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Author Topic: Paddlewheel design specs questions  (Read 450 times)

Offline bobworkman

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Paddlewheel design specs questions
« on: September 15, 2018, 11:10:56 PM »
Hi

So I am working on design for a DIY paddlewheel and a few questiona seem to need answering.

First and foremost what is the most common method of attaching a plastic wheel (hub & spokes etc) to the metal drive shaft? E.G glue or setscrew.

2nd, what is most common/useful sized shaft to use for the drive shaft? E.G 6 mm or 8 mm etc.

What is a good/common spoke size? E.G. 2mm x 3mm.

Does material matter for this dimension ?   E.G plastic vs wood.

I am working on a parametric 3d model which can then be printed on a 3d printer and while my design is a
representative Mississippi Steamboat with a full width paddlewheel  I hope the design will allow definition of parts suitable
for sidewheelers as well. Current design is only for fixed paddles.

I have attached a preliminary version of my hub. It is designed to handle 16 spokes each 3mm wide and 2mm thick
and a drive shaft size of 6 mm.

Thanks in advance for any input.

« Last Edit: September 17, 2018, 12:12:47 AM by bobworkman »

Offline Bierjunge

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Re: Paddlewheel design specs questions
« Reply #1 on: September 17, 2018, 05:10:33 PM »
I have attached a preliminary version of my hub. It is designed to handle 16 spokes each 3mm wide and 2mm thick
and a drive shaft size of 6 mm.
These values seem reasonable to me, but we don't know neither about your prototype, nor your model scale or size.
In general, I would suggest to stick as close as possible to scale, even if it might be a generic freelance model with no particular prototype.

In this respect, I cannot recommend highly enough Alan bates' books The Western Rivers Steamboat Cyclopoedium and The Western Rivers Engineroom Cyclopoedium. Besides countless other useful data, information and data, they contain tables with typical measures and specifications for all relevant parts, timbers, flanges, shafts and so on of a typical steamboat and its wheel, all being derived from the engine size.
So I would suggest to calculate these values for your type of steamboat from Alan Bates' tables and formulae, and then divide them by your chosen model scale. But in the end, it is not unlikely that you end up at similar values you already have given.

Moritz

Offline bobworkman

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Re: Paddlewheel design specs questions
« Reply #2 on: September 17, 2018, 10:32:50 PM »
Thanks for your reply.

The specs I am using where taken from a collection of plans downloaded from this site.
I am not really sure of the scale as the full size dimensions are not on plans, model is 1265mm.

My CAD model (Openscad) will be parametric so most features of wheel will be able to be changed.

My biggest question is how to secure the wheels to the drive shaft. Glue seems unreliable and a setscrew hub is rather bulky.
A commercial metal flange may be smaller but I am trying to avoid the need to source fittings.

Bob

Offline Bierjunge

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Re: Paddlewheel design specs questions
« Reply #3 on: September 18, 2018, 01:46:46 AM »
The shaft of real steamboats usually had hexagonal sections where the flanges were fitted.
In model scale however, a simple pin through flange and shaft might be an unobtrusive solution.

Moritz

Offline bobworkman

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Re: Paddlewheel design specs questions
« Reply #4 on: September 18, 2018, 03:11:28 AM »
Had not though of a simple pin drive. would not need to be as big as a set screw hub and  could be backed up with glue if paranoid. I will likely size drive shaft based on available bushings/waterproof bearings.

That decision made I now finish design for wheel. Paddles will be easy so I should be firing up the printer RSN.
 Thanks
   Bob :beer

 

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