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Author Topic: Noisy universal couplings  (Read 3134 times)

steve pickstock

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Noisy universal couplings
« on: May 17, 2016, 06:05:14 PM »

I just ran the motor and power train in my flower build and it's really loud. I've isolated it to the coupling/prop shaft.

I reckon the prop shaft will quiet down a bit when there's some oil in the tube, but is there anything that can be done to quiet down the coupling short of taking them off and using a tight tube fitting?
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Klunk

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Re: Noisy universal couplings
« Reply #1 on: May 17, 2016, 06:42:40 PM »

someone will correct me, but I was once told a normal huco type coupling is only good for 14000rpm anyway. I personally now prefer rubber /flexi type couplings like those supplied by mobile marine. there are other suppliers!!!
normally noise is made by vibration, this can be caused by misalignment of the coupling, motor, propshaft. in some cases i have had the motor mount flexing causing this (cheap motor mounts!) the coupling not being snug enough, or the propshaft sliding in the outer tube! also there is some discussion as to the distance between the propshaft coming out of the hulll and where the coupling is, ie the amount of unsupported area of the propshaft to the coupling, more relevant to m2 /m3 props. Also the type of propshaft, is it a proper metal bush or a nylon bush?? is the propshaft bent (roll of glass to check).
But in your case it could be that if your building the matchbox/revell flower, then its the fact that its a plastic hull, very unforgiving for vibration and noise!
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roycv

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Re: Noisy universal couplings
« Reply #2 on: May 17, 2016, 08:13:26 PM »

Hi all I had some vibration with the couplings, unexpected as I always use them, I traced it to the lock nut on the 4 BA end of prop shaft skewing the coupling.  The cure was to place several close fitting washers between the coupling and the locking nut.  All quiet now.
regards Roy
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Shipmate60

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Re: Noisy universal couplings
« Reply #3 on: May 17, 2016, 08:16:16 PM »

Use the coupling ends and silicone rubber between them.
Silent and will transmit huge torque if rubber kept short.


Bob
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Davenotdone

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Re: Noisy universal couplings
« Reply #4 on: May 17, 2016, 09:06:51 PM »

I used the 'universal' type once, noisy and loads of vibration. >:-o  Changed to a ' rubber tube ' type one from Marks Model Boat Bits
( i think ) and smooth as silk with no noise :-) .   Regards, Dave.
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Stavros

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Re: Noisy universal couplings
« Reply #5 on: May 17, 2016, 09:34:31 PM »

If Truth was really known the Huco type couplings are only good for around 5k revs !!!!

Dave
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Welsh Wizard!

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Re: Noisy universal couplings
« Reply #6 on: May 17, 2016, 09:50:56 PM »

Hi Steve,
Contact Steve trainer ( modelboatbits.com )
I use his alloy/rubber couplings in all my model boats they are quiet running and are approx the same length as Hugo couplings, Steve will make them whatever motor/prop size you require.
Cheers
Dave.
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Bob K

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Re: Noisy universal couplings
« Reply #7 on: May 17, 2016, 10:20:52 PM »

Paradoxically, the idea of these couplings is to make up for any slight misalignment between prop shaft and motor, but with even a small misalignment vibration can set in.  End float is also critical, which is why the splined ones can be better.  I usually set the shaft tubes to motor shaft using a brass guide sleeve (you get it accurately aligned you almost don't need a coupler).

The rubber / silicone ones are nice but rarely available for small shaft sizes.  ie M4 upwards.
Here slight misalignment will absorb power as the rubber flexes.

LOGIC do rubber 'push on' ones, but strangely the smallest is 2.0 x 1.5 mm.  Could do with a 1.5 x 1.5 to push fit onto 2 mm shafts.  Had to use h/shrink & superglue - hardly engineering that. 

It's all a compromise.
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canabus

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Re: Noisy universal couplings
« Reply #8 on: May 18, 2016, 02:12:08 AM »

Hi All
Check out my idea for a motor alignment tool in model boating section, motor alignment tool.
As for couplings I use solid ones and have no problems now.

Harry Smith
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steve pickstock

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Re: Noisy universal couplings
« Reply #9 on: May 18, 2016, 07:23:38 PM »

Many thanks for all the replies.

I think the way forwards is to try and nail the alignment first and should that not be satisfactory look at going down the tube route.

Thanks chaps.
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Klunk

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Re: Noisy universal couplings
« Reply #10 on: May 18, 2016, 07:44:57 PM »

Please note my last section.......its a hard plastic model kit. It will amplify all vibration. I have a solid graupner coupling in mine, with the motor mount fixed to a rubber base and I sill get a noise.
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steve pickstock

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Re: Noisy universal couplings
« Reply #11 on: May 18, 2016, 09:33:59 PM »

I appreciate it will never run silent (and hope fervently it will never run deep) I'm just trying to get it to run more quietly than it is presently.
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chas

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Re: Noisy universal couplings
« Reply #12 on: May 18, 2016, 11:19:03 PM »

My Snowberry is completely silent ( in the water) . I use a silicone tube between the motor and the shaft, and the motor is embedded in silicone bath sealant.
 It's been running for several years with no problems. The proverbial switch on and go model.
 Keep it simple!
Chas.
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