san mai with tungsten carbide

[Natlek]

Will be interested to see what comes of this.

We had buckets and buckets and buckets of scrapped shattered Tungsten at my old job. But even In the shattered state it was valuable. We would send it back to be recycled.

Maybe instead of knife i should try to make some gold bars ...at least that would be easy

 

[Josh Rider]

I think you’re nailing all the best ways NOT to make a knife.

 

[Bigfattyt]

We had a guy who was stealing the scrap, and good anvils. He sold $250,000 worth of anvils for $32,000 before he got caught and charged!

 

[PEU]

You will have a hard time sharpening that knife, only diamond or CBN will touch it, forget any ceramic belt. To me its more of a novelty than an usable knife.

Pablo

 

[Natlek]

We braze and grind tungsten carbide at my workplace (we manufacture milling cutters & reamers), and a few guys here have tried many times to do this same thing.

When brazing strips together side by side (to make a knife blade), the steel backer and carbide expand and contract at different rates, which cause the carbide to crack. However, I don't think anyone has tried a san-mai lamination.

Assuming a successful braze is possible, the next issue is grinding. The carbide is ground with diamond wheels under oil. Grinding into steel causes them to load up and stop cutting. You would need to make the outer layers of a san-mai from a very hard steel, like Rex-121, in order to grind both together. We will sometimes use T15 at 68-70Rc for tool bodies, but even that is on the soft side for a diamond wheel.

Those are just the issues we've had - if you can figure out a way please share!

If you want something insanely sharp and brittle, maybe make a blade from tungsten carbide with a polycrystalline diamond edge?

Ok , this is the plan .I can get here rods for brazing which they use for brazing diamond and tungsten carbide insert on circular saws.First I will braze only sides of stainless steel , as much thin layer as it is possible then assembly everything , insert three short pin /for scale/to keep everything aligned and in oven let it soak on right temperature ..............get them out and in press. No need for very high pressure ,just to hold them tight and flat ....I hope 2 x 3 mm thick stainless from sides will hold temperature enough long till i press it on press.
Now i need to figure way how to get alive from my friend shop when i tell him what i want from him to cut and what I plan to do ...100% he will kill me
Something like this ,knife pattern cut in exact dimension and shape .....the drawing is a cross section.
What do you think ?

 

[Natlek]

You will have a hard time sharpening that knife, only diamond or CBN will touch it, forget any ceramic belt. To me its more of a novelty than an usable knife.

Pablo

You think that ceramic knives are more durable then tungsten carbide ? And they are many years on market .............
They are already on market PEU .Search Sandrin tungsten carbide knives ...they make even big kitchen one knife .Again i know with what i work ...BUT again ..........for light use , why not ? Plus it is so cool .....

 

[Sam Dean]

Ok , this is the plan .I can get here rods for brazing which they use for brazing diamond and tungsten carbide insert on circular saws.First I will braze only sides of stainless steel , as much thin layer as it is possible then assembly everything , insert three short pin /for scale/to keep everything aligned and in oven let it soak on right temperature ..............get them out and in press. No need for very high pressure ,just to hold them tight and flat ....I hope 2 x 3 mm thick stainless from sides will hold temperature enough long till i press it on press.
Now i need to figure way how to get alive from my friend shop when i tell him what i want from him to cut and what I plan to do ...100% he will kill me
Something like this ,knife pattern cut in exact dimension and shape .....the drawing is a cross section.
What do you think ?

I don't think pins are a good idea. Attempting to remove from a furnace and apply pressure is also very risky. It's going to lose heat too fast and cool too quickly, which will probably crack the carbide.

Instead, flux & layer your stack (steel - flux - braze - flux - carbide - flux - braze - flux - steel), place a fire brick or ceramic block on each side so it won't slide around. Bring oven up to braze temp, soak for a few minutes, then shut it off & let the stack slowly cool.

To reduce stress and increase strength, you can also try to find some clad braze strips with a copper core: https://www.stella-welding.com/en/carbide-brazing-alloys-trimetals/ These have the braze alloy already applied. We use this at work for brazing very large tips on.

You could also try wrapping the stack in stainless foil to keep it all together. I'm not sure if that would work or not.

I REALLY want to see how you're going to grind this stack once it's brazed together!!

 

[Natlek]

I don't think pins are a good idea. Attempting to remove from a furnace and apply pressure is also very risky. It's going to lose heat too fast and cool too quickly, which will probably crack the carbide.

Instead, flux & layer your stack (steel - flux - braze - flux - carbide - flux - braze - flux - steel), place a fire brick or ceramic block on each side so it won't slide around. Bring oven up to braze temp, soak for a few minutes, then shut it off & let the stack slowly cool.

To reduce stress and increase strength, you can also try to find some clad braze strips with a copper core: https://www.stella-welding.com/en/carbide-brazing-alloys-trimetals/ These have the braze alloy already applied. We use this at work for brazing very large tips on.

You could also try wrapping the stack in stainless foil to keep it all together. I'm not sure if that would work or not.

I REALLY want to see how you're going to grind this stack once it's brazed together!!

That clad braze strips are best thing for this .Italy is not far from me i think that i can get that trimetals ....Thanks !
But I need to try this NOW I have plenty of this TC knives to practice .Braze material i can find here are rods......that s why I want to braze sides of stainless then put all together /flux between tungsten and braze material and in oven .Make sense that will lose temperature fast .So this would work .....I have one inch thick 304 stainless plate so i can use two of them as weight over san mai sandwich .In oven on temperature and let all cool down inside .Must work , I can t see what can go wrong . Why you don t like idea to use pins ? I need them to keep everything on place .If you think that they will expand from heat and crack tungsten i can use pin from glass ? I was thinking to use copper one so i can easy drill them after ... Tonight i try something .........small diamond disk on Dremel cut TC like water and fast .....I cut piece of ceramic knife , piece of SIC and tungsten carbide and I was surprised at how fast it was going ...faster then ordinary cutting disk on dremel cut steel .I will try myself to cut tomorrow that small shape of knife on bottom , some wood for handle and to try how will behave on cutting some things.It already have sharp edge so why not to try ..
Abut grinding ..........Sam , it is only 1.2mm thick TC core .Spine thickness would be around 3.5mm and i would not grind bevels to high ...I will grind bevels like on any knife till I get to TC .After that diamond plate .....i will need to remove very little of TC from both side to get to 0.5 -0.4mm BTE .

I will cut one piece for plate behind belt just to see how long it would last ?

This is what i will try to make sanmai

PS.If nothing else I can always make wood-tungsten-wood tree-mai...epoxy is cheap

 

[Sam Dean]

Why you don t like idea to use pins ? I need them to keep everything on place .If you think that they will expand from heat and crack tungsten i can use pin from glass ?

PS.If nothing else I can always make wood-tungsten-wood tree-mai...epoxy is cheap

My concern with pins is another material to add stress, and holes in the carbide creating weak points.

There is a high temperature aerospace epoxy made for bonding metals that would be perfect for this! Would an epoxy lamination be a better way to go? That's probably what was done with this:

 

[Natlek]

I like it ....I have one blank ready from last year to mold in marble carbon fiber . It is 67-68 HRC M42....One day i will do that .

Diamond ...............I like them to , they cut TC Now I have 80hrc blade without handle.....I need to sharpen it , cut easy paper but it is to loud .

I cut some walnut ........

 

[Natlek]

My concern with pins is another material to add stress, and holes in the carbide creating weak points.

There is a high temperature aerospace epoxy made for bonding metals that would be perfect for this! Would an epoxy lamination be a better way to go? That's probably what was done with this:

I make frame handle for this one i cut .And I get idea..................why should i use full length of TC in sanmai ?Why i would not do something like this frame handle ??? That way i don t need pins and I can weld corners to keep aligned everything ....

 

[fishface5]

I am very interested in this project! But if you don't clad the whole length including the tang, then doesn't it seem risky to have the blade snap off at the handle, since it's so brittle?

 

[Natlek]

I am very interested in this project! But if you don't clad the whole length including the tang, then doesn't it seem risky to have the blade snap off at the handle, since it's so brittle?

I m sorry for not be clear what i mind .Clad would go on whole blade/bevel.What i was thinking is to make TC with hidden tang shape and use another one stainless part in middle to match tang inside .Just idea which now i don t like .It will hidden TC core on handle side....
I have knife, weird one What i should try to cut ,maybe 16D nail
I make one test ...............I heated to bright red color with torch several times this small cut off TC and NOTHING happened.Seems that this TC can handle fast heat and cooling in air .I think that I worry to much ,brazing would be easy !Then I quench it in water ...................to see grain inside

 

[Sam Dean]

Hahahaha! Good thing you have a bunch of those things!!

 

[Natlek]

Hahahaha! Good thing you have a bunch of those things!!

I have good news , I just talk with my friend .No need for EDM , water jet will cut TC with 80mesh Garnet.

 

[Sam Dean]

I have good news , I just talk with my friend .No need for EDM , water jet will cut TC with 80mesh Garnet.

That's great! Do you know the cut speed? I had Omax do a trial a few years ago; their machine cut 1/8'' carbide at 3 hours per inch on garnet. Our EDM cuts about 13 inches per hour.

 

[Natlek]

No, I didn't ask that .That is to slow ???? I cut this plate in 10 minutes this afternoon with my Dremel and cheap diamond disk . There's no way i will bothering him with my foolish experiment if that take that long ...I will cut it with Dremel .
First thing first ...knife can wait I cut plate for my new grinder .I hope that will last longer then ceramic glass..............anybody try that ?

It is flat in all length ,just one part was mirror polished ,I can t fill with nail difference , maybe some thousand of millimeters , taper start further on corners where cut was ..
What can i do with this half moon piece except for the ordinary knife ? I know that there are knifes for something in that shape but i can t recall ??

 

[Natlek]

OK, if you say so. I'll wait and see how it turns out. I am mostly interested on how you will make it into a knife shape.

If water jet is that slow ,most probably with Dremel and diamond disk .I have only this what come in that box with million things inside .....most of them worth nothing .....any recommendation for quality one ?I mean on really quality one if they exist ?

 

[Natlek]

Hahahaha! Good thing you have a bunch of those things!!

It is not knife , it is other small cut off piece Knife is still OK , this days i will make some test .........When i was shaping handle on grinder on several occasions i touch blade on ceramic belt ........You know how that look .....I turned it around for a few minutes to see where I made scratches....then realize that this MF is harder then belt

 

[Scaniaman]

Why not put a smooth edge diamond disc in your angle grinder instead?

If water jet is that slow ,most probably with Dremel and diamond disk .I have only this what come in that box with million things inside .....most of them worth nothing .....any recommendation for quality one ?I mean on really quality one if they exist ?