My First Quad Build - The FT Gremlin

[Michael9865]

I have lurked on the sidelines watching all the people building and enjoying their quadcopters and tricopters, not to mention the hexs and octos. When I saw the FT guys flying the Gremlins around their shop I knew that my first Quad build would be a FT Gremlin. I didn't order quickly enough to get in on the first wave of kits, I impatiently waited for them to come back in stock. I received my kit very quickly.

I will admit that I watched the build video a few times while I delayed and waited. I did have some pause when I saw the tight soldering that was required. I actually debated getting a 250 sized quad to try first but, something that big could not fly "safely" in my apartment during the winter months. After many more hours of YouTube videos I was sure that the Gremlin would be my starter quad. While I waited to decide I did purchase some motors and ESCs for a 250 quad, so maybe another outdoor quad to carry my GoPro aloft is in the future.

I decided to build to the build video step by step. I am glad I have YouTube on my TV.





I ordered it with TJ's frame. I also want to try Alex's frame at some point. (I may be in trouble here. I have over a dozen planes and I am already liking the looks of multiple quad designs.) :black_eyed:



ESCs are attached and sitting next to the frame designed by Victor, cucu on the forum. This print didn't come out to well due to me trying to make it thinner and trying a new type of filament. Should have the original thickness version reprinted for tomorrow.



I left the motor and ESC cables a little long to allow me to try different frames out. I am going to use a LemonRX Satellite RX



Don't look to closely. It has been a while since I soldered stuff in this tight of a space. Everybody was not joking about the tight soldering that is needed.



I checked for shorts after I tinned the pads and after I attached each component. All the checking added to my build time but I do not want to have to trouble shoot a bunch of connections if I screw something up. Tomorrow I should be able to assemble the electronics onto my Pittsburgh Steelers colored frame and then start the Betaflight setup.

 

[Huffheinz]

Looking good! I like the frame design (actually, I'm crazy jealous of you 3D printer guys). I can't wait to see the end result.

 

[PsyBorg]

Not a bad start and its good to take more time and do it right. Not too bad a solder job but I do see a potential problem and feel I should point it out. I am not putting your work down in anyway as some of your joints look better then mine do.

Take a good look at the white wires on the lower right corner and the upper left of the FC. The wire covering has shrunk back far enough that it could potentially short on the adjacent pads if it gets to moving around. I suggest either redoing those connections to close the gap between covering and FC or to at minimum coat that area with a dab of hot glue or liquid tape. Better safe then sorry mate as where that is WILL fry the board if they short.

I can not wait to see the final build specially since you mentioned the Steeler's colors as I am a Steeler fan since I knew what a football was.

 

[Michael9865]

Huffheinz - Thank you. Victor, cucu, designed a nice frame. I really like how screw heads on the motors sink into the frame, really nice detail. I wish I had a 3D printer. I used the ones at my county library or the local MakeSouthBend site/store.

Psyborg - Thanks for the encouragement and your sage wisdom. I decided to use hot glue on the wires and I also put some at the camera base. After all it wouldn't be a proper FT build without a little hot glue.















Time for Betaflight.

 

[Michael9865]

The smoothness of this build has ceased. The little quad says the it is not going to cooperate. Motor 4 will not turn. When turned by hand it feel different from the other 3. BLHeliSuite has a "--" where the info for the 4th ESC should be. Time to search the forums.






:black_eyed:

 

[PsyBorg]

The motor 4 issue is common with these Femto flight controllers mate. Seems people either have it work with Oneshot or they have it work with Dshot ( no rhyme or reason for either). I was going to try this fix so I could run Dshot as I am one who's esc's all worked fine on Oneshot but not Dshot.

AirKaos found some information for the fix and posted it in this thread post number 242

http://forum.flitetest.com/showthread.php?33056-Flitetest-DIY-Gremlins&p=346978#post346978

 

[Michael9865]

The motor 4 issue is common with these Femto flight controllers mate. Seems people either have it work with Oneshot or they have it work with Dshot ( no rhyme or reason for either). I was going to try this fix so I could run Dshot as I am one who's esc's all worked fine on Oneshot but not Dshot.

AirKaos found some information for the fix and posted it in this thread post number 242

http://forum.flitetest.com/showthread.php?33056-Flitetest-DIY-Gremlins&p=346978#post346978

Thank you! I will check that out tomorrow afternoon. Cheering on the Penguins at the moment.

 

[Huffheinz]

The smoothness of this build has ceased. The little quad says the it is not going to cooperate. Motor 4 will not turn. When turned by hand it feel different from the other 3. BLHeliSuite has a "--" where the info for the 4th ESC should be. Time to search the forums.

Oh boy. Sorry to hear that. When blheli didn't see ESC 1&3 on my build, it turned out to be my poor soldering skills (loose ground wire and bridged +& signal on the other) so some careful resoldering did the trick for me.

In your case, I would be worried about the motor that feels different than the others when turned by hand. Sounds like a bad motor to me. I would swap motor 4 with any of the other motors to see if #4 motor, or #4 ESC is bad.

Good luck with the troubleshooting!

 

[Michael9865]

Score!!!!!!! The little ESC and motor that could is now running!!!!

I started my day at 6am Bible study and then taught noonday Bible study today. During my drive home I was anticipating troubleshooting my little Gremlin when I got home. When I got home, I started the disassembly of the Gremlin frame. I swapped ESC and motor #2 & 4 at the flight controller, plus cleaned up my solder joints and dressed the wires better. Checked for shorts. Hooked it up to BLHeli Suite and the original #4 was still not operating. So I started checking for shorts again, no short found. my old fingers let the multi-meter's probes slip and I heard a tone. Hey wait a minute the didn't touch. Where is the short? So I started checking the signal wire to positive, no tone. Negative to signal, I have a tone. So I cut off the heat shrink and checked the little black wire solder joint to the signal, I have tone. So I figured that it wasn't being used so why not de-solder it to eliminate that point of failure. Eureka!! No more tone. So it was a short on the factory solder joint on #4 ESC between the small black wire and the white signal wire. I actually Didn't screw something up and it turns out I don't need any replacement parts except the shrink wrap.

When I build another one I will add the signal wires to my short testing while building.

Now to reassemble and finish the setup process.

 

[Michael9865]

My final weight with a 800mah 2S battery that I had on hand and the oversize velcro strap is 124 grams. Without the battery and after trimming the velcro battery strap it's weighs 79 grams. Now to wait for the rain to go away and my batteries to arrive.

I also need to search the internet to figure out why my aux 3 button on my Turnigy 9XR is only showing two positions in Betaflight. It could be that I am using a LemonRX Satellite receiver. Hmmm.

I will upload and link the video shortly of proof of spinning props after arming the Gremlin.

 

[Michael9865]

See the video linked below proof of spinning props after arming the Gremlin.

https://youtu.be/_0upc1vQsGU

 

[Huffheinz]

All right. Glad to hear you sorted it out! Good luck on the maiden!

 

[PsyBorg]

Aww man what a tease!!!

You cant send video of spinning props and NOT put it in the air for at least a bunny hop.

Anyways glad ya got it sorted to that point the next phase is get it off the ground!!!

 

[Michael9865]

Thank you guys. I did debate on goosing the throttle to try a bunny hop, but the thought of my Gremlin biting me won out. LOL

 

[JimCR120]

Thanks for sharing your build with the finds along the way. I'll look at my suspected bad esc, but not tonight. I was doing a brake job and am ready for sleep. I have another esc on the way. I think it should be here tomorrow.

 

[Michael9865]

Thanks Jim, we sailors need to help each other out.

 

[Michael9865]

Thanks to Dennis Baldwin, the link below, I have Aux 3 programmed correctly on my Turnigy 9XR. I now have access to Angle, Horizon, and Acro modes. Come on back-ordered batteries and good weather. If I get good weather I may be tempted to see what will happen if I use the 25C batteries I have. LOL

https://www.youtube.com/watch?v=eWDX6i9yt4Q

 

[Michael9865]

I had clear skies and little wind all day. I had to practice hovering and moving around in my front yard even though I only have 2S 800mah 25C LiPos on hand. I set my alarm for 5 minutes and the batteries are running about 7.6-7.7. I even played around in horizon mode for a while. This is different than the fixed wing aircraft I normally fly. Video below as proof of flight.

https://youtu.be/ICIP6zk4jSc

Have a safe and quiet Memorial Day weekend.

 

[GuzziKevin]

Thanks for posting about the 800mah batteries. I was wondering if they would work. I have several from a Blade 200qx that I would like to try. I think the connectors are the same. I don't mind if it doesn't fly fast, just don't want to hurt anything. This will be my first quad build as well.

 

[hogtownjon]

Enjoyed the thread and videos so far as I have also been looking at making the gremlin my first quad build. Keep the updates coming.