Sprocket

Need a new sprocket for my axe bot as the one i had originally is a bit too big to use, looking for anything from 50 tooth upwards, preferably one that has a boss that i can put some grub screws through to attach to the shaft

Pitch? Check technobots or
http://www.beltingonline.com/roller-...ts-962/index-2
maybe this is useful.

Sorry Harry, 6mm pitch the only problem with technobots is that i need a 20mm bore and the grub screws already tapped preferably so it makes what i need around £25

get technobots to machine it for you. Job done.

What's the delivery time like from Technobots?, i literally get paid about 5 days before the champs and if it's quick enough i could still have a couple of days beforehand to test

Delivery time is usually pretty quick (and you can usually choose next day delivery for extra) but if you're getting custom machining done to it, it will probably take a bit longer. Best bet would be to email them and ask for a rough timeframe.

Okay thanks, just another question, would two m5 grub screws through the boss of the sprocket onto the axle be strong enough? i'd rather avoid drilling and bolting the axe shaft if at all possible

Hmm, depends on the force of the axe hits, but to be honest, I would expect them to work loose quite quickly. If you can drill some dimples on the axle where the grub screws will touch it could help, or you could drill a hole all the way through the axle and run a bolt through instead. Would probably need to be bigger than M5 to resist bending though.

Thanks again Jamie you've been very helpful, my original plan was the have just a flat plate wheel sprocket bolted through the axe shaft with a hdpe spacer either side but i'm guessing this would be a bad idea?

M5 should be ok I use 2 x m6 in the heavyweight drive.