Small Retracts for Rc planes

thingiverse

The retract Design is based on purchasable Hobby King retracts and functions almost identically. Its purpose is just to provide a 3D printable version for those of us that prefer the DIY route. The Twin servo arm Mechanism is designed to fit most 9g servos and the geared servo arms have push rod spacing for 45 - 90 degree rotation from the servo. I have also included STL files for standard servo arms to actuate the retract mech as well. The Retract and servo assemblies each weigh 2 - 3 grams each. The majority of the weight when installed will be servo and actual landing gear weight (Wire, wheels, gear covers). Unfortunately this design dose NOT support steerable gear.....Yet ;) Currently I have tested these retracts on a plane that weighs 600 grams with no battery and about 700 grams with. And the gear works well. I would heavily recommend using 2mm wire for any plane heavier than 500g as thats when I found the wire would start flexing a bit too much to the sides. 2mm wire can be used by carefully up drilling the whole were the gear wire is mounted. When assembling the retracts all pins are designed to be 1.5mm wire which can also be used for the landing gear leg it self. The hole for the landing gear leg can be up drilled some too to fit larger/ stiffer wire. It is also CRUCIAL that a stiffening ring be put on the base of the Gear arm part to prevent the gear leg from splitting the layers on landing. I used a section from a large pen tube for this and glued it on. Any piece of Tubing will work so long as its inner diameter is approximately 4mm. An example can be seen in one of the photos of the gear mech above. I also highly recommend gluing the pin for the gear arm in place as a friction fit will not hold it in place long term. A good fillet of super glue from the sides to the pin will do very well. However a friction fit will suffice for the push/ pull arm that rides in the slot. When attaching the gear to the retracts i found reffung up the wire with sand paper and inserting it into the gear arm with some super glue (CA glue) worked very well. Printing: Infill: 100% Layer Height: .15mm for better layer adhesion Print Temp: 200-210 degrees to improve layer adhesion as well Support: only the Gear arm requires support. NOTE!: Unless print comes out near perfect most parts will likely require some clean up to get fitting together tight and for the gears to mesh properly.