What's happening in the David Mary Custom shop?

Now that I am home with the benefit of a computer keyboard to type on instead of the phone:

As you can see the 15N20 blanks started off kinda rough, with lots of relatively deep lateral scratches. So I had to freehand surface grind all those to clean them up, starting with 120 grit ceramic belts. I used to go up to 220 grit with ceramic belts after that, but those belts lose their cutting ability relatively quickly despite being ceramic. Now I find them more useful for sharpening and already profiled edge, and the worn ones are great for the second last step of cleaning up crowned spines, before lateral hand sanding.

But I have a new belt, at least for the next little while, called compact grain aluminum oxide. This belt is unbelievable. It seems to last forever. Red Label Abrasives gave me a 3 pack to try out when I talked to them about finding a 220 grit that would work better for me than the green ceramic ones, which they discontinued. The compact grain ones look like a corase grit because the individual :compact grains" of AO on them are about the size of grains of rice.

IMG_6043.jpeg

But don't let the appearance fool you. Those grains are 220 grit, and over time, they wear away to constantly expose fresh abrasive. Because they start off relatively thick, they act kind of like a force buffer, whereas ceramic belts in this and finer grits are very thin, and as such even a slight deviation on a pass can instantly gouge a blade, requiring a frustrating trip all the way back to 120 grit. But these compact grain belts not only buffer the force, allowing for a more forgiving grinding experience, they also are much slower to build heat than those thinner ceramic 220 and higher grit belts.

Unfortunately Red Label Abrasives lost their supplier of the materials they use in building these, so I made sure to buy up all they had left, which at the time was only half a couple more packs of belts. They are looking for a new supplier, but nothing yet. That being said, the belt you see above has already been used on dozens of 15N20 blades, and it still seems to be cutting as well as when it was brand new!

After the compact grain, the front pinhole area and blade get a fine surface conditioning belt finish (aka scotchbrite, kinda like how a tissue paper gets called a Kleenex). You might wonder why go to the trouble of finishing the surface before the bevels are even ground. This was the small ricasso area between the plunge line and the front of the handle scale material can look nice. Trying to do this after the blade is ground has been problematic in the past, and so this may take longer but I believe it will result in better quality.

Anyway, on top of the surface grinding, I also hade to remove the "tabs" from the 15N20 blades, as those ones were plasma cut by Jarod Todd, and since plasma has a wider kerf than waterjet, Jarod programmed tabs in to avoid the issue of gouges in the blade profiles where the cut starts on each blade. That job took a but of time as well, but I used worn 36 grit belts for that, since a fresh belt is far too valuable to be wasted on a menial task like this. Work belts generate heat faster, but since we are dealing with full stock thickness on the blanks at this point, it is easy enough to manage it well below the temper threshold.

The AEB-L blanks and the two 3V guard dog blanks were waterjet from older CAD files that I had not quite worked out the pinhole sizing on. So the holes are functionally below the just over 1/4" they need to be when I receive them. That means every single one of those holes got the diamond bit dremel treatment. Fun fact: I destroyed a fresh bit doing the four pin holes on the 3V Guard Dogs, whereas an already semi-worn bit was enough to do all the holes on the over half a dozen AEB-L blades.

So this Lucky Dog job is one that is going to start off slow and gradually build momentum. Next I have to cut 64 brass tubes for handle attachment, cut scale material and assemble some composite scales, and of course, grind the blades. I still haven't even decided what I'm going to do for the 3V Guard Dogs' handles. These are extras that were left over from the original Lucky Dog run. I had a dozen extras and he was kind enough to give me creative license on them, so I to come up with special configurations for him in premium handle materials. He features them on his site as "Best in Show".

Anyone curious to know, here is how it started:

1758672795830.png
 
David Mary said:
But I have a new belt, at least for the next little while, called compact grain aluminum oxide. This belt is unbelievable. It seems to last forever. Red Label Abrasives gave me a 3 pack to try out when I talked to them about finding a 220 grit that would work better for me than the green ceramic ones, which they discontinued. The compact grain ones look like a corase grit because the individual :compact grains" of AO on them are about the size of grains of rice.

View attachment 2983546

But don't let the appearance fool you. Those grains are 220 grit, and over time, they wear away to constantly expose fresh abrasive. Because they start off relatively thick, they act kind of like a force buffer, whereas ceramic belts in this and finer grits are very thin, and as such even a slight deviation on a pass can instantly gouge a blade, requiring a frustrating trip all the way back to 120 grit. But these compact grain belts not only buffer the force, allowing for a more forgiving grinding experience, they also are much slower to build heat than those thinner ceramic 220 and higher grit belts.
Click to expand...

It was hard to visualize these over the phone, but man that belt looks dangerously aggressive. The engineering in that thing is impressive.
 
When I talked to Andrew from Red Label Abrasives over the phone today while placing my next order, I told him how much I like these belts, and his term for it was "They are sneaky good". I said "sneaky good"? He said "Yeah, they are really good, but almost nobody knows about them!". Sadly it looks like that will be the case for a while longer, if they can't find another supplier for the materials....
 
At some point, as an experiment, I am going to finish a MagnaCut knife with my "15N20 only" finishing belts, with the goal of making a MagnaCut knife that develops a patina on the surface, while being virtually impervious to corrosion where it counts.
 
That looks like a really coarse belt !!!

This is the coarsest grit sand paper I’ve ever used and it was tricky to get a good finish

https://flic.kr/p/XH9JAd

Just kidding, I came up with that a few years ago when there were conversations about different grits available so I took a stone and put it in the center of a sheet of paper and called it One Grit

🤣
G2
 
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