Thanks for these videos! I am planning an epoxy granite structure for a CNC. I will primarily be working with aluminum 6061 or possibly 7075 and maybe some mild steel. I'd like to consistently get 50 micron accuracy or better. We'll see. I haven't done aggregate epoxy tests yet. I don't have access to "Dust" so I am leaning towards aluminum oxide 1200 grit, and following the basic composition of Granite which, according to Berkeley Geology Dept is: "The chemical composition of granite is typically 70-77% silica, 11-13% alumina, 3-5% potassium oxide, 3-5% soda, 1% lime, 2-3% total iron, and less than 1% magnesia and titania." So I am thinking along the lines of silica sand, aluminum oxide in various grit sizes, Carborundum and or steel grit in various sizes along with decomposed granite (strained to control aggregate sizes and percentages) and crushed Feldspar if I can find it. I overthink things. Silica Sand, crushed gravel, sifted decomposed granite and aluminum oxide may be sufficient.
On one other site (russian) a guy uses both vibration and vacuum, at the same time - to drive out majority of air from the mass. He uses it for jewelry purposes, but I think after some compacting this may provide good results to compact mass. Obviously for your Z axis this may not be great as it would require very big vibration/vacuum table, but for smaller things - I think this may be viable solution.
I have been considering something like "stenmjöl" or rockdust, that can be bought at the local building supply store. Perhaps running it through a filter to extract the finer grade material would give a similar product to the sand blasting dust. If you wanted to crazy you could also try microsilica concrete additives, or perhaps something from a pottery/ceramics supplier, but this would probably create a very thick, non-flowing epoxy paste.
I did some very basic calculations - ibb.co/WP5gHy4 ibb.co/6WXvWh2 ibb.co/10kTqfWSome observations : Possibly the ultimate mixture is where the epoxy acts as a binder only (it's role is to stop lateral movement of rock materil within block) so that the majority of the bending force channels through the very dense rock material. So the rocks take the force being applied directly and the epoxy stops them shifting (slipping ) at an angle to the force. If there is too much binder some of this force will go into bending the epoxy material within the structure and contribute to that bend measurement. The other problem seems to be air being trapped in the structure not allowing epoxy nor rock material to occupy that space. We could solve this problem by possibly using a vacuum chamber and testing how much air is a participant in these results youre getting . The other note would be a way of processing fabrication to expel this air efficiently. You demonstrated even a small amount of vibration will add 10% to the strength therefore I anticipate 3 researching frequencies for vibration being added to these tests to find what frequencies epoxy and air slide. Also , A frequency that moves each roc particulate seems to make sense and would be different for each size rock . Therefore possibly we need a white noise vibration which emits all frequencies as a blanket solution ? Explaining the results of more epoxy and less dust or vice versa it may have to do with the amount of air that is being trapped and or being evacuated.
Thanks for sharing the video. I'm afraid I don't understand the percentages at 1:20 as they don't add up to 100%. For example, with Dust 10% + EP 13%, what's occupying the remaining 77% of the mixture?
Thanks for the idea, haven't looked around, tried to use what I had around. I don't think there is any magic with the dust/powder I use, it is just that the effect on stiffness was so big and I kind of want to stay with it now when I know how is behaves. Great tip for anyone unable to come and plunder my cyclone filter.
Would placing the samples under vacuum help reduce voids in combination with the sander vibration? For the small samples they could be placed in a small vacuum pot, for large parts perhaps they could be vacuum bagged similar to composite layups. Really enjoy your videos!
Maybe I can test that. I also want to see what happens when I use 15% epoxy, or maybe even 17% to avoid voids. I'll have to vacuum bag it, but it should be okay.
@@vikassm I have seen that some get foam. I tried, no foam. Depends on epoxy used I guess. But it is a bit messy, so I'll think I pass on that and go for violent vibration.
I think a big part of reducing the bubbles with vacuum chambers is putting both components into a vacuum chamber before mixing to eliminate all the dissolved gases first. The resins can absorb gases and water vapor and if you then put the mixed epoxy under vacuum they create a lot more bubbles than there were just trapped in the resin under atmospheric pressure.
@@siggyincr7447 It can also be that totally legit substances in the epoxy enters gas form at low pressure. That would result in foaming. I tested resin and hardener separately in a vacuum chamber (glass jar) and could only see some small bubbles rising to the surface. Not a lot, didn't cover the whole free surface. I assumed that was some dissolved gasses/air that was released. It stopped after half a minute and the bubbles slowly popped. 0.02 bar.
It comes from the cyclone filter of the sandblaster cabinet, from silica sand blasting media. It is very fine-grained sand, like dust, with a bit off iron rust in it.
Maybe because granite is a collection of minerals "glued" together, one of which is quartz, which itself is a crystalline lattice of silica. Use epoxy as the binding agent, and "epoxy granite" is, at worst, a metaphor for the resulting substance. Is there a more accurate name for this substance that should be used?
@@metalmusings How could I disagree with the findings when I don't even know what the hell the test was. After 2 videos and 30 mins of watching you make the every single sample even though it's the same thing over and over, finally make it to the testing and you don't even show you doing the damn test!
Steve, this was a deflection test, not a failure test. He applied an equal force to all the samples and measured the deflection (notice the dial indicator). No samples need to be broken to test them.
Thanks for these videos! I am planning an epoxy granite structure for a CNC. I will primarily be working with aluminum 6061 or possibly 7075 and maybe some mild steel. I'd like to consistently get 50 micron accuracy or better. We'll see. I haven't done aggregate epoxy tests yet. I don't have access to "Dust" so I am leaning towards aluminum oxide 1200 grit, and following the basic composition of Granite which, according to Berkeley Geology Dept is: "The chemical composition of granite is typically 70-77% silica, 11-13% alumina, 3-5% potassium oxide, 3-5% soda, 1% lime, 2-3% total iron, and less than 1% magnesia and titania." So I am thinking along the lines of silica sand, aluminum oxide in various grit sizes, Carborundum and or steel grit in various sizes along with decomposed granite (strained to control aggregate sizes and percentages) and crushed Feldspar if I can find it. I overthink things. Silica Sand, crushed gravel, sifted decomposed granite and aluminum oxide may be sufficient.
On one other site (russian) a guy uses both vibration and vacuum, at the same time - to drive out majority of air from the mass. He uses it for jewelry purposes, but I think after some compacting this may provide good results to compact mass. Obviously for your Z axis this may not be great as it would require very big vibration/vacuum table, but for smaller things - I think this may be viable solution.
I have been considering something like "stenmjöl" or rockdust, that can be bought at the local building supply store. Perhaps running it through a filter to extract the finer grade material would give a similar product to the sand blasting dust. If you wanted to crazy you could also try microsilica concrete additives, or perhaps something from a pottery/ceramics supplier, but this would probably create a very thick, non-flowing epoxy paste.
Good results. I wonder where such fine silica dust could be sourced. I also wonder about s-glass fiber effect on an epoxy granite.
I did some very basic calculations - ibb.co/WP5gHy4
ibb.co/6WXvWh2
ibb.co/10kTqfWSome observations : Possibly the ultimate mixture is where the epoxy acts as a binder only (it's role is to stop lateral movement of rock materil within block) so that the majority of the bending force channels through the very dense rock material. So the rocks take the force being applied directly and the epoxy stops them shifting (slipping ) at an angle to the force. If there is too much binder some of this force will go into bending the epoxy material within the structure and contribute to that bend measurement. The other problem seems to be air being trapped in the structure not allowing epoxy nor rock material to occupy that space. We could solve this problem by possibly using a vacuum chamber and testing how much air is a participant in these results youre getting . The other note would be a way of processing fabrication to expel this air efficiently. You demonstrated even a small amount of vibration will add 10% to the strength therefore I anticipate 3 researching frequencies for vibration being added to these tests to find what frequencies epoxy and air slide. Also , A frequency that moves each roc particulate seems to make sense and would be different for each size rock . Therefore possibly we need a white noise vibration which emits all frequencies as a blanket solution ? Explaining the results of more epoxy and less dust or vice versa it may have to do with the amount of air that is being trapped and or being evacuated.
Thanks for sharing the video. I'm afraid I don't understand the percentages at 1:20 as they don't add up to 100%. For example, with Dust 10% + EP 13%, what's occupying the remaining 77% of the mixture?
the rest of the percentage is Sand
I looked around online. It looks like you may be able to buy fine grit blasting media that is intended for wet blasting. Just an idea.
Thanks for the idea, haven't looked around, tried to use what I had around. I don't think there is any magic with the dust/powder I use, it is just that the effect on stiffness was so big and I kind of want to stay with it now when I know how is behaves. Great tip for anyone unable to come and plunder my cyclone filter.
Would placing the samples under vacuum help reduce voids in combination with the sander vibration? For the small samples they could be placed in a small vacuum pot, for large parts perhaps they could be vacuum bagged similar to composite layups. Really enjoy your videos!
Maybe I can test that. I also want to see what happens when I use 15% epoxy, or maybe even 17% to avoid voids. I'll have to vacuum bag it, but it should be okay.
Swiss cheese. I tried 😁
@@vikassm I have seen that some get foam. I tried, no foam. Depends on epoxy used I guess. But it is a bit messy, so I'll think I pass on that and go for violent vibration.
I think a big part of reducing the bubbles with vacuum chambers is putting both components into a vacuum chamber before mixing to eliminate all the dissolved gases first. The resins can absorb gases and water vapor and if you then put the mixed epoxy under vacuum they create a lot more bubbles than there were just trapped in the resin under atmospheric pressure.
@@siggyincr7447 It can also be that totally legit substances in the epoxy enters gas form at low pressure. That would result in foaming. I tested resin and hardener separately in a vacuum chamber (glass jar) and could only see some small bubbles rising to the surface. Not a lot, didn't cover the whole free surface. I assumed that was some dissolved gasses/air that was released. It stopped after half a minute and the bubbles slowly popped. 0.02 bar.
You say “dust” but it is unclear what kind of dust and how it is made...
It comes from the cyclone filter of the sandblaster cabinet, from silica sand blasting media.
It is very fine-grained sand, like dust, with a bit off iron rust in it.
Why do you keep calling it "epoxy granite" when it seems it is in fact silica sand dust???
Maybe because granite is a collection of minerals "glued" together, one of which is quartz, which itself is a crystalline lattice of silica. Use epoxy as the binding agent, and "epoxy granite" is, at worst, a metaphor for the resulting substance. Is there a more accurate name for this substance that should be used?
@@charetjc Thanks. I have no idea. So silica is a component of granite, but not the only one. Epoxy silisa might be more accurate.
What the hell even was the test? The samples are not even in 2 pieces.
I take it that you disagree with my findings?
@@metalmusings How could I disagree with the findings when I don't even know what the hell the test was. After 2 videos and 30 mins of watching you make the every single sample even though it's the same thing over and over, finally make it to the testing and you don't even show you doing the damn test!
@@Steve_Just_Steve Aah you mean pulling the bar and measure deflection? I did that in the video called tests and results.
I shouldn't have left out that piece in this video I guess. But was hard to make non-boring.
Steve, this was a deflection test, not a failure test. He applied an equal force to all the samples and measured the deflection (notice the dial indicator). No samples need to be broken to test them.