3D Printed TriCopter

by Alex kasty | February 10, 2014 | (7) Posted in Projects

Hi, 

this is my first attempt at designing my own tri copter design based off of David’s design and some of flit tests rotor bones but with my own inputs, some good some bad. 

First let’s start with the frame. i designed it in Solidworks and  wanted it to encompass certain traits that i liked about David’s quad (ability to fold) and Flite test's cheap simplistic parts. First i wanted to change the ability to fold all the arms in all directions, in case of crash i don’t want anything to break. especially the frame as it takes 8 hours to print and at a cost of 55$ (5$ a cubic inch) so with that in mind i looked at many ways of holding the arms in place, and i thought of something like a wood dowel that would fail on a crash, but that would be a pain to change all the time and to fold up quickly. so i thought of magnets and after getting some neodymium 1/2 magnets form the local lee valley i put to test and found that it would have good force. i calculated the weight at the end of the arm and then calculated the MOMENT force at the magnet and what it took to slide the magnets apart and found that if the tri copter was on the side( high bank turn) then it would not collapse under its own weight. http://www.splung.com/content/sid/2/page/moments  ( to learn about moments) 

Once I was happy with this i went on to designing the frame. Measuring my board cam, go pro, kk2 board ect. 

Once finished i was left with this ! 


You can see the recessed spots in the arms for the magnets 

i then printed the frame at school on our dimension printer. 

and ended up with this ! 


The black material is the support material that the printer prints on as it can’t print in 3d space. Think of it as scaffolding that you dissolve when your part is finished. 

as you can see the board cam fit like a glove but when Cadding the camera slot got messed up a little but still works.

 

The next challenge was the Yaw mech. i was going to 3d print the yaw mech but i did not want to make an expensive breakable part. So i went to the local plastic shop and bought some Delrin ( what flitetest uses) this plastic has really good where resistance and is high flex and is tough. so it makes for perfect motor mounts/ landing gear/ yaw mech. so after sitting down and measuring and 2d modeling. i sent it off to the laser cutter  to get cut out and the whole cut took about 10 minutes for all parts. Here are the pictures of the yaw and landing gear and the tri copter as is. 

Still waiting for my electronics from hobby king. i will update this post as i build it and then will upload some fpv shots. 

COMMENTS

rcflyer729 on February 20, 2014
That is cool it just makes me want a 3d printer more and more
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Alex kasty on February 20, 2014
do it! additive manufacturing has become very popular, and now even more so in the rc community. it is very straight forward to learn how to use one and design simple parts.
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rcflyer729 on February 20, 2014
It is too much $$$
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Splat01 on February 22, 2014
Yeah! I certainly can't afford to pay $5/cubic inch on something that may or may not work.
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Alex kasty on February 22, 2014
your right it is expensive and i was lucky enough to have my school pay for the materials, but for me being a engineer, thinking of an idea and them prototyping it to see if the calculations and design work then its a cool feeling.
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peddiparth on February 20, 2014
This tricopter design looks great. I like the magnet idea in your design.

The one lesson I learnt the hard way (from 2 crashes) is that the motor mounts should be separated from the landing gear, else hard landings will break the printed landing gear and the motor mounts with it. You may not have this problem based on your pics.

All the best :)
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UltraPigeon on February 23, 2014
How strong is the frame?
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carsonpauli on February 20, 2014
this design looks great cant wait to see the update
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Cyberdactyl on February 21, 2014
I like the concept.

To me, however, knowing the strength of what appears to be 1/4" x 5/32" (at most) N45, or even an N52 neodymium, and what appears, at most, to be around 30mm from the pivot axis to the center of the magnet. . . the booms appear much too long and will put quite a bit of moment on the contact patch of the two magnets when in fast forward flight. I'm assuming you have only one embedded magnet? Maybe if you had two, staggered on the boom . . .

I could very well be wrong. I wish you luck with the idea.
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Alex kasty on February 22, 2014
thanks for feedback, the magnets are 1/2 inch by 1/4 yes, and there are two in each boom and two in the frame for each arm, they are 40mm from pivot and each magnate has 9lb of force needed to shear, yes it hasn't been tested yet but everything so far looks promising.
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Splat01 on February 20, 2014
Very nice. Looks very original!

My neck is a little sore from tilting to see the photos :)

I'm curious about where the power distribution will go, and do you think the magnet is strong enough to keep the rear boom in place when the rear motor yaws?
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Alex kasty on February 20, 2014
shall fix pictures :) and since the yaw still has a force upwards there is increst friction on the magnets to keep them still. ( hopefully)
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Eddy Current on February 20, 2014
Nice job, I like the booms that can fold backwards or forwards in a crash, that reminds me of the FortisAirframes TITAN tricopter design.
Are you going to put the cad files online (thingiverse, shapeways ?) so that other people can print a copy of your design?
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Alex kasty on February 20, 2014
also, i saw the titan design after seeing this, and from a manufacturing perspective his design makes more sense because laser cut parts are so much cheaper. what i do like about mine, is not having any set up time due to the arms just drop into place.
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Alex kasty on February 20, 2014
i would upload the designs if somone asked for them yes. should i add them ?
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Ballwiz23 on February 24, 2014
I would definitely appreciate you uploading your designs. I'm more into quads, but I'd like to check out your folding arms design. Thanks!
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CIRRUS on March 17, 2014
Care to share the STL file?
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3D Printed TriCopter