Laser Cutter Base Build

The laser cutter design is done! It’s time to start building. This project update will be a little bit different from the previous ones as it won’t cover the design process, but the manufacturing process. It’s more a log than an explanation.

Materials

The main structure of the base is similar to traditional lumber-framed structures. Each base surface is a ¾ inch thick sheet of OSB plywood on top of a frame structure. Like an 8 shape, there are 2 long beams that span the entire width of the table, and 3 joists supporting the plywood between these spans.

Then, each surface is held together with columns. The bottom surface is a few inches longer than the top, and this was connected with an angled column, where the back ones are straight. This is just an aesthetic choice, however, the extension does make a nice step. The angled columns on the front form a triangle that eliminates rocking front to back. Later, some braces were added along the back columns to the top surface to stop side to side motion induced by the laser rastering.

I wanted to ensure the base was strong enough not to rock under dynamic conditions from the laser, so it’s probably overbuilt. I chose 4″x4″x8′ beams for the long spans and for the columns, and 2″x4″x8′ beams for the joists.

To create the table surfaces, an OSB board was used. It’s very cheap compared to plywood and has approximately the same strength. Two 4’x8’x3/4″ sheets were required. It is something to note, that these boards will eventually sag into the holes of the frame. This isn’t ideal, and future reinforcement may be added. Thankfully this isn’t a huge problem as all of the critical laser components mount around the outside edge where deformation will be minimal.

House framing uses brackets to hold beams in place, but because this was not necessary, plus the fact that the brackets would limit my design ideas, I opted to use long wood screws and wood glue for construction.

Preparation

The lumber from Lowe's had some rough surfaces, so I opted to plane them to smooth surfaces first, but then cut them to length on the miter saw as required for the frames. I also cut the plywood sheets to within 2″ of the required size for final assembly.

Miter saw cut img

Assembly

The first step was to make frames, then plywood would be layered on top of the frames to finish each base layer. To start each frame, a 4″x4″ beam was pre-drilled for screws. Then each 2″x4″ “joist” is marked, drilled, glued, and screwed into place on the first beam.

After this is repeated two more times, the final beam can be attached in the same manner to the other side of the joists. This finishes the frame, and I repeated this process to create the two frames.

After the frames were done, it was time to attach the plywood top surfaces. As mentioned before, the tops are oversized to account for any mistakes or out-of-squareness in the frames. The tops are secured with drywall screws, and then I flush-trimmed the tops using the router. I felt this was a pretty unique way to ensure the tops exactly matched the frame, and it definitely made the process much easier than trying to match the shape with a handheld circular saw.

Now with the two frames of the base done, it was time to connect them. There are four legs separating the frames and the front two taper in to connect the differently sized frames. I used the miter saw to create accurate angled beams from 4″x 4″ for the front legs. Then they were attached with screws and wood glue. Then the process is repeated to attach the top.

Finally, I casters to the bottoms of the base so that the machine can actually be moved. The base alone weighs about 80 lbs, and the casters are rated for 120 lbs each.

Next Steps

The base is ready to go! It got a coat of dark stain/polyurethane to protect it, and make it look a bit better. The next step in the build process is to acquire and cut the aluminum extrusion.

Next: 0.4 Extrusion Cutting and Bin Packing Algorithm

Previous: 0.2 Laser Cutter Enclosure Design

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