For my CNC i used a special concrete (UHPC), in this video i show you the recipe and some tips that may be useful if you want to use the same material.
Hello thank you for releasing this information. I was thinking on making a steel frame within epoxy granite. This looks like a good alternative but I’m not well versed in concrete and wonder if it binds to steel or aluminum well when curing?
Aluminum Is not good with concrete because It has a very different thermal expansion coefficient. Steel rods are ok but you need some sort of ancor points like bolts to ensure a good bond.
@@marson_cnc thanks for your response, I’m guessing that laying in square tubing or square plates are adequate too as long as I use bolts or rods to anchor?
@@JTSMW By all accounts, it would be useless. The torsion would manifest itself in the metal wall thickness, not in the concrete mass. There is no gain from using UHPC in tubing, not because UHPC is wrong, but because the shear ratio between length/width/thickness is wrong.
@@geekoid183 This is basic physics. It is called moment of inertia and it is a measure of how a tube opposes itself to torsion; its value is zero in the center of a tube and maximum on the periphery of the tube. If the force applied is higher, one should thicken the walls of the tube, not pour concrete in to "help" the walls get stronger. The thicker the wall of the tube, the greater the torsion it can take. Dumping vibration with concrete is a different objective and it is not to be confused with making the tube more resistant to torsion. If you pour concrete into a stationary part of the machine, it shouldn't bother you that the machine gets heavier if you want to move it around the shop. But if you want to pour concrete into moving parts of the machine (gantry for instance), you should think twice about that because your acceleration droppes dramatically unless you change your (servo/stepper) motors for beefier ones. And forget about aluminium when thinking about concrete frame; whatever you gain when using concrete will be hampered by aluminium.
@@marson_cnc longevity is highly dependend on the shrinkage reducer, otherwise at some point microcracking will occur and the part will be useless as a machine tool, that's at least what the durcrete engineer told me.
Awesome! thank you for sharing. I’d be eager to see a breakdown cost for the whole unit. Cheers
Material cost for the structure was about 300 euro. Whole machine about 5000 euro.
Thank you for the video!
Good presentation
Hello thank you for releasing this information. I was thinking on making a steel frame within epoxy granite. This looks like a good alternative but I’m not well versed in concrete and wonder if it binds to steel or aluminum well when curing?
Aluminum Is not good with concrete because It has a very different thermal expansion coefficient. Steel rods are ok but you need some sort of ancor points like bolts to ensure a good bond.
@@marson_cnc thanks for your response, I’m guessing that laying in square tubing or square plates are adequate too as long as I use bolts or rods to anchor?
@@JTSMW By all accounts, it would be useless. The torsion would manifest itself in the metal wall thickness, not in the concrete mass. There is no gain from using UHPC in tubing, not because UHPC is wrong, but because the shear ratio between length/width/thickness is wrong.
@@mihailfelixdumitrescHi,
Could you provide some more details about this ?
A paper on the subject showing your point
@@geekoid183 This is basic physics. It is called moment of inertia and it is a measure of how a tube opposes itself to torsion; its value is zero in the center of a tube and maximum on the periphery of the tube. If the force applied is higher, one should thicken the walls of the tube, not pour concrete in to "help" the walls get stronger. The thicker the wall of the tube, the greater the torsion it can take. Dumping vibration with concrete is a different objective and it is not to be confused with making the tube more resistant to torsion. If you pour concrete into a stationary part of the machine, it shouldn't bother you that the machine gets heavier if you want to move it around the shop. But if you want to pour concrete into moving parts of the machine (gantry for instance), you should think twice about that because your acceleration droppes dramatically unless you change your (servo/stepper) motors for beefier ones. And forget about aluminium when thinking about concrete frame; whatever you gain when using concrete will be hampered by aluminium.
What exactly is durigid? It sounds like some sort of slag, but maybe it is composed of Al2o3 or SiC or something else for its extreme hardness
I don't know the exact composition but is a selected natural mineral processed at high temperature.
Its a calcined bauxite.
It is basalt
@@vnuendru1 alumina (aluminum oxide)
How do you finish the surface? They all look smooth and level.
Because there Is a mould.
i'm vietnamese, i'm researching on the topic of UHPC concrete
What is the size of the quartz sand?
How many psi?
For what?
@@marson_cnc compressive strength
@@mhxxd4about 150 MPa, but useless for a cnc frame.
@@marson_cnc I was just searching for uhpc in general. What does a cnc frame need?
oh nice you went with dyckerhoffs E80, did you remember to chamfer all edges?
Yes, you can't forget It, i guess.
@@marson_cnc did you use shrinkage reducer?
Shrinkage Is very very low even without additives
@@marson_cnc longevity is highly dependend on the shrinkage reducer, otherwise at some point microcracking will occur and the part will be useless as a machine tool, that's at least what the durcrete engineer told me.
I don't know... In the recipe from the producer there is no additive. Others are used this concrete with no additives, only water and plasticizer.