Epoxy Leveling Gantry

After planing the gantry, I realized that the front face, where I intended to mount the Y axis rails, is no longer perpendicular to the base. Since I was planning on using epoxy for the rail mounts anyway, I figured I could just use epoxy for leveling the front side of the gantry.

With the gantry on its back, I made sure the gantry bottom was perpendicular to the machine base, since that is where the X Axis bearing guides will be mounted. To minimize the use of expensive epoxy, I made a dam out of 1/2″ plywood covered with blue painters tape, which releases easily from epoxy, then sealed at the edges with clay. This dam allows the epoxy to flow only to the areas where the rail mounts and the ball screw bearing support mounts will sit for the Y-axis, with extra room allowed for the meniscus of the epoxy at all edges.

gantry with epoxy dam in place

Once the epoxy was mixed with hardener, I poured a small amount into another container and mixed in a little acetone to thin it out. I didn’t want to thin the whole batch because acetone can change the strength properties of the cured epoxy. I poured the non-thinned epoxy throughout the area and let it settle for a few minutes, and then poured the thinned epoxy over the top to achieve a very flat surface.

gantry after pouring epoxy

Remember, all of this work is driven by the fact that I didn’t start with a perfectly flat work surface. If the gantry had been properly square, I would have just attached my rail mounts and bearing supports directly to the wood face of the gantry. However, it is a good learning experience and I’m glad to have been able to test out the epoxy leveling method in case I want to use it for my next machine.