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Author Topic: True C/V joint.for our boats  (Read 17086 times)

Stavros

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Re: True C/V joint.for our boats
« Reply #50 on: March 10, 2013, 06:28:06 PM »

Am I now going to throw a spanner in the works with this.......Yes I applaude you for all the hard work that you have done with this but suerly a CV Joint is designed for things that move in various planes.
 
What I am getting at is that when an engine or suspension moves a CV joint is designed to allow for that movement either in an up and down plane or side to side.Our Model motors simply do not move they are static.
 
The way I see it and fully agree that allignement is parramount to smooth running of the shaft to elliminate any wear on the bearings on the shaft let alone the motor.
 
I use a solid coupling to join my shafts to motor and pack up the motor to give perfect allignment of shaft and Motor.....thus elliminating the use of a coupling.I will only use a solid coupling for high reving motors...ie brushless or silly voltages of a 900 motor.
 
Also I make sure that the shaft end near the coupling is solidly mounted to eliminate any shaft movement and also the prop end can not whip either.
 
If I have a small Model I will still set up with a solid coupling then use a huco type coupling.
 
What are the advantages of using a cv joint if your motor shaft are aligned initially with a solid coupling ?????
 
Or would it be advantageous to use some sort of rubber mountings under the motor to allow the CV to work properly ??
 
 
 
Dave
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oldiron

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Re: True C/V joint.for our boats
« Reply #51 on: March 10, 2013, 06:33:40 PM »

  Ian
    Youíre correct, a hydraulic coupling would certainly be a Cadillac way to drive a prop shaft, however, as you pointed out it would be completely impractical from an expense and engineering standpoint in our models.  As to Uncle Henryís single universal joint, donít forget that was done with a torque tube arrangement that kept the rear end in constant alignment with the shaft while the differential moved up and down in a fixed arc with the arcís center at the universal joint at the rear of the transmission. In that case you can get away with one Cardan joint. Not ideal, but it works.  On a model boat we are at a disadvantage due to size of equipment and skill of the various builders. It may be true that correct alignment of the prop shaft and motor shaft is easy by using a piece of tubing to do the aligning, I know that not every modeler has the skill, despite his work ethic, to know how to do the job properly. Thatís not my judgment, but reasons offered by fellow modelers building their own boats.  In that case you are bound to get the motor out of alignment in one or more planes due to poor alignment (and the alignment situation works the same on both sides of the Atlantic). If the motor shaft and prop shaft alignment intersected at exactly the pivot pint on the Cardan joint you would have a point that one U joint would suffice (go back to Uncle Henry). However, since we canít guarantee alignment in one plane, we are certainly not going to guarantee alignment at a pivot intersection. Any deviation from those parameters is going to cause noise and vibration.  The solution is a double (phased) Cardan shaft arrangement or something along the lines that Mick is promoting. Either arrangement falls into the capabilities of all modelers and produces a quiet smooth running vessel.  Donít forget this whole thing started a year ago when some one asked ďwhy does my boat run noisy?Ē

John

 
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vnkiwi

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Re: True C/V joint.for our boats
« Reply #52 on: March 10, 2013, 06:50:54 PM »

Hi Stavros,
good to get your two bob's worth.
Our models are usually made from wood, in its various forms, or fibreglass, and as such flex, and move with temperature, and moisture content. I agree that IF our motors and shafts where perfectly aligned, then all will be quiet and smooth.
In real life, this is just not going to happen, with varying degrees of misalignment.
Also, the practice of fixing the motor solidly to the hull, as is the shaft tube/bearings, simply ensures the best sound path from the motor to the sounding box, the hull, so that any vibration/noise is amplified, usually more than somewhat.
Even though I've been guilty of solid fixing, I am now going back to rubber mounting my motors in all my boats.
They do run quieter, but necesitate a coupling to allow for this.
I'm sure Mick is on the right track, and will achieve what he's looking for. Just wish I had access to machine tools, and had the skills to use them
cheers
vnkiwi
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irishcarguy

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Re: True C/V joint.for our boats
« Reply #53 on: March 10, 2013, 07:46:20 PM »

Hi Stavros I too use alignment sleeves to set up my alignment, In a mad moment I made a complete set with just about every combination you could think of. However there are a wide range of skills on here & experience teaches me that we are not all created equal, you only have to look at some builds to see how far out of alignment some shafts & motors are. I still feel happy if I am within 4/5 degrees & really that is not that good. This is not for the experts among us, it is for the guys & girls where skill is limited & it gives them a better set up with no headaches. It is not expensive to do & most us of know someone with a machine that will do it for us if we ask nicely. For me it works well & I am happy with the results. That will not stop me trying to build a better mouse trap however, I am now off the model shop to try & find the other half of the dogbone end. Mick B....     
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Mick B.

Circlip

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Re: True C/V joint.for our boats
« Reply #54 on: March 10, 2013, 08:10:07 PM »

Firstly yes John, the Enery saga, I used to have a Ford special with that configuration on it, (38 10HP base) and later on a different car, double Hardy Spicers with a sliding spline cos the back end moved in different directions and about forty odd years ago my first "Lemon" sorry, Citroen "G" series with trick gas suspension and C/Vs. So I am fully aware of the coupling systems.
 
 Your picky shows the problem precisely and the top two diagrams can be coupled with Micks C/V or more cheaply a single ball joint. I'm not even adding a Huco cos we know it will couple anyway.
 
  It's the second two pictures that highlight the main grunt. This is where inefficiency abounds for drive loss as there are two couplings needed .
 
 Now with the  most basic bits, sixty years ago we could achieve a situation that the top two pictures represent at worst case, the angular line up in both directions was better, then to even think that we can't match this shows how much we have "advanced" to have to consider the second two. In that example a good ole pin and disc would be better and take up far less room.
 
  One advantage of the double carden and miss alignment, - you don't need a separate "Noise" generator to sap your batteries.
 
  Regards  Ian
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Norseman

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Re: True C/V joint.for our boats
« Reply #55 on: March 10, 2013, 09:44:01 PM »

Thanks for the illustration John - any new lads looking in will find it a great help too. 

Dave
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irishcarguy

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Re: True C/V joint.for our boats
« Reply #56 on: March 11, 2013, 12:23:53 AM »

Hi Stavros, yes I think it would be an advantage to put a rubber base under the motor after alignment with a solid coupling & then using the C/V joint.You would have to try different density rubber to test how it deadened the sound, also you should use lock nuts on the mounting bolts if mounted on rubber. I am afraid I did not have any luck finding the outer dogbone matching end,no stock. Mick B.
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Mick B.

oldiron

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Re: True C/V joint.for our boats
« Reply #57 on: March 11, 2013, 02:58:08 AM »

  Drawing from my old model railroad days, I used to mount motors on a base of silicone sealant. Set down a pad of the sealant, then place the motor in it. There was enough stickability in the sealant to keep the motor in place and provide a sound deadening.....no bolts required. I never bothered on boats, as once they're off the dock I can't hear them anyway.

John
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Mad_Mike

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Re: True C/V joint.for our boats
« Reply #58 on: March 11, 2013, 08:35:36 AM »

circlip what are these ball joints or ball and pin your talking about, I googled it and could only find caravam tow bars. Is the same as these dog and bone couplings?
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Circlip

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Re: True C/V joint.for our boats
« Reply #59 on: March 11, 2013, 09:09:34 AM »

Don't need to use Goggle Mike, posts #7 and 9 are much closer  O0
 
   Regards  Ian.
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Mad_Mike

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Re: True C/V joint.for our boats
« Reply #60 on: March 11, 2013, 12:38:49 PM »

ah the dog n bone couplings. awesome name that. I use to have an toy rc truck with them on, but only for the propshaft. It being 4 wheel drive the steering couplings however had dog and bone couplings but with 4 pins rather than just 2. They looked like these:
http://www.vac-u-boat.com/images/Catalog/M10456.jpg

It took so long trying to find a pic to show that i forgotten what point i was trying to make
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Circlip

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Re: True C/V joint.for our boats
« Reply #61 on: March 11, 2013, 12:49:19 PM »

Similar, but those of fifty years ago are like the ones in 7 and 9, only half what you show  :-))
 
  Regards  Ian
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tt1

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Re: True C/V joint.for our boats
« Reply #62 on: March 11, 2013, 01:26:10 PM »

 {-) {-) {-)  Know the feeling (Mad) Mike  O0  been there done ....(Do!) that many times, oldtimers setting in for me I think %%  Good pic of the coupling though.
              Mick - Irishcarguy, admire your integrity and your relentless pursuit of success in your project - as do many others no doubt I wish you well   :-))    Kind regards, Tony.
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Mad_Mike

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Re: True C/V joint.for our boats
« Reply #63 on: March 11, 2013, 02:29:17 PM »

Similar, but those of fifty years ago are like the ones in 7 and 9, only half what you show  :-))
 
  Regards  Ian
What i was saying was though that the truck had both, but the angles were most extreme and continuously moving on the front wheels it had 4. If a 4 point type dog and bone coupling was used, then the slots could be opened up to allow for some sideways movement. I dont think this would work very well for 2 a pin type especially at angles because the pins would come out under torque. Also with 4 pins because at least 2 is allways in proper contact i suppose you wouldnt lose the efficieny threw the coupling that you get with UJ type couplings at extreme angles. Ive drawn a picture anyway :embarrassed:  The dog is see threw so you can see how the bone would fit inside it.
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Circlip

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Re: True C/V joint.for our boats
« Reply #64 on: March 11, 2013, 02:38:30 PM »

As soon as you induce an angle into the joint, efficiency does a nose dive. Most efficient is a straight line.
 
  Regards  Ian.
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vnkiwi

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Re: True C/V joint.for our boats
« Reply #65 on: March 11, 2013, 05:29:37 PM »

Most efficient is a straight shaft. Motor with bearing solid one end, prop with bearing solid other end.
As per some brushless installations.   O0

That 4 pin dog bone is better than the 2 pin variety, in my humble opinion anyway.   %) But would have to try one.

The aim here is to see how near one can get to an efficient, quiet method which takes up misalignment, with minimal power loss.
just my thoughts, should have stayed in bed, think its going to be one of those days   >>:-( :o

cheers
vnkiwi   %%
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Mad_Mike

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Re: True C/V joint.for our boats
« Reply #66 on: March 11, 2013, 05:34:36 PM »

of course you would not have angle such as that in the picture but the coupling would compensate for some angle and misalignment.
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irishcarguy

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Re: True C/V joint.for our boats
« Reply #67 on: March 11, 2013, 07:32:03 PM »

I like that 4 pin joint Mike, it is better I think than the 2 pin one which is on the other end of the shafts that I got. The beauty of C/V joints is that they do exactly as their name employs & that is keep the velocity constant at different angles. Thanks Tony for the vote of confidence, I feel like a pit bull sometimes,I find it hard to let go until I feel I have solved the problem....Cheers, Mick B..
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Mad_Mike

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Re: True C/V joint.for our boats
« Reply #68 on: March 11, 2013, 08:35:38 PM »

i dunno what its called that type of coupling. It of course wouldnt suit seriously angles connections but probably still better than a huco. I dont think that the velocity would dip either but it could possibly be still noisy if its slightly baggy to compensate for misalignment. It would need making and testing.
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oldiron

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Re: True C/V joint.for our boats
« Reply #69 on: March 12, 2013, 04:18:45 PM »

 A friend of mine just brought over an HO 4-4-0 model steam locomotive produced by Rivarossi many years ago. Its tender drive as the loco is so small. What really hit me was the universal set up between the engine and tender. Bear in mind a tender can move in many directions relative to the locomotive so a good smooth universal is vital.
  The closest thing I can relate it to is a poor man's constant velocity joint. The "dog bone" (if i may call it that for now) has a hex at each end. This hex fits into a corresponding receiver in the tender (motor end) and the locomotive (driven end). The dog bone can move freely in the receivers in any direction with no hinderance. For us, its very easy to make from hex brass shapes. I dare say a half hours work would have enough made up for a twin prop vessel with no special tools and be very inexpensive.
  In fact the parts would appear to be available here:
http://www.bowser-trains.com/Parts/Parts.htm


John
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Re: True C/V joint.for our boats
« Reply #70 on: March 13, 2013, 05:04:36 AM »

I take it the joint is held in place by the position of the locomotive relative to the tender, sort of like the Dumas dogbones?


I have always liked the dogbones as they can take a fair bit of misalignment, can be threaded easily to attach on threaded shafts and they can be extended by cutting the nylon part and fitting a brass/aluminum tube over it (and pinning that in place, of course).  I installed a new motor in my tug 'Peninsula' which is significantly larger in diameter than the original, meaning that the motor could not be aligned with the shaft (keel was in the way).  Dumas coupling was duly extended, drilled out to fit the huge new motor shaft and it works just as well as it did originally
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hopeitfloats

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Re: True C/V joint.for our boats
« Reply #71 on: March 13, 2013, 05:27:35 AM »

i have seen the same system as oldiron has shown using 3/16'' rod with nuts screwed on either end and a 1/4'' drive socket to suit the nut being used as the female part of the connector. i guess that could also be scaled down and the same type of set up used on a boat.
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oldiron

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Re: True C/V joint.for our boats
« Reply #72 on: March 13, 2013, 10:41:40 AM »

I take it the joint is held in place by the position of the locomotive relative to the tender, sort of like the Dumas dogbones?


  Yes, you're quite right. I like the Dumas dog bones myself too. Mick has been advocating, rightly, a constant velocity joint. When I looked at this yesterday I thought there's a nice cheap way of getting pretty close to the same thing. I've got some telescoping brass  hex stock, I'm going to try building one.
  That socket/nut idea sounds good for larger vessels.

John
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grendel

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Re: True C/V joint.for our boats
« Reply #73 on: March 13, 2013, 11:18:24 AM »

just a thought and going right back to basics, there already exists a similar pairing in the allen key and allen screw -






now while I can feel the setup binding slightly when it gets a long way off alignment, it does seem pretty smooth when its close to alignment, plus it has the advantage of allowing the joint movement within the socket back to front, just thinking here it might be another good start point for a coupling.
Grendel
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Mad_Mike

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Re: True C/V joint.for our boats
« Reply #74 on: March 13, 2013, 11:42:17 AM »

I like this hex idea you lot got going on. If you make the coupling oldiron post it on here. The only thing that would concern me about it being brass is that the hex might round off. The allen key/screw idea is brilliant. You would just need to cut the angle off the the end of the allen key and then lock it in one of these chuck type couplings:
http://www.ebay.co.uk/itm/PZ216-1pc-couplings-flex-4mm-motor-to-4mm-Flexible-Aluminum-alloy-Methanol-boat-/111016901019?pt=UK_ToysGames_RadioControlled_JN&hash=item19d91f799b
or even 2 sleaves with grub screws would do it for the motor and propshaft end.
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