Brass welded bolster/tang on western mono carbon? (Kogetsu SK5)

Kitchen Knife Forums

Help Support Kitchen Knife Forums:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Joined
Feb 6, 2015
Messages
2,807
Reaction score
3,359
Location
Oregon
I recently picked up a Kogetsu SK5 western mono because I totally fell for the ultra wabi sabi hand made charm, which you just don't see often in western mono carbons. Here's a first shot to set the stage, dentoukogeshi sticker and all:

1 - Kogetsu SK5 - Right Side.jpg


Fit and finish is of course rustic and demonstrates traditional craftsmanship in cool ways, for example, the blade shows obvious signs of being stone finished, perhaps both sharpened and lightly thinned:

1.5 - Kogetsu SK5 - stone finish.jpg


But there was something that I really didn't expect and had no idea what to think about at first, which is what appears to be a brass weld that spans the entirety of the blade/tang/bolster junction:

2 - Kogetsu SK5 - right weld.jpg



3 - Kogetsu SK5 - left weld.jpg



4 - Kogetsu SK5 - spine weld.jpg



5 - Kogetsu SK5 - under side weld.jpg



Now, I have seen these knives sold by a few different retailers, and none of the listings on any retailer's website has ever shown this feature, as far as I know. My initial thought was maybe there was a poor fit between the bolster and tang on this particular specimen, and perhaps the maker opted to fill it by welding brass and then grinding it flush? Alternatively, perhaps the maker has opted to do this on all new knives from this line to shore up that fit, regardless of whether any individual knife has gaps. Or, perhaps this is sort of like moritaka knives I've seen where the maker opts to weld a stainless tang to a high-carbon blade in order to make the tang more resistant to water intrusion if any water gets inside of the handle. That moritaka-style construction makes sense in a wa-gyuto where the handle is not always very well sealed. But does it make sense in a western configuration?

I wrote the retailer to inquire about the brass weld and its purpose, but was only told that the maker has now decided to make all knives in this line with the brass weld, and that they will update their sales listing with pictures showing the new feature. The retailer did not tell me what the purpose of the weld was, so I sent a reply requesting further clarification.

Meanwhile: any of you KKF knife gurus have any additional thoughts about what this could be? I'm not upset about this knife at all, just really curious about what's going on.

Have at it!

PS: special thanks to @tostadas and @blokey for already entertaining my questions about this knife over PM.
 
Last edited:
I follow them on Instagram, and there the maker said they brazed because the temperature is lower, so there are fewer negatives effects on the heat treat compared to welding (where the steel melts)

Cool thanks for the reply. So which are the parts that are being bonded via brazing at this junction? Are the blade and tang a single forged piece and it's just the bolster that's being attached by brazing? Or is this a braze that joins three separate pieces: blade, tang, bolster?
 
You can see part of the process here.


Okay that's really cool. So it does appear that the blade and tang are forged from a single piece and that it's just the bolster that's being joined by brazing.

I guess a follow up question is if there's any concerns for structural integrity in this particular model where there are some chunks missing from the braze:

6 - Kogetsu - Braze Pitting 1.jpg


7 - Kogetsu - Braze Pitting 2.jpg


My guess is there's no issue because the actual bonded surface is bellow the pitting, i.e., neither the blade nor tang are exposed at any point. However, I would like to do a little rounding of the spine in that area so I will make sure not to remove any more metal from the pitted spot.
 
Okay that's really cool. So it does appear that the blade and tang are forged from a single piece and that it's just the bolster that's being joined by brazing.

I guess a follow up question is if there's any concerns for structural integrity in this particular model where there are some chunks missing from the braze:

View attachment 325452

View attachment 325453

My guess is there's no issue because the actual bonded surface is bellow the pitting, i.e., neither the blade nor tang are exposed at any point. However, I would like to do a little rounding of the spine in that area so I will make sure not to remove any more metal from the pitted spot.
My background hobby is bicycles with 2 years as a mechanic but returned to being a chef due to pay. Fillet brazing like that wouldn't be OK on a bicycle and is normally indicative of over heating.
 
Very curious what some of our resident makers and/or other experts would think of these voids in the braze, whether they present structural integrity concerns or are likely just cosmetic. If cosmetic, I think they're just wabi sabi charm no worries, if structural I would be a bit worried especially because I intend to round those locations a bit and wouldn't want to exacerbate any issues. See below:

@HSC /// Knives
@MSicardCutlery
@Knot Handcrafted
@Kippington
@Andrei
@RDalman
@JBroida

PS you can respond without fear of sticking your neck out, I am not publicly identifying the source of the knife and am just curious about expert feedback. Also, don't feel obligated to respond if you don't want to, don't have time, etc. This is just for my own education if you're willing to share your thoughts 👍



6 - Kogetsu - Braze Pitting 1.jpg


7 - Kogetsu - Braze Pitting 2.jpg


3 - Kogetsu SK5 - left weld.jpg
 

Attachments

  • 2 - Kogetsu SK5 - right weld.jpg
    2 - Kogetsu SK5 - right weld.jpg
    281 KB
I wouldn't make a knife that way, but it should be structurally sound.

lol dude no doubt, if your custom order sheets are any indication, I would say that your attention to detail extends all the way down to the last quantum particle 😁 Thanks for weighing in, I definitely value your opinion and appreciate your assurances about structural integrity.
 
Very curious what some of our resident makers and/or other experts would think of these voids in the braze, whether they present structural integrity concerns or are likely just cosmetic. If cosmetic, I think they're just wabi sabi charm no worries, if structural I would be a bit worried especially because I intend to round those locations a bit and wouldn't want to exacerbate any issues. See below:

@HSC /// Knives
@MSicardCutlery
@Knot Handcrafted
@Kippington
@Andrei
@RDalman
@JBroida

PS you can respond without fear of sticking your neck out, I am not publicly identifying the source of the knife and am just curious about expert feedback. Also, don't feel obligated to respond if you don't want to, don't have time, etc. This is just for my own education if you're willing to share your thoughts 👍



View attachment 325471

View attachment 325472

View attachment 325474
cosmetic only
 
Based on my work experience, I only use this method of processing when I'm short on parts and don't want to spend a lot of money ordering a batch of suitable components.
1)

Based on the picture, I determined that the blade and the handle are two separate pieces, joined together by brazing.
2)

The dimensions between the two parts are likely mismatched. So, brazing with filler material is used, followed by grinding to make them look like a single piece.
3)
Don't worry about those welding pores. This is just a cutting knife. These small defects won't affect its performance.


From a producer's perspective, for small-scale production, this is a very effective way to control costs. Although it increases labor costs, it significantly reduces material costs while still achieving the necessary practical quality.


It's a very good knife. A few minor flaws don't affect it. It can still perform at 100%.
 
Based on my work experience, I only use this method of processing when I'm short on parts and don't want to spend a lot of money ordering a batch of suitable components.
1)

Based on the picture, I determined that the blade and the handle are two separate pieces, joined together by brazing.
2)

The dimensions between the two parts are likely mismatched. So, brazing with filler material is used, followed by grinding to make them look like a single piece.
3)
Don't worry about those welding pores. This is just a cutting knife. These small defects won't affect its performance.


From a producer's perspective, for small-scale production, this is a very effective way to control costs. Although it increases labor costs, it significantly reduces material costs while still achieving the necessary practical quality.


It's a very good knife. A few minor flaws don't affect it. It can still perform at 100%.

Thanks for your detailed assessment, Bill!
 
Thanks for your detailed assessment, Bill!
There's also a possibility that this knife was made a long time ago, back when there wasn't a mature handle supply system like there is today. In such times, when suppliers were not well-developed, each manufacturer would have their own production techniques.
Unlike now, the finished knife production system has become so mature that the products being made all have identical structures, processes, and materials.
Bill
 
Hey. I'm considering buying the same knife. How is your impression of the knife so far? And does the brass hold up?

Thanks.
 
Back
Top