Epoxy Granite CNC Tabletop Mill

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Post Project Report: "ALL YOUR CNC BASE"

29 July 2013

A couple of months have elapsed since we finished the EG base and I feel comfortable saying that designing and casting a composite base may be a good idea for some applications, depending on your machine requirements and with only a few reservations that I will go into later.

Below, I will go over the basic process that we used to make our base. I will not cover the advantages or disadvantages of the use of epoxy-granite in this write-up as those are discussed in far greater detail and with the appropriate nuance at other public resources that can be found on the internet.

Design

The design for our base was primarily derived from the need to be as easily molded and demolded as possible. The other critical design criteria was the need to have a design that would take advantage of our construction material's strengths while making allowances for its potential weaknesses. One example of this kind of consideration is making sure that we had a thickness of at least 3 inches of composite material in all areas.

The Use of Melamine

We used melamine board as the structure of our mold because it is both affordable and has a smooth surface that makes it easier to demold. Using melamine will probably continue to make a lot of sense as the mold material unless someone is intending to make a lot of epoxy-granite structures. If we were to go into production on these things I would probably try to make a mold out of steel or aluminum as soon as it became economical to do so. Melamine can warp. In fact in the months that transpired between getting our mold parts cut and doing our pour, our melamine mold components warped a bit. In order to avoid this in the future I recommend checking the flatness of your potential melamine sheets carefully before purchasing and then using that material as soon as possible.

I cannot say with significant confidence one way or the other if it should be possible to reuse the melamine boards for subsequent castings. While demolding our pour, we found that it was necessary to break a few of our melamine mold components. However, this could be attributed to a number of factors including the warping that I mentioned earlier. It seems to me that it should be possible to reuse at least some of the melamine components given proper mold design and the correct use of demolding agents.

Update History

30 May 2013

  The base has been molded YES!! (fist pumping).

20 Apr 2013

  Parts (on order) have been rolling in, mold assembly has started.

Status 4 Feb 13

 Mold has been made, waiting for planning of plumbing (cutting fluids) and parts (fastener and epoxy)