source for belt drive parts?

I just know someone here will have a source..

I am trying to make small belt drive gearboxes for model aircraft..

..there used to be a guy in the USA who sold them, but he has stopped.

Various places do some of the parts - e.g. small pulleys and belts - but I need reduction ratios around 3 or 4:1 and the larger pulleys of aluminium get very heavy. About 3 oz. Thats a bit OTT. Trying to get the whole box less than that.

So... a 10 tooth pulley and a belt - 2.5mm pitch - you can get...but a

40 tooth plastic pulley? Nah.

Power levels up to around 400W max, typically 200W, and shaft RPM 10-15K with sort of 2500-3500 being a desirable output shaft speed.

The model shops stock but one aircraft unit typically - the Olympus

2.3:1 unit..and its pretty naff. Otherwise their stocks are spares for helicopters and cars and are pretty much wrong.

surely there is a supplier of small belt drive parts SOMEWHERE in the UK.

Rapid electronics stock Como Drills who seem to stock what comes from here:-

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you note that the larger pulleys have a different belt width from the smaller ones..

these guys

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a nice range, but oh! the weight,the weight! 147g (6oz) for a 40T one...and its 5mm pitch which is a bit coarse on the belts..

RS components? well similar..good range and up to 6:1 reduction on 2.5mm pitch belts..but again, it looks like Al. pulleys only..