Boring Brick

[geeza]

Put an appropriate size nut under the chain pin then hit it with a hammer and punch combo. When one side of the chain is loose twist it out of the way and turn the chain over and repeat.

To reassemble use the nut again held in a pair of needle nose pliers on top of the link. Then with the chain pin through the middle of the chain and on a hard surface hit the nut with a hammer. Turn over and repeat.

Been using this method for years, tricky but you will get better with practice.

[mrsam]

I've tried my luck at breaking some chain for the axe today and it has not gone well, i've been using a hammer and pin/screwdriver/punch basically anything and every time the chain moves or the tool im using just slips off the pin, does anybody have ANY suggestions because i don't have the money left for a chain breaker and at this rate the axe won't be working in time for the champs.

[mrsam]

Just received an 11 tooth pulley for the motor from Jamie so the axe is back on track. Not sure how powerful it will be as the ratio now will only be about 3.5:1 but only time will tell, so once i've cut 15mm off the back of one of the bulkheads, bolted the motor down, made up a chain and bolted the whole robot back together it'll be ready for a test, still got loads of time right? . If the axe is too underpowered for my liking i'll order a cheap 58 tooth mini moto sprocket from ebay and bolt that to the existing sprocket thus bringing the ratio to just over 5:1.

[mrsam]

So after my near mental breakdown over the motor sprocket yesterday i've been greeted today by some good sprocket news i.e my Custom machined main sprocket from Technobots, only 40 tooth but as my initial idea was to have an 8 tooth on the motor giving an overall reduction of 5:1 it was fine for that, ( the ratio now will be like 4:1 but should be okay). Heres a pic of the sprocket and the motor Dave delivered to me on Thursday

[mrsam]

Jamie that would be great, I'll have a look at the motor tomorrow and see which model it is, the 11 tooth would lower my axe ratio but I could always add a second stage with the sprocket that doesn't fit the motor

[RogueTwoRobots]

Sam, is it the MY1016 scooter motor? If so, I've just taken delivery of a new one for Onyx that has the sprocket still attached. I don't use it (I weld a Technobots one on instead) so if it looks like it will fit, it's yours.

It has got 11 teeth though, not sure how that plays into your axe ratio. The scooter motor currently in Onyx also came with a sprocket that might have been 9-tooth (certainly was double-D). Can't remember if I held on to that one but I'll have a look tomorrow morning and let you know.

Here are a couple of pics of the 11-tooth sprocket:

P1020814.jpg

P1020818.jpg

[harry hills]

if you've got a D shaft, is using a massive set screw an option?

[Ellis]

Is this not an option? http://www.ebay.co.uk/itm/Electric-S...item27dfccef95

With a half-round needle file you could file out one of the flats in the bore to make it a D shape, or you can grind/file a second flat on the scooter motor shaft to make that fit the sprocket. Both will work.

[mrsam]

So after realising that i need a sprocket with a 'D' shaped hole and hastily cancelling my ebay order i'm back to square one, which at this point looks like i'll have to get ANOTHER custom job from technobots, only problem with that is that at this point my robot budget is blown for this month and although i do get paid 6 days before the champs it's going to be a very tight squeeze to get the axe running before, so my plan to have the axe fully tested and working weeks before has slightly backfired

[mrsam]

Okay thanks Ellis, scooter sprocket it is

[Ellis]

Sounds like you're describing a cotterpin system. It would work in theory, but I'd worry a 4mm hole through would weaken it a lot. A much smaller hole for a pin of some sort, perhaps. You may find you can't drill the scooter motor shaft easily anyway, I imagine it's a decent, possibly heat treated steel that regular small drill bits might struggle to go through. Getting a designed-for-scooter-motors sprocket may be the path of least resistance.

[mrsam]

Just a quick question before i go ordering the sprocket, if i drilled a hole straight through the boss of the existing sprocket and drilled a hole through the shaft of the motor and used say an m4 bolt to hold it all together would that work or would it just be a waste of time?

[mrsam]

Thanks for the advice, having looked at the current one again I think modifying the bore to 8mm would weaken the boss too much anyway so it'll probably cost me less in the long run to just buy the one made for the motor

[razerdave]

Adams got a point, it's just as costly to get the current one altered than to get a new one. You're better off getting the new one. If you want, I can mod the other one a a spare, up to you.

[adz600]

To be fair £8 is not alot, would cost that much nearly to post it too Some one and back again and then a drink for there time,if you have a drill and and bits a tap set is cheap.