[jayty97]

Keep in mind that concrete is designed for use in compression, not tension. The bottom of that X beam is in tension, so it will likely crack, unless it is under heavy pre-stress tension, and even then, you can find cracks in well-engineered setups.

If you are really convinced to go concrete, consider this:
- Pour a pad of self leveling epoxy to make a dead flat area
- make a mold using steel channel on the floor, then your mdf sides to the top. Use the floor as the bottom of your router and add some spoil board on top of it.
- Use self leveling epoxy to level the top of the concrete and a bridge between the sides to level them to each other.
- Mount your rails on some ground flat steel plate and then fasten them to the top of the epoxy / concrete sides.

When it is time to move, take the parts that are valuable, and crash the concrete walls down.

As this whole thing is just concept at this point, I'm not sure of where I want to use the concrete yet. Originally I just wanted to do a concrete gantry. I'm now thinking that may still be best. I do want the machine to be movable and don't want to be tied to the floor with anything more than bolts. That being said, I'm looking at tried and true designs of larger industrial routers. The biggest difference in design that I see are not only beefier parts, but how the gantry uprights are made. Most companies seem to use cast iron. My machine has cast iron. It seems as though they all seem to make an extremely rigid structure at this point. That is where the concrete part came to mind. I couldn't use cast iron, but i could make a perfect mdf mold for not just the Gantry uprights, but the bridge as well as a solid unit. I understand that concrete has great compression strength and poor tensile strength. That is why we use rebar. With some of the new fortified reinforced concrete mixes, combined with more conventional reinforcements, I am under the impression that a relatively small structure such as a router gantry could be poured with much success seeing as though there are people using this method to create some abstract pieces of outdoor furniture which are not only relatively thin, but have extremely high tensile strength. I did concrete form work for some time and understand the dynamics of standard concrete pours, but It seems that there are smaller scale methods which may be able to be applied here like this that take a different line of thought.



I am now leaning towards a conventional steel frame with only the gantry being concrete may be the best combination. I do like the concept of using self leveling epoxy and may be able to incorporate that into truing thing up.

Thanks, Jay