WKM Quad and RC Carbon GoPro mount

[RTRyder]

I've just spent the last three days tweaking, tuning, and rebuilding on WKM #2, a 580mm quad using an MK Frame, Flycam motors, Graupner 10 x 5 props, and the RC Carbon landing gear and 2 axis GoPro mount, a flying box of mismatched parts if there ever was one!

Much of the time spent was on making the GoPro mount work better and I think I've finally got it as good as a direct drive mount can ever be. The only thing that would improve on what I've got it to would be a belt drive conversion and that isn't going to happen on this mount, simply not a design that you could do it to.

The past two days have been extremely windy here which is actually a good thing if you want to test the ability of a camera mount, provided you feel comfortable trying to fly in those conditions, a couple times it was questionable if the quad was going to make it back to the ground upright and in one piece.

I've just posted a video I made about a half hour ago and it is certainly the best result I've gotten so far, probably not going to get much better than this and honestly I can live with this for the raw video, a little work with an editor and a bit of stabilization thrown in and I think it would be decent video considering it was done with a small quad, cheap camera mount, and a GoPro.

Ken

 

[Emowillcox]

Ken looking good. Footage looks great specially for how windy it was. Could really see the wind when you went to the front of the house.

 

[RTRyder]

Well, not being entirely satisfied with the results I was getting from the RC Carbon mount after the last video I posted I've kept at it for the past two days and I can now say with certainly it's as good as it's ever going to get. There's still a minor bit of fine tuning I need to take care of since some of what I did was thrown together for test purposes, now I have to make those changes a permanent part of the setup.

Heres' the latest test flight out back and as you can see I'm not being gentle with it, I wanted to see if the mount is fast enough and smooth enough to keep the horizon level regardless of how the quad was being flown, appears it can do that now without vibrating and twitching...

Ken

 

[Tahoe Ed]

Ken it looks good!. Two questions, one what were the permanent fixes other than the servos and two, what settings are you using for the camera mount?

 

[RTRyder]

Ken it looks good!. Two questions, one what were the permanent fixes other than the servos and two, what settings are you using for the camera mount?

A quick rundown of the mods, all mounting points have been modified and better anti-vibration materials used in the rebuild, all servo drive linkages have been modified, servos are now running on separate power feed of 6 volts with only signal wire connected to the WKM, alignment of the tilt servo has been fixed so it is in line with the shaft it drives, damper mechanisms installed on both roll and tilt axis. The only changes to the settings so far are the roll and tilt gain, around 20 on tilt and I think about 28 on roll axis plus whatever offset was needed to center both roll and tilt servos. Once I tidy up the damper setups I'll probably set the motion limit on the roll axis, tilt will stay at maximum mainly because I think it doesn't move far enough as is.

Ken

 

[Tahoe Ed]

Thanks. My roll servo is toast. Fortunately I have an Align 500 setting around that I am not using right now so I took two of the DS510's out for now. They are not quite as fast as the Savox but then I don't have to wait for them to show up and I can complete my build.

 

[RTRyder]

It wasn't done messing with me yet, I've just spent another hour fixing the last bits of poor build quality (I hope!). Had just finished the final setup of the dampers on both axis and powered it all up to check operation. Heard this strange clicking noise, tracked it to its source and I noticed that the linkage balls for the roll axis servo links were just screwed into 1mm carbon fiber with no nuts on the backside to keep the bolts from backing out and sure enough they were 1/3 of the way out. Had to hunt up some really small nuts, 2mm I believe and install them, thats when I found that rather than just use the correct length bolt they were longer ones that had been cut down with cutting pliers and trying to put a nut on the cut end would quickly result in stripped threads. Ok, now hunt up some correct length 2mm bolts, fortunately I have a pile of Trex 450 parts and the correct length and diameter bolt is the one used to hold the rotor head on the Trex so I was able to come up with all new nuts and bolts then had to rebuild all the linkage mounting points because they were all assembled in the same half a** way, no wonder the wobble was starting to come back on the roll axis on the last flight, the linkage was about to fall off...:disgust::nightmare:

Ken

 

[Tahoe Ed]

I had to recenter the arm piece on the roll servo. He drilled holes that were not allowing the assembly to be centered on the servo shaft. I don't understand since the holes that were manufactured into the piece behind the arms aligned the piece perfectly. I am going to have to use one of the original servos. I don't have the time right now to modify the tilt mount to fit the Align servo. I will fix the alignment issues and see what happens.

 

[RTRyder]

I had to recenter the arm piece on the roll servo. He drilled holes that were not allowing the assembly to be centered on the servo shaft. I don't understand since the holes that were manufactured into the piece behind the arms aligned the piece perfectly. I am going to have to use one of the original servos. I don't have the time right now to modify the tilt mount to fit the Align servo. I will fix the alignment issues and see what happens.

Yeah, that was another bit of "craftmanship" that got tossed in the rebuild. Easy fix, I put two longer nylon screws leftover from an MK project into the C/F piece on the tilt axis shaft and then used a small round wheel on the servo. The spacing of the bolts in the C/F was really close to the hole spacing in the servo wheel and all I needed to do was open the holes up large enough for the nylon bolts to fit through. The alignment then needs to be set by slightly lengthening the slots the servo mounting plate sits in so the servo can move forward a bit to make both shafts concentric, might not be too far off with the original servo. Also found the servo mounting plate location slots are not square to the rest of the pieces on that side and had to shim the back end of the servo mounting on the plate to make the servo square to the rest of the assembly. I found that no matter what I did with the original servo its impossible to get the tilt motion smooth, it's very jumpy probably due to the servo having low resolution. Even with the Savox its still a tiny bit jumpy and the Savox is 4096 res, that I fixed as much as possible by adding a servo arm to the outboard end of the opposite shaft and installing a TMaxx shock absorber minus the spring to act as a damper, did a similar setup on the roll axis and it seems to be doing the job.

I found the Savox SH-1250MG servos to be the perfect replacement for this mount, they fit the existing mounting exactly the only difference from the originals is the output shaft is in a slightly different position on the Savox so minor adjustments needed to be made for that. Otherwise the speed is perfect and they work really well with the WKM controller. That reminds me, the original servos I could not make work with any Mk F/C I have, they just start spinning on power up and nothing will make them stop, I found that really weird!

Ken