Source for drive Pulleys?

[lowndsy]

Right. Trying to knock up my belt drive with roughly a 1.5:1 ratio. There are plenty on Amazon but most only have 1 in stock or take 2 months to arrive and I obviously need 1 for each side, plus perhaps a spare or two.

I need 6mm shaft for the smaller pulley, 8mm for the larger. Size is an issue because my robot is pretty low to the ground. Does anyone know a great source for items like this? https://www.amazon.co.uk/dp/B00TGQJW...I27SBVAX4NWH9O

Also, I should probably know this but how do you join the belts together? glue?

Cheers,
Steve

[Ellis]

I have been using www.beltingonline.com for years. They can do customisation (such as different bore size, keyway groove, etc, for a fee) and stock the "HTD" range which is my preference for combat stuff. For the belts, you state the width (would suggest working around the standard widths) and figure out the right length for your setup. I'd recommend HTD5 9mm wide for drive, or 15mm wide for weapon stuff, in feathers.

A calculator like this can make the centre distance, pulley size and belt length calculations fairly painless: http://www.bbman.com/belt-length-calculator/

You may find some Ebay sellers (UK based) are a little cheaper on the belts themselves once you know the size you need.

[lowndsy]

Thanks Ellis, that is perfect. I was sticking to Amazon / ebay to keep prices down but those prices are fine and at least I know they'll arrive in a reasonable time.

Steve

[Ellis]

Don't forget the prices are subject to VAT. Makes them a little less attractive, but still hard to beat. Again I've found the belts themselves can be a couple quid cheaper via Ebay, as long as you want a standard width.

[lowndsy]

Thanks Ellis. £35 for all the pulleys in the exact ratios I need is fine. I'm looking at 24:16 teeth for a 1.5:1 ratio and a matching 9mm belt. They are welcome to make the belt as well but I'll have to wait until I can make accurate measurements before I order it.

Next job... a nice strong 8mm shaft. So my next question is... where do I find a 3 inch 8mm shaft?

[Ellis]

I'd typically go to Ebay for small stuff like that. You can buy a length of 8mm silver steel (search 8mm silver steel) for peanuts. I'd suggest getting double what you need just to have the backup.

[lowndsy]

I saw it on eBay, but is that the strongest stuff? I was expecting to be told to go for some secret alloy made of unicorn horns or something.

[Ellis]

Well you could use grade 5 titanium, depending on the application and what tooling you have access to (much harder to work with). That would be fancy.

[lowndsy]

Junior hacksaw...

[lowndsy]

Hmm. Looking at a bunch of posts on here I think perhaps I have the wrong idea for my wheel set up. It looks like most people are threading into the wheel or using hex fittings on to the shaft ?

I was going for a floating shaft supported by pillow bearings and clamped at both ends with a smooth bore polypropylene castor wheel (already bought) attached to the belt pulley with adhesive, screws and clamps.

[emisnug]

Hmm. Looking at a bunch of posts on here I think perhaps I have the wrong idea for my wheel set up. It looks like most people are threading into the wheel or using hex fittings so the shaft ?

I was going for a floating shaft supported by pillow bearings and clamped at both ends with a smooth bore polypropylene castor wheel (already bought) attached to the belt pulley with adhesive, screws and clamps.

If you've already designed for a floating shaft, why not use a keyway for your drive? You can pick up castor wheels with keyways in them for fairly cheap, and belting online can cut keyways for you at a very reasonable cost.

[lowndsy]

That might be an option, thanks Robert.

I have all the parts for the current design so I'll give it a go as-is, but if it doesn't look reliable I'll have a rethink.