Case for Seven Decade Programmable Resistor Board

thingiverse

This is an adaptation of zapta's Gerry Sweeney's Seven Decade Programmable Resistor Box, http://www.thingiverse.com/thing:521303. The remix adapts the design for use with a different China-sourced seven decade programmable resistor board available on eBay. These boards are approximately 65 by 90 mm in size. The board listing titles include the text "1R 9999999R Seven Decade Programmable Resistor Board Step 1R". I was initially planning on building a switch-based decade box, but for $9.98 USD total cash outlay I couldn't resist purchasing one of these boards. In addition to dimensional changes for the different board and size of corner screws, the remix also uses the MCAD library polyhole function for improved dimensional control of the corner screw mounting holes. Various improvements have been made regarding geometry overlap in order to provide a cleaner preview in openSCAD and to minimize any mesh issues in the design. Additional revision notes are provided in the openSCAD source. Print Settings Rafts: No Supports: No Notes: The test print was generated on an 8-inch MakerFarm i3v customized with Smoothieboard and an e3dv6 hot end with 0.40mm nozzle. Simplify3D slicer settings included 0.20mm layer height, 2 perimeters, 2 solid top and bottom layers, 20% rectilinear infill, no support, and a print speed of 80 mm/sec. I used Voltivo Excelfil 1.75mm Cool Black PLA filament at a hot end temperature of 215 degrees C, printing onto a hair-spray coated glass bed set to 55 degrees C for the first layer and 50 degrees after the first layer. No additional print cooling or minimum layer time constraints were applied. Simplify3D estimates include 5.8m of filament being required and a print time of 55 minutes. Post-Printing Remove the corner screws and standoffs from the eBay board, saving the M2 screws for reuse. Slightly bend the solder tabs on the resistor board banana jacks up so that they clear the edge of the programmable resistor board. This will ensure they clear the raised outer edge of the box after board installation. Place the resistor board in the recess of the printed box and thread the four M2 screws removed earlier into the corner holes. Add self-adhesive rubber bumpers to the bottom of the box as desired.