As we are remodeling our showroom at our parent company, Fiberglass Supply, we have had the opportunity to cast some projects including these standing desk tops. The idea behind these castings was that we wanted wood hexagons to be suspended with clear resin in between them for a surreal look.
The first order of business was to find a suitable wood for the project. While I was considering what to use for the project I happened to be in Home Depot and noticed acacia wood countertops, while checking those out I decided to look in the back section and found that they had birch butcher block countertop, which I decided to go with.
Using Rhino and Fusion 360 I drew up the hexagon pattern and spaced the hexagons about 3/8″ (9mm) apart. I figured this would give enough space for the effect to come through but not so much that I would have issues with the resin getting too hot. I also assumed I would run a 1/4″ bit on the CNC machine to do the routing.
After I had the hexagons laid out in Rhino I brought the line drawing into Fusion and modeled the 3d model. The plan was to cut almost all the way through the wood leaving about 1/16″ at the bottom of the cut, and to cut to within 1/4″ of the edges so that I would have a watertight cavity to pour into. The modeling went pretty quick and soon it was time to produce the machine code.
As far as programming goes this is a pretty straightforward part, consisting of 1 operation at this stage, a simple 2d pocket op to remove the wood from between the hexagons. However as I was double checking the tools I realized the 1/4″ bit didn’t have the cutting edge length needed to get to the bottom of the cut, so we would either have to order a new tool or use a 3/8″ tool. I didn’t want to wait so we used the 3/8″ tool. Of course the software said, no you can’t make a 3/8″ pocket with a 3/8″ tool, so we lied to it and told it the tool was slightly under 3/8″ so it would let us do our thing, this does result in a cut a little larger than 3/8″ but only by about .010″. The cut went smoothly and was surprisingly clean with nice sharp edges, very little chipout, and no fuzzing!
To prep the slab for pouring I had the guys tape off any knot holes on the bottom that might leak resin and to level the slab up on the pouring table.
On this particular table we wanted a light blue tint to the resin so we used Resin Research 2000CE with the slow hardener. We mixed in 2 main batches of about 3000ml each (around 100oz each) and then a smaller batch to top off. I like to mix the batches by hand and then let them induct for about 5 minutes before pouring them in. With the slow hardener there is still plenty of working time.
Once they were poured we checked them about every 5 minutes for air bubbles and used a heat gun to pop them as needed.
The next day after the epoxy had set it was time to plane both sides of the table top flat and parallel. The top had become slightly cupped from the pour and the way that it was supported so we put it in the machine with the cupped side down and planed down that side first revealing the Hexagon pattern on that side . Next we flipped it and planed down the other side so that both sides were now flat and parallel. After that we then did a contour cut that removed the wood from around the perimeter until we had cut into the epoxy so that it looks like the hexagon blocks are completely (and they are) suspended and surrounded by resin.
Of course we couldn’t help wasting some time just gawking over how cool it looks and seeing what it will look like back lit.
Next week we’ll sand it, put a round over on the edge and begin the finishing process.
Oh and don’t worry, we are putting together a video on the whole process!
Products used in this project are:
Resin Research 2000 CE with Slow Hardener
