In this week’s project, we delved into the plasma cutter to make two identical diamonds! The project challenges us to not only practice good manufacturing but also consistency in fabrication. The steps for making the final product are as follows.
1) Modify the original diamond Adobe Illustrator template to a personalized design. In my case, I added an ‘S’ cutout in the middle. In order to add a laser cut instructions plaque, the diamond will need two holes on either end, slightly larger than the dowel size which is intended to be used. This file will be used to plasma cut the diamond out of a metal sheet, with settings determined based on thickness of piece.
The images below show the final results of plasma cutting. The first two images show front and back views, the latter of which is more charred. The up close image shows how the edges are lined with dross and not perfectly smooth. The two dowel holes in my case are a little bigger than 0.5 inches, which is the dowel size I will be using.
2. In the next step, the piece is post-processed through some sanding, filing, grinding, and sand-blasting. A file was used for the inside edges, along with sandpaper to smooth off chunks of metal sticking out from the plane of the plasma cut. However, since the outer edges are more accessible, the brushed angle grinder can be used to create a smooth outer edge. After all the edges have been cleaned up, the piece is ready to be sand-blasted. The sand-blast machine is located in the wood-shop, and this process serves to add a clean surface finish on the piece. As pictured, the machine requires the pieces to be dropped into a sealed compartment and the sand-blast gun is used to apply the finish. The final sand-blasted pieces are shown.
3) After the plasma cut piece has been sand-blasted, it is ready for the final step in post-processing: paint. In my case, I used blue spray paint but other colors can be explored. Make sure to have some waste cardboard/newspaper pieces below your plasma cut pieces, and follow the directions on the spray paint can to correctly apply it. Each side will need some spray paint application in multiple rounds of drying. Multiple coatings on each side are recommended in order to get a good finish. The final product is shown.
4) Prepare the instructions plaque by laser cutting it out of plywood, 1/4 inch recommended. The Adobe Illustrator file for the plaque will need to also include two holes, distanced the same amount as the holes on the plasma cut file. In this case, the hole size should be almost the diameter of the dowel in order to ensure a press-fit. This sizing might need to some experimentation. Two donut rings will also need to be printed as pictured in order to serve as stoppers for the dowel. Lastly, dowel pieces will need to be cut to size in order to accommodate the thicknesses of the plaque, the donut, and the plasma cut piece itself. The table jig saw downstairs is a good tool for cutting the dowels.
After all the individual materials are ready, the final product can come together. Use the dowels to go through both holes on the plasma cut diamond with press-fit on both sides: the instructions plaque on one end and the donut stoppers on the other. Pictured below, the final outcome showcases the diamond on one side and the plaque on the other!
Lessons LearnedÂ
The plasma cutter is an amazing tool for 2-D prototyping. However, it does have some drawbacks. The cutting is not very accurate as was obvious in some of the circles on my diamond. It also leaves a lot of charred edges that need to be post-processed. In the future, I would also try to avoid very thin section in the plasma cut (the ‘S’ in some places was a little flimsy). In the process, learning to use the angle grinder and the sand-blasting machine were two amazing post-processing tools!
Cost Analysis
This project combined the use of various machines and materials along with time spent in fabrication. As a creative exercise in this cost analysis, all equipment will be bought.
- Material: Aluminum Sheet, 36″ x 36″, $21.98
- https://www.homedepot.com/p/M-D-Building-Products-36-in-x-36-in-Plain-Aluminum-Sheet-in-Silver-57000/100351161
- Material: Satin Ink Blue Spray Paint, $3.97
- https://www.homedepot.com/p/Rust-Oleum-Painter-s-Touch-2X-12-oz-Satin-Ink-Blue-General-Purpose-Spray-Paint-314754/300456590
- Plasma Cutter, $5671.00
- https://www.grainger.com/product/31XV52?cm_mmc=PPC:+Google+PLA&s_kwcid=AL!2966!3!281698276047!!!g!471887498553!&ef_id=VdVN1QAABCl3KHX5:20181001164015:s&gclid=EAIaIQobChMIq4OPpdfl3QIVw7rACh07GQvmEAkYASABEgK5TfD_BwE
- Note: could not find a quote of the exact plasma cutter used
- Angle Grinder and Brush, $49.98+$26.82=$76.80
- https://www.homedepot.com/p/Husky-1-4-in-Angle-Die-Grinder-with-Accessory-Kit-H4230C/304783959
- https://www.homedepot.com/p/Lincoln-Electric-8-in-Crimped-Wire-Wheel-Brush-KH322/202939674
- Sand Blaster, $63.20
- https://www.homedepot.com/p/Powermate-Air-Sandblaster-with-50-lb-Hopper-009-0367CT/202591391
- Work Time, 4 hours, $40
- Total Cost: $5876.95
