Scaling the design up to the full size will be easy, now that the file is in the computer. Creating a scaled-down sample of the CAD design allowed Steve to test the concept, and to clean up some of the sharp angles created in the leaves in the original CAD file. In the art world, the term for a scale model of a full-sized sculpture is “maquette.” The full-size tree will be 120” wide, with areas for projecting on during the show. Each opportunity to actually cut something out is an opportunity to go through the steps for setting up the ShopBot for machining, so Dave ran through the check list to be sure that everything was ready to start a file: correct bit in place, ShopBot zeroed out in the X and Y axes, z-zeroed using the Z-Zero plate on top of the material, spindle power on, etc. With a few other tools in VCarve, we cleaned up the new vectors, then created a profile toolpath to cut out the spider with an end mill bit. Since a scanned object is a bitmap rather than a vector, we imported the scan into VCarve Pro, and used the trace function to find the edges of the spider he had drawn. So, his “homework” one evening was to draw something on paper, then scan it and save it on a thumb drive. While Steve was familiar with running a CNC machine, and engineering design software such as Fusion 360, his co-worker, Dave, is a painter and artist, and was a bit dubious about the skills needed to design a file, choose a bit and toolpathing option, and cut out a part. Flat end mill bits like the ¼” down spiral, ¼” up spiral, and ¼” and ½” straight bits that are found in the ShopBot starter bit kit are the bits used for those types of toolpaths. Profile (inside, outside, or on the design line or vector), pocket, and drill toolpaths are toolpaths where the bit plunges to depth, then stays at that depth for the entire operation or pass. MACHINING TO ONE DEPTH: FLAT END MILL BITS Vacuum and other kinds of hold-down are worthy of a blog of their own, so this blog will concentrate on the types of files that Steve and Dave, faculty members of the theatre program, worked on during training.įor every training, Sallye likes to demonstrate the three major categories of toolpath options, and the bits that are related to those toolpaths. The plumbing for the vacuum hold-down system is not yet in place. As a reminder, the computer station is positioned at the “Front” of the ShopBot (the long rails are the X-axis), and the spindle moves along the gantry in the Y-axis. The ShopBot Control Box is mounted on the far side of the table, away from the operator. The VFD for controlling the spindle is also mounted on the side of the table near where the operator will be. The ShopBot CNC in its final position, with the Becker Pump shut off box mounted on the ShopBot table leg near operator. Steve had a lift jack to move the Becker crate, and a forklift with chains ready to go when the table was partially built and in the approximate final location. The Becker is a heavy critter, and so it helped that Steve and Sallye had planned ahead to know where it would sit under the ShopBot table, and what equipment would help get it out of the crate and into position. The system that they have on their tool uses a Becker Rotary vacuum pump that will pull a vacuum through the top layer of bleeder board (MDF) to hold down a large sheet of material. The first order of business was to get the ShopBot PRSalpha 5’ x 8’ built and the vacuum hold-down system prepared. With the purchase made, Sallye Coyle headed to Ukiah in December, while students were on winter break, to install and train people on the use of the new CNC. The funds for purchasing the equipment came in the form of a Workforce Development grant from the State of California. As part of his hiring contract, he requested a ShopBot CNC router with vacuum hold down and a new welding set-up. But Steve Decker, CVPA Technical Director and instructor of Technical Theatre and Design, had plans for how to update the skills that could be taught through the theatre program at Mendocino College. The back side sports black marker lines for a jigsaw to cut out the leaves and branches, and a metal frame is welded together to provide support. An old theatre prop in the form of a tree greets you as you enter the back door of the Set Design Studio at Mendocino College in Ukiah, CA.
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