Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[Colin Bishop]

Double joints do make for a long coupling which can impose mounting problems.

As I implied earlier, this topic seems to concentrate on varieties of direct couplings when in fact a degree of gearing using a pulley drive will give a much more efficient result.

Colin

[grendel]

stationary engineer - you made paper planes ?   

[davejay]

Crikey........I never thought I would cause such an uproar in opinions, I guess that what forum posts do sometimes. My intention wasn't to cause a global contest in what is better and what is not, we should leave that to Trump and the little rocket man!


My issue with the coupling thing is.....if I use one Huco UJ it brings the motor closer to the shaft end and because the motors are mounted on a plastic type dedicated motor mount there is not enough free space under the mount to bolt/screw the mount to a ply sub base, using two Huco UJ's pushes the motor and mount further towards the fore and gives me sufficient space under the mount to build a sub mount under the motor mounts which would in turn glassed in to the hull and the motors would be in the right place for the centre of balance (crucial apparently on planing hulls).


My initial question was......with two couplings is perfect alignment crucial..........I like to do things perfectly and both couplings will be perfectly aligned (as near as poss).


Cheers Dave

[Stan]

Hi Dave  if you are happy using two huco couplings  go for it. During our conversation I did say that I two couplings on my fishing boat due to mis alignment it works fine no vibration or noise. Hope all goes well looking forward to some pictures.




Stan.

[imsinking]

The simple answer is , a SINGLE huco type UJ will NOT allow an offset drive line . . .  the centre line of the motor & the centre line of the propshaft MUST intersect at the centre of the coupling , you can angle it sideways , up or down but not off the centre lines . . .  a double UJ with an insert to connect the UJ's to each other will allow an offset centre line , not too far off tho' otherwise you'll lose power , I notice a lot of solid couplings now with high speed Brushless motors , could this be the way to go , make an custom extended coupling to suit your set up ? just a thought . . . .
Bill

[canabus]

Hello All
I have had this problem of alignment of the motor and after three days I finally got it right.
It all works OK direct drive, but what pain in the butt !!
So, I had my go to mate make a disc with a 4mm centre hole for the shaft and the holes for 28 and 35mm motors.
You can change this to your requirements.
My next boat I installed the drive shaft and before skinning the hull.
I setup the engine mount with the alignment disc bolted to the motor mount.
A close alignment of the motor mount and with a reinstall to epoxy glue the motor mount bracket all done!!
Installed to motor and direct drive coupling(my go to club mate, again ) .
The drive shaft went straight in and after two years of running, no bearing problems.
This is all running in a brushless motor setup in a little Sea Hornet at a loaded rpm of about 20,000 rpm max.
Forward planning of setting up you boat is the big key in saving you a lot of headaches, time and money.

I built this boat and I am installing motor, drive lines and radio's later!!!!

Canabus

 

[chas]

Hi Dave, my apologies for helping to distract the thread from your question. In my opinion, go for the double Hugo coupling. They might not be my favourite, but they are commonly used and recommended by Deans, who definitely know their business. You mention getting as near perfect alignment as possible, that all any of us can do.
  As for getting a lot of opinions, try asking about using grease or oil for the prop shaft.......wow, that can raise some hackles.
Best of luck with the build.
Chas

[Shipmate60]

If you need the space for additional motor clearance the easiest way is to use the double coupling.


Bob

[davejay]

Guys, I really appreciate all of your feedback, even if it did digress slightly, that's what happens in conversations (I've been to enough team briefings to know that!).


Anyway, I will go with the dual Huco couplings as it allows the clearance I require under the mount. These will be aligned as near as perfect as possible even if dual couplings do allow for some mis-alignment!


The motors going in are Deans Kestral V, not an over torqued motor I presume and are brushed motors rather than brushless..........I presume brushless motors have more torque and therefore a silicone type coupling would be more appropriate.


I tend to over-engineer things, hate the idea of failings etc.......comes from my RC aircraft days.........over-engineering is king with these guys!


Next question is....................oil or grease for the propshaft?..................JOKING!!


As I said, thanks for the feedback and taking the time to answer my question. Top guys on a top forum.


All the best Dave


Stan, I will endeavour to get pics on here sometime..........although they wont match the superbness of your builds, I can only dream of matching such glorious modelling. Thanks also for taking time to chat on the old dog and bone. Cheers mate and enjoy Blackpool!

[davejay]

If you need the space for additional motor clearance the easiest way is to use the double coupling.


Bob

My thoughts too Bob.


Cheers Dave

[davejay]

Hi Dave, my apologies for helping to distract the thread from your question. In my opinion, go for the double Hugo coupling. They might not be my favourite, but they are commonly used and recommended by Deans, who definitely know their business. You mention getting as near perfect alignment as possible, that all any of us can do.
  As for getting a lot of opinions, try asking about using grease or oil for the prop shaft.......wow, that can raise some hackles.
Best of luck with the build.
Chas

Hi Chas, no need for apologies, I value your input.


Wont ask the question about oil or grease!.......Although I might........may be not!

[steamboatmodel]

Hi Dave,
As for grease or oil a lot depends on what type and how much.
In my opinion;
If you are using grease, a thin coat will do the trick, you have to watch to see how the operating temperature goes. Used to run a tug with grease, which worked fine in the summer, but when the temperature both air and water you could barely turn the prop over by hand. Flushed all the grease out and then applied a thin coat, the model would then even work in ice water.
If you are using oil you want it thick enough that it does not seep past the bearings, and as with oil you have to watch the temperature.
As for the debate on couplings vs tubing, except for small models I prefer couplings.
Regards,
Gerald.

[grendel]

well I have been looking at the coupling for the second of two identical models, well they are not quite identical, as on the second I can just squeeze q 35mm prop on, whereas the first can only take a 30mm.
unfortunately inside the boat, the prop shaft is lower in the hull, and there is less space for the motor, time for a rethink.
looking in my box of model bits, I found a half shaft from a nitro car, with fittings, and a sort of cv joint.
the good part, the huco splines are a perfect fit inside the end pieces, so playing around with these pieces, I have found you can get quite a mis alignment of motor and prop shaft and still not lose any power. one of these pictures is the motor running at full chat - 7750 rpm

[steamboatmodel]

Those are Dog Bone couplings, they will take a fair amount of misalignment, but like a couplings work best when aligned as straight as possible.
Gerald.

[RAAArtyGunner]

Hi Chas, no need for apologies, I value your input.


Wont ask the question about oil or grease!.......Although I might........may be not!

No need to, it has already been done  as has the coupling, do a forum search, there is loads of good valuable commentary.

Knock yourself out.

It's "Model Boat Mayhem" for a reason

[irishcarguy]

Somewhere on this forum there has been a very long & some heated discussion & conclusions on the forum previously. Because of my background as an Automotive Technician ( ex U/K & X RAF trained I have removed & installed my fair share of U/Joints). 
Most rear wheel drive vehicles(skip the double & dual shaft ones) have two Cardan joints & they need to be aligned correctly or the dreaded vibration arrives & it is very nasty. However it is easily corrected if aligned properly. Here I say read the manual & then READ it again. If you use solid connectors you will need an assortment of these i.e.: one end to fit the motor shaft & the other end to fit the drive shaft. when connected properly you can now join them (motor & prop shaft ) in what should be as close to accurate as you can get with this setup. Now we move on to the C/V joint that has found its way into most front wheel drive cars these days. In my humble opinion this is still the best one. The curve that the ball bearings run in is very accurate & it can drive through a 29 degree angle in any plane without any measureable loss of power, the originals were first made for the B.M.C. Minis & had some teething problems but Sir Alex ( IGGI to his friends) & his brilliant team of engineers solved their problems but got very little praise for them. There are some 20,000,000 minis on the road today (or wrecking yards) all with C/V joints taking the power to the road without much problems. My last word on these C/V joints is read the workshop manual & then READ IT AGAIN. It is well worth the trouble if doing it right the first time can be considered trouble. Mick B. Irish car guy.

[imsinking]

CV joints ? A bit BIG for model boat's Mick    tho' if any one can miniaturize them  put me down for a few , come one you 3D printer's get designing , show us your skill's . . . .
Bill

[roycv]

Hi all, if you use a Shuco coupling that is threaded then it is essential to make sure this is square to the shaft.  If the plastic centre fails, they usually crack around the brass spline and are not always noticed but they can be replaced also a thick tube will do a great job as well.
Heat the plastic tubing up with boiling water first and it will slip nicely into place and resolve any stresses there might have been if fitted cold.
regards Roy

[canabus]

Hi All
Have a look at the metal uni joints at banggood website part No.87379.
Good price!!
3 to 4mm/3.17 to 4mm/4 to4mm/5 to 4mm and 5 to 5mm.
Free postage too!!!

Canabus

[RAAArtyGunner]

Hi All
Have a look at the metal uni joints at banggood website part No.87379.
Good price!!
3 to 4mm/3.17 to 4mm/4 to4mm/5 to 4mm and 5 to 5mm.
Free postage too!!!

Canabus

Also available from Aliexpress with free postage.

[Brian60]

Hi All
Have a look at the metal uni joints at banggood website part No.87379.
Good price!!
3 to 4mm/3.17 to 4mm/4 to4mm/5 to 4mm and 5 to 5mm.
Free postage too!!!

Canabus

I was going to offer this solution, the adverts keep popping up on my facebook page for r/c cars

https://www.banggood.com/Feiyue-FY-01FY-02FY-03-Upgrade-Rear-Wheel-Transmission-RL-RC-Car-Spare-Parts-p-1084002.html?rmmds=search

[Onetenor]

Another way round this is parallel shafts and either straight cut or worm and spur gears. Experiment I always say  In extreme circs they could be at right angles to each other . Now that's put the cat among the pigeons

[irishcarguy]

Hi John it might put your cat among the pigeons but not mine L.O.L. Mick B. in Canada.

[Onetenor]

Glad about that   One of our cats will be 30 on 5th next month and she chases seagulls here .The only pigeons are wood pigeons and they have more sense to land in our garden