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[derekwarner]

Hullo George......who says .... "In all my years working in the engineering industry with 10 years in a gear box manufacturing company this is the first time that I have heard such a statement" .....odd to even gearing...... 

I did not invent this...but in my basic grounding 30 something ++  years ago.... in the 'history of mechanical computers for train & elevation of gun mounts from WW1 ' included the fact that gearing was odd to even ratio + included antibacklash compensation...remember we are only talking straight cut bronze on bronze gearing of approx 3/4" to 1 1/4" to 2 1/2" diameter

The same engineering protocol relates to roller chain pinions.........Derek

[nick_75au]

Heres a couple of links that may be able to help you out

http://www.econobelt.com/

I found them to be much cheaper including shipping than local suppliers if your willing to trawl through it

jdarke1@tpg.com.au

John Darke of Darke Horse Model Supplies

An all round good guy that will be able to advise and supply what you require.

I'm with Derek on the number of teeth, just look at the gear ratios of cars (but for our modest requirements it will be of little matter)

Gearing matches the prop to the motor, electric motors like to spin at high RPM for efficiency, but props like low LRPM to reduce cavitation. When a motor is forced to spin at lower than optimal RPM it draws more current and gets hot.

Nick

[ooyah/2]

Hi,Derek,
Thanks for the info on gearing and as I have never studied the principle of gearing I bow to your knowledge of Naval Gearing and I stand corrected.
When we designed heavy industrial gear boxes odd to even teeth were never a consideration but I accept what you say.
However we digress again from the original inquiry on a 2/1 reduction for a model boat and in my opinion it doesn't matter if the teeth are odd or even.
The Delrin gears in my boat , much to my surprise are still churning away without any sine of wear and very quiet in running, are cheap and easily obtainable .
I must add that I didn't think a grub screw tapped into the Delrin boss would hold, I always think steel, it must be that on drilling the 4mm hole for the shaft that when drilled it's a tight push fit on the shaft which must add to the grub screw grip.

 I am sure that there must be a supplier in OZ where Delrin gears can be had to make a simple gear box so a quick search with Google may turn up a supplier.
George.

[Lt. Raen]

@stan out of interest I contacted model slipway anmd recieved this reply "Sorry, we are not a model shop, we manufacture and sell products suitable for Model Slipway and Model Slipway kits." So doesnt look like they will be of any help.

@bluebird PM sent

Tim

[Lt. Raen]

Just a quick update for anyone interested,
I have ordered the Belt drive and now avidly await its arrival on our golden shores 


Regards,

Tim

[ooyah/2]

HOPEITFLOATS.
Here is a link to my Brave Borderer on You-Tube, running on  2 x 7 Sub 'C' cell packs x 3700 amp in parallel (http://www.youtube.com/watch?v=c2FxmJ20mkk&feature=mfu_in_order&list=UL ) the motor is a brushless 3750 kv
It's a bit of a whine but not unacceptable and don't forget Lt Raen will not be running such a high reving motor.
This set up has been very successful and a cheap way to make a 2/1 reduction G/Box.
George.

[Peter Fitness]

I have used a pulley reduction system in a number of my models with very good results. I use nitrile O-rings as the belts, they are cheap, very quiet, and last quite a long time. In early models I used a single belt system, but now generally use a double belt set up for extra grip and reliability. I turn the pulleys on my lathe using aluminium rod of suitable diameter.

I have attached a photo of the single belt set up in use on my Billing "Nordkap", and another of a twin motor set up in a pusher tug. This has since been changed to a double belt arrangement.

Peter.