Last stone grit vs strop starting grit

[ToddS]

What holds the agglomerate together? It also sounds like the scratch pattern would not be as uniform as a stone with the diamonds evenly dispersed in the resin.

In the Venev, it looks like simple polymer. The problem with F2000 grit that it needs to be exposed and held in a way that allows it to cut/grind, and I don't think that's going to happen in a mostly-resin stone. These agglomerates have a very high density of diamonds, so the ones at the top are supported by diamond not resin. Just like with the 3M lapping film, you don't need a lot (per unit area) of these grinding centres.

How much would it cost to make a resin stone with 0.25 micron diamonds that is over 50% diamonds by weight?

 

[Diemaker]

How much would it cost to make a resin stone with 0.25 micron diamonds that is over 50% diamonds by weight?

Of course that depends on where you get your diamonds, US or China, the quality of diamond you get, and how much resin/diamond volume in the stone. For run of the mill EP style stones you're talking about $1-$5 for good quality diamond here in the US, which is the bulk of the material cost, so being cheap with your diamond is poor economics.

I haven't tested the new resin Venev F2000 stones, which are 1.5-micron?, but the original version left the same scratch pattern in a bevel as the Matrix 2300 stones, which are 8-micron. Perhaps the agglomerates vs evenly dispersed diamonds explain this?

 

[ToddS]

It seems that with the original/legacy version they used 10 micron boron carbide as a resin filler, so not surprising the scratches were comparable to the Matrix 2300.

The new version looks like 0.5 micron and smaller and obviously a non-abrasive resin filler.

 

[Diemaker]

Interesting, under the microscope all the diamonds in the coarser Venev stones were black, making me suspect boron carbide. Sounds like it was popular with them.

 

[Gritomatic]

What holds the agglomerate together? It also sounds like the scratch pattern would not be as uniform as a stone with the diamonds evenly dispersed in the resin.

The Van der Waals attraction holds agglomerates together. I guess Venev uses diamond powder in liquid form in specific conditions where agglomeration occurs in an uncontrollable manner. Venev F2000 OCB is the only diamond with such a problem (AFAIK).
May I ask why Matrix series lost 6000 grit?

Interesting, under the microscope all the diamonds in the coarser Venev stones were black, making me suspect boron carbide. Sounds like it was popular with them.

Boron Carbide has been officially confirmed by Venev as the component of composite in non-OCB diamonds.

 

[Diemaker]

Hi Konstantin, the coarser the grit the harder you want the bond, the finer the grit the softer the bond. It is around 5 microns, the Matrix 4000, that the bond starts getting a little hard for this fine of abrasive. Exactly where the bond gets too hard depends on what you are sharpening. With really hard steels the 6500 works fine, which is 4 micron, but the difference in the polish of the bevel between 5 and 4 microns is pretty small. With ceramic knives I can use the Matrix 9000, which is 2.5 microns, and get a really polished bevel. This is something I have noticed with other stones as well. I can't get the Shapton Glass 16,000 or 30,000 to polish the bevel any better than the 8,000 no matter how much I try, and often the 30,000 degrades it. While the 6500 did work in some instances it was determined that it was too specialized so it was dropped to keep people from buying something that they would be better served not buying. I think for most a strop would work better than the 6500 stone.