HEXA frame continues: Anti Vibration Motor Mounts

step by step, the HEXA frame is being constructed.

haven't worked on it for a while, but now i'm done with an interesting part:

 

 

 

I used the original arducopter motor mounts (the plates that come with the motors, which are not used on the official arducopter frame)

to be tied on the square arms, and between the mount and the motor, i've used:

*bling*bling*  RUBBER MOUNTS *bling*bling*

 

on the video you can see it works perfectly. isolating the motor from the aluminum arm.

with 6 motors working at very high throttle to keep this 4.5-5kg hexacopter, i'll need this vibration isolation to make nice and smooth videos.

 

and now, some pictures, 'coz we all like 'em !

 

 

 

 

 

 

 

 

 

 

COMMENTS ARE WELCOME !

 

 

 

Views: 6437


Developer
Comment by Jason Short on April 27, 2011 at 10:00am

First question is did you make them?

Second, it looks like the rubber isn't doing the deflection. It's the actual metal? Are you worried about fatigue? 

Jason

Comment by ARHEXA on April 27, 2011 at 10:13am

No, i've bought them.

how come the rubber dont make the deflection ? it's tightened to both sides, so if the rubber wouldn't have been flexible, the cable wouldn't move relatively to the arm let's say...

 

i'm worried about many things...

fatigue isn't the main thing. i'm worried about the motors heating the rubber  mounts.

i'm worried about the motors cooling less because they dont sit directly on the aluminum arm which would dissipate lots of the motors heat...

i'm worried of the rubber mounts un-mounting suddenly.

i'm worried about the added weight.

i'm worried about when i'll finish this hexa frame...

 

I think the workaround is to use 2 rubber mounts and 2 long screws through rubber spacers for each motors.

that way the 2 rubber mounts will supply the isolation and the 2 long normal screws will supply the security and the pressure of the motor towards the arm, locking the rubber mounts and preventing them to fall apart.

 

anyways i got the rest of my rubber mounts soon, i've got only 4 now.

so it was only a test and here as you see - i'm having better ideas coming on the way...

Comment by Ritchie on April 27, 2011 at 10:35am
@AR do not worry about cooling the motors are directly under the props. Do not worry about sudden unmounting use loctite on the threads. Do not worry about the added mass it will be inconsequential given the power of your motors. Do not worry about deflection as the type of rubber used so not deform easily (which is good as they are meant to support much heavier hard drives). Fatigue will be your issue but will be made worse by any fiddling you accomplish thanks to the manufacturing of the of the mounts so when you are done leave it alone.
Jason they are hard drive mounts. I have 5x 7200rpm HDDs in my main PC and have tried many mounts over the years to reduce noise and vibration including these and only one thing has worked. I hope that being smaller than a hard drive these work because I have 20 of them xD
If anyone is interested the only good hard drive isolation I have found is thick rubber bands stretched around the mounts then crossed to snuggly hold the drives. I have been to many LANs and have compete in the European CSS ladders so my hardware is pretty good and this has not failed me yet.
Comment by T.D. Gonzales on April 27, 2011 at 10:42am
Impressive! It might be worthwhile to set up a motor on an automated test bench to run for a prolonged period of time to see if the whole thing falls apart.

It might save you some money in the long run.
Comment by ARHEXA on April 27, 2011 at 10:46am

actually i got them as "RC boat rubber mounts".

 

and um, there's no chance i'm leaving it AS IS.

dismounting - i meant the two screw parts disconnect from the rubber part -

it just happened to me now when filing the screws a bit.

the screws are just glued/molded in the rubber but there is nothing to avoid them falling apart !

the force here is pulling both screws OUT of the central rubber piece, so i must use 2 of the 4 screw to 'pull' the motor towards the arm.

assuming 6kg, divided to 6 arms, divided by 4 mounts, that's 250g of force vertically pulling on the mounts.

hard drives are much lighter, and ESPECIALLY they are mounted horizontally, so each mount gets the fore at 90 degrees off the screw axis, plus they are 'trapped' between metal brackets that forces the rubber mounts towards the HDD so there are no chances they come off.

 

there is absolutely no chance i leave it this way.

and an important tip for other users: BEWARE OF USING ONLY RUBBER MOUNTS as fastening method.

they need force on the two screws to push towards the center rubber piece.

Comment by SciFly on April 27, 2011 at 10:48am
Id love to see a spectrum analysis w and w/out the rubber mounts....
Comment by T.D. Gonzales on April 27, 2011 at 10:57am
Wow yeah some kind of safety line is very important.

Have you seen these? http://www.karman.com/k69-compression.cfm?metric=1 I'm worried they might be too wide at the bottom for you.
Comment by Ante Vukorepa on April 27, 2011 at 11:52am
Nice! I use those on my hard drives.
Comment by Peter Seddon on April 27, 2011 at 12:34pm
Wouldn't it be easier to resiliently mount the Oilpan board which is lighter and is not subjected to high accelerations?

Peter
Comment by ARHEXA on April 27, 2011 at 12:35pm

@T.D. -

these look GREAT !

but even with such a good metal structure inside the rubber, i can't count on it to be safe enough, like a M3 metal screw is.

 

I really like the way i thought of re-doing the mounts -  with two rubber mounts and two normal screws THROUGH rubber mounts....

will try it soon

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