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.

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.

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.

Well done and extremely helpful. Cheers mate!

Interesting, thank you for having shared these results.

Many thanks for your postings

amazing numbers ! thank you !

great work

Those look delicious. Especially the chocolate ones.

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.

Bravo and thanks.

How do you produce your dust?

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 .

you mean dust like the one is over the old tv?

what wound up being the best mixture?

What kind of dust is it - brick dust, metal dust, ....?

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

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.

Nice video but what do you mean by "dust"? sawdust?

what type of dust did you use?

I wonder resulta if u used fiberglass mat

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

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?

wonder how portland cement would work for the dust component

Can you define dust ? Was that granite crushed ?

What is the size of box

dear, i don’t understand what is dust! can you clear it please? what typs of dust i can you? is it saw dust?

Interesting results. I wonder what it would take to perform a damping test?

what is dust?????

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!

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 ?

What is "Dust" material?

dust???? what is dust?

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.

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.

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

What is the gravel size ? Why your total percentage is more than 100% when u add epoxy %?

that is science

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.

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.

? dust of what?

Gött med en "svensk" kanal för nördigheter i min smak :)

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?

Replace 'dust' with graphene and retest, please. 😁😁

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?

what is dust? what is dust? what is dust?

I find it interesting when you laid them out you didn't order them in stiffness , just an interesting observation

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

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.

Silica flour is really cheap 1eu/kg, that's how they make artificial stone

If "DUST" is do hard to get in quantity then this whole experiment is useless for 99 percent of viewers.