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Author Topic: shaft and motor alignment  (Read 7374 times)

d-jnana

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shaft and motor alignment
« on: August 01, 2008, 08:30:39 PM »

Hi guys, and gals,
Anyone else find aligning motors and shaft to be really difficult or is it just my beng totally crosseyed?
How do you do it?

GARY
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catengineman

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Re: shaft and motor alignment
« Reply #1 on: August 01, 2008, 08:46:45 PM »

Hi,

when you say you are having tropuble are you fitting the motor direct to the shaft or are you puting a Universial Joint assembly in between?
 

R,
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SteamboatPhil

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Re: shaft and motor alignment
« Reply #2 on: August 01, 2008, 09:26:08 PM »

I fit the motor first well fixed in, then use a tube the same lenght as your chosen coupling to join the motor shaft to the prop shaft, then fix in the shaft, because you should have a small amount of movement through the hull. When set remove the tube, insert coupling, and you should (no really you should) have a near perfect line up
Phil
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barryfoote

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Re: shaft and motor alignment
« Reply #3 on: August 02, 2008, 08:33:06 AM »

Set the prop shaft in place and attach the coupling to it. The put a dollop (if the word really exists) of P38 car body filler, or similar where you want the motor. Attach the motor to the mount and then press the motor, which has been wrapped in cling film into the filler until all is lined up. It never fails...

Barry
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FullLeatherJacket

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Re: shaft and motor alignment
« Reply #4 on: August 02, 2008, 08:50:40 AM »

Gary

One tip I've seen is to connect a single cell (1.2 - 1.5v) to the motor, with an ammeter in series. Connect up the motor, U/J and prop shaft. Dollop the P38 onto the motor bed and squidge it into the hull in roughly the right place, then turn on the current. If you move the motor around, the current will increase or decrease, which indicates more or less misalignment. When the current is the lowest you've hit the optimum alignment. Let go, turn off the current and let the P38 set.

For big gaps under the motor bed e.g. in a hull with a deep keel I prefer P40, which includes chopped GRP strands.

Works for somebody - although, like Phil,  I use a rigid tube to couple the two halves of the U/J while I install the running gear.

FLJ
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Arrow5

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Re: shaft and motor alignment
« Reply #5 on: August 02, 2008, 08:59:37 AM »

A variation of Footski`s is to use silicone bath sealant instead of body filler. I use a block of wood glued to hull bottom that is 1/4" lower than engine mount , sealant  dollup is squirted onto block, support the mount ,with motor fitted, till sealant cures (24 hrs).  A brass tube is slid over the coupling to keep it solid and the line-up will be automatic, when cured the brass lining-up tube is removed.   I also remove the centre block of Raboesch-type couplings and replace it with large diameter silicone tube pushed onto the splines. All this to try and quieten noise. I was thinking of trying sealant to fix the prop-shaft tube through the hull, anybody tried this ?  
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d-jnana

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Re: shaft and motor alignment
« Reply #6 on: August 02, 2008, 06:29:11 PM »

I have tried silicon to fit the tuebe through the hull. In time it leakes as vibration makes it let go of the metal tube.
Well thats what I think anyway.
GARY
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Bee

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Re: shaft and motor alignment
« Reply #7 on: August 02, 2008, 11:14:36 PM »

Recently I have been fitting a new motor in an old hull. I made a template of the tube angle wrt the keel by placing a bit of wood on the keel next to the tube and scribing along it. I used this to set a motor plate at the right angle. I then packed up the motor to height by sighting up through the tube to see the end of the shaft.
As I haven't glued it in I might give the ammeter test above a try.
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funtimefrankie

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Re: shaft and motor alignment
« Reply #8 on: August 03, 2008, 08:21:59 AM »

I use the 1.5 volt battery method, but just go by the sound/revs of the motor, the faster the better.
Works for me
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d-jnana

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Re: shaft and motor alignment
« Reply #9 on: August 04, 2008, 10:17:25 AM »

Thanks guys,
I like the idea of using blobs of sticky/squidgy stuff to seat the motor. I take it the blobs go under the motor mount. I'm going to give it a go in conjunction with the ammeter test using milliput so that I can tap a couple if holes in it to screw the mounting plate down firmly.

GARY
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Arrow5

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Re: shaft and motor alignment
« Reply #10 on: August 04, 2008, 11:14:55 AM »

Yes under the mount but you could perforate the mount base and allow the squidge to ooze up through the holes and form mushroom "rivets". Wrap a bit round the edges too while it is still liquid-sh.  I just re-fitted the motor in a Springer last night, should have photographed the process, sorry !  The balsa box in photo are just a dam to contain gunge while it cures, can be left insitu or removed to reveal a solid block of silicon "rubber".  Also pics of my lining-up tool, simple brass tube push fit over coupling (slots to clear rivets). I now use only the end pieces of this type of coupling with thick-wall silicon tube pushed over the splines. Much quieter. The anti slip rubber is also for same reason and to help batteries from moving.
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alan colson

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Re: shaft and motor alignment
« Reply #11 on: August 04, 2008, 07:44:17 PM »

A few years ago Bryan Ward at Mobile Marine Models used to sell a gadget for alignment of motors to props, if you are still having problems it may be worth a try.
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Arrow5

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Re: shaft and motor alignment
« Reply #12 on: August 04, 2008, 09:07:04 PM »

I`m sure a block of brass same length as a coupling with appropriate dia hole each end to suit motor and prop-shaft would be a boon.
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Martin [Admin]

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Re: shaft and motor alignment
« Reply #13 on: August 04, 2008, 09:14:20 PM »

Can you take a photo and show the problem Gary?
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taxi

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Re: shaft and motor alignment
« Reply #14 on: August 04, 2008, 10:23:00 PM »

An old wooden cotton reel is the same size as the red plastic bit on a coupling and the brass bits will fit nice and snugly inside the ends of the reel.
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Martin [Admin]

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Re: shaft and motor alignment
« Reply #15 on: August 04, 2008, 10:37:06 PM »

Here how I did the same thing in the Puffer....

http://www.modelboatmayhem.co.uk/Builds/Puffer_Jan/Part_4.htm
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tony23

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Re: shaft and motor alignment
« Reply #16 on: August 05, 2008, 01:14:28 AM »

I have never built a boat yet but have you guys thought of using 'No Nails' for bonding in motor mounts  :embarrassed:

Tony
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toesupwa

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Re: shaft and motor alignment
« Reply #17 on: August 05, 2008, 05:16:57 AM »

I have tried silicon to fit the tuebe through the hull. In time it leakes as vibration makes it let go of the metal tube.


You are using SILICONE?.... the rubbery bath sealant stuff to fit a prop shaft in to a hull?..  :o :o :o no wonder it comes loose and leaks!.

Nooooooo, rough up the outside of the brass outer tube with some sandpaper and EPOXY it in...

If you must, stick the motor mount in to the hull  >>:-( , but a wooden block in the bottom of the hull and some small brass woodscrews through the motor mount to hold the mount down is a far more professional job. It also allows you to remove the motor for maintainence or replacement at a later stage.
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Colin Bishop

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Re: shaft and motor alignment
« Reply #18 on: August 05, 2008, 09:27:09 AM »

Golden Rule: NEVER mount anything inside a hull that you cannot remove at a later date. If you do, you will come to regret it!

Colin
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catengineman

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Re: shaft and motor alignment
« Reply #19 on: August 05, 2008, 09:33:02 AM »

Well said toesupwa

with your way (and mine) if you change the motor to a new one then you have a pre aligned base to fork of. ie same motor  same coupling all fits OK even if you have to use a different motor or coupling the base plate is set at the angle to the shaft.

R,

I have to undo a pair of motors in an Alkabha (spelt wrong I think) and then fit fixed shafts, knowing the owner I will probably need to change the motors at a later stage too.  :(
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Martin [Admin]

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Re: shaft and motor alignment
« Reply #20 on: August 08, 2008, 04:04:42 AM »

Got to admit, double / 'cardan' coupling or overshaft gearbox or belt drive every time.
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catengineman

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Re: shaft and motor alignment
« Reply #21 on: August 08, 2008, 07:57:58 AM »

True having a double cardigan is the easiest way to fit motor to shaft though there is a draw back to that fitting system and that is the length of the installation. Some models are restriced in what you can squeeze in.

Also as a foot note every bend in a drive line = a loss in performance = increase in drag = possible deflection vibration = noise

just my look on things you understand.

R,
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Martin [Admin]

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Re: shaft and motor alignment
« Reply #22 on: August 08, 2008, 04:27:02 PM »

Agreed. in very tight installations, I've used solid coupling to make up an entirely solid drive line.
With a solid drive line, I've mounted the motor in place, assembled the driveline, left the stuffing tube free
while it was glued in place which leaves the the tube to take on the the natural angle.

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DickyD

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Re: shaft and motor alignment
« Reply #23 on: August 08, 2008, 04:51:39 PM »

Does that allow for any movement in the motor shaft. ie wont the weight of the propshaft put the motor shaft off centre, and wont it still be off centre when you glue the prop shaft in. :-\
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Martin [Admin]

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Re: shaft and motor alignment
« Reply #24 on: August 08, 2008, 05:51:56 PM »

When I done it, the motor is in it's final fixing place which is best alignment as possble and
the tube and shaft are loose in the hull hole. With everything tightened up, it's already lined
up and held in place by itself, all you have to do is glue in place. Only recommended for small
installations, flexy shaft setups or Very confident builders!

On another note, just browsed through Terry Smalls build of the Slipway FSB Tenby Scale 1:32,
he used electrical "choc block" connectors as solid couplings!?!?!? The thing must have shook 
itself to pieces in minutes!
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