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Discussion
CG Scale geek way
Hi
After seen those nice cg scales that showed recently for sale, the other one in this forum and the pierre rondel post about how the obtain the cg with two scales i feel that i need to get one... in a low budget mode but keeping the geek spirit. I think in design one using weight cells and an arduino and looking for info on those cells i found a nice project on a github repository https://github.com/olkal/CG_scale You can fin in this repo a bom file with all components listed, schematics and stl files.... all you will need to build one. The owner its a nice person he even modify the supports stl files to fit my f5j glider... Thanks Olav!!! because it was originally made for narrow f3f/f3b fuselages. So im going to do a build thread on building one of those gadgets. I have the 3d files printed and hope to get my electronics this week ![]() ![]() ![]() |
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I started buying stuff for this as well. Takes a few weeks to get stuff from China here in the states.
It looks pretty straightforward. Do you really need another Arduino pro mini for the LCD? Why not just go with a 4 wire display? Makes no difference but it saves a lot of soldering. |
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Of course, the original supports sizes fits ok my stream f3k, if im going to use exclusive on f3k planes i will use cells weight of lower range... for example 1kg or less Quote:
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Here its a photo of the two supports, smaller one its the original from repo and the other its the other that the repo owner modify to fit my xplorer 3f 5j.
https://github.com/olkal/CG_scale/issues/1 |
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Im also bulding mine to cover f3k, f3f and f5j so i have a max weight a little bigger than you. |
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I built a CG Scale last year using 3 load cells
https://www.rcgroups.com/forums/show...9&postcount=42 The full thread is here https://www.rcgroups.com/forums/show...5-Measuring-CG It uses an Arduino, 3 load cells, 3 amplifiers, a 4x24 display and a 4x4 keypad. The first version is somewhat crude but very effective. I am working on a much more refined version with the aim of making construction simple and cheap plus giving something better looking. I considered versions using both 1 and 2 load cells but decided on 3 simply because the resulting platform is more stable. I think any device that uses load cells and a cradle of some sort is a much better way of measuring CG and I use mine all the time. Frank Edit. It also gives lateral balance reading |
Last edited by Frank Campbell; Jul 09, 2017 at 03:01 AM.
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I've received some of my parts and will start the printing this week.
I've gone for 2x 5kg load cells. Might be over kill for my F3F models but I thought that way I could print some brackets that would allow me to put a wider fuzz on with a heavier scale model if needed in the future. Im also using a slightly different arduino board. Just the one will be fine for both cells and the lcd. Looking forward to seeing more of your progress. |
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Thread OP
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Im still waiting to receive the cells, and go to buy some screws and nuts.
i made the lcd part, i only used a pot in the lcd part and also modify two pins wiring, pinks A and K from lcd are used to power the backlight, K goes to ground and no resistance. I think its easier to have the pot and also you can use to adjust contrast. |
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Very cool guys. This looks like a fun project. I have no previous experience with Arduino, so hopefully I can get some help along the way.
Frank, I like your design with the 3 load cells for lateral balance, larger display and keypad. Once you get your design finalized, would you be willing to share your Aurduino programming, and perhaps a wiring diagram? Thanks. |
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I'm trying to find materials that are easy to get and cheap. Making it all wood is one option but requires some precision woodworking I find the 3D printer approach in this thread and the one kcaldwel started very interesting but not something I want to try at the moment I don't want to hijack this thread so when I am ready to publish what I have I'll start a new thread. Frank |
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