I only have experience with my own experiments, from aluminum oxide to boron carbide. Resin is the least aggressive bond, with the one I use on the least aggressive end, so it takes the most aggressive abrasive to make it work as a bond, IME. I think this showcases just how special diamonds are as an abrasive. While I never liked my boron carbide stones on any of my own knives they did work well on a friend's Cuisinart knives, which were way too soft to be useful. With all of this said I think it shows how important the bond is to how a stone works.
Anyone else make their own resin bonded stones?
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Were the aluminum oxide stones lacking in aggression from the start? I just tried to make one out of 60 grit aluminum oxide blasting media and resin, and after exposing the abrasive with an old 36 grit belt, it barely cuts at all. Maybe I just need to move to diamond and consider aluminum oxide to not even work as "practice"?
Yep. Same for any other abrasives, other than diamond.
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Blasting grit in general tends to be less sharp in shape than other grades.
Exposing aluminum oxide grit with a belt that likely is composed of aluminum oxide or silicon carbide abrasive... See the problem there? It's not any surprise at all that the newly exposed (or more properly, dulled) abrasive didn't cut very well. Loose grit will work better, but 60 grit aluminum oxide is probably not a great choice for a resin bond unless you're going to make it very very soft. For a finishing hone made just for carbon steel it would probably be okay at a much finer grit.
Cool. I guess I'll get to the diamonds then, thanks.
Huh. I was a little worried that buying the cheapest blasting grit would get me reclaimed blasting grit which would be less sharp, but I didn't know blasting grit in general was less sharp. Good to know.
People use diamond to condition aluminum oxide, SiC to condition SiC, and SiC to condition diamond... so no. It seems the bigger problem is that the bond is just too strong and perhaps filling in the gaps too well.
Yeah, the best use of a 60 grit stone is not for finishing, lol.
Sodium silicate seemed to work pretty well as a binder though; the resulting stone is aggressive, at least.
For silicon molds, I'd suggest checking out BITY for silicon. I've been buying it from them for years, to make molds for casting chess pieces.
This is what I get: Platsil 73-20 silicon
This is what I get: Platsil 73-20 silicon
They use loose grit, not a belt. Totally different mechanism at play.
And yes, my point was that you can't use a 60 grit aluminum oxide without also using an extremely soft bond to allow the dull particles to remove themselves. Unless you feel like dressing the hone every use or two. I was saying that you *could* use a finer aluminum oxide grit to create a finishing hone with a harder bond, but it wouldn't be of much use on any modern carbide-heavy steels, only for simple carbon steels like found in a straight razor or something like softer kitchen knives.
With this one, definitely oil. I did a little playing with finer (1.2-3u) sodium silicate bound stones earlier, mostly dry just for just a few passes for apexing. However, the finer ones absorb much less water and so they don't dissolve crazy fast. Still not sure if it's impractically fast for real use though. Now that I have these silicone molds I'll give it another try and see if it's worthwhile.
It's not clear to me what the difference would be that would make loose grit work better. Obviously rolling vs sliding is different, but how does that make loose grit work better? I think I did use some loose blasting media between the two resin hones after belt sanding them, btw.
I think we're on the same page with the rest. My knives are mostly low carbide anyway (even if hard) so that's an option, but diamonds might just make more sense anyway.
The reason I started playing with sodium silicate bound alumina stones in the first place is that the resin+diamond stones struggle with gouging on edge leading strokes, but I may have found a solution. Instead of trying to form a microbevel with the resin stone, if you form an excessively obtuse microbevel with a fine diamond plate, you can then backsharpen down to the desired microbevel angle without the edge digging in. I still need to play with it more, but it seems promising.
Using loose grit removes material through a mechanism known as 3-body abrasion. Generally a fairly coarse abrasive is used and it doesn't do much abrading of the grit in the hone you are surfacing. Instead it cuts the bond around those bound abrasive particles and sort of "scoops" and/or knocks them out of the bond, leaving those grains that are still bound standing proud of the mean surface of the bond.
A belt sander removes material through 2-body abrasion, directly scrubbing across a surface to cut away material. The abrasive grains in a hone will be abraded/cut at the same time as the bond in this instance, dulling those grains and leveling them with the surface of the bond. Or even worse, pulling them out completely and leaving a level surface that is mostly binder and very little abrasive.
Using loose grit for a short while after using the belt will help mitigate this "dulling" of a hone, but take care to do it long enough to properly expose the sharp abrasive.
And yeah diamond is probably just a better way to go all around for anything that isn't a razor finishing hone.
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Has anyone made any more stones lately. I took a crack at making one of my own with a massive failure. I ended up getting about 5 grams of diamond on Amazon of 400 grit and mixed it about 50/50 with silicone carb. Mixed it in about 3fl oz of deep pour epoxy and poured it in a mold. Well it ended up taking 3 days to actually start curing and all the diamond and sic settled to the bottom of my makeshift mold out of a wooden floor laminate and hot glue for the sides. I definitely should have used petroleum jelly or something to keep the epoxy from sticking to the laminate before pouring which was my first mistake, second mistake was not realizing that I had mixed way too much epoxy for the little amount of diamond that I had. The 3oz of epoxy made a nice 8mm or so thick, and 8x3 L&W plate and is probably the perfect plate dimensions for a metal blank, but ways way too little abrasive. By the time ended up getting the laminate separated from the epoxy. I good amount of the veneer was still stuck to the bottom of my pour, so I ended up flattening the veneer off of it with a diamond plate, taking away a good amount of the settled abrasive with it. I think I'm going to give this another go with some 120 grit and some aluminum plate blanks, only this time, I'm going to try making some kind of silicone/corn starch, or clay mold and using some quicker curing table top epoxy that I have, thinking that I'll be able to get a faster cure in about 30 minutes or so and I'll have less abrasive settle to the bottom this way. I got about 40 grams of 120 grit diamond coming and will try the sic 50/50 again with way less epoxy, I read somewhere earlier in this thread to do about a 50 percent epoxy to about 50 percent abrasive but I wasn't sure if that was by weight or volume. Does anyone have any suggestions to make this go a little smoother for me this time around? I sharpen a lot of kitchen knives and go through a ton of regular course diamond plates because of how bad they abuse the apexes by bouncing them off the tables or whatever else they do. Some other thoughts that I had was using some bondo with abrasive, maybe trying epoxy putty with abrasive, and also thought about just mixing abrasive with teracota and baking the stone in my knife furnace. I even thought of trying cement but thought maybe that would give my inconsistent scratch pattern with the cement acting as extra abrasive
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give me a couple hours and i can comment on some things that will help you. i still daily have and use mine with no change, still kickin butt.
Yes on phenolic resin but the process is rather involved. My suggestion is to only use diamond as anything else isn't sharp enough to work with a soft bond like most resins. CBN may work but not as well and it costs much more. You can't heat diamonds up very much with oxygen present. The only way to use high heat with diamonds is in a vacuum furnace at insanely high vacuum and short heat cycles of 5 minutes or so.
There is a reason resin bond diamond stones only have a diamond/resin layer measuring a few millimeters thick at best. I suggest you make a dam around your aluminum plate with masking tape and pour your resin/diamond mixture onto the blank in a thin layer for best results, and don't be shy with how much diamond you are using. No one is commercially making thick resin bond diamond stones for a reason.
I expect your problem with the epoxy curing is an improper mix. I learned many years ago that weighing A and B out on a very fine resolution scale will make a huge difference in how well epoxy cures, no matter how well you measure it out by volume.
There is a reason resin bond diamond stones only have a diamond/resin layer measuring a few millimeters thick at best. I suggest you make a dam around your aluminum plate with masking tape and pour your resin/diamond mixture onto the blank in a thin layer for best results, and don't be shy with how much diamond you are using. No one is commercially making thick resin bond diamond stones for a reason.
I expect your problem with the epoxy curing is an improper mix. I learned many years ago that weighing A and B out on a very fine resolution scale will make a huge difference in how well epoxy cures, no matter how well you measure it out by volume.
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if you can, for a mold i would go and buy one of those plastic cavities for your stones, something like the fishing plastic boxes you would store plastic worms etc in. like this, https://hrtackle.com/products/bubblegum-worm-kit minus the worms of course. this will allow for your epoxy to not stick to the walls like before. choose the size mold that fits the stone your trying to make. rule of thumb for viscosity, mix as little epoxy as possible to the abrasive, but make sure its not so thick that it doesnt settle flat. if it has too much abrasive you will see it rise in mounds that will never level out. if your using grit size ballpark 600 and heavier 240 grit, 120 grit etc, when mixing it will not stay suspended at all(in my experience with deep pour). it is heavy it will sink to the bottom of the epoxy as you had happen, like sand on the ocean floor settled. I actually prefer this because I know the cutting area is most condensed at the bottom of the stone where it settled. the smaller grit like 800 plus ive had good luck with it staying in suspension while the epoxy cures. it takes alot of abrasive to make a big stone for sure, and i would make sure you only use identical sized grits if your going to mix diamond with sic. they typically take over a week to cure and for me even like 6-7 days in i could still slowly bend the stone, so dont be impatient if you use the long cure stuff, i had a few bend on me that I had to put so much effort into flattening it wasnt worth the headache. you can try the faster setting stuff, I hadn’t tried it but im sure it will work just as well. once you have a hardened stone, i used a belt sander/sandpaper and a flat surface to cut off the top excess epoxy and then I lap the other concentrated side on rough stones. its a tedious project but hands down worth the fact you can make 10 stones to the cost of 1 if you have the energy to spare. I like saying I made stuff.
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hmm, thats interesting, I thought that those diamond resin bonded fickerts and the ones for polishing floors and countertops were pretty thick resin based? I have some that are easily 10mm thick and they are super awesome.
Those are "diamond" like many polishing pads for stone. I am pretty confident that diamonds are not the most abundant abrasive in them. I made stone, quartz, and ceramic switchplates for 18 years so am pretty familiar with polishing stone. In fact, the Matrix stones began life polishing stone as motorized disks long before they started polishing steel, and were about 3 times faster on hard granite than commercial pads.
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I figured their whole matrix is of mostly other cheap hard compounds too for sure. plus even though they are listed as resin bonded they are using im sure something that can handle those high rpm temperatures compared to the resin im using. so why was it again you think the resin bonded stones are not produced thicker? the more i thought about it i have some closer or larger than 20mm thick. for the application im using to produce them and the way im using them at slow speeds etc, they work identically thick or thin for me and see no reason why there couldnt be thicker ones offered?