Adams gremlin journey

[Adams]

Hello all, This was my first quad build. I dont know why I choose the gremlin for my first quad build but its been a lot of fun so far. I have an FT270 awaiting to be built that I'll get around to. I wanted the little gremlin to fly around my yard and power loop my apple tree because the tiny whoop just cant pull out of the fun stuff.

Building the gremlin was easy, it seems like there is a lot of soldering but when I finished soldering I was sad it was over haha. I pretty much just followed along with the FT build vid. I didnt order a gremlin kit, I just ordered the parts separate. So a couple things seemed a little different. For ex. my f3 femto board orientation was different then on the FT vid, and it had wires for the esc's and a receiver plug. I didn't take a pic, I was too anxious to get building. No big deal, unsolder those, tin the pads and onto the esc's.

parts list
FC: f3 femto
ESC: 12a emax bullet
Motors: emax 1106 6000kv
RX: spektrum quad race serial receiver
Frame: TJ's
Battery: turnigy nanotech 850 mah 3s that I had laying around
FPV: 25,50,200mw adjustable camera and tx, was in my parts bin
Props: gemfan 2040

A couple things I did.. The motor mounting holes in the frame only had 2 holes that lined up with these motors, so I drilled the other holes(which were the small dia. holes) also they arent the same spacing as what the motor needed, so as I drilled them I kept pressure on the drill bit to widen the spacing, hope that makes sense. I wasnt comfortable mounting the motors with only 2 screws each, maybe it would have been fine. Anyone use only 2 screws to mount their motors?

I also soft mounted the motors with 2 pieces of electrical tape. I did that after it seemed to fly with a decent yaw twitch. Maybe I could have ironed that out with some tuning, idk.

After the first deuce into the ground, 4 plastic screws that screw into the stand offs broke. So I replaced them with metal. I'm not sure if thats the best solution, but I crash more then I think I should so I need this to be tough as possible.


https://youtu.be/RhaanrV4SvI


Right now I just used hot glue to mount the FPV camera until I can figure out a better more durable camera and vtx.

Ill be updating this thread as I go. I'm excited to get it out to a park to stretch its legs a bit more and see what she is really like. It seems to rip pretty good on 3s, but something inside me is wanting 4s.

I got some gemfan 2035 4 blade props to try and I have some emax 2345 3 blade props on their way to me.

 

[LitterBug]

Hi Adams, and welcome to the FT Forums!
Great having you here and sounds like you have a good start on the hobby! Looks like none of your pictures came through in your initial post. Can you upload them directly to the post rather than using external links? Looks like a permission problem to your other picture hosting site. Looking forward to your progress on these FT builds. I have two FT Gremlin Frames, a handful of foamboard planes, and just pulled the trigger on the FT270 yesterday too.

Cheers!
LitterBug

 

[Adams]

Thanks for the welcome.
I fixed the pics I hope, if not I'll try again, let me know if you cant see them.

Just flew the grem at a park for the first time, I'm getting more comfortable flying it. I am surprised how stable this little guy is. Still working on the tune. I'll probably pull everything off the frame soon and mount the FC and ESC's better. I used zip ties for the esc's and I think some sticky tape will be better. I mounted my FC with some rubber type double sided sticky tape and I want to redo that with some foam sticky tape. I also have a delrin andres frame that I want to swap the guts over to. The frame looks like it will fit a camera better, and is a little wider so the motors aren't in the view so much like TJ's frame. I do have to say, after flying TJ's frame, the motors in view like they are isn't as bad as I was expecting. Being my first build I'm learning a lot. I'm glad I built the grem before my ft270 cause I probably would have got insta flip with the 270 first flight like I did the grem.

I'm getting 4:30 min flights with the grem, I probably could a little longer, but I'll be easy on these old turnigy batts

 

[makg]

According to the FT guys in the Gremlin build vid, you really only need two screws to keep the props on. I would think any more just increases mass moment of inertia and decreases acceleration/increases load (albeit just a little). You could possibly add a small amount of blue Locktite 242 to the two screws for peace of mind.

I wish I would have thought about soft mounting my motors when I was having some serious yaw twitching. After I tried several different combos of foam/hot glue I found that a square double stick foam pad with the center cut out eliminated all of my issues, I figured it was a good way to isolate the microcontroller on the FC.

I have broken several of my black nylon m3 screws as well, from fairly low impact indoor accidents. I thought about upgrading them, but I bet I would start breaking props or bending motor shafts. I think they are good sacrificial components and they are easy/cheap enough to replace.

 

[Adams]

According to the FT guys in the Gremlin build vid, you really only need two screws to keep the props on. I would think any more just increases mass moment of inertia and decreases acceleration/increases load (albeit just a little). You could possibly add a small amount of blue Locktite 242 to the two screws for peace of mind.

I wish I would have thought about soft mounting my motors when I was having some serious yaw twitching. After I tried several different combos of foam/hot glue I found that a square double stick foam pad with the center cut out eliminated all of my issues, I figured it was a good way to isolate the microcontroller on the FC.

I have broken several of my black nylon m3 screws as well, from fairly low impact indoor accidents. I thought about upgrading them, but I bet I would start breaking props or bending motor shafts. I think they are good sacrificial components and they are easy/cheap enough to replace.

I was talking about mounting the motors not the props. My props can only mount with 2 screws. The way the carbon frame was only 2 screws would fit, mounting the motors.

I took the rubber sticky tape off that my fc was mounted with and stacked up 3 layers of foam sticky tape and that stopped the twitch for maybe 8 flights. The twitch is now back tho. So are you saying the double stick foam with the hole in the middle is how you mounted the flight controller? cause the soft mounted motors don't seem to have helped haha.
I will have to swap to new props to see if maybe my crashed up props are making it twitch.
Thanks for the input!

 

[Adams]

I wasn't happy with my hot glue mounted camera and vtx AIO because I think I crash too much and it wasn't holding. Also the vtx was almost useless on 25 and 50mw. It was decent on 200mw.
I like trying new things, so I ordered a lumenier 25mw micro vtx with a separate micro camera



I then wanted to mount it securely with adjustable camera tilt, so I machined a new top plate.

first try


too big

second try



I liked it, so then I found some plastic off amazon and cut it out





wired it up, and test flew it. Much better, much much better. It sticks the camera out a bit more so the motors aren't in the camera view, but the blades are still in view a bit. Not a problem tho.

Now I just need to play with the yaw twitch

 

[FlyingMonkey]

I like the adjustable camera mount!

 

[Adams]

I like the adjustable camera mount!

Thank you. It works fantastic so far. Already has survived 4 crashes, one was probably the hardest crash yet into my house.



I just tried new blades, still twitching. I think I'm going to try and find some small o rings to soft mount the motors with instead of the electrical tape.
I also just tried the gemfan 4 blade 2 inch props. More floaty and more bite in the corners, I liked them. The mounting holes were a bit too small tho.

now I'm off to fix the twitch issue.

I'm going to try full rebuild with better double side sticky tape on the fc with a hole cut out of the center, wrapping tape around the esc's(the sticky tape isn't holding them secure, so maybe thats causing weird vibes with the fc) and I might also try the delrin bottom frame. The little grem flies so good when its not twitching. It's even pretty fun when it is twitching haha

 

[PsyBorg]

The things that will make a Gremlin yaw twitch are things hitting the frame like loose wires, cameras or antennas, I have also found that my connection from the receiver to the FC was not making good contact and that caused yaw twitching as well. I hard solder EVERYTHING now and have not had any issues with yaw twitch since. (I do this on all my quads)

Soft mounting the motors on such a tiny quad really wont get you any realistic results. If you have shakes when you fly that's a tuning thing. Soft mounting everything does not solve the problem and only keeps your FC and esc's working harder to fly then if tuned properly. This is also one of the reasons people are frying motors when they try to run 3s on stock Gremlin kits. They don't tune the quad and only mask its issues with internet fixes.

Good build practices as well as a little effort in tuning goes a lot further then those fancy "add more weight" to any quad gimmicks.

I would look specifically at the way you have your antenna and VTX mounted. If that bounces on the frame at all it will cause twitching.