In this video the tests are performed. I present the results, discuss around the different test specimens and finally what I take with me from this test.
I see a lot of comments asking what the dust is (and he's replied that it's 'dust' from his shot blast cabinet filter). For super dense epoxy castings at my old company, we used aluminium oxide power or slate powder. Both easily available and really densely packed in their dry tubs. I never really used them myself 'hands on' too much but the old guys' sage advice was to cram as much as you possibly can into the resin.
This reminds me, my father in law generates a bunch of granite dust mixed with some aluminum oxide dust from his granite memorial sandblasting business.
For anyone coming across this, there are multiple different kinds of "dust" that you can use: Fine powdered silicon carbide is going to give the most stiffness, but less damping. It's also expensive. A cheaper alternative is aluminum oxide which is also strong and hard, but not as stiff as silicon carbide, but provides slightly more damping. Another alternative if you can find it for cheap is iron oxide powder, which has a lower stiffness than both silicon carbide and aluminum oxide, but it's denser and offers more damping. For all of these, you want to search for a fine grit (#220 or above = very fine), and mix it with larger particles such as the sand. Sand is a very cheap filler by weight, but is not very stiff, and not very dense. An alternative for higher stiffness and density than sand is steel grit that you can buy from sandblasting supply stores. One thing to remember: If you are looking for strength/stiffness as your primary criteria, then use metal to fill in as large of a space as possible. I.e. If you have a cylinder that you want to reinforce for strength/stiffness, it's better to stick rebar down the cylinder with the epoxy granite mix surrounding it than it would be to fill the whole cylinder with epoxy granite only. The purely epoxy granite fill may offer greater damping and resonance control though if you don't need the extra stiffness.
What a nice organized display of the options from the materials you can select from for a machines base/column/bed/table/ saddle. Thank you for the share. Lance & Patrick.
It looks to me that the best mixture seems to pack the most density of stone with epoxy binding that mix. So starting with the gravel you would measure the density of a test cube and then calculate the number of gravels ,then calculate the average gap between gravel . Once that is known you then want to find a material thats average size is the average gap size calculated above. Calculating a test cube of the 2nd material you can calculate the average gap between those particles and find a third material thats average size is that gap. With this 3-4 materials should almost fill all the air gaps and the epoxy can be used to bind that very small remaining micro gaps that exist between 4 materials leaving very little low density fracture lines and a very tight and large density. I Really appreciate showing your method .
Yes, I think that is a reasonable way. Given I had what I had, I could see that the fine-grained stuff really made a difference, I tried to vary the mix of the coarser material gravel and sand, but what really mattered was the fine-grained dust.
@@metalmusings the question is why fine grain 100% is less strong than a mix of larger grains because there should be very little gaps between all particles
@@das250250 it's puzzling. Maybe the amount of epoxy over 20% wasn't beneficial. There seem to be an optimum amount of dust for stiffness I am guessing close to or lower than 30% dust. Not more than 30%.
@@metalmusings Yes it seems to me that the maximum stiffness will be found when there is more rock material in contact with itself ( maximum surface area connecting) This means dust filling in the micro pockets of air and the even smaller areas being filled by epoxy as a binder but not taking any direct force but only keeping the sediments from sliding between each other. Anything less starts to reduce to the stiffness. The trick will be to remove ALL air by way of process eg: a vacuum and mixture order : mixing dust with epoxy first , vibrating it and vacuum it , then add to larger material then repeat vibrate and vacuum , this is to remove the most air from inside the material.. This is my intuitive thought based on my other calculation comment. So being able to weigh the mould so that you know you have maximum density ( ie: maximum amount of dense rock matter ) is important. I would calculate the density of the rock by way of water and rock tests and then once you know the volume of your mould you should be able to calculate how heavy that mould should be when completely saturated in rock material ( very small epoxy )
@@das250250 Gaps are smaller with dust, but percentage of space occupied is same. Using bigger sand, and than filling gaps between sand with smaller dust will end up with higher percentage of space occupied. It is similar to "Sphere packing" : en.wikipedia.org/wiki/Sphere_packing, especially section "Unequal sphere packing"
Great video! Thank you so much for sharing your work and data with us all and what a fantastic result! Really encouraging to see such a wonderful project move from an idea through to finish.
Below post he writes...Stefan Stamatov It is the finest stuff/sand I hade available. I have a sandblasting cabinet and a cyclone filter connected to that for evacuation of dust/small particles. The dust comes from that cyclone filter. I would think it is basically broken down silica sand grits, so small that it can travel with the air. Plus some rust particles, it is after all sandblasting of rusted iron pieces. That's where the color comes from I think. I don't think it is anything magic about the dust I use. Any tiny, tiny particle sand would do, I think. 3 months ago (edited)
@@zachary3777 “stone dust” that you can buy is coarser than sand. It is a byproduct of stone crushing process. The “dust” used here is a mix of fine particles of silica and metal/metal oxide. Those are very different materials.
Hi. If you ever make another polymer concrete would be interesting to see if adding Graphite would make it stronger. According to experiment made by Tech Ingredients channel it should be 50% stronger. If you want to know more watch "Making Graphene could KILL you... but we did it anyway?!" at 41:00. Love you Machine BTW. 👍
I am designing a 2x1m epoxy granite CNC at the moment. Can you recommend a minimum material thickness? 2cm concrete would be very brittle and chip, would epoxy granite be better? I really need to reduce the volume of my casting.
The bars I used in these tests were 15mm thick. They are quite strong, they will not break easily. I think 2cm is fine if it is just for a side cover or anything that shouldn't carry a lot of load. Provided you can get the EG in there and pack it. Part of using epoxy granite is, I think, to use large sections to compensate for the lower stiffness (compared to cast iron etc). By nature the designs will be bulky and weigh a lot. On the other hand, cast iron fundaments weigh a lot too.
MetalMusings Thank you. I will use 2cm then. I plan to add styrofoam to the base. Then I need less epoxy. I will keep ribs for stability, but reduce the bulk a little bit. The base is 2.5m long and 1m wide and 20cm high. That is a lot of epoxy.
@@MaxMakerChannel Wow that is a completely different scale. You should do some test castings to dial in the mixes. Now amount of epoxi = money. Not like my toy castings. And how will you mix it? A concrete mixer? And use a concrete vibrator? It will weigh a tonne. Oh man, that is something!
MetalMusings Yes I will use an old concrete mixer. I will install a hoist on my basements roof to lift it up. I figured that stuffing it down with sticks has to be enough. I cannot vibrate a 600kg mould.
Max Maker - On Amazon.com - and presumably elsewhere - you can get a concrete vibrator motor that bolts to the mold; it’s about $100 USD last time I looked. When I do a machine that’s what I’m going to do to help get the air out & compact the epoxy granite.
maybe a bit too late, and not for your application, but the reason that CNC manufacturers use epoxy granite is not only for the stiffness but also because it is superior in damping fibrations, the fibrations are most of the time the reason why the surface quality is inconsistent. the other thing I did mist in the test is a good way to compact the samples, this would change the result but not the outcome, this seems most of the time to increase the strength and flexibility ( and the filling of the samples air does not help to make a stiff and strong part) the best results I did see before were a mix from gravel, small gravel/sand, and rock dust. epoxy should be the agent to connect all the stone parts, its the weakest part in the mix
I was thinking the same thing but with some carbon fiber a to prevent fracturing in the casting Stefan Stamatov It is the finest stuff/sand I hade available. I have a sandblasting cabinet and a cyclone filter connected to that for evacuation of dust/small particles. The dust comes from that cyclone filter. I would think it is basically broken down silica sand grits, so small that it can travel with the air. Plus some rust particles, it is after all sandblasting of rusted iron pieces. That's where the color comes from I think. I don't think it is anything magic about the dust I use. Any tiny, tiny particle sand would do, I think. 3 months ago (edited)
hi, could you activate subtitles option? thanks I suppose gravel/sand/dust mix has more strength/epoxy consumption ratio, the thicker the gravel the less epoxy used. To reduce epoxy consumption you can use plasticizer which also make it less brittle (ultra high performance concrete use plasticizer too but to reduce water content) and has better vibration damping, or make a recycled thermoplastic-epoxy blend. Also you can add glass fiber powder to the mix and stringers of unidirectional glass fiber
Hi! I am about to fill up my machine too. At the end you out the weoght ratio of each sample but of I sum the percentage they give above 100%. How should I read 67%sand, 33%dust and 14%epoxy? Thank you!
he makes a mix of 67 gr sand plus 33 gram dust....this total is 100%..then scale on zero and add 14 gram epoxy....so read all is weight...they all together are 100 percent,so the epoxy% in total is less then written.but....his way is easier to mix in reality....Make a mix without epoxy.devide total by 100.that...times his percentage of epoxy.
I have read before that a mix of sizes ( from course to ultrafines) gives a superior result. You have confirmed that ultrafine material is quite necessary. I have read that diatomacious earth is is good choice. I'm wondering if Portland cement could be a simple to access source of ultrafines. Has anyone tried it?
Its a very late reply, but Ive watched a dude do that with his massive DIY machine, his YT name is FloweringElbow. ****Edit: instead of epoxy, he actually cured the cement with water in the mix (even added glass fiber along with the typical different grain size minerals) with internal rebar reinforcement and this mix was embeded in the steel frame, so not quite comparable.
If you are aiming for casting you should consider doing some samples with a reinforced core using, for example, a metal bar inside the sample and test the differences.
In principle this acts as two parallell springs. The metal part stays the same, I can influence the epoxigranite part of it. For overall max stiffness the stiffness of the epoxigranite should be maximized.
@@metalmusings I saw people doing this and it made a lot of difference in the results. Casting without reinforced core can lead to cracks or broken casting since the casting is more or less act like a solid piece of granite It will break if you drop it!
@@NourMuhammad I agree to that. It is just that the casting I have in mind will not have this problem. The epoxy granite will be more or less surrounded by cast iron and there is limited deflection. It is meant to stiffen up an cast iron piece. Similar to my foot casting video, but not same czcams.com/video/ZJM7aQ3H338/video.html
@@NourMuhammad since im interested in building my own cilyndrical grinder i saw i video of STUDER and they dont put big reinforsment.the only reinforment is near the metal bolt holes near surface and so,but overall none.czcams.com/video/cnQjjkuJXWc/video.html.
Yes that is interesting as well. Maybe drop a steel ball on the end of the bar and look at the sound response in some phone app? I think one can dream up a test that doesn't require high-speed precision recording of resonance curve form. But I have a reason to focus on stiffness, can't say more right now.
@@metalmusings damnit. I really want to know what the new project is that you are using this for. Am keeping an eye out for any posts you make on the LinuxCNC forums. You come up with some of the best ideas, like tying linear encoders into the HAL software.
It would have been much better if you wrote down the mix ratio for every sample in your result sheet so people can have more sense of the results. Anyway, thanks for sharing the results.
Hi MetalMusings, the dust effect was a surprise to me, never saw it anywhere in all epoxy/granite attempts, nice improvement you found. What about testing a sample of cast iron of the same size for comparison ?
So, I did test a piece of cast iron. At least I think it is cast iron. More red than yellow sparks, and all grinder traces ends in an explosion, well you know what I mean, the traces don't just die, it sparks always. Not the same size, so after scaling with area moment of inertia I think the cast iron is 6 times stiffer.
Hi, very interesting study. Do you think polyester resin would be as effective as epoxy resin in this application. It is more cost effective in my location.
Difficult to say. But I am changing only the "filler" parameters. I think you can start from these results, but for precise findings you need to do your own tests.
Polyester resin shrinks alot more then epoxy when curing and is more brittle, something take into account if you want precision. You want epoxy resin with no solvents or reactive dilutents.
Polyester resin is much weaker than epoxy. If you cannot get epoxy, try vinyl ester. It is still not as stiff as epoxy but it will be almost as strong at least.
So I will have to join in asking what is the dust you are talking about? Stuff that you find on furniture if you don't clean room? Illegal drug? Is it some powder? If yes powder of what? Where can one buy it?
It's like a drug but much more boring than that. I have sandblasting cabinet and from there the air full of sand and other things is extracted to a cyclone filter. "Dust" is what is left in the cyclone filter. There wasn't a big thought around that. I just wanted a few different fraction sizes and came to think of the cyclone filter when looking for a very powdery, fine sand. It is very powdery sand possibly with some ferrit from the sandblasted pieces.
Hi, maybe adding a little amount fibers could increase stiffness. But I guess that they should be at least 3 times longer than the largest particles. By the way, do you have a milling machine in your bathroom?
The purpose of the epoxy granite in a CNC machine is absorbing vibrations. You should measure the dampening capabilities, and not stiffness. Now you have the most rigid mixture, is that the recommended one ? Not at all, absolutely not, but the best dampener. Thats the goal, the purpose.
Your mixes need much more epoxy. The epoxy makes it hold while the filler gives it stiffness. Normal mixes I have seen are 30-40% epoxy or higher. So yours are only 1/4 of that in some cases.
I see a lot of comments asking what the dust is (and he's replied that it's 'dust' from his shot blast cabinet filter).
For super dense epoxy castings at my old company, we used aluminium oxide power or slate powder. Both easily available and really densely packed in their dry tubs. I never really used them myself 'hands on' too much but the old guys' sage advice was to cram as much as you possibly can into the resin.
This reminds me, my father in law generates a bunch of granite dust mixed with some aluminum oxide dust from his granite memorial sandblasting business.
For anyone coming across this, there are multiple different kinds of "dust" that you can use: Fine powdered silicon carbide is going to give the most stiffness, but less damping. It's also expensive. A cheaper alternative is aluminum oxide which is also strong and hard, but not as stiff as silicon carbide, but provides slightly more damping. Another alternative if you can find it for cheap is iron oxide powder, which has a lower stiffness than both silicon carbide and aluminum oxide, but it's denser and offers more damping. For all of these, you want to search for a fine grit (#220 or above = very fine), and mix it with larger particles such as the sand. Sand is a very cheap filler by weight, but is not very stiff, and not very dense. An alternative for higher stiffness and density than sand is steel grit that you can buy from sandblasting supply stores. One thing to remember: If you are looking for strength/stiffness as your primary criteria, then use metal to fill in as large of a space as possible. I.e. If you have a cylinder that you want to reinforce for strength/stiffness, it's better to stick rebar down the cylinder with the epoxy granite mix surrounding it than it would be to fill the whole cylinder with epoxy granite only. The purely epoxy granite fill may offer greater damping and resonance control though if you don't need the extra stiffness.
What a nice organized display of the options from the materials you can select from for a machines base/column/bed/table/ saddle. Thank you for the share. Lance & Patrick.
It looks to me that the best mixture seems to pack the most density of stone with epoxy binding that mix. So starting with the gravel you would measure the density of a test cube and then calculate the number of gravels ,then calculate the average gap between gravel . Once that is known you then want to find a material thats average size is the average gap size calculated above. Calculating a test cube of the 2nd material you can calculate the average gap between those particles and find a third material thats average size is that gap. With this 3-4 materials should almost fill all the air gaps and the epoxy can be used to bind that very small remaining micro gaps that exist between 4 materials leaving very little low density fracture lines and a very tight and large density. I Really appreciate showing your method .
Yes, I think that is a reasonable way. Given I had what I had, I could see that the fine-grained stuff really made a difference, I tried to vary the mix of the coarser material gravel and sand, but what really mattered was the fine-grained dust.
@@metalmusings the question is why fine grain 100% is less strong than a mix of larger grains because there should be very little gaps between all particles
@@das250250 it's puzzling. Maybe the amount of epoxy over 20% wasn't beneficial. There seem to be an optimum amount of dust for stiffness I am guessing close to or lower than 30% dust. Not more than 30%.
@@metalmusings Yes it seems to me that the maximum stiffness will be found when there is more rock material in contact with itself ( maximum surface area connecting) This means dust filling in the micro pockets of air and the even smaller areas being filled by epoxy as a binder but not taking any direct force but only keeping the sediments from sliding between each other. Anything less starts to reduce to the stiffness. The trick will be to remove ALL air by way of process eg: a vacuum and mixture order : mixing dust with epoxy first , vibrating it and vacuum it , then add to larger material then repeat vibrate and vacuum , this is to remove the most air from inside the material.. This is my intuitive thought based on my other calculation comment. So being able to weigh the mould so that you know you have maximum density ( ie: maximum amount of dense rock matter ) is important. I would calculate the density of the rock by way of water and rock tests and then once you know the volume of your mould you should be able to calculate how heavy that mould should be when completely saturated in rock material ( very small epoxy )
@@das250250 Gaps are smaller with dust, but percentage of space occupied is same. Using bigger sand, and than filling gaps between sand with smaller dust will end up with higher percentage of space occupied. It is similar to "Sphere packing" : en.wikipedia.org/wiki/Sphere_packing, especially section "Unequal sphere packing"
Great video! Thank you so much for sharing your work and data with us all and what a fantastic result! Really encouraging to see such a wonderful project move from an idea through to finish.
Those look delicious. Especially the chocolate ones.
What kind of dust is it - brick dust, metal dust, ....?
What is "Dust" material?
Below post he writes...Stefan Stamatov It is the finest stuff/sand I hade available. I have a sandblasting cabinet and a cyclone filter connected to that for evacuation of dust/small particles. The dust comes from that cyclone filter. I would think it is basically broken down silica sand grits, so small that it can travel with the air. Plus some rust particles, it is after all sandblasting of rusted iron pieces. That's where the color comes from I think. I don't think it is anything magic about the dust I use. Any tiny, tiny particle sand would do, I think.
3 months ago (edited)
You can buy stone dust
@@zachary3777 “stone dust” that you can buy is coarser than sand. It is a byproduct of stone crushing process.
The “dust” used here is a mix of fine particles of silica and metal/metal oxide. Those are very different materials.
How do you produce your dust?
Interesting, thank you for having shared these results.
Well done and extremely helpful.
Cheers mate!
amazing numbers ! thank you !
Hi. If you ever make another polymer concrete would be interesting to see if adding
Graphite would make it stronger. According to experiment made by Tech Ingredients
channel it should be 50% stronger. If you want to know more watch
"Making Graphene could KILL you... but we did it anyway?!" at 41:00. Love you Machine BTW. 👍
I am designing a 2x1m epoxy granite CNC at the moment. Can you recommend a minimum material thickness? 2cm concrete would be very brittle and chip, would epoxy granite be better? I really need to reduce the volume of my casting.
The bars I used in these tests were 15mm thick. They are quite strong, they will not break easily. I think 2cm is fine if it is just for a side cover or anything that shouldn't carry a lot of load. Provided you can get the EG in there and pack it.
Part of using epoxy granite is, I think, to use large sections to compensate for the lower stiffness (compared to cast iron etc). By nature the designs will be bulky and weigh a lot. On the other hand, cast iron fundaments weigh a lot too.
MetalMusings Thank you. I will use 2cm then. I plan to add styrofoam to the base. Then I need less epoxy. I will keep ribs for stability, but reduce the bulk a little bit.
The base is 2.5m long and 1m wide and 20cm high. That is a lot of epoxy.
@@MaxMakerChannel Wow that is a completely different scale. You should do some test castings to dial in the mixes. Now amount of epoxi = money. Not like my toy castings. And how will you mix it? A concrete mixer? And use a concrete vibrator? It will weigh a tonne. Oh man, that is something!
MetalMusings Yes I will use an old concrete mixer. I will install a hoist on my basements roof to lift it up. I figured that stuffing it down with sticks has to be enough. I cannot vibrate a 600kg mould.
Max Maker - On Amazon.com - and presumably elsewhere - you can get a concrete vibrator motor that bolts to the mold; it’s about $100 USD last time I looked. When I do a machine that’s what I’m going to do to help get the air out & compact the epoxy granite.
Many thanks for your postings
maybe a bit too late, and not for your application, but the reason that CNC manufacturers use epoxy granite is not only for the stiffness but also because it is superior in damping fibrations, the fibrations are most of the time the reason why the surface quality is inconsistent. the other thing I did mist in the test is a good way to compact the samples, this would change the result but not the outcome, this seems most of the time to increase the strength and flexibility ( and the filling of the samples air does not help to make a stiff and strong part) the best results I did see before were a mix from gravel, small gravel/sand, and rock dust. epoxy should be the agent to connect all the stone parts, its the weakest part in the mix
you mean dust like the one is over the old tv?
Bravo and thanks.
Great video. Just subbed!
What do you think of using steel shot ( steel blasting media ) instead of sand. It steel shot is more dense!
Thanks
dear, i don’t understand what is dust! can you clear it please? what typs of dust i can you? is it saw dust?
wonder how portland cement would work for the dust component
I was thinking the same thing but with some carbon fiber a to prevent fracturing in the casting
Stefan Stamatov It is the finest stuff/sand I hade available. I have a sandblasting cabinet and a cyclone filter connected to that for evacuation of dust/small particles. The dust comes from that cyclone filter. I would think it is basically broken down silica sand grits, so small that it can travel with the air. Plus some rust particles, it is after all sandblasting of rusted iron pieces. That's where the color comes from I think. I don't think it is anything magic about the dust I use. Any tiny, tiny particle sand would do, I think.
3 months ago (edited)
hi, could you activate subtitles option? thanks
I suppose gravel/sand/dust mix has more strength/epoxy consumption ratio, the thicker the gravel the less epoxy used.
To reduce epoxy consumption you can use plasticizer which also make it less brittle (ultra high performance concrete use plasticizer too but to reduce water content) and has better vibration damping, or make a recycled thermoplastic-epoxy blend.
Also you can add glass fiber powder to the mix and stringers of unidirectional glass fiber
2 parts muesli, 1 part rice puffs, 0.5 part psyllium husk, 5% portland cement, 14% epoxy makes for a not too wet and not too dry mix.
Replaced the psyllium husk with silica fume and it should be ok
Hi! I am about to fill up my machine too. At the end you out the weoght ratio of each sample but of I sum the percentage they give above 100%. How should I read 67%sand, 33%dust and 14%epoxy? Thank you!
he makes a mix of 67 gr sand plus 33 gram dust....this total is 100%..then scale on zero and add 14 gram epoxy....so read all is weight...they all together are 100 percent,so the epoxy% in total is less then written.but....his way is easier to mix in reality....Make a mix without epoxy.devide total by 100.that...times his percentage of epoxy.
I have read before that a mix of sizes ( from course to ultrafines) gives a superior result. You have confirmed that ultrafine material is quite necessary. I have read that diatomacious earth is is good choice. I'm wondering if Portland cement could be a simple to access source of ultrafines. Has anyone tried it?
Its a very late reply, but Ive watched a dude do that with his massive DIY machine, his YT name is FloweringElbow. ****Edit: instead of epoxy, he actually cured the cement with water in the mix (even added glass fiber along with the typical different grain size minerals) with internal rebar reinforcement and this mix was embeded in the steel frame, so not quite comparable.
If you are aiming for casting you should consider doing some samples with a reinforced core using, for example, a metal bar inside the sample and test the differences.
In principle this acts as two parallell springs. The metal part stays the same, I can influence the epoxigranite part of it. For overall max stiffness the stiffness of the epoxigranite should be maximized.
@@metalmusings
I saw people doing this and it made a lot of difference in the results.
Casting without reinforced core can lead to cracks or broken casting since the casting is more or less act like a solid piece of granite It will break if you drop it!
@@NourMuhammad I agree to that. It is just that the casting I have in mind will not have this problem. The epoxy granite will be more or less surrounded by cast iron and there is limited deflection. It is meant to stiffen up an cast iron piece. Similar to my foot casting video, but not same czcams.com/video/ZJM7aQ3H338/video.html
@@NourMuhammad since im interested in building my own cilyndrical grinder i saw i video of STUDER and they dont put big reinforsment.the only reinforment is near the metal bolt holes near surface and so,but overall none.czcams.com/video/cnQjjkuJXWc/video.html.
@@metalmusings everybody is very interested what is the dust made of?
dust???? what is dust?
what wound up being the best mixture?
great work
Can you define dust ? Was that granite crushed ?
I wonder resulta if u used fiberglass mat
Nice video but what do you mean by "dust"? sawdust?
what type of dust did you use?
What is the gravel size ? Why your total percentage is more than 100% when u add epoxy %?
I assume he makes example 60 sand 40 dust makes 100 grams..add 14 gram epoxy makes 114%.
Replace 'dust' with graphene and retest, please. 😁😁
Interesting results. I wonder what it would take to perform a damping test?
Yes that is interesting as well. Maybe drop a steel ball on the end of the bar and look at the sound response in some phone app? I think one can dream up a test that doesn't require high-speed precision recording of resonance curve form.
But I have a reason to focus on stiffness, can't say more right now.
@@metalmusings damnit. I really want to know what the new project is that you are using this for. Am keeping an eye out for any posts you make on the LinuxCNC forums. You come up with some of the best ideas, like tying linear encoders into the HAL software.
What is the size of box
It would have been much better if you wrote down the mix ratio for every sample in your result sheet so people can have more sense of the results.
Anyway, thanks for sharing the results.
It is all there. What do you miss? czcams.com/video/gjw5juGG1g8/video.html
17:42
what is dust?????
Hi MetalMusings, the dust effect was a surprise to me, never saw it anywhere in all epoxy/granite attempts, nice improvement you found. What about testing a sample of cast iron of the same size for comparison ?
Guessing, but I would think cast iron is 10-100 times stiffer.
Bad guess, I guess,. Looked around and EG stiffness is around 30% of cast iron, so not so bad really.
So, I did test a piece of cast iron. At least I think it is cast iron. More red than yellow sparks, and all grinder traces ends in an explosion, well you know what I mean, the traces don't just die, it sparks always.
Not the same size, so after scaling with area moment of inertia I think the cast iron is 6 times stiffer.
For dimensioning your granite/dust/epoxy structure, 6 times thicker than cast iron and you are good ;-)
@@pimzk2 Is this coming from the beam deflection calculation where the deflection is inverse proportional with the cube of the height?
Hi, very interesting study. Do you think polyester resin would be as effective as epoxy resin in this application. It is more cost effective in my location.
Difficult to say. But I am changing only the "filler" parameters. I think you can start from these results, but for precise findings you need to do your own tests.
Polyester resin shrinks alot more then epoxy when curing and is more brittle, something take into account if you want precision. You want epoxy resin with no solvents or reactive dilutents.
Polyester resin is much weaker than epoxy. If you cannot get epoxy, try vinyl ester. It is still not as stiff as epoxy but it will be almost as strong at least.
So I will have to join in asking what is the dust you are talking about? Stuff that you find on furniture if you don't clean room? Illegal drug? Is it some powder? If yes powder of what? Where can one buy it?
It's like a drug but much more boring than that. I have sandblasting cabinet and from there the air full of sand and other things is extracted to a cyclone filter. "Dust" is what is left in the cyclone filter. There wasn't a big thought around that. I just wanted a few different fraction sizes and came to think of the cyclone filter when looking for a very powdery, fine sand. It is very powdery sand possibly with some ferrit from the sandblasted pieces.
Thanks :) And very good idea to try it out!
Hi, maybe adding a little amount fibers could increase stiffness. But I guess that they should be at least 3 times longer than the largest particles.
By the way, do you have a milling machine in your bathroom?
what is dust? what is dust? what is dust?
Think of super fine sand, like when you rub two clay rocks together.
Dust is just the finest grit sand and rocks you can find
that is science
The purpose of the epoxy granite in a CNC machine is absorbing vibrations. You should measure the dampening capabilities, and not stiffness. Now you have the most rigid mixture, is that the recommended one ? Not at all, absolutely not, but the best dampener. Thats the goal, the purpose.
Not nessiccarily - people also use EG as their entire machine frames, so it must provide stiffness as well.
? dust of what?
Gött med en "svensk" kanal för nördigheter i min smak :)
Your mixes need much more epoxy. The epoxy makes it hold while the filler gives it stiffness. Normal mixes I have seen are 30-40% epoxy or higher. So yours are only 1/4 of that in some cases.
epoxy + titanium oxide + chromium oxide
I find it interesting when you laid them out you didn't order them in stiffness , just an interesting observation
Silica flour is really cheap 1eu/kg, that's how they make artificial stone
And cancer
If "DUST" is do hard to get in quantity then this whole experiment is useless for 99 percent of viewers.