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[canabus]

After the last motor install in a boat which took all day, I sat down over a few pints!!!
I finally worked out a little tool for the perfect alignment of motor to the drive line.
Using a piece of aluminium (33 x 20mm) turned down a 4mm area for the motor holes which you can add a number to your requirements.
The common sizes 16, 19 and 28mm for 28 and 35mm brushless motor.
On a lathe drill a 4mm centre hole for the shaft and added a grub screw thread.
The size of these tools can vary to your requirements (3/16" shaft, larger size area for larger motors and different engine hole spacing for your motors.
This will work on rear mounted engines like the D3648/4 1100kv 910watt 3-5S.

[oldiron]

Nice work. However, if you use a proper double cardan shaft couplng, you don't need it.

John

[davidm1945]

Nice work. However, if you use a proper double cardan shaft couplng, you don't need it.

John

But the noise from it will probably drown out the expensive sound system you just bought. A correctly aligned solid or rubber coupling will always be the best. A carden coupling is really a bodge to use when you can't, for some reason, properly align the motor and shaft.
Oh dear, I suspect that the wrath of Mayhem is about to descend on me for posting that. Hey-ho!!


Dave.

[oldiron]

But the noise from it will probably drown out the expensive sound system you just bought. A correctly aligned solid or rubber coupling will always be the best. A carden coupling is really a bodge to use when you can't, for some reason, properly align the motor and shaft.
Oh dear, I suspect that the wrath of Mayhem is about to descend on me for posting that. Hey-ho!!


Dave.

I don't necessarily agree. The majority of model boaters use a single cardan universal joint for some reason, and this is where the noise and vibration issues come from. We had a lenghty piece about 5 years ago on the various aspects of universal joints of various types. Failry long thread. I completely agree with your view point on the typically used single cardan joint, but a properly set and phased double cardan joint is just as quiet.

John

[Shipmate60]

I only use the splined ends coupled with silicone tubing.
Completely quiet and can be lined up by eye as very forgiving.


Bob

[NFMike]

I don't necessarily agree. The majority of model boaters use a single cardan universal joint for some reason, and this is where the noise and vibration issues come from. We had a lenghty piece about 5 years ago on the various aspects of universal joints of various types. Failry long thread. I completely agree with your view point on the typically used single cardan joint, but a properly set and phased double cardan joint is just as quiet.

John

Quite right. Cardan shafts are used extensively in the full size world (such as propshafts in cars) without noise being a problem.
I've used them in one of my boats which unfortunately hasn't been run in the water (ie. with a load) but when tested in air I was quite surprised at how quiet and smooth the system was.

[canabus]

Hi All
I use a solid coupling with grub screws, made by Roger again!!!!
I bought 1 metre of aluminium solid rod and gave him half for his boats.

[davidm1945]

Cardan shafts are used extensively in the full size world (such as propshafts in cars) without noise being a problem.

Yes, but car prop shafts have to allow for the rise and fall of the suspension - not a problem in a boat. Cardan couplings are mainly used when some degree of movement between the motor and driven unit is needed. I still think that a properly aligned (and that is the important point) solid coupling will be mechanically more efficient and less noisy. Still each to their own as they say...


Dave

[NFMike]

I still think that a properly aligned (and that is the important point) solid coupling will be mechanically more efficient and less noisy.

I agree to a point. The problem is that at these sizes getting that alignment requires considerable skill and patience, and, no offence intended, not all modelers have it. In addition the coupling itself can be a little out of true, especially those secured with a single grub screw.
Also it requires the motor to be solid mounted and that in itself transmits noise into the hull.

On the boat mentioned above I've actually aimed for a quiet drive and the motors are mounted on rubber and can actually move quite a bit. So even though I did a thorough job of aligning the shafts a flexible coupling was needed.

[Martin (Admin)]

Nice one canabus, like it!

How about one for 540 / Speed 600 type motors!


Bob: What size Silicon tube do you use?

[canabus]

Hi All
You can make to suit any number of motors.
We only did 3 on the first two, but, I think you can fit about 6 different sizes.
Also if you made the shaft hole larger and made sleeves for different size shafts you make the tool more versatile.
GOOD 3D PRINTER PROJECT FOR SOME ONE!!!!
It's the idea for the alignment tool and what motors I had in the workshop.
I have a few brush motors but I do not use them.
The 35mm brushless screw holes are the same as the 540 motor.
My first brushless was in an old Tamiya dune buggy Falcon(90 watts(22000rpm) up to 550watts(26640rpm)) and dropped 50 grams changing to a 3S 2650mah Lipo, so it's total insane to drive and runs for over an hour.
By that time the driver requires a nap!!!

Bob, 2.5mm silicon fuel tubing (OR005-00601) from Hobbyking in one metre lengths(about $2 AU dam cheap).
 

[Shipmate60]

Martin,
I got the size and supplier from Mark at MMB.
For ease of fitting and SILENCE I wouldn't go back to plastic Universal Joints.
Some of which have been drilled off centre so have to make a noise.


Bob