on it.

Thanks, here's a picture that's not too unfocused. Choil is a little beefy, but I wouldn't expect the cutting feel to be as bad as it is judging from the choil shot

 

[deltaplex]

You've got many MANY hours of working those low grit stones by hand to get it close to Birgerson level. At least you'll build up a lot of strength and endurance with the undertaking? I'd usually do macro stock removal with powered tools on a knife that I intended to thin as much as you've stated you want to for this one, and then move over to the low grit stones after the bulk of it was taken care of by the belts/wheel/etc.

 

[gaijin]

Not to spoil your fun on the stones, but I'd start by dropping a mail to Jonas @ Isasmedjan and get his opinion too.

 

[jsandvad]

Ah, was afraid so. Unfortunately I don't have any power tools for this.
@gaijin, not a bad suggestion, I'm sure Jonas will have some good hints to share.

 

[jsandvad]

Cutting a carrot, Birgersson first, then mine

 

[Nikabrik]

A user on another forum suggested for beginner bladesmiths to use strips of ceramic belts in a filing jig if they're working hardened steel. I think it'd yield a good consistent angle and reduce the pressure on your finger joints, and not potentially use up an expensive plate.

 

[tostadas]

Based on the photos/video you provided, this is going to require significant steel removal to get it to the state you're looking for. Maybe not the best learning experience for your first thinning, simply due to the amount of material that needs to be removed. By hand, it will take a long time. As others have suggested, I would start by reaching out to the maker for recommendations first. Knife looks nice though, good luck!

 

[HumbleHomeCook]

You've got many MANY hours of working those low grit stones by hand to get it close to Birgerson level. At least you'll build up a lot of strength and endurance with the undertaking? I'd usually do macro stock removal with powered tools on a knife that I intended to thin as much as you've stated you want to for this one, and then move over to the low grit stones after the bulk of it was taken care of by the belts/wheel/etc.

How do you mitigate heat on the powered equipment. I've thought taking one of the Wok Shop cleavers to the belt sander but don't want to toast the heat treat.

 

[ian]

How do you mitigate heat on the powered equipment. I've thought taking one of the Wok Shop cleavers to the belt sander but don't want to toast the heat treat.

I'm assuming it runs at a fixed high speed? Use fresh belts, and make sure to dip the knife in water very often. Like, move the knife across the belt reasonably quickly, like 1-2 seconds to get all the way along the edge, dip, move across the belt, dip, etc....

 

[MSicardCutlery]

And work barehanded. You'll get burned way before you ruin the HT.

 

[HumbleHomeCook]

I'm assuming it runs at a fixed high speed? Use fresh belts, and make sure to dip the knife in water very often. Like, move the knife across the belt reasonably quickly, like 1-2 seconds to get all the way along the edge, dip, move across the belt, dip, etc....

And work barehanded. You'll get burned way before you ruin the HT.

Thank you both.

Yep, just a simple 1" vertical belt sander.

 

[MSicardCutlery]

Should work ok. Just use long even strokes, and even pressure. Try to start on the outside edge of the belt, and finish on the inside edge. The way the whole blade has as near to uniform grinding time/time in contact with the belt as possible. Divots are usually the result of uneven contact when initiating contact. Thick spots near the tip are usually from letting up as you're finishing the pass.

 

[MSicardCutlery]

Of course, nothing says you can hog out the middle and work the points down by hand just to be safe. Overgrinds on the points are probably pretty easy with such a narrow belt.

 

[ian]

Be careful near any parts of it that may be thinner, e.g. the tip, although on your cleaver that may not be a big deal. I burned a lot of tips on my 1x30. Those things heat up much faster than a 2x72.

 

[gaijin]

As shown in another thread, I recently did a similar adventure with Fredrik Spåre. The knife I ended up making was also a bit more of a workhorse grind and noticably chunkier than my previous Spåre knife... My test cuts have been very good but I have not yet attacked carrots yet. Will probably have to do that now that ARM is over.

However:

Things that Fredrik insisted on doing himself was the grind, the polish and the sharpening - basically everything with a rotating machine. This was for several reasons, including safety (a flying blade stuck in a customer is probably bad for business even if the customer did it himself), performance/result and finally to not mess up the heat treatment.

So if I feel that bigger work is needed once I start using it more, I'd surely start by contacting Fredrik in this case. Regular sharpening I'd do myself.

 

[jsandvad]

Yes, on Jonas' course we did the grind ourselves on belt sanders, with thorough instructions on how to do it without having blades flying around the workshop (and without ruining the HT, basically doing as Ian said, but I still managed to ruin the tip). Obviously if Jonas did it I would have a better knife now, but the course was more about getting an intro to all the steps needed for making a knife than producing a good result. Anyway I would like it to be a knife that I'm happy to use, so willing to spend some time and money to get there. Thanks to all for your advice so far! I guess my plan to thin it on stones is more or less doomed to fail, so I'll have to look into other options. I don't have a belt sander, so will see if I know someone who does, or perhaps could rent one somewhere.

 

[mengwong]

I am told when the HT is ruined the knife cannot hold an edge. But I’d like to understand what that means, exactly. Can anyone enlighten me? Like, how would it be apparent in practice.

 

[jsandvad]

Jonas told us that the steel would turn bluish-purple in color and that the only thing to do is to remove the ruined material. It was very easy to see when it happened on my knife tip. I don't know what it means for the steel, if it just reduces hardness or changes other properties.

 

[Benuser]

I am told when the HT is ruined the knife cannot hold an edge. But I’d like to understand what that means, exactly. Can anyone enlighten me? Like, how would it be apparent in practice.

It's not so much about not holding an edge, as well about not taking it. The steel feels as soft as tin and won't take a burr. Quite common with vintages after a lot of steeling or sharpening on uncooled grinders. Until the seventies a lot of sharpening took place in Europe by carts. Most vintages are just ground away.
Have seen vintages where 3/8" of the width had to be taken off before reaching steel that took an edge.

 

[mengwong]

Thanks. In my research I only got as far as reading about embrittlement: THE HEAT TREAT DOCTOR: The Embrittlement Phenomena in Hardened & Tempered Steel

But it wasn’t clear what the failure mode would be in practice.

(TME makes me wonder why people blue their woks during seasoning… wouldn’t that just make the woks break sooner?)

 

[blokey]

Thanks. In my research I only got as far as reading about embrittlement: THE HEAT TREAT DOCTOR: The Embrittlement Phenomena in Hardened & Tempered Steel

But it wasn’t clear what the failure mode would be in practice.

(TME makes me wonder why people blue their woks during seasoning… wouldn’t that just make the woks break sooner?)

Modern woks are mostly just iron, not enough carbon content to be hardened, even with 1% of carbon content there will be no problems since they are not quenched and hardened, take a hammer to your seasoned wok you will find it and be shaped like play dough, not brittle at all.

 

[gaijin]

(TME makes me wonder why people blue their woks during seasoning… wouldn’t that just make the woks break sooner?)

One key aspect of hardening is that the cooling process must be very quick. This does not happen by accident, you have to cool down the metal in a liquid.

 

[deltaplex]

Thank you both.

Yep, just a simple 1" vertical belt sander.

Without some sort of cooling system for the sander, having a dunk bucket near bye and working bare handed will allow you to take off material and have feedback on when it's getting too warm before raising to temps near where the HT may be affected. I tend to avoid removal near the edge with it and do a majority of that on the stones since those mechanisms are less reliable for that area of minimal mass. Learning on the cheap chinese chef's knife is a great plan though, there's lots to learn from it and if things go south, you're not really going to feel terrible.

 

[deltaplex]

Yes, on Jonas' course we did the grind ourselves on belt sanders, with thorough instructions on how to do it without having blades flying around the workshop (and without ruining the HT, basically doing as Ian said, but I still managed to ruin the tip). Obviously if Jonas did it I would have a better knife now, but the course was more about getting an intro to all the steps needed for making a knife than producing a good result. Anyway I would like it to be a knife that I'm happy to use, so willing to spend some time and money to get there. Thanks to all for your advice so far! I guess my plan to thin it on stones is more or less doomed to fail, so I'll have to look into other options. I don't have a belt sander, so will see if I know someone who does, or perhaps could rent one somewhere.

I wouldn't say it's doomed as a concept, but it will be extremely taxing and tedious. I still have to remind myself that any significant thinning is going to take longer than I expect it to. You are way more prone to mistakes when you start to fatigue (both physically and mentally) and tackling this by hand will have a lot of situations where you just want to push through but you probably shouldn't.

 

[Bear]

In February I went on a knife making course at Isasmedjan, and made the knife shown in my profile picture. It was my very first attempt in knife making, and I don't really plan to start making my own knives, but was curious about the craft of forging knives. It was a great experience, Jonas is a great teacher and an exceptional knife maker, and with a bit of help from Jonas I ended up bringing home a sharp, knife-shaped object.

View attachment 234685

I would love this to be my daily workhorse, but unfortunately it just doesn't cut very well. It's fine on tomatoes, but on carrots it needs too much force, and the carrot is wedged rather than cut. So, I guess it needs some thinning. I have been working on it with sandpaper using those cork bricks to hold it, but so far hasn't done the trick. Comparing with my favourite knife, the Birgersson short gyuto, it is a bit chunky.


View attachment 234686
I will spare you my terrible, out of focus choil shots, but I think it is safe to say that the main issue is my knife is still way too thick behind the edge. So, now on to plan B: My lowest grit stone was a Naniwa pro 600, so now I bought an Atoma 140 and a Suehiro Debado 320 grit and will give it another go tomorrow with the thinning (it was already my most expensive knife by far, it will be Kamon expensive before I'm done )
Will keep a journal in here on progress. Any advice very welcome!

To me you have to look at the forging of Birgersson's distal taper and overall thinness, not necessarily the grind, I don't know if yours could ever cut carrots with ease, but that's not the end of the world, if it cuts good on non dense produce I would consider it a big success.

 

[ian]

I think cutting carrots has much more to do with thickness bte than anything else. OP, thin your knife down and it’ll cut carrots fine.

 

[HumbleHomeCook]

I think cutting carrots has much more to do with thickness bte than anything else. OP, thin your knife down and it’ll cut carrots fine.

I nearly always find significant gains in simply thinning and smoothing the edge shoulders. It's amazing the difference it can make in performance while still having a thicker overall grind.

I would agree to start here and see what you think. It might make just enough difference.

 

[Keith Sinclair]

I thin with a 1" X 42 Kalamazoo belt sander & bucket of water. I'm sure it was recommended on KKF. Had it about 10 years & it has come in handy for all types of jobs. Small footprint, powerful motor, easy belt change. It was around 300.00 $.