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[MvModeller]

Hello and Happy New Year....


Been thinking about what type of drive to install in my model. I like the idea of the drive being as quiet as possible, also the area where the propshaft enters the hull through the keel is quite tight, Ive tried to look for a propshaft thats shorter than 4inch but cannot find any. I have read that the knuckle joint? On the shaft causes quite a bit of vibration and noise,as it would be on an angle, so I did some research and I came across a belt drive motor (MFA Torpedo) that I think might help, but would appreciate some expert advice.


I have provided a link to an Image that I have drawn onto to explain the issue and hopefully a solution?


https://www.instagram.com/p/BsGnRaSnK-U/?utm_source=ig_share_sheet&igshid=1kopeiz6g0mjk


The Ruler is there as a guide to show how much room I have.


Please do Move this post If I have posted in the wrong place

[Taranis]

Steve at model boat bits will make you a prop shaft. Not expensive https://www.modelboatbits.com




https://www.modelboatbits.com/MIDIDRIVE-SHAFT-TUBES-1

[Fred Ellis]

I have belt drive in one of my tug's, I think that my late friend had to use it as there was no room to fit direct drive along with the battery, 
I find it to be very quiet

[nemesis]

You could also use a rubber inset coupling, "cheapest option". If you get the shaft from Steve look at his catalogue as he does the couplings I have just mentioned. nemesis

[taucher]

You need stuff ? https://www.maedler.de/product/1643/zahnriemenraeder-zahnriemen-und-zubehoer

Note that everything has the same profile.


Ralph

[chas]

I get the impression your model is around 30 inches long, and a stately model. Keep life simple, use a small motor, for example a 385 on 6 to nine volts and use a pulley on the motor and shaft. 2 to 3 to one reduction with an O ring between them will be fine. It's easy to install, cheap, simple and reliable. This method has been used for decades and still much favoured by many experienced modelers. To get a 4 inch prop shaft and tube, either get one made, or if you want to learn a new skill make your own from brass tube and rod. Simple bushes are easy, and a die will put the thread on. If I were making this for myself, I wouldn't bother with bushes on such a short shaft. These are fine for low powered models.
Chas

[tonyH]

How narrow do the last couple of frames get? Or is it a nice fat hull down to the keel?

[malcolmfrary]

What size is the boat that is being fitted?  A short shaft on a very small boat makes sense, but a larger one will have room for a more common size, allow a slight angle and a nice straight run to the motor via tha coupling.  Not many boat models where the motor needs to live in the confined space in the stern.

[MvModeller]

The ship is 1100mm x 220mm, its a Bulk Carrier so not a speed boat. The keel Tony is not that narrow, but its height has become the issue.. its 1 inch high at the frame after the prop exit area, but half inch at its lowest point ( might want to see the image in my last post to understand that) I didnt really want to reduce its height anymore along the keel incase it weakened the area.


Chas when you say O ring do you mean a belt drive set up or somethingb els.. sorry a little new to the tech terms.


I was hoping to install a brushless motor to this model as it sounds appealing to me, I'd also like a smooth slow realistic speed with this... The plans suggest a 48mm diameter 4 blade  propeller. With my lack of experience in this hobby with regards to power and drive, theres so much on the market its difficult to know what will work with the best outcome.


[size=78%]MV  [/size]

[Tug Fanatic]

………………..Chas when you say O ring do you mean a belt drive set up or somethingb els.. sorry a little new to the tech terms...……………...

I use the same system. A pulley on the motor & another on the propshaft with a O ring used as the "elastic band" that goes around them. I have generally use 2 pulley & O rings but I use larger motors driving larger props than you are planning. The difficulty that I have found is knowing which O ring to buy. You need it tight enough that it will not slip but any unnecessary tightness just puts load on the propshaft / motor bearings. The more powerful the set up the bigger the problem.


I am planning on going over to belt drive with toothed pullies as it requires little tension and the parts can be purchased very easily. I have sadly lost the friend who used to make the pulleys for me.

[chas]

Hi again, the O ring I mentioned is a fat-ish rubber ring. However as your model and its prop are larger than I guessed I withdraw what I said, too much chance of slip, although a double pulley will work as has been said. I would be fitting a toothed belt and a 545, or 555 motor with a 2 or 3 to 1 reduction. I would also use a steel shaft and decent bearings because there is a significant side load and brass would wear out.
    All that said, I wonder if you can't angle the shaft a little and lengthen it to make an easier installation. Lots of choices then and experimenting with motors is a doddle. Most of us make a cut out in the keel when it's needed for the motor, there is plenty of strength once the planking / skins are on.
Chas

[Fred Ellis]

I know that M.F.A. do toothed pulleys and belts. www.mfacomodrills.com

[hopeitfloats]

toothed belt drive on my bulk carrier. twin props both turning the same direction. hasn't caused any problem and quiet and reliable.  it looks ugly as a hat full of spiders but cant be seen unless hatch is off so all is good. 

[Subculture]

SHG marine do a nice range of pulleys and belts. They can supply in aluminium or resin, the latter are cheaper and should be perfectly adequate for model use.

Another very inexpensive source are GT2 pulleys off ebay. These are used a lot for 3d printers, so are cheaply produced, a couple of pulleys and belt can be had for about three quid or less if you but them in lots of five or more.

The snag is you may need to machine a bush, as they tend to come with standard size bores which may be too large for your application. Easy enough if you have a small lathe, else you're probably better off with the alternative suppliers.

[Tug Fanatic]

is GT2 really meaty enough with the right profile for larger motors?

[Subculture]

I guess that would depend on what your idea of 'large' is?

Certainly more than adequate for what the original poster needs. Nothing I would wish to build would need anything more, but I'm not into super size stuff. Generally I favour direct drive, and only go for reduction if I need very low RPM and plenty of torque.  Plenty of information and calculators online if you have an idea on the power transmission needed.

[radiojoe]

I see from your photo, you have drawn the shaft level ?  it's quite acceptable to raise the forward end and have an angle on the shaft this would give slightly more room for the prop and negate the need for a belt drive.


Joe.

[John W E]

hi there, judging by the size of your model that you give (just over a meter) its a similar size to the Duburg model which I built a while ago of a cargo vessel.


this has a direct drive with an MFA 540 low drain motor driving a 50 mm prop.  There is no real requirement to put a belt drive in unless space is really tight.

[Plastic - RIP]

I think I'd be using a long drive shaft to put the motor in the middle of the boat with direct drive. Much simpler, easier to sort out any problems and accessible for maintenance.

[MvModeller]

hi there, judging by the size of your model that you give (just over a meter) its a similar size to the Duburg model which I built a while ago of a cargo vessel.


this has a direct drive with an MFA 540 low drain motor driving a 50 mm prop.  There is no real requirement to put a belt drive in unless space is really tight.

With a 50mm prop, powered by a 540 low drain motor... is there any rules or recomended sizes for the Shaft?  For this size Model?

[NickelBelter]

4mm is a very common size and will give you a wide range of props to use.  You can also cut down existing stuffing tube - I've done this a lot with Caldercraft shaft and tube assemblies in order to model exposed shafts on warships. 

[GG]

NickelBelter has the right idea.
Take an existing prop shaft and tube assembly, cut the tube down to the desired length, knock out(carefully) the bearing from the discarded tube and refit into the cut down length.
The prop shaft can then be cut to the required length.  The new inner end of the prop shaft will be smooth, but this is only a problem if you are determined to use a threaded coupling.
Glynn Guest

[MvModeller]

Many thanks for your replies, So 4mm being the thinkness of the rotary part of the shaft, M4?
I shall look into them, the model is as mentioned just over a 1m,
I have seen a 5inch long shaft that is 4mm.. does it make any difference being shorter or longer on a model of this size?


Im also likely to have a coupling between motor and prop

[Colin Bishop]

Shaft length is irrelevant. There just needs to be room for a prop at one end and a coupling and motor at the other. A M4 (4mm) diameter shaft is pretty standard for this application. Length of shaft is generally determined by where you want to place the motor.

Colin

[MvModeller]

Thats great thanks colin. I have ordered an M4 shaft, 5in. Now i just need a coupling.. I dont want to much vibration, ive heard this could be a problem. Do you recommend a coupling with a rubber center?


Im looking at getting the MFA silent 5 pole motor... just need to learn about how to wire it up, then im pretty much there.


I have my radio gear,  any recommendations for the power supply? Battery type? Wanna keep this simple here..