Technology Table

Inspiration

Our lower school technology teacher asked me if we could get a new worktable for his classroom that students could use for building projects. Rather than buying a table, we decided to fabricate our own. This design is based on a robot sticker that our team printed on holographic sticker paper to adorn all of the laptops in their classroom. The concept was to print a much larger version of the sticker and use it as the surface and outer contour of the table. The project ended up giving us multiple opportunities to explore new fabrication techniques.

Prototype

We wanted to try to use the same type of holographic sticker that was used on the laptops to make the surface of the table. The sticker material we had on hand was only about 20" wide and we wanted to make the table as big as possible to give the students the largest possible area to build projects. We found a similar glitter holographic material that came in a 50" wide roll and decided to try it out. Phase 1 of this project was to try and print out a medium sized version of the sticker using our large format Roland TruVis printer and see how well it would work to adhere our robot design to the surface of a sheet of plywood. After printing out our image we attached the sticker to the surface of some 3/4" plywood and took the rectangular sheet to the CNC router to cut it out. We weren't sure how well the sticker would handle being milled, but it worked really well. We even added a small round over using our table router and that worked reasonably well too. Finally we added a coating of System Three Mirror Coat bartop epoxy to protect and seal the sticker onto the surface of the wood.

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First prototype being milled on the CNC router.

Finished milling and rounding over the edges of our prototype for the table.

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Test pour of bar top epoxy. Tried taping the edges of the table with painters tape to see if that helped control dripping. The tape became saturated / heavy and fell off the edge as the epoxy was curing. Overall, this tape technique didn't seem worth taking to the next version.

Going big!!!

I used Adobe Illustrator to scale the artwork to maximize the size of the table that would fit on a 8' x 4' sheet of plywood. Based on the proportions of the sticker design I was able to scale the rectangular area around the robot and TECHNOLOGY text to 72" x 48". I printed the scaled rectangular image on the glitter paper and we set out to come up with a plan to adhere the large sticker to the plywood.

We fabricated a 48" wide plywood and fabric wrapped squeegee to aid in applying the sticker with the least amount of bubbles, wrinkles, etc. It ended up working really well!

Full sized robot table fresh of the CNC router. The edges of table top were rounded over using a palm router to smooth transition from surface to edge.

3D Modeling

I modeled the larger table in Fusion 360 starting with the table top and then began working on a design for the metal legs. We decided to custom fabricate the steel legs out of 1.5" square tube and 3/16" flat plate. We had been experimenting with powder coating larger items than what fit in our small toaster oven sized powder coating oven, so we modeled the legs to fit inside the large kiln used in our school's ceramics studio.

Table Leg Fab

We cut the 1.5" square tube to size and welded the components to create the two legs.

After the legs were welded and cleaned, we added Prismatic Powders Pixie Blood colored powder coat. The powder coating process worked remarkably well in the ceramics kiln.

Bartop epoxy

For the final table top, rather than repeating the taped edge technique that we experimented with for the small prototype, we tried adding a thin epoxy coat around the edges before doing the main pour on the face of the table. The hope was that by sealing the edges of the table and sanding it back to smooth, we would get a better final product. We calculated the appropriate quantity of epoxy to mix with room for a bit extra because we were planning on having it drip off the edges. We used popsicle sticks to smooth and spread the epoxy as evenly as possible to get the best possible coverage. As the epoxy began to set over the subsequent few hours, we made sure to wipe the bottom edge of the table to smooth any drips that accumulated.

Installing the legs

After the epoxy coat was dry, we set about to install the two steel legs. We previously marked the exact location of the holes in the steel plates at the top of each leg to make drilling precise holes into the bottom of the table top. We drilled 3/8" holes to fit our threaded inserts and installed them in the bottom of the table top. Then we attached the legs using 1/4"-20 bolts. The table looks beautiful with the legs attached, however the table had more flex than we had wanted when pushing down on the surface of the table top. We decided to weld two steel tube supported on the underside of the table to add rigidity to the final table. After welding the two support tubes in place, we noticed the table isn't sitting completely flat on the ground, so the last addition will be some adjustable feet to allow for small adjustments under each corner of the table legs.

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