Crossfire 2 Tube arms

thingiverse

This is a remix of the crossfire 2. https://www.thingiverse.com/thing:234867 Please consider it a work in progress. This is an experiment to try and lighten the craft, and to provide stiffness for the arms. While this is still under construction, i share it freely. The arms are cut from 16mm thin wall aluminum tubing. The GPS is a UBlox 6, china special, and mounts on a 5mm chunk of tubing. Yes i know that there are screws on the GPS enclosure, and they are stainless, and do not interfere with the compass. However ideally they would be nylon hardware. Also a copper tape, grounded to the UBlox PCB was applied as a shield inside the bottom part. (careful not to short anything). Three versions of the motor mount were designed, a 16x19mm and a larger 25x25mm hole spacing versions. One larger mount has a dimple for the motor shaft. I am running afro 30Amp controllers, and mounted them with a "clip" on holder. It is a bit tight to snap the controller in and onto the tubing, but it seems to offer a chance for more airflow for cooling. Also designed a hole drill guide, and tubing support piece, for use on a drill press, when drilling the arm mount holes. See included pictures. NOTE do not drill too forcefully, see last pic for tube dimpling to be avoided. The tubing was cut with a tubing cutter, but go slowly through it. Tube dimensions are in the pictures. The arm root mount block is in two pieces, and is 25mm tall. It is indexed with a flat edge that functions as a clamp. I chose to use long 3mm hardware to assemble the base, and to use the nut pockets on the back to hold it to one plate for easy later assembly. The landing gear had to be "McGyver'd" to clear the arm tubing, but does not affect anything. Lastly i printed a small sbec holder for the APM power supply, it mounts it vertically, between the bottom two plates, and in theory could allow for two sbec's to be mounted in a small space. Instructions Printed in PLA, a nice flexible one. Most of what i printed was in 3 perimeter, 0.3mm layer, and 20% infill. Use your good judgement, as always. Here is what i used. Tubing 16mm ( 5/8" ) Wall: 0.016" - 2 36" lenghts used. I cut two spare arms. 5mm ( 3/16" ) Wall 0.14" - 1 ( length up to you ) GPS stalk. 10cm is what i used. Cap Screws ( stainless ) 8 - 3mm x 35mm tube-mtr mounts 8 - 3mm x 25mm arm tube to root mount 8 - 3mm x 40mm tube - root - frame 8 - 3mm x 45mm tube - root - frame - gear 4 - 3mm x 20mm GPS cover I have been getting my 3mm hardware from here : http://stores.ebay.ca/northern-supply-2012?_rdc=1 In addition, 3mm hardware used Flat washers Lock washers Nuts Nylon standoffs and nylon hardware. Screws and washers for mounting your motors. It was my intention to use RTV silicone when i assembled the motor and root mounts on the arm tubes, but once tightened things locked down nicely with only a small amount of kaptan tape on the tube. The GPS stalk however has NO LOCK screws, and i will use RTV silicone to "stick it in" so it doesn't move, yet can be replaced when i crash the craft.... and i will... The ESC mounts "move" and i had to put a dab of RTV silicone on them to hold them in position. :/