Compression OR Tension Anti-Vibration Damping System.....?

[Maverick]

Hey Folks!

I'm thinking of replacing my PH AV130 for a 2 axis BL gimbal, on my Droidworx ADX-3 V3. The cameras I use are Sony Nex 5n and Sony CX410VE. I'd like to get a gimbal which can accommodate both (separately of course), but if push came to shove, the Nex 5n gives the more superior results. The controller will be AlexMos.

When looking at the different options, I have it narrowed down to a few options -

1). GotHeliRC's VX5N-V2-2X-C : http://gothelirc.com/shopdisplayproducts.asp?id=203&cat=VX+Gimbal+System

OR

2). Kamkop's 'Brushless Gimbal S'. : http://kamkop.de/gimbals/standard/7/brushless-gimbal-s

OR

3). Mikrokopter Altigator's 2 axis Sony Nex Series Gimbal. : http://mikrokopter.altigator.com/2-axis-brushless-camera-mount-with-motors-for-sony-nex-p-41371.html

Option 1 is the preferred one at present, because it's the lightest, and has got great reviews, but I can't seem to find any details or images of it mounted on a DW.

My PH AV130 has the DW load rails going through its 4 mounting holes with grommets, but in order to mount GotHeli's gimbal, I'd have to fit DW's camera mount adapter plate on to the load rails, and then screw the gimbal to that. From what I gather, the anti-vibration dampers fit between the top of the gimbal and the DW adapter plate, and they function as a 'hanging' or 'tension' damper, rather than a 'compression' damper.

Option 2 Kamkop's gimbal, requires the silicone anti-vibration dampers to be bought separately, at a price tag of €120 for a set of 4!!! They are also 'hanging' dampers.

Option 3 has the 'compression' damping system, where the top plate is carrying the load, thus compressing the dampers, and the bottom plate screws to the DW adapter plate via the stand-offs.

How do you guys mount yours'....?

Is one a preferred damping system over the other...? Any Pros / Cons...?

Help me make my decision, so I can quickly upgrade without any fuss...

Thanks,
Maverick.

 

[tahoelight]

My opinion is that any frame can hold any gimbal with a simple plate and stand-offs if you are hanging it right below. Just drill the holes in the right place. I also think the compression design is what those balls were designed for, and it offers more security in that the camera won't fall off if the balls fail. Lastly, go with 3 axis gimbal, not two, even if you are a single operator. Alexmos firmware has a follow mode that works great to follow the pan of your MR but will smooth out unwanted yaw within the perimeters you set (ie 5 degrees).

 

[Maverick]

Thanks tahoelight,

I agree, the balls are designed for compression, not tension, but GotHeli's dampers are specific tension dampers, not balls.

View attachment 14926

I was thinking of going with the 3 axis gimbal, as the follow mode seems to be a really cool feature to smooth out unwanted yaw, but it's the extra weight of the third motor that was putting me off. I'm getting 11:30 mins flight time, using 2 x 5200mAh, with the CX410 @ 370g, which is about 15g heavier than the Nex 5n, and that's landing with 3.70v/cell, unloaded.

I don't know if I'm near my MTOM, nor do I know how to calculate it... Tried using Ecalc, but can't get my head round too many unknowns...

But now you've got me thinking..... Hmmmm! Should I or shouldn't I...?

 

[ZAxis]

Mav...

KamKop gimbal... We don't use KamKop's dampers, our gimbal is hung from a std Droidworx quick release system which has dampers (in compression) built in. The KamKops ones were too expensive to even consider and not needed.

andy

 

[Maverick]

Mav...

KamKop gimbal... We don't use KamKop's dampers, our gimbal is hung from a std Droidworx quick release system which has dampers (in compression) built in. The KamKops ones were too expensive to even consider and not needed.

andy

Unfortunately, I'm still on the antique AD gear rail and landing gear.

I actually bought the AD/VM upgrade quick release gear rail and landing gear assembly, during the 50% spring sale, but it's just over 3 times the weight of my existing set up, and don't want to sacrifice flight time...

 

[jes1111]

Thanks tahoelight,

I agree, the balls are designed for compression, not tension, but GotHeli's dampers are specific tension dampers, not balls.

View attachment 18685

No they're not - those are regular compression-mode dampers - they may "kinda" work in tension but I doubt they'll work well. The pricey ones from KamKop look like they are actually working in compression - clever little design and I'm not surprised they are pricey, but that's no guarantee they'll work any better than the ball type (in compression) - so many variables with vibration isolation that it's impossible to say what's best - every rig would need to be tuned for the specific frequencies and amplitudes present, the specific resonances within the structure, the mass being isolated, etc. Probably wise to start with the $2 option and see how you get on.

 

[Maverick]

No they're not - those are regular compression-mode dampers - they may "kinda" work in tension but I doubt they'll work well. The pricey ones from KamKop look like they are actually working in compression - clever little design and I'm not surprised they are pricey, but that's no guarantee they'll work any better than the ball type (in compression) - so many variables with vibration isolation that it's impossible to say what's best - every rig would need to be tuned for the specific frequencies and amplitudes present, the specific resonances within the structure, the mass being isolated, etc. Probably wise to start with the $2 option and see how you get on.

Ive got an e-mail from GotHeliRC that says different - he says that his dampers use the hanging method :

"Hi Ronan,

I understand what you're saying about compression vibration. Yes, compress are indeed better, however it add more part, make it harder to mount, move plate... ect. Also, with compression you have to FIND the exact right amount of degree of tightness otherwise the gimbal bounce all over the place that can cause extra vibration.

The reason why I choose hanging method using these rubber because they are very very hard. They only serve as electronic vibration damper for the gimbal IMU. We always suggest our customer to eliminated vibration at the source (motors, props). The aircraft should be vibration free. I believe in this more than using damper to get rid of vibration, most of the time they introduce more vibration. So I have found using this method with our gimbal work best.

Each of this rubber damper can hang to 2-4lbs, so 6x of them is more than enough to handle gimbal/camera. "

 

[jes1111]

Yep - that makes sense - he says they are "very very hard" and they are being used in tension (hanging) therefore they are underperforming relative to their intended usage (in compression, 2-4lbs per unit), hence "they only serve as electronic vibration damper for the gimbal IMU" i.e. they are only attentuating high-frequency vibration (which would upset the IMU).

Frankly, I wouldn't be satisfied myself with GotHeliRC's attitude - for that much money I'd want a complete, workable solution rather than a lame cop-out ("eliminate the vibration at source"). Other anti-vibe solutions work, so should his

 

[Maverick]

Yep - that makes sense - he says they are "very very hard" and they are being used in tension (hanging) therefore they are underperforming relative to their intended usage (in compression, 2-4lbs per unit), hence "they only serve as electronic vibration damper for the gimbal IMU" i.e. they are only attentuating high-frequency vibration (which would upset the IMU).

Frankly, I wouldn't be satisfied myself with GotHeliRC's attitude - for that much money I'd want a complete, workable solution rather than a lame cop-out ("eliminate the vibration at source"). Other anti-vibe solutions work, so should his

Any suggestions for fitting a gimbal to Droidworx AD Camera Mounting Bracket...?

http://aeronavics.com/products/shop/vm-accessories/camera-mounting-bracket-xmvm/

 

[tahoelight]

Any suggestions for fitting a gimbal to Droidworx AD Camera Mounting Bracket...?

http://aeronavics.com/products/shop/vm-accessories/camera-mounting-bracket-xmvm/

Use the mounting plate, like you have linked to with the grommets. Use 4 stand-offs and mount the gimbal to that plate. Just takes drilling 4 holes on each that match. Compression mounts come with these standoffs usually. Not sure about extensions. Anyway, super easy. I was home and not sitting by a pool in Mexico waiting for the waves to glass off, I would attach a drawing.

There is a small chance you will need a larger plate in between, but this should be an easy DIY project.

If you are getting 11+ minutes if flight, I would not think adding a 3rd axis would matter. It is soooo worth the extra weight in video quality.

 

[jes1111]

I don't have anything specific for you but, in general, study the successful examples and notice the common features. Most important is that the isolators work in compression, their number and their softness are in a calculated proportion to the weight of the gimbal+camera, and (very important) the mounting is spread out as wide as possible. This last feature is important to control unintended flexure in the joint - otherwise, as GotHeliRC says: "the gimbal bounce all over the place"

 

[Maverick]

Use the mounting plate, like you have linked to with the grommets. Use 4 stand-offs and mount the gimbal to that plate. Just takes drilling 4 holes on each that match. Compression mounts come with these standoffs usually. Not sure about extensions. Anyway, super easy. I was home and not sitting by a pool in Mexico waiting for the waves to glass off, I would attach a drawing.

There is a small chance you will need a larger plate in between, but this should be an easy DIY project.

If you are getting 11+ minutes if flight, I would not think adding a 3rd axis would matter. It is soooo worth the extra weight in video quality.

Isn't it well for some, eh...? I was in Cancun twice, and Cozumel once - absolutely amazing place!

My next question was gona be, "What about needing dampers" as I didn't know they came with stand-offs...

Anyway, now you have got me looking up 3 axis gimbals all day now, trying to suss out the best one for my MR, and I've found a thread on Multikopter.co.uk where a Scot has done a whole series of videos on a DYS 3-Axis gimbal for Sony Nex. He's very happy with his, and its only 328g excluding motors and board. Motors are around 93g each. And...it comes with its own compression balls and stand-offs to fit to DW plate.

http://www.dys.hk/ProductShow.asp?ID=220

 

[tahoelight]

Isn't it well for some, eh...? I was in Cancun twice, and Cozumel once - absolutely amazing place!

My next question was gona be, "What about needing dampers" as I didn't know they came with stand-offs...

Anyway, now you have got me looking up 3 axis gimbals all day now, trying to suss out the best one for my MR, and I've found a thread on Multikopter.co.uk where a Scot has done a whole series of videos on a DYS 3-Axis gimbal for Sony Nex. He's very happy with his, and its only 328g excluding motors and board. Motors are around 93g each. And...it comes with its own compression balls and stand-offs to fit to DW plate.

http://www.dys.hk/ProductShow.asp?ID=220

I wish I cold find a simply designed gimbal like that for a GH3. Al of the GH3 gimbals look like cincester clones and way overkill in my opinion. Anyway. That gimbal should work fin for you, just make sure to use a real Alexmos board so you can update to a firmware with follow me option.

 

[Maverick]

I wish I cold find a simply designed gimbal like that for a GH3. Al of the GH3 gimbals look like cincester clones and way overkill in my opinion. Anyway. That gimbal should work fin for you, just make sure to use a real Alexmos board so you can update to a firmware with follow me option.

I sure will!

Thanks for all your help, and enjoy some tequila.....

Mav.

 

[Maverick]

I wish I cold find a simply designed gimbal like that for a GH3. Al of the GH3 gimbals look like cincester clones and way overkill in my opinion. Anyway. That gimbal should work fin for you, just make sure to use a real Alexmos board so you can update to a firmware with follow me option.

What about this one...? : http://www.uavobjects.com/product/l...version-dslr-brushless-gimbal-and-controller/

Or this one : http://tppacks.com/store/index.php?route=product/product&path=60&product_id=55

Mav.

 

[Maverick]

Here you go tahoelight,

heres the simple design you were looking for :

This will carry a GH3, no problem - ready-built, no fuss!

http://www.coptersquad.com/en/carboncore-3-axis-gimbal.html

Here's it here carrying the new Sony A7 :


View attachment 14960

Mav.