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Author Topic: Motor Mounts  (Read 3510 times)

Mike M

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Motor Mounts
« on: January 06, 2021, 12:54:04 am »

Hi, need some help on mounting my Raboesch motors #109-73 in my Fairmount Alpine.I purchased Vibr. absorbers #104-03 and tried to make a motor mount by attaching these parts to a wooden plate.I am getting a lot of noise and vibration.Looks like everything is aligned.
What could be the issue?
There are only 2 threaded holes on this motor, doesn't seem like enough??  Any help would be appreciated.


Regards Mike :-))


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Martin (Admin)

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Re: Motor Mounts
« Reply #1 on: January 06, 2021, 02:12:25 am »


Shafts may be very noisy if:

1. How long are the shafts?
2. At high speed, out of water / not under load.....
3. Usually modellers don't use those types of rubber mounts in-line with a motor,
4. Usually the motor is screwed hard to a mount and soft mount the mount to hull if required.
 








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Mike M

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Re: Motor Mounts
« Reply #2 on: January 06, 2021, 02:23:26 am »

Thank for your prompt response.Shafts are from Raboesch . Would you recommend the motor mounts pictured and not use the rubber mounts ?? Could you provide a link for the motor mounts? I think the problem is the rubber mounts do not give enough solid support to my homemade mount.


Regards Mike
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Martin (Admin)

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Re: Motor Mounts
« Reply #3 on: January 06, 2021, 03:41:12 am »


Can you post a photo of your current setup?

( https://www.modelboatmayhem.co.uk/forum/index.php/topic,61103.0.html )


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Mike M

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Re: Motor Mounts
« Reply #4 on: January 06, 2021, 04:37:50 am »

Tried uploading not working for me
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Martin (Admin)

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Re: Motor Mounts
« Reply #5 on: January 06, 2021, 09:48:47 am »

 
OK, email me any photos, I'll post for you,  martin@modelboatmayhem.co.uk
 
 
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ChrisF

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Re: Motor Mounts
« Reply #6 on: January 06, 2021, 11:41:48 am »

Hi Mike

Have a look at UKMike's Fairey Huntsman Becomes a Sports Fisherman in Pleasure Boats etc. as he has used them. But he has used 4 and a metal cross mount.

Most of us don't use those though and use the brackets as shown which are perfectly fine. Use a decent coupling though - the alloy ones with the rubber piece in the middle are good.

Chris
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Martin (Admin)

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Re: Motor Mounts
« Reply #7 on: January 06, 2021, 03:28:55 pm »

Hi Mike
Have a look at UKMike's Fairey Huntsman Becomes a Sports Fisherman in Pleasure Boats etc. as he has used them. But he has used 4 and a metal cross mount.
Most of us don't use those though and use the brackets as shown which are perfectly fine. Use a decent coupling though - the alloy ones with the rubber piece in the middle are good.
Chris

Link:  https://www.modelboatmayhem.co.uk/forum/index.php/topic,64836.msg689684.html#msg689684

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Mike M

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Re: Motor Mounts
« Reply #8 on: January 06, 2021, 03:36:16 pm »

Hi, This is something I had in mind, my motor can only has 2 mounting holes.  BTW sent you a pic


Again thank you for your help  Mike
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Martin (Admin)

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Re: Motor Mounts
« Reply #9 on: January 06, 2021, 06:25:53 pm »


From Mike....


Hi Martin, Here is the pic of my set-up As you can see the rubber motor mounts are screwed into the can.I have since taken them off so I can figure out a different solution.My couplings seem OK,would they have to be perfectly aligned,or is there some self alignment? I have since contemplated buying some proper motor mounts.Beyond me why Raeboesch doesn’t have the motor mounts available.Probably some of the noise is because the props are not under load.


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CGAux26

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Re: Motor Mounts
« Reply #10 on: January 06, 2021, 06:50:41 pm »

I make motor mounts from a piece of L-shaped aluminum from the hardware store.  It comes in 3 ft. lengths, so just saw off a piece a bit wider than the footprint of your motor.  No vibration isolators between motor and motor mount.  But I do use a piece of ⅛" thick black rubber sheet between the motor foot and the hull, or whatever the motor sits on.  On this boat I made a sub-base for the motor from ⅛" plywood.
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Mike M

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Re: Motor Mounts
« Reply #11 on: January 06, 2021, 06:55:46 pm »

I make motor mounts from a piece of L-shaped aluminum from the hardware store.  It comes in 3 ft. lengths, so just saw off a piece a bit wider than the footprint of your motor.  No vibration isolators between motor and motor mount.  But I do use a piece of ⅛" thick black rubber sheet between the motor foot and the hull, or whatever the motor sits on.  On this boat I made a sub-base for the motor from ⅛" plywood.
Excellent How thick is the aluminum?When you run your motor on land is it noisier then when in the water under load??
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Mike M

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Re: Motor Mounts
« Reply #12 on: January 06, 2021, 06:57:57 pm »

 
 Have since taken off the mounts waiting for a solution.
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Martin (Admin)

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Re: Motor Mounts
« Reply #13 on: January 06, 2021, 07:17:00 pm »


From the photo, the rubber should be between the wood bulkhead and the motor..... but the shaft then won't be long enough.
... plus there are only two rubbers, you'll get side to cushioning but not up and down....  {:-{


This is a way I did it:
  https://www.modelboatmayhem.co.uk/forum/index.php/topic,63982.msg686051.html#msg686051


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tugboyben

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Re: Motor Mounts
« Reply #14 on: January 06, 2021, 08:23:25 pm »

Hi Mike m


Are these style of mounts in the link available to you in canada   


https://howesmodels.co.uk/product-category/radio-control/motors/motor-mounts/


Jason
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tugboyben

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Re: Motor Mounts
« Reply #15 on: January 06, 2021, 08:26:39 pm »

Mike


A picture of mounts i  make my self 3mm aluminium angle

[/size]Jason [/font]
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Mike M

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Re: Motor Mounts
« Reply #16 on: January 07, 2021, 04:54:13 am »

Thank you everyone for your helpful advice Much appreciated :-))



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malcolmfrary

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Re: Motor Mounts
« Reply #17 on: January 07, 2021, 10:05:46 am »

Excellent How thick is the aluminum?When you run your motor on land is it noisier then when in the water under load??
The aluminium section will be whatever thickness the hardware shop sells.  Usually sold in 1 metre lengths of extruded section.
As pictured, the mount is just using the treaded section at one end, the rubber section appears to be just hanging there, doing nothing.  Motors are mostly intended to be rigidly mounted to a bracket using the two screw holes provided, then the bracket is used to spread the fixing load.  Usually a screw in each corner.  If the rubber decouplers are used, they go under the bracket feet.
As suggested earlier, a layer of rubber sheet between the underside of the bracket and whatever it is fived to will do the job.
Model boat hulls do tend to act like musical string instrument bodies - any sound inside them gets amplified.
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Mike M

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Re: Motor Mounts
« Reply #18 on: January 07, 2021, 03:25:10 pm »

Thanks  :-))
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Mike M

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Re: Motor Mounts
« Reply #19 on: January 08, 2021, 04:15:42 pm »

Hi Mike m


Are these style of mounts in the link available to you in canada   


https://howesmodels.co.uk/product-category/radio-control/motors/motor-mounts/

They do not ship to Canada
Jason
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ChrisF

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Re: Motor Mounts
« Reply #20 on: January 08, 2021, 04:36:25 pm »

He was asking if that style of mount is available in Canada rather than ordering from Howes.

Just done a search on Ebay Canada for Model Motor Boat Mounts and plenty come up including some I wish we had over here!

Note that water cooled mounts are fine as well even if you don't use the water cooling.

Chris
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Mike M

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Re: Motor Mounts
« Reply #21 on: January 13, 2021, 08:30:57 pm »

I have made my own mounts and have the motor lined up with the shaft.When testing the alignment I am noticing the shaft at the point where it connects to the coupling gets quite warm.Is this normal?? I am using the Raboesch self lubricating shafts with the compatible Raboesch nylon couplings.Second question.when testing the motors on high speed on a work bench, will it be more noisy than when the props are under load?
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ChrisF

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Re: Motor Mounts
« Reply #22 on: January 13, 2021, 10:30:33 pm »

The shaft will get warm as it is transmitting the heat from the motor. Be careful of how long you are running the motors as the lower bearing in the prop shaft is Delrin and is water lubricated.

Noise will be less when the boat is on the water as some of the noise will be deadened by the water and the motors won't be able to rev as high.

How are you testing the alignment? Using a solid connector to set up is a good idea and then replace with the flexible coupling. Some folks prefer to use a wattmeter.

Chris
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Mike M

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Re: Motor Mounts
« Reply #23 on: January 13, 2021, 11:00:44 pm »

Excuse my ignorance How is a wattmeter used to align the shaft to the motor?? Right now I have things set up with clamps and run the motor and shaft and shift until sound is minimal.At that point the part that goes through the hull gets quite warm.Interesting you say the part of the shaft gets lubricated by water.I thought they where sealed with lubrication.I try to align by using straight edge and a mini level.Maybe I am expecting it to be too silent while out of the water.


BTW thank you for your advice so far. One more thing, I have 2 versions of mounts I'm trying.One is a flat piece of ply mounted to the rib with motor attached  second two 45 degree blocks which cradle the motor and then put in place with silicon.Maybe better to source a proper mount???


Regards Mike
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ChrisF

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Re: Motor Mounts
« Reply #24 on: January 13, 2021, 11:33:00 pm »

Hi Mike

It's not a method I've used but basically you get the lowest reading on the wattmeter when the resistance to turning is lowest i.e. when the alignment is correct. Even when using a UJ or other flexible coupling the alignment needs to be as accurate as possible. As it's that side of the coupling that's getting warm it does suggest an alignment issue. The ballrace housing isn't turning is it causing the heat? This should be epoxied to the prop shaft though I'm going to tape some of mine in place, initially at least.

I use the Raboesch maintenance free prop shafts as well. The top bearing is a greased ballrace and the lower one is Delrin as stated. There is no other lubrication in the prop shaft. Given the ballrace bearing and accurate location of the shaft accurate alignment is very important and so yes source some proper mounts. The only boat I've got without one is my Club 500 race boat where the motor is held in a cradle with rubber bands, but that is a cheap and cheerful boat and gets some abuse unlike my Fairey scratchbuilds!


Photos of one of my installations; with solid alignment coupling and then with UJ.

Chris

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