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Zenghiaro - Slightly Evil Robotics - SA
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evil_steve



Joined: 06 Sep 2015
Posts: 301
Location: Adelaide, SA


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Zenghiaro - Slightly Evil Robotics - SA

So, featherweight sportsman time?

Post Sat Feb 06, 2016 11:11 am 
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Nick
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Joined: 16 Jun 2004
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Location: Sydney, NSW


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Any ideas about the weapon yet?
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Post Sat Feb 06, 2016 11:45 am 
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evil_steve



Joined: 06 Sep 2015
Posts: 301
Location: Adelaide, SA


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Yeah, lifting prongs, already got some motors scavenged from junked radiology equipment that are (hopefully) appropriately geared. I've got the design worked out in my head (and badly sketched), I'm making a plywood mock-up of the chassis to get the layout/geometry right, I'll post photos when it's at a stage that you can tell what's going on.
First though I'll be disassembling the drills (based on the helpful guide on this site) and working out how I'm going to mount them and attach the wheels.

Post Sat Feb 06, 2016 12:17 pm 
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evil_steve



Joined: 06 Sep 2015
Posts: 301
Location: Adelaide, SA


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Well, my son and I have disassembled all the drills and I've soldered new wiring on two of them. I suspect I'll have to rebuild/redesign the whole lifting system - I'm being foolish and ignoring the advice of Matt Maxham and using two lifting motors directly driving the lifting forks, plus the motors are likely far too small (which is why I'm using two!) with piddly wires I can't easily replace. But the motors were free and for now it lets me put something together, if it fails I won't be upset.

The switch is just for testing - I'll probably do a removable link for the actual robot, I'm just dreading wiring it all up (I'm not convinced my soldering skills are up to joining four thick wires together). I've got a smaller battery on the way as well, but if I can fit the larger one in the weight budget it should go a few bouts between charges.

Post Sun Feb 14, 2016 4:17 pm 
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Nick
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Joined: 16 Jun 2004
Posts: 11799
Location: Sydney, NSW


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11 out of 10 for neat wiring! Those lifting motors do look undersized and the shafts on the gearboxes are also on the small & bendable size.

A neat trick for soldering several wires to a connector is to strip the ends, tin the wires, then bundle them together and put some temporary heatshrink around the bundle (just behind the tinned wire ends to hold them in position. I sometimes add a bit more solder to the wire ends at that point, or just solder them to the connector terminal. Once everything has cooled down, just cut off the heatshrink.
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Post Sun Feb 14, 2016 5:37 pm 
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evil_steve



Joined: 06 Sep 2015
Posts: 301
Location: Adelaide, SA


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Thanks, although the heatshrink hides some terrible soldering Very Happy

The temporary heatshink idea sounds good. I tried this method for splitting the output of the other ESC (not pictured here because I messed up and used a female rather than male XT60) - it worked well, but it was a pain keeping the wires together to wrap, should be easier with the heatshrink.

Post Sun Feb 14, 2016 5:59 pm 
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Nick
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Joined: 16 Jun 2004
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Location: Sydney, NSW


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Agreed, wrapping wire around a bundle isn't easy until you get to much larger wire. You can also use a cable tie like in the Instructable; the trick is to get the tie or heatshrink right up to the stripped ends of the wires. If you don't already have one, making a 'third hand' (and a fourth hand!) to hold the hot parts is a major help. At events, I just wrap a strong elastic band around my pliers handle to make them grip parts while I work on them.
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Post Sun Feb 14, 2016 6:11 pm 
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evil_steve



Joined: 06 Sep 2015
Posts: 301
Location: Adelaide, SA


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Got all the motor and ESC wiring done, and somehow managed to get all 4 motors the right way around first go (well, apart from that one xt60 plug I had to redo). Still got to properly split the power and wire up the removable link though.



With the weapon motors/ESC as well. The bot isn't going to be as big as I've laid them out, was just trying to orientate all the motors as they will be to check they all turn the right way.

Post Wed Feb 17, 2016 10:13 pm 
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evil_steve



Joined: 06 Sep 2015
Posts: 301
Location: Adelaide, SA


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I've decided that I'll be using something other than the tried and tested Bunnings red wheels as a) I want something larger, and b) I had some in the shed already that I got cheap. To make them work I'm using a method I'm pretty sure I first saw Ellis mention, and I got some 3/8 UNF manifold nuts that seem to work well.



I've got this week off and while I've got a list of other things I'm supposed to be doing, I'm thinking about finding time to throw together a crude chassis with all the scrap wood we have lying around ("I'm organising it honey, honestly") and seeing how it drives.

Post Sat Feb 20, 2016 8:07 pm 
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marto
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Joined: 08 Jul 2004
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Location: Brisbane, QLD


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Looking like some good progress.

The problem with most of those white wheels vs the bunnings red wheels is there really isn't much meat around the point where you attach the drill to the wheel. Just watch out for the plastic cracking or the nuts spinning.
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Post Sat Feb 20, 2016 8:17 pm 
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Spockie-Tech
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Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia


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I used those white wheels in Inspector General. They allowed me to be invertible by poking out the top of the shell, *But, they put some serious loads on drill motors and reduce their reliability significantly.

They are *heavy (heaps of rubber tread) that I had to drill big radial holes into to lighten (which improved their traction on crud strewn floors as well) and and the higher rotational inertia smashes drill gearboxes to bits on reversals without some improved boxes *and rotational-shock-absorbtion on the motor/gearbox mounts.

They also need a bracket to move the drive torque away from the center to the rim or you will just tear the centers out. Gary made me a wheel adapter with an arm that screws to the outer edge of the hub.

They give you a nice turn of speed being large diameter, but stress the motors a lot. I regularly melted the internal cooling fans on my 18v high quality johnson motors. dont even think about hung-chang motors, they will melt, and/or break brushes in no time.

Additional, if you are up for serious combat, you should support the outside edge of the axle shaft with a flexible bearing as well to help take the heavy twist loading off the little bearing in the drill gearbox.

Of course all of this is combat-experience learned over 3 or 4 versions of Inspector General. if youre just building a platform to experiment with, slap them on and go for it.. but you have to *work to make them survive in a fight.
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Post Sat Feb 20, 2016 9:58 pm 
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evil_steve



Joined: 06 Sep 2015
Posts: 301
Location: Adelaide, SA


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Thanks for the advice! While the general philosophy of building this bot is "throw something together and see what breaks" I would like to take it to at least one interstate event before the inevitable complete rebuild. The invertability is certainly a big part of using them, but I could shift the lifting motors (my other likely failure point) and make it invertable with smaller wheels.

I was already planning on using additional bearings to support the axle shafts, and I was thinking about drilling "speed holes" in the white plastic of the wheels but your idea of drilling into the rubber sounds a good option. What size holes did you drill, and do you have any photos of them?

Post Sun Feb 21, 2016 8:54 am 
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evil_steve



Joined: 06 Sep 2015
Posts: 301
Location: Adelaide, SA


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I've been thinking about the potential issues with by bot, especially with the helpful feedback/experienced advice I've got from you guys. My two main worries/solutions are:

1) The lifting motors - they're far too small. I've had a dig through my box of random motors and found alternative ones. They're chunkier but still 12V and 250:1, the shafts are still 1/4" diameter but they're longer so I could support the ends with bearings. Here they are with one of the originals for scale.



2) The wheels - they're far too big/heavy for my crappy drill motors. If I go with the bigger lifting motors and mount them behind the front motors instead of above them I could go down to 5" wheels and still be invertable. I was thinking, at least initially, of cutting some out of 12mm HDPE with my 5" hole saw and screwing tread onto them (a la Ellis), and embedding the manifold nuts in these. Not sure how long they'd last but I could make them with stuff I already have lying around, hopefully they won't stress the motors like the monster white wheels, and I can always replace them with something better down the track. What do people think?

Post Tue Feb 23, 2016 11:01 am 
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evil_steve



Joined: 06 Sep 2015
Posts: 301
Location: Adelaide, SA


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Well, the last couple of weeks have been far too busy with non-robotics stuff, and now it's insanely hot. I managed to do some soldering this morning before the shed got unbearable though. I've had some issues with my shoddy soldering, especially where I've joined two chunky wires to the XT60 plugs. I've decided to make adapters instead, which will hopefully also make it easier if I use these ESCs in a different bot down the track. I tried getting a decent close up pic of the adapter but my camera is shit at that sort of thing, this is the best one I got.


Post Sat Mar 05, 2016 8:04 pm 
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Glen
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Joined: 16 Jun 2004
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Hobbyking sell an adaptor just like that for next to nothing, only found out after making a bunch as well lol!

Wiring looks very nice, I tend to use bolt together junctions with ring terminals to make lots of connections at one point. Small and easy to use.
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Post Sat Mar 05, 2016 8:26 pm 
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