The PrintBone: a fully printable playable trombone

thingiverse

A 3D printable trombone that's fully parameterized in OpenSCAD - see https://github.com/pieterbos/PrintBone for the code and wiki instructions on creating your own design. Check out http://www.thingiverse.com/thing:2252952 for an updated version with improved print quality, but sound remains the same. The bell is modeled after a large bore 8.5 inch symphonic bell, fitting a Bach 42 or Bach 50 slide, and possibly other brands as well. It's designed to work with a PVC slide, which can be replaced with any type of tube by editing the .scad file found on github. The OpenSCAD file also works for creating carbon fiber outer slides for different trombones, if you can find the correct tube diameter. A Bach 42B inner slide fits widely available 15mm diameter tubes, but 14.9mm would be better - see github for improved designs that print without support. Check out https://soundcloud.com/pieter-bos-2013025 for a recording of both a regular brass bell and this bell, can you guess which one is which? It also has a recording of the PLA slide, work in progress with still a leak somewhere and it will sound better later. Printing instructions for the bell: Print the bell in PLA on an original Prusa I3 MK2 with 0.2mm layer height, choose any infill you like. Print time should be around 25-30 hours, but you can probably do faster with a 0.6 or 0.8mm nozzle and a faster printer. The bell flare is cut for an at least 21x22x20 printer, if you have a smaller one, you'll need to adjust the files accordingly. Print the tuning slide with the pegs upward, and support enabled - the two small midair rafts will be supported and make for a much more stable part. A two piece bell flare that can be more easily printed without support is available as a setting in the OpenSCAD file, it has not yet been tested. Printing the slide parts: Add lots of infill or even solid for the inner handslide brace because it needs to be stiff. The rest, just print whatever is the most airtight. I printed the leadpipe in spiral vase mode with a 0.3mm nozzle and 0.37mm wall thickness, 0.1mm layer height. The leadpipe is relatively bright, if you don't like it, increase the venturi diameter in the openscad file a bit. Post-Printing: Bell assembly instructions: Print tuning slide and both neckpipe parts Sand connections and test fit parts and parts to trombone If they fit, continue. If not, download openscad file and adjust clearance parameters. You can keep the tuning slide even if fit is not correct, it will not be altered. Print the rest of the parts Sand all connections to make a good fit Test all parts for airtightness. Use superglue to fix any leaks (perhaps acetone for ABS?) Glue all connections except for bell flare Test assembled bell without flare for leaks and fix them. It's easier to close the ends without the flare attached. Glue bell flare Tips: You can use a practice mute to seal the bell when checking for leaks. Use soapy water to find the location of leaks. WARNING: soapy water slowly dissolves superglue :) Slide assembly instructions: Get 2 meters of 3/4 and 5/8 inch PVC pipe. Print parts Test for leaks. Fix all leaks. Coating with an epoxy lacquer might help. Cut the upper inner slide tube to correct length. Assemble without gluing. Assemble rest of smaller tube and cut to same length. Assemble outer slide tube, check length and cut. Test the slide. Glue the parts Put stockings on a piece of tubing you have left after step 5 and sand the stockings with increasing grit sandpaper. I used 180 - 320 then 600. They should be very smooth. Put stockings on trombone, check fit and glue. Lubricate stockings with slide cream (slide-o-mix and yamaha lubricant do NOT work well) If parts do not fit, check the openscad file and you can input your own measurements.