Paddlewheel drive using servo modified for contonuous rotation

[rpringle1028]

Does anyone have any experience, good or otherwise, using a standard-size servo modified for continuous rotation to power the sidewheels for a small (18" LOA) paddle steamer (Talisman)?  I realize the final output wheel is revolving too slowly but I was wondering if the final "step-down" in the gear train could be removed OR if I could use a large-to-small O-ring pulley (with the appropriate ratio to get around 150-200 rpm) on the final circular output "horn".  I know modified servos are used to drive propellers for small models but I haven't seen any evidence that they have been used to drive paddlewheels.

Yes I know small models of this size are finicky at best but I need to build an N-scale (1:148) steamer for a model railroad and I would like it to operate in its own right as an R/C ship model.

Any comments would be appreciated.

[Cracker]

You could try instead of a servo one of the Polulu range of geared micro motors, available from Technobots in the UK. The motor and gearbox together weigh only about 10 grammes. The Technobots web-site has data-sheets for all of these motors, which are available with a many different reduction ratios.

For a speed controller I can recommend those supplied (at least in the UK) by Amazon, produced in China. Just do a search on the Amazon UK web-site for "10A ESC no brake". The controllers come complete with BEC, JST connectors and an on/off switch. They are very small, very light (9 grammes) and very cheap. They work too! The last batch of four units I bought was delivered directly from China in about ten days for less than £20 including postage! 

[rpringle1028]

Thanks to Cracker for the alternative method.  I have a bunch of older Futaba standard size servos that are too large for the aircraft I now fly so I was hoping to adapt one of them.  As I understand it, the servo electronics also provide speed control, both forward and backward, if the potentiometer is adjusted appropriately (or replaced with a resistor network).

Regards
Rob

[Eddy Matthews]

The following video should explain everything about converting a servo...

https://www.youtube.com/watch?v=iv6VsPzT_W0

Regards
Eddy

[chewbacca]

Happy New Year 2016 to all ,

I used this system for a radar it works well, 150 / 200tours are a little bit fast for wheels!

We find the point 0 of the potentiometer a point of cyano and it is OK.

[bill stafford]

be carefull, as small side wheeler paddlers dont work to well,as they are hard to ballast ,and tend to  be tender.
i have a 3/4 built PS Gemma, a very small murrey river paddler, ans a friend has built a similar small paddler, and ballasting is proving hard work.
my hull has increased draft+100mm beam, uses barrys paddle wheel kits+"O" ring drive, should have almost 300 rpm max. at paddle wheel shaft
bill s

[rpringle1028]

Hi Bill S
I am curious about the physics associated with increasing the draft to improve stability.  On the one hand, adding buoyancy down low would seem to increase the destabilizing moment.  On the other hand, adding ballast down low in the extended draft would seem to offset that.  Does the increased draft allow you to add more ballast down low to more than offset the effect of the added buoyancy?

Regards
Rob

[Ioicy]

Back to your original question, I do know a mini servo can move a 12" paddler, so I would guess a standard size would have no issues with an 18" boat.

Regards


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