Team Kaizen - Kaizen

[Ocracoke]

I'll drop a M5 bolt through the shaft, possibly grind a small flat onto the motor shaft and then stick a nyloc nut+washer on it if it works.

[Triceratop]

Are you going to Leeds (Robodojo)? if so bring the parts with you, we can have a look then. Not sure what you are proposing, but need to keep it simple - why grind flat on motor shaft? are you putting bolt through flanged hub shaft and motor shaft then bolting through?
Sorry for all the questions...

[RogueTwoRobots]

Is the flanged hub aluminium? If so, you could see if someone would make you one from steel (if you were able to do a basic drawing) then secure it with a couple of decent spot welds to the shaft.

I did a similar thing on a slightly larger scale for using some big wheels on wheelchair motors with quite a stubby shaft. The tubular part was a threaded connection from eBay and the circular discs I drew up in CAD, glued a print out onto a sheet of metal then cut and shaped it with a grinder, and drilled it. I then welded it to the wheelchair motor shaft and it's solid. Just need to make sure the body has a suitable cutout for removing the motor with hub attached (looks like yours does)

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[Ocracoke]

Are you going to Leeds (Robodojo)? if so bring the parts with you, we can have a look then.

Unfortunately not, I had planned to go but then other commitments popped up which I cannot avoid.

Not sure what you are proposing, but need to keep it simple - why grind flat on motor shaft? are you putting bolt through flanged hub shaft and motor shaft then bolting through?

A mistake on my part, I meant on the flange shaft so the nut can seat properly against it. Yes, bolting through.

Is the flanged hub aluminium? If so, you could see if someone would make you one from steel (if you were able to do a basic drawing) then secure it with a couple of decent spot welds to the shaft.

The flange is steel. The side panel where the motor pokes through is indeed unboltable and the hole is bigger than the flange so I could get it welded. Probably the quickest solution.

[Triceratop]

Hi Michael, have you thought about using roll pins. Welding is quite permanent and not easily removed if need to change anything. Forgot to ask, is the flanged coupling threaded to screw onto motor shaft?

[Ocracoke]

No, I've little engineering experience myself so still learning what things are and what they are used for. Looking at an example, I can see that working though. The flange is threaded to fit onto a M12 shaft.

[Triceratop]

Ok, so motor shaft is M12 thread also and screws into flanged shaft? if that is the case then have the end of the flanged shaft castellated like on the end of a car wheel shaft. make sure the castellations are deep enough so as not to cover any of the motor shaft hole. You can then screw the flanged unit onto the motor shaft get it tightly home and press ? gently knock the roll pin through the castellations and motor shaft. this will stop the flanged unit from unscrewing. If you want belt and braces a little loctite doesn't hurt. If unsure google castellated nuts.

[Ocracoke]

So a bit of a sea change. I really did need the time off from building this thing, just having The Honey Badger and Shu! plus all the ants and BotFest has really taken it out of me. I came back to it just before BotFest and decided to stop making this and start again. I wasn't happy with the overall build quality of the thing and having seen Voodoo's bodywork, it would have been a lumbering mess by comparison.

So this time around, taking a little inspiration from the likes of Griffon, I've made the robot shorter in all directions and gone for polycarbonate panels this time, likely make 12mm thick on the top and 10mm at the bottom (recycled from the original attempt). 4mm thick steel box section make up the "chassis" of the thing and will likely not paint it in an attempt to make look junkyard chic. :P The main body, discounting the wheels, is 66mm tall. Same sort of build methodology, massive bolts will hold the top and bottom panels together through the box section for compression fitting.

Been making new motor mounts and learning lessons from The Honey Badger 3.0, these are far stronger. Two are done (save for a bit of trimming) and two are on the way. I've also recycled the axe from The Honey Badger 2.2 as that never saw any action in Manchester. I've weighted the head a bit more and will reinforce it with stuff from the original attempt at Kaizen soon enough. I have a CIM motor around so what I'll do is make some side panels for the wheels for protection and then use the left over from that to make an external axe mount to sit on top of the robot.

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[Theo]

I'm actually really jealous of how that looks, absolutely love that compact rectangular shape, and it looks nice and simple to make, what with the box-section and polycarb sheets.

[Ocracoke]

It is deliberately simply to build, got one and a bit months to go until Chatham :P I'll be working on the other 2 motor mounts and securing them to the chassis panel. Who knows, I might even have it running by the end of the week.

[Theo]

Oh don't remind me. Still have quite a lot to do, mainly sorting out these pesky wheels. The nyloc wasn't put far on enough, so the wheel slips forwards and backwards out of its key. Sadly the nut has rusted onto the shaft now so any more force trying to free it will mangle the gearbox. Plus just lots of testing to get done - I've never had a robot that drives in one direction without veering violently to one side, it's all a learning curve!

[Ocracoke]

So I've had some free time today to actually get the robot built. Thankfully, the uber simple design means that I am nearly done with the bodywork. Had a slight hiccup with the pillar drill in that all the bolts needed to hold the drill in the air and the drill in the holder decided to strip their threads so a new set of M6 bolts for that. Also managed to destroy a HSS drill bit. Think I went too hard too fast.

Anyway, a few hours drilling and the end result actually doesn't look too bad. Even the M10 bolts are relatively perpendicular in the holes! (I know, a little sad). The top panel is a single sheet of 6mm polycarbonate but I plan to double that with the left over sheets from the original attempt so it has 12mm on top.

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I also has a go at getting the machine to run. A bit hodgepodge but it is definitely moving. Needs better batteries in it (the video only has 4S LiFe batteries in it, going to see what 6S looks like with all the extra material on it now but definitely moves. I might fit some more grippy rubber on the front wheels, not decided yet.

[Ocracoke]

Well, 22 days to go until Chatham and a lot has changed since. The electronics have been screwed down, the new 2x 4S1P batteries arrived and I am awaiting a few connectors to get them wired in series to 8S1P. The axe weapon has also been made and it actually works!

The axe, as I noted before, is powered by a CIM motor, overvolted to 19.8v (6S LiFe). I had intended to have it driven by a single channel FeatherTwo that drove the axe from The Honey Badger 2.2 but the horrors of Extreme Robots Manchester came back to haunt me. The PCB had split, taking out a chip in the process. So now it is being powered by a TZ85A until I find another controller to drive the axe. The axe is going through a 3:1 custom gearbox on a dead shaft. Drilling the reduction gear was a bit of a faff but worth the effort.

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I've still got a fair way to go with this one, such as fixing the electronics, fitting a safety pin to the axe and so on. The big issue is weight, or rather the lack of it. It weighs 20.5kg at the moment and the minimum for a Middleweight is 30kg. I've got a substantial amount of 25mm HDPE around to add more armour on with and if all else fails, I'll add a solid brick to the thing. :P I have a worklist of things to do to this one but I've signed up for EXR Chatham, Maidstone and Gloucester in anticipation for this one making it.

Here is a video of the axe firing. The axe arm definitely needs reinforcing before combat but it works for all intents and purposes. The issue here is the grub screw undoing itself through shock (you can hear the motor spinning after the axe arm retracts). I suspect some threadlock might be enough here but I am open to drilling the shaft to allow for a pin of some description.

Next video will be of it moving about under its own steam on the 8S batteries and hopefully "done" before Chatham.

[daveimi]

I wondered how you get your drilling accurate enough for making your own gear reductions. Would I need a pillar drill to be accurate like you? Or have you found a way to do it accurately with a cordless drill etc? Any help with this would be appreciated.

[Ocracoke]

I have a pillar drill attachment for my corded drill. It isn't the most robust thing in the world (I've had to replace all the hex head bolts with a set of M6 bolts already) but it does the job well enough.

https://www.amazon.co.uk/gp/product/B0119K2XIQ

Worth the investment but does need securing down to fully work (I use mine freestanding as I have nowhere in the house to mount it to yet). I cut a panel of HDPE in half, marked out where I wanted the hole on one of the panels, mounted the second panel underneath the first panel, taking a bit of time to line them up (ended up clamping them down together when I had it right), drilled a 4mm pilot hole through both and then a 10mm hole through both again.