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Author Topic: Dog-bone orientation  (Read 3979 times)

Jani

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Dog-bone orientation
« on: November 09, 2009, 03:19:07 PM »

Hi!

Who get's the bone, motor or the shaft?  :embarrassed:

I'm talking about the Dumas type dog-bone shaft coupling, and I'm wondering which way is the common practice to install these - will the "bone" part be at motor's shaft or in the propeller shaft?


Cheers,

^Jani
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Martin [Admin]

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Re: Dog-bone orientation
« Reply #1 on: November 09, 2009, 03:59:16 PM »

Good question Jani!

 I've only used them a couple of times and I've usually fitted the 'bone' to the shaft and the socket to the motor....

 PS. Welcome aboard the good ship Mayhem!


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HS93 (RIP)

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Re: Dog-bone orientation
« Reply #2 on: November 09, 2009, 04:12:45 PM »

normally they are threaded for an IC motor and shaft so they will only go one way can I ask what you are using it on as they can be very noisy both in sound and electrically And interference (due to metal to metal)  and so the ones with a plastic or rubber insert is normally used

Peter
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Jani

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Re: Dog-bone orientation
« Reply #3 on: November 09, 2009, 05:09:42 PM »

I've only used them a couple of times and I've usually fitted the 'bone' to the shaft and the socket to the motor....

 PS. Welcome aboard the good ship Mayhem!


Thank You, it's nice to be here. Hope I can contribute something someday :)

One might ask "Why won't you just pick one and be done with it", but I'm asking this since I've already, in this very early stage of my hobby, have benefited from adopting commonly chosen approaches, plugs, etc. So much so, that I would even consider it important to follow these conventions, what such there may be.

Searching pictures from the web hasn't really brought conclusive evidence one way or the other. If nothing else, I will most likely go whatever way gets more "votes" here  :-)

^Jani
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Jani

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Re: Dog-bone orientation
« Reply #4 on: November 09, 2009, 05:13:57 PM »

normally they are threaded for an IC motor and shaft so they will only go one way can I ask what you are using it on as they can be very noisy both in sound and electrically And interference (due to metal to metal)  and so the ones with a plastic or rubber insert is normally used

Peter

Hi Peter,

The ones on my hands currently are plastic cast housings and brass inserts such as the accompanied picture (hopefully - my first attempt to include pictures) shows;

Original higher resolution image can be found at this link;
http://img18.imageshack.us/img18/2146/09112009386.jpg

^Jani

EDIT: My inserts are not threaded, and these can be installed either way. Are these kinds of couplings meant to be operated in one specific way - you mention vibrations forexample?
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HS93 (RIP)

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Re: Dog-bone orientation
« Reply #5 on: November 09, 2009, 06:35:16 PM »

what type of motor are you going to use it with ?

Peter
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Jani

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Re: Dog-bone orientation
« Reply #6 on: November 09, 2009, 06:56:27 PM »

what type of motor are you going to use it with ?

Peter

Motors are Bühler 1.13.055.220 (slightly customized as may notice comparing the datasheet picture with the attached picture, but not that it has any relevance here). 12V, 13W low r/min and reasonable torgue - within the propeller requirements.

Shafts are Raboech 4mm (301-07) and propellers are 40mm 4-blade R and L plus 45mm 5-blade R and L props. Total of 4 motors and shafts.

Cheers,

^Jani

EDIT: Forgot the datasheet link; http://www.buehlermotor.com/C12572D40025EAF8/vwContentByKey/W274AHF5391WEBRDE/$FILE/DC-Motor-1_13_055_de.pdf
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Jani

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Re: Dog-bone orientation
« Reply #7 on: November 12, 2009, 09:02:06 AM »

what type of motor are you going to use it with ?


Are these kinds of couplings meant to be operated in one specific way - you mention vibrations forexample?

I'm wondering if this type of coupling is used rarely... :-)
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grasshopper

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Re: Dog-bone orientation
« Reply #8 on: November 12, 2009, 09:39:18 AM »

As long as the coupling doesn't 'bind' at any point, then either way round works.
Just remember to align the motor and shaft as accurately as possible - when setting motor and shafts up, I fit the couplings to both parts and then clamp together using split tubing and cable ties, then screw down / glue in and when set/hardened, remove clamps and half tube and that should be that.

Some manufacturers actally supply alignment pieces - same length as coupling but solid for just this purpose.
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dodgy geezer

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Re: Dog-bone orientation
« Reply #9 on: November 12, 2009, 10:17:31 AM »

Good question Jani!

 I've only used them a couple of times and I've usually fitted the 'bone' to the shaft and the socket to the motor....

 PS. Welcome aboard the good ship Mayhem!



I also have used them with the socket at the motor end and the ball-end (bone?) on the shaft. That was how they were tapped for prop-shaft and crank-shaft when I last used them, on an I/C boat, in the 1960s....

I suspect that the connector developed from the old 1930s connection technique of drilling two holes in the motor flywheel face, and fitting posts into these. This is the way lots of marine motors came from the factory. Then the shaft would have a disk or t-bone end which the two posts meshed into. The illustrations below give the idea....
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dodgy geezer

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Re: Dog-bone orientation
« Reply #10 on: November 12, 2009, 10:19:07 AM »

whoops - didn't give the motor end as well....
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Circlip

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Re: Dog-bone orientation
« Reply #11 on: November 12, 2009, 01:05:20 PM »

Ditto to D/G, socket on motor (I/C) Funnyly enough, the first type of uni couplings offered for I/C engines before RipMax sold a good one was the brass Straight knurled ones you show but WITHOUT the plastic mouldings. What they did supply was a thick PVC sleeve type material, superb at breaking prop shafts when driven by a "Racer".  Thanks Max Coote for saving me Dad going prematurely grey.

   Regards  Ian.
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dodgy geezer

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Re: Dog-bone orientation
« Reply #12 on: November 12, 2009, 02:11:32 PM »


I suspect that the connector developed from the old 1930s connection technique of drilling two holes in the motor flywheel face, and fitting posts into these....

and by the 1960s a motor from the factory might look like the picture below...

I'm pretty sure it doesn't matter which way round they are connected, but the weight of history suggests the ball on the shaft and the socket on the motor. A bit like your hip joint.... and who are we to go against tradition....?
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Jani

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Re: Dog-bone orientation
« Reply #13 on: November 12, 2009, 04:00:38 PM »

Looks like most have seen or used these in socket-in-motor and bone-in-shaft way around, so in order to be conformist I shall adopt that way as well.

Oh and the tube idea for alignment help is brilliant idea, cheers grasshopper!

^Jani
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