Team Bodge Job

[Bodge Job]

Re: Team Bodge Job

undoubtedly the best conditions to work in... :P

[mattsdragons]

Re: Team Bodge Job

Now that's dedication! I've bought what work I can inside though a day or two in the shed will be needed soon if this snow doesn't clear up

[Bodge Job]

Re: Team Bodge Job

Yeah! im not sure why im so eager to get it finished, I dont have an event for another month!

[Bodge Job]

Re: Team Bodge Job

Done a little work, new base and back. and did 18 volt testing, and the motors definitely don't like 18v . so going to change to a 14.8 volt lipo (i presume i have to buy one and that people dont want me taking a cell out of the current one?).

I changed the base plate for 6mm HDPE to 5mm HPDE to save some weight. And the bake was replaced so the robot can run on the back wheels at all angles. And to make it easier to have a strongish the top at the back. + it looks awesome!

and I can finally say:

[Bodge Job]

little to no work on the bot, just tested the robot on a 24:1 gear ratio as the last one broke at 36:1, but that broke too! may change it to 2 speed 900 size motors (stolen from bruiser 2) and use them, but i don't know if they would have enough power to self right at the small 5:1 ratio, what do people think?

here is the video on Ben's build diary, http://www.fightingrobots.co.uk/thre...688#post440688
thanks ben!

[Ellis]

Speed 900 clones at 5:1 would most likely not even move the axe properly (rule of thumb), let alone self right. They definitely have the power, but only after a lot more reduction would you see the sort of power you're getting from the current setup (the 120-180:1 ratios the 550s are running should say it all, you need a lot more than 5:1!)

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Next step, I'd say, is try and either get a normal drill in there or a larger drill. You can have the torque limiter still in place, which should help take up a lot of the stresses. If it is the pins on the gearbox shafts that are coming loose and letting the gears strip then there are quite straight forward solutions to that.

[Bodge Job]

now thats a good idea, i didnt think about the torque limiter on drills, that could work! i think i have a small drill motor free so i could set that up and try that, thanks!

[RogueTwoRobots]

If you want to save a bit on space, just go with the traditional grub-screw fitting on the drill instead of having the whole torque limiter setup in place. You can still have the torque limiting just by screwing the grubs down a little less than what you would for drive. It'll take a bit of trial and error though to find the sweet spot between having enough torque to swing the axe but limited enough to slip once you've hit something.

[Bodge Job]

yeah, thanks, i think it would be best to try it with the torque limiter first, as i think it would be eaiser to test, and get the torque right, but if i have to i will change it to that, i just think it would be good if i could make adjustments without taking the whole thing apart.

thanks though its a good method to fall back on

[Bodge Job]

found the problem with the latest motor damage (ii had presumed it was the gears stripping causing it to spin, but instead it turns out the gear on the motor has come loose). And ive never had this before. The gears are only pushed on like the some of the older drill motors i first bought, rather than the later ones i got which had the flat.

Was wondering if there was a way I could reattach it on well? as if i try another motor i fear the same thing is probably going to happen with the stress of the motor? there appears to be glue one some of the motors gears probably to help with the push fit, but if that wasn't strong enough, how do you think i should attach it?
could attempt to glue again with the torque limiter and see if that prevents it, or could i somehow weld them together?
what do you think as im unsure, or should i just do a few tests?

[Ellis]

If you have any old motors with the flat, use one of those? If not, we have had success with a drive motor by crimping the motor shaft (by which I mean hitting it with something very hard and sharp to misshape it), repressing the gear onto the now slightly distorted (be careful not to bend) shaft, and using a decent two-part metal glue. Can't remember how many fights our fix did, 10 or so, with no problems. :]

[Bodge Job]

yeah problem is its a different gear so doesn't fit the shafts with the flat. i may try welding it first, and then grinding it flat as i think that will be pretty strong (and i dont have any desent two part glue atm) will practive on an old burnt out motor first though and if that fails ill buy some glue.

[plargen]

i guessing you have a tig set if your gonna try welding it

[Ellis]

The motor shaft material might not mind you welding, but of course bear in mind on the other side of the front bearing there is a lot of glue and plastic. Might be worth opening on old motor, seeing what it looks like, close it back up to test weld it, and then seeing if it looks molten or damaged on the inside. If it does, eh...

As for welding the pinion on, if you try to weld the drill shafts they become weak and brittle (something to do with the way they're made) and the gears, as I believe they're made in the same way, may suffer from this too.

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If the motor test weld goes okay, can I suggest you put a small blob of weld on the shaft, then file it down to just a fraction too big for the bore of the gear and try repressing the gear? Essentially the same thing as crimping but you're adding material instead of misshaping it. The shafts are quite tough, you can support the back of the shaft on the other side of the motor and hammer quite hard fairly safely. Just trying to avoid welding the gear as I think it might make it useless.

[plargen]

if i remember correctly with welding the weld itself is strong but there is a patch around it that becomes weak due to the heat, its the bit to do with annealing i think (the rat that steel get cooled cooled affecting their properties)

not 100% but that sortof what i remember from my welding classes 7 years ago