Columbia Gorge Stoneworks Resin Bond Diamond Stones

Diemaker

Knifemaker / Craftsman / Service Provider
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Apr 28, 2017
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771
I am starting this thread for tech support of my bench stones, just like I did for the Matrix stones. I am linking to it on the Technical Support page of my website hoping most tech help and general questions can be answered here. Since I am a one person shop it's hard to impossible to answer the phone while molding stones or running my CNC mill. My new bench stones use the same diamond and resin bond as the Matix stones and the same aluminum alloy for the mounts. I have modified 3 of the grits a small amount so these stones have even 50% reductions in the abrasive size as you drop down in grits. All advice I have given regarding the use and care of the Matrix stones applies to my bench stones and vise versa. My philosophy is to make the best products from as much American made materials as feasible with the least waste. All the work and expense go into the stones or other products I will be making and nothing else, so the packaging is pretty minimal. Hopefully this will be accepted, if not I will adjust accordingly.

I still haven't settled on a name for them and would really like help with this, please! So far I am thinking Pirannahs but I am open to suggestions.
 
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Out of curiosity, what is the grit distribution like in these? In other words, for a hone for example with a target size of 5 micron grit, what amount of particles of other sizes are in the mix?
 

Diemaker

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Apr 28, 2017
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771
I get Particle Size Distribution charts with all of my diamond powder but am not 100% sure how to read all of it. For the last batch of 5 micron powder I got the average size is 5.869, median or 50% above and below size is 5.796, average surface area size is 5.184, mode or size of most frequency is 6.452, d10 is 3.493, d90 is 8.426. This batch of 5 micron has a bit wider differential than normal and the coarser grits are also tighter than the 5 micron, the finer grits have a higher percentage size swing since the mean is so small. A 2-3 micron size swing has a bigger effect with 5 micron powder than 80 micron powder. I have tried tighter controlled size powder but did not see any difference when viewing the sharpened bevel under the microscope. Since my bond is on the soft side and it's resin to begin with it really seems to average how the diamonds cut. The harder the bond the more pronounced the scratches from stray larger crystals, and there always are some. While we can put numbers on the abrasives we really can't on the bond, which is just as important, so eventually you just need to try the stones out to see how they cut. Another huge variable is how much diamond is in your stones and how much of other abrasives are in there.
 

777 Edge

Gold Member
Joined
Sep 16, 2019
Messages
105
I get Particle Size Distribution charts with all of my diamond powder but am not 100% sure how to read all of it. For the last batch of 5 micron powder I got the average size is 5.869, median or 50% above and below size is 5.796, average surface area size is 5.184, mode or size of most frequency is 6.452, d10 is 3.493, d90 is 8.426. This batch of 5 micron has a bit wider differential than normal and the coarser grits are also tighter than the 5 micron, the finer grits have a higher percentage size swing since the mean is so small. A 2-3 micron size swing has a bigger effect with 5 micron powder than 80 micron powder. I have tried tighter controlled size powder but did not see any difference when viewing the sharpened bevel under the microscope. Since my bond is on the soft side and it's resin to begin with it really seems to average how the diamonds cut. The harder the bond the more pronounced the scratches from stray larger crystals, and there always are some. While we can put numbers on the abrasives we really can't on the bond, which is just as important, so eventually you just need to try the stones out to see how they cut. Another huge variable is how much diamond is in your stones and how much of other abrasives are in there.
With AlOx and Silicon Carbide a lot of manufacturers seem to use d50, but it varies so much who quoted which values. With those "softer" abrasives, d50 use makes sense.

With Diamond or CBN, the d90 value would be more important to know because those stray particles can show extreme scratches. Only problem is, if you quote d90, then people seem to think your stones are not as "good" as other brands...which is not true. Your stones are great. For the finer grit hones, it is great that your bond is on the softer side to compensate for the d90 particles.

For your 80 grit Matrix stone, I have found that it might be better to have a much harder bond? Especially because this is the "work horse" when it comes to setting a new bevel or removing chips. I've found that with my matrix stones, the 80 wears quite fast so I end up using diamond plates to "save" the 80 grit stone. Yes - doing edge trailing strokes like in your videos is great and the stones will last longer, but if you have a lot of bevel setting to do edge leading and trailing is what will be done inevitably just to get the job done. This seems to be hard on the 80 grit. Any chance you can make the bond harder for the 80 grit?
 
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Diemaker

Knifemaker / Craftsman / Service Provider
Joined
Apr 28, 2017
Messages
771
What type of resin are the stones made from? Can you use them with oil or synthetic lapping fluid?
I want to keep the exact resin to myself but you can use oil with them, preferably simple mineral oil. I know some solvents will attack the resin but I would think synthetic lapping fluid would be ok, but no guarantees. I find water with a hint of dish soap is best. The only downside is it evaporates, but it washes the swarf off way better than oil and makes far less of a mess.

With AlOx and Silicon Carbide a lot of manufacturers seem to use d50, but it varies so much who quoted which values. With those "softer" abrasives, d50 use makes sense.

With Diamond or CBN, the d90 value would be more important to know because those stray particles can show extreme scratches. Only problem is, if you quote d90, then people seem to think your stones are not as "good" as other brands...which is not true. Your stones are great. For the finer grit hones, it is great that your bond is on the softer side to compensate for the d90 particles.

For your 80 grit Matrix stone, I have found that it might be better to have a much harder bond? Especially because this is the "work horse" when it comes to setting a new bevel or removing chips. I've found that with my matrix stones, the 80 wears quite fast so I end up using diamond plates to "save" the 80 grit stone. Yes - doing edge trailing strokes like in your videos is great and the stones will last longer, but if you have a lot of bevel setting to do edge leading and trailing is what will be done inevitably just to get the job done. This seems to be hard on the 80 grit. Any chance you can make the bond harder for the 80 grit?
D50 is the mean size, or average, so if you are going to show anything that would be it. I understand that too much information can look bad unless you understand what it really means, which is generally quite complicated. The bond is just as important as the abrasive and mine does a good job of averaging the scratches, or so my microscope tells me.

Generally, when someone is seeing excessive wear with their 80 grit stone it is from swarf, which acts just like the loose abrasive used to dress the stone, it simply erodes the resin away, or being too aggressive on too small of a bevel. A good photo may shed light on what is happening. Have you measured how much your stone has worn?

Edge trailing strokes are only important if you have reached the apex, and with the 80 it is more for the safety of the knife than the stone. This coarse of a stone will really tear up the apex requiring a lot more work with the next grit to clean up the damage to the apex from the last grit. If I have not reached the apex I use back and forth strokes.

I agree a harder resin for the 80 would have benefits, but it would also have drawbacks. The harder resin would help the stone be more aggressive but it would also cause more damage to the apex. It would be better at reprofiling but not as good for maintenance sharpening, IMO so far. While I have some things in mind and would like to test them further the harder resins use a totally different process vs what I am doing now. Of course, the most interesting harder resins are much harder to process than the more mainstream ones, this rabbit hole turns out to be a cavern!
 

777 Edge

Gold Member
Joined
Sep 16, 2019
Messages
105
Good to know you're already considering a harder resin for the workhorse 80 grit!

It won't matter for maintenance because the 80 it not really a maintenance stone in my opinion. More of a re-profiling and bevel setter.
 
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