Chipped edge...

[jackorion]

Hi all,

I bought a Castrom Woodsman a few months back, very happy with it but I've got a little bit of a problem with chips in the edge...

Now I'll admit I'm not the world's most skilled sharpener, but I can get this knife to 'shaving' sharp using a 1000/6000 bear whetstone and then stropping on my belt. However I keep getting tiny little nicks/chips in the edge - hopefully this photo will show one...

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I had one of these before up by the tip and I got rid of it by starting on a 250 stone for a few minutes, then back on the the 1000/6000/strop - all good, but now there's another one and I don't think I've used this knife for more than a few minutes taking some back of some hazel...

Is there a possibility that I'm doing something wrong in the sharpening or am I expecting the edge to last longer than it should?

 

[Kadushu]

I suspect that the edge is a bit brittle.

 

[jackorion]

I suspect that the edge is a bit brittle.

OK, so why is that? because of something I'm doing when I sharpen or the steel?

 

[Robson Valley]

What have you selected for the total included bevel angle? Perhaps you've got the edge too thin (12 - 15 degrees) when it should be more like 25 degrees total included bevel. That's about 12 each side.

I've paid plenty for top quality wood carving edges, adze blades in particular. There has to be enough steel behind the edge to support it in a strike. A crumpled thin edge means jointing the whole damn thing and starting over to make the bevel. A single sand grain in dirty wood will ruin my day.

 

[jackorion]

What have you selected for the total included bevel angle? Perhaps you've got the edge too thin (12 - 15 degrees) when it should be more like 25 degrees total included bevel. That's about 12 each side.

I've paid plenty for top quality wood carving edges, adze blades in particular. There has to be enough steel behind the edge to support it in a strike. A crumpled thin edge means jointing the whole damn thing and starting over to make the bevel. A single sand grain in dirty wood will ruin my day.

I’ve just followed the bevels that were on the knife already…

 

[Broch]

There are only three reasons a knife edge chips:

1) bad/wrong heat treatment
2) wrong bevel angle for the steel or intended use
3) use for tasks not intended for the design

If you're 100% sure you've kept to the supplied bevel angle it must be 1) or 3) IMO

 

[Murat_Cyp]

Are you sharpened enough to get rid of "the factory edge" sometimes (i.e. when the edge is burned in the factory) the edge resistance to chipping increases dramatically after 2-3 sharpening?

Also, zero Scandinavian grinds are not the strongest types of grind types, so chipping could be expected if you use it without any consideration of that.

For example, my smallest carving knife got a very tiny (i.e. microscopic, not visible to the naked eye) chip when I have used it to cut out relatively (for its intended purpose) large chunks of seasoned wood. That knife is small and thin that is made to use for detail carving where the larger knife would struggle. So, in that case, I accepted that it was my fault that the edge got chipped. There is no question about the edge angles and heat treatment as it was made by Nic Westerman. On the other hand, if I get a nick while doing the same thing with my larger bushcraft or carving knives then I would assume either geometry of the knife (i.e. edge angles) or the heat treatment is wrong.

 

[Nice65]

Sleipner steel should have very good chipping resistance, that’s why it’s a premium knife steel. There’s a PDF here:

https://www.uddeholm.com/app/uploads/sites/40/2017/11/sleipner-eng_p_R1609_e11.pdf

GENERAL
Uddeholm Sleipner is a chromium-molyb- denum-vanadium alloyed tool steel which is characterised by:
• Good wear resistance
• Good chipping resistance
• High compressive strength
• High hardness (>60 HRC) after high
temperature tempering
• Good through-hardening properties
• Good stability in hardening
• Good resistance to tempering back
• Good WEDM properties
• Good machinability and grindability
• Good surface treatment properties

Good stability in hardening, good through-hardening, and good chipping resistance. It may be that you’re taking it to such a fine edge, ie: razor that it’s almost foil thin and chipping. A micro bevel would sort that out but many people don’t like them. Has it chipped from new? Or after sharpening over a period of time?

 

[jackorion]

well I'm now wondering if i was sharpening it too 'fine' - I took it to my 'old' stone last night, which is just a b&q blue oilstone that I've always used for sharpening my Mora, and then I gave it a decent strop afterwards.

Spent the day today in the woods on a course and did some batoning, carving, feathersticks etc etc with it and it seemed to hold up fine with no chipping...

 

[TLM]

well I'm now wondering if i was sharpening it too 'fine' - I took it to my 'old' stone last night, which is just a b&q blue oilstone that I've always used for sharpening my Mora, and then I gave it a decent strop afterwards.

That is somewhat hard to do on normal geometries as it would require a local hollow right by the edge. I would do deburring before stropping but then I don't strop my knives. There might be a small chance that it was the burr that broke of taking that small piece of edge with it. I don't really know how common that would be but that happened at least once to me when deburring kind of hastily.

 

[Robson Valley]

Damage on wood carvings looks like scratches done with a pin. But based on that alone, I can't tell if the gouge edge is folded/crumpled or that a very fine piece was brittle and broke off.

I have an old geologist's 10X loupe magnifier and in this day and time, a very bright LED light. Commonly, that's good enough to see that the edge is folded, like I have hit a sand grain in dirty wood. Jointing the edge and totally reestablishing the bevel is a chore that I never like to do. Easy fix is to buy clean wood from a mill, not to go scrounging in debris piles in logging sites.

So I'll ask you my question: is it folded or really chipped?

 

[Mesquite]

I have a Spydeco Bushcrafter that as original comes in a scandi grind and it constantly chipped.

I had Dave Budd reprofile it into a high sabre grind with a secondary bevel and it's never chipped since doing that. All I do to maintain the edge is strop it occasionally and it stays sharp as a sharp thing can be