Nice write up on the servo LitterBug. I'm considering re-building my tricopter and adding something like this myself using an emax mg servo. Here is the step by step. 
First build with DB's Junk
- Thread starter LitterBug
- Start date
Huston, we have some problems....
Got my DYS XS30A ESCs in last night and got quite a bit of work done on the Trifecta build. Firmware was BLHeli_S 16.1 so I immediately flashed them up to 16.2 and applied the recommended starting point parameters to avoid desyncs. (startup power 0.125, demag high, timing med-high) Tested motors both before and after flashing with a servo tester and confirmed that the newer software and settings cure the hiccups. Also confirmed that all of DB's Junk motors run very nicely.
With all the ESCs hard wired to the motors with the correct rotations, I was able to move on to final aseembly of the arms. That's were I ran in to the next problem. The EMAX servo height is shorter than the HK recommended turnigy so I had to make 2mm shims to get the gears to mesh correctly on the tail.
Once it was all together, I hooked up my servo tester to the tail servo. Next problem.... The steel on aluminum pivot started binding up again after a few pivots back and forth. Disassembled the pivot and hit the steel pin with the 800 and 1500 grit paper again till everything was moving smooth again. This time I threw some white lithium grease in there to keep the steel and aluminum from fusing together.
Did a bunch more pivoting back and forth to make sure there was no more binding up then assembled all the arms to the body.
Bottom view showing ESCs mounted up:
Top view. Waiting for FC to arrive. (Shipped yesterday from RCExplorer.se )
Cheers!
LitterBug
Got my DYS XS30A ESCs in last night and got quite a bit of work done on the Trifecta build. Firmware was BLHeli_S 16.1 so I immediately flashed them up to 16.2 and applied the recommended starting point parameters to avoid desyncs. (startup power 0.125, demag high, timing med-high) Tested motors both before and after flashing with a servo tester and confirmed that the newer software and settings cure the hiccups. Also confirmed that all of DB's Junk motors run very nicely.
With all the ESCs hard wired to the motors with the correct rotations, I was able to move on to final aseembly of the arms. That's were I ran in to the next problem. The EMAX servo height is shorter than the HK recommended turnigy so I had to make 2mm shims to get the gears to mesh correctly on the tail.
Once it was all together, I hooked up my servo tester to the tail servo. Next problem.... The steel on aluminum pivot started binding up again after a few pivots back and forth. Disassembled the pivot and hit the steel pin with the 800 and 1500 grit paper again till everything was moving smooth again. This time I threw some white lithium grease in there to keep the steel and aluminum from fusing together.
Did a bunch more pivoting back and forth to make sure there was no more binding up then assembled all the arms to the body.
Bottom view showing ESCs mounted up:
Top view. Waiting for FC to arrive. (Shipped yesterday from RCExplorer.se )
Cheers!
LitterBug
Servo Feedback, What is it, why would I want it, how do I get it?
So in this great learning adventure of TriCopters, I came across a new term to me: "Feedback servo". Had to find out what it was to determine if I needed it. The Simple explanation is the servo provides a voltage that represents the angle it is currently positioned. This gives the Flight controller another piece of data that can be used for it's calculations. Rather than the Flight controller sending a signal to the servo and assuming it went where it was supposed to, the flight controller actually knows the angle of the rear rotor and can better model the thrust. If my flight controller can use it, I would want to give it all the information it could have for smoother reactions. How do I get it? It's actually very simple. 1) buy one that has been modified and hope it fits your size, speed and torque needs, or 2) Take the ideal servo you have and solder a wire to the center lead of the potentiometer. I do not have my Flight Controller yet, but when the package comes, I will go through the configuration and calibration in TriFlight for adding the feedback. Here are some photos I took with the servo at 0, 50, and 100% with the voltage provided.
Cheers!
LitterBug
So in this great learning adventure of TriCopters, I came across a new term to me: "Feedback servo". Had to find out what it was to determine if I needed it. The Simple explanation is the servo provides a voltage that represents the angle it is currently positioned. This gives the Flight controller another piece of data that can be used for it's calculations. Rather than the Flight controller sending a signal to the servo and assuming it went where it was supposed to, the flight controller actually knows the angle of the rear rotor and can better model the thrust. If my flight controller can use it, I would want to give it all the information it could have for smoother reactions. How do I get it? It's actually very simple. 1) buy one that has been modified and hope it fits your size, speed and torque needs, or 2) Take the ideal servo you have and solder a wire to the center lead of the potentiometer. I do not have my Flight Controller yet, but when the package comes, I will go through the configuration and calibration in TriFlight for adding the feedback. Here are some photos I took with the servo at 0, 50, and 100% with the voltage provided.
Cheers!
LitterBug
My overall impression is it is a good kit that can take some abuse. My biggest concern is the rear pivot. It bound up right out of the box and bound up again after cleaning it up once. Very fine sandpaper and lube may become a regular maintenance on the tail... Time will tell. If you are building this kit, pay attention to the tail and pre-flight check it for proper travel every flight.
Cheers!
LitterBug
Waiting on customs.....
Looks like my pre-release PDB and FC from http://rcexplorer.se/shop/ are still hanging out in customs.
Tracking events
Date/Time Location Tracking event
7/24/2016 8:02 AM UNITED STATES The item has arrived at the international terminal in the destination country for sorting
7/23/2016 3:28 AM Stockholm utr The item has been dispatched from Posten´s international terminal for onward transport abroad
7/22/2016 5:13 PM PostNord Mariestad The item has been redirected within Posten to a sorting terminal
7/22/2016 4:37 PM PostNord Mariestad The item has been deposited
Looking forward to checking out David Windestål's designs when they get here!
Cheers!
LitterBug
Looks like my pre-release PDB and FC from http://rcexplorer.se/shop/ are still hanging out in customs.
Tracking events
Date/Time Location Tracking event
7/24/2016 8:02 AM UNITED STATES The item has arrived at the international terminal in the destination country for sorting
7/23/2016 3:28 AM Stockholm utr The item has been dispatched from Posten´s international terminal for onward transport abroad
7/22/2016 5:13 PM PostNord Mariestad The item has been redirected within Posten to a sorting terminal
7/22/2016 4:37 PM PostNord Mariestad The item has been deposited
Looking forward to checking out David Windestål's designs when they get here!
Cheers!
LitterBug
WE HAVE A BRAIN!
WOOHOO. Mr. impatient here jumped the gun on the previous post. FC and PDB were in the mailbox today! Going through pre-install flashing, config and testing. (and the lights are flashing too! Have a bunch up in the air right now, so it may be a week or so before it's ready for maiden.
Cheers!
LitterBug
# dump
# version
# TriFlight 0.5 Beta 3/RCE 1.12.0 Jun 2 2016 / 20:16:50 (0b3fce7)
WOOHOO. Mr. impatient here jumped the gun on the previous post. FC and PDB were in the mailbox today! Going through pre-install flashing, config and testing. (and the lights are flashing too!
Have a bunch up in the air right now, so it may be a week or so before it's ready for maiden.Cheers!
LitterBug
# dump
# version
# TriFlight 0.5 Beta 3/RCE 1.12.0 Jun 2 2016 / 20:16:50 (0b3fce7)
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PsyBorg
Wake up! Time to fly!
I had an idea from back in my skateboarding days. Any type of lube or grease will attract and hold dirt and other particles of junk. This can be a huge cause of binding. It also tend to provide a certain amount of resistance specially in colder or damp weather. That could further stress the servo and mechanical movement.
What we used to use was graphite powder in our bearings. It made everything super smooth and didn't hold gunk. It does need to be applied more frequently but the effect of less maintenance keeping it clean was a good trade off. If you cant find any you can always take a pencil to some 1000 grit sandpaper or finer and make your own to try it and see what results you get.
AHHH! Great idea PsyBorg!!!! I have a tube of graphite from the days of my Son's Pinewood derbys. Should have thought of graphite myself since I had all the 800/1500 grit sandpaper axle polishing and lubing skills. I had tried going dry at first to prevent the grease crud and sludge, but that obviously did not work out. I think the aluminum they used for the gears is a tad on the soft side so it easily melds with whatever it touches. (including the plastic frame! DOH!)
Cheers!
LitterBug
Crazy Goats
Active member
Been tied up the last few weeks rebinding, remapping, reprogramming, etc after upgrading my DX6i to a DX8. Had to drop everything after magically selling my DX6i the day after getting the DX8. Now that is all behind and the build can commence. Updates and maiden soon!
Cheers!
LitterBug
Cheers!
LitterBug
Danal The Dragon
Member
Well at least you are enjoying your projects.
Just be wary that graphite and aluminum might not be a good long term lubricant:
https://en.wikipedia.org/wiki/Graphite
I thought I saw someone else post this recently in this forum...
makattack,
Thanks for bringing that back over to this post. I have been meaning to bring that info over here. I currently have a very light coating of white lithium grease on mine and will be revisiting that as time goes on.
Cheers!
Info regarding lube from the other Trifecta thread:
Cheers!
LitterBug
Oh yeah, I had forgotten that... I also used a parafin based (wax) lubricant on that tail shaft: Boeshield T-9 which I also use on my brushless motors
I had that stuff for lubing my bicycle chains, so I figured it would do for these purposes. Probably the best thing to use would be just a simple light machine oil, which I didn't have handy.
Funny enough, that stuff seems to be used in the aviation industry too (I guess that explains the name):
http://boeshield.com/why-boeshield/
http://www.experimentalaircraft.info/articles/aircraft-corrosion-protection.php
Haha, EAA seem to suggest it's use as a covering/rust inhibitor.
Cheers!
LitterBug
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