I would get those wheels but then screw bike tyre into them.
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I would get those wheels but then screw bike tyre into them.
Well I've got several of those white nylon wheels at home (or at least used to) so that may not be a bad shout... They seem a little brittle from what I remember though; I'd have thought they might crack if you put screws in them...
Now there's the problem that I don't know if I still already have a set of white nylon wheels, and I wouldn't have time to buy them if I get home and not. Plus, though they're only 80p each, they have £5 shipping on them, so I don't want to buy a pair to find I have loads at home... I'll have to give my dad another thing to search for!
I have those grey wheels from eBay, with bike tyre screwed into them they grip nicely. I originally used knobbly bike tyre, but hardly got any grip, so I've just changed to motorbike racing slicks, lovely soft rubber.
@Gabe01 i was worried about the hubs on those wheels not been up to it, do they feel solid enough to you?
They're a nice wheel and they feel pretty solid, not battle tested of course. I choose them because they are cheap which means you can have lots of them. When you hold them in your hand they are a nice wheel and certainly not brittle. I used the 'melt-in' method in my drill press and the shafts dropped in easily without compromising the hub strength.
We used very knobbly tyre for T2's wheels and whilst grip isn't "bad" it isn't massive. I made Rango's wheels with a softer compound fine-pattern knobby bike tyre (local bike/car spares) and the grip the stuff gets with wide wheels is nuts. Harry used the same stuff on Massacre and also found it just stuck to the ground. Perhaps you can find something similar:
http://i1088.photobucket.com/albums/...0288shrunk.jpg
It buries a small buttonhead style screw in the pattern nicely. :)
well I've got loads of old tires and bits of rubber lying around at home... hopefully should be able to find something half decent in there. Though as long as they're better than what I've currently got (which is not hard) for the next event then I'm not too worried; just need to be able to throw it all together in two or three days..
How much does that size of HDPE wheels weigh? Gives me an idea...
Well, once again I had almost no time to do do a ton of work on Richie: this time I had a day and a half to fit new wheels, new motor mounts, a Lipo, and self righting in time for Guildford... I got 3 hours sleep before the event...
The new wheels worked great, all for the cost of £0.00. :)
All I did was replaced the rubber sheets that made up my wheels with a thick piece of plywood which I lathed round, and then screwed bike tread into. Had no problems with them at Guildford and they had plenty of grip. Also mean I now have about 2cm of ground clearance which is a great improvement, and very much appreciated at Guildford!
The new motor mounts I made worked well too; They were just some blocks of HDPE and wood machined to fit the motor and house a support bearing. I also shifted the motors forward about an inch for better balance. Unfortunately the new wider wheels meant that the back of the motors were less than 1mm away from the linear actuator slider, which meant that when Major Damage decided to hammer me whilst I was on my side, my motors were shifted in and caught on the actuator, which tore out one of the screws holding the motor to the gearbox, leaving me with a very bent drive motor. Marco kindly lent me a hammer to beat it straight again, and I made it through the last two fights fine, but I plan to entirely replace the gearbox housing with metal, and add a rear motor support. They'll basically end up looking a bit like the motors that Gimson sells if all goes to plan.
The Lipo conversion caused an interesting problem; as I no longer had a 2.5Kg SLA in the back of my robot, every time I tried to lift someone I would just tip forward instead. This means I'll have to spend most of my spare weight adding big armour plates or something to the back. I also intend to move my motors to the back when I have time for the 4wd upgrade, which should help a bit.
I fitted a wing type schrimech to Richie before the event, but didn't have time to try and get it working until the break between shows. I quickly found it was much more effective just to have them stuck out permanently, so I plan to replace them with just a bit of stiff plastic pipe. Not pretty, but effective!
Still, all problems aside, I still drove into every fight, and even drove out of a few! Was a lot of fun, and am planning to do a lot of upgrades when I get more than a day or two to work on it!
Oh and on a side note, if anyone here does antweights and is looking for an ESC, I've finally started taking orders on my home made antweight speed controllers. See http://robotwars101.org/forum/viewto...=2128&start=75 for more details.
I am interested in an ESC off you :) Should I PM you etc?
Check the second to last post in the thread (http://robotwars101.org/forum/viewto...=2128&start=75) for details on ordering.
In an unprecedented turn of events, I'm almost ready for an event more than a few hours in advance!
The chassis has been completely rebuilt to make it 2 inches wider and 1 inch longer... sounds like a lot of effort for very little, but the extra width stops the motors catching in the lifter, and the extra length gives it some more stability lifting
Attachment 4728
(Richie During rebuild)
The motors have also been rebuilt with new aluminium plates between the motors and gearboxes; should stop them bending in half so easily:
Attachment 4729
The motor mounts are the same, but they're mounting onto a much stronger frame. The motor mount for the lifter has also been improved.
Attachment 4730
New ESCs have been fitted for all motors due to my homemade one randomly dying during testing... The drive ESCs are not homemade, but they're really cheap chinese ones that I've heavily modified to actually work. Feel slightly bad for using bought ESCs, but they don't lock up with sudden stick movements at least.
The armour's the same old, just stretched out a little to fit the bigger chassis.
Just need to tidy up the electronics, refit the armour, and maybe add some weights at the back and I'm pretty much done :)
Here's a vid of some rather mediocre testing: https://www.youtube.com/watch?v=h06Z...wp0tSCHzqPS4jQ
Looking good
I'm almost ready, usually more prepared than this!
New ESCs have been fitted for all motors due to my homemade one randomly dying during testing... The drive ESCs are not homemade, but they're really cheap chinese ones that I've heavily modified to actually work.
-- So what sort of mods?
Bigger cables, noise suppression, new firmware etc...
I go into detail on it in this thread: http://www.fightingrobots.co.uk/thre...heap-drive-esc
Nice test video. The robot looks great and definitely got that old-school feel to it, almost makes me want to go out and pick up a pair of wiper motors :)
Damn it house robots!
Attachment 4733
That is one video to watch out for :D
what happened?
Featherweight house robot (Battle Axe?) hammered it after it blew it's fuse... some how tore the armour up pretty bad. Also hit the roof at some point courtesy of the floor flipper... Mechanically it's all still fine at least, which is the important part :L
Looking at upgrading the lifter motor to something with a little more poke but without spending any real amounts of money.
Came across a pair of Johnson 600's on eBay (here) for £8.50 (or 3 for £10). Looking at the spec sheet with them, they seem quite a lot better than the 550 I'm currently running.
Attachment 5061
Does anyone know anything about these motors; are they actually any good? If so, I'm considering buying the 3 for £10 and upgrading my drive as well (though slightly cautious about trashing the drill gearboxes...)
I'd assume they are considering the Johnson 885s Ellis got for Rango were total powerhouses for near enough £5, and they only blew because the gear ratio was wrong (through no fault of his I might add). I'd say try them and see, especially for that price!
I would doubt they are anything special. Won't see much difference from a 550 and they might even be worse going on the ebay seller's description rather than the data sheet.
Well, I'll grab a couple anyway and give it a look; given the cost I'm not too fussed if they turn out to be useless.. I'll report on how they do.
Have to say though that the 550's I have have a no load current of 0.8A at 9V, where as the 600's are quoted at 2A, so either the 600's have lower winding resistance therefore more power, or the 600's just have rubbish bearings :P
Yeah good stuff. If they can at least match a 550 then I would get some.
I measured the wattage of a few different drill motors at around 80 watts or so, and that data sheet talks about 110 watts give or take. I imagine it will be noticably more torquey than your 550. I think for a time Little Hitter ran Speed 600's at something like 22v and that goes like hell and quite happily shoves stuff about in the fw champ vids.
If you want to try out something different then you could try and stick a pneumatic muscle in there, very cheap to make and could power it off a small compressor or CO2 bottle with regulator. Could make for a very cheap pneumatic setup and doesn't need to be too quick as it's just a lifter.
Yeah, I'm only looking for something like a 50% improvement or whatever; the 550 in there works fine, it's just a little on the slow side and pretty strained lifting another robot (the lifter has a max lift of 20kg before it stalls). A bit of extra power and speed would just be nice.
I've got all the parts to make a pneumatic lifter setup like the one you described Max, but it'd be too drastic a change; the lifter I've got works very nicely so don't want to change it too much. May have a look at pneumatics in another robot; I'm currently hoping to experiment with LP pneumatic flippers made from 2 stroke engine parts at the moment :P
Well the 3 Johnson 600's arrived. The build quality of them actually looks better than the 550's in the argos drills, so that's a good start.
They have a winding resistance of 0.2 ohms, as opposed to the 550's 1 ohm, giving it a stall current of 60A at 12v. This is understandable when you have a look at the windings; they're quite a bit thicker in the 600s, which also implies fewer windings as they're packed in the same space.
Idle current is about ~2A at 9.6V, which is what was quoted in the data sheet.
They are slightly longer than the 550, which is mostly down to the stronger bearing mounts, but there is a little extra length in the coils.
Attachment 5076Attachment 5077
Running on 12V, the 600 sounded about 30-50% faster, though I have no way to quantitatively test it atm.
Also seemed to have plenty of torque, though again, grabbing the output shaft with pliers is not a very accurate test. Did heat up quite quickly when put under load though.
The mounts at the front are a direct match to the 550, so the 600s can just be a drop in replacement
To summarise, these are very nice motors given the price, but I believe these are 9V motors of a similar nominal power to a 550 (relying more on current than voltage for its power). Therefore when you overvolt them to 12V you get more power, as you would overvolting a 550 on 16V. It will definitely make Richie's lifter faster (dunno about extra lifting power yet..), but that's only if they don't catch fire first... I will try installing one over the Christmas holiday.
They look pretty beefy and solid.
Can't complain for £3.50 each :P
I have a couple of those Johnson motors that i was planning on using with some drill gearboxes, wasn't convinced they'd fit in with the extra bearing support though. I'll be watching with interest to see if they are an improvement, nice cheap motors.
"Can't complain for £3.50 each :P"
Jobsaguddun :)
After one of the ESCs burnt out at the last event, Richie's been sat in my attic as a pile of parts. However with Whitwick coming up and it being half term, I decided I should probably start putting it back together.
I've fitted those Johnson 600 motors to the drive as that was a lot easier than fitting it to the lifter with the tools I currently have. They're a little close to the actuator, but not as close as the 550s used to be before the chassis upgrade so hopefully it's fine. I'm yet to test them out so don't know yet how they perform compared to 550's.. look good so far though.
To drive these, I've got my 400A heavyweight ESC in there atm, as the Johnsons draw a lot more current than the 550's, and I don't have any other ESC suitable to drive them. I'm using this as an excuse to test out the ESC to check it hasn't got any odd hardware/firmware bugs; It's a lot less scary to discover them in a Feather then it would be to find out in my heavy :L I'll have to find/ make a new ESC for Richie in the summer when this one moves to my heavy, but it'll do for now.
Also upgraded the wiring loom to be all XT60s (rather than a few PC Molex thrown in), and upgraded the battery to a 40C 2200 mAh, and swapped the fuse for a 60A one rather than two 30A fuses in parallel. Should all be a little less... flamey..
Unfortunately it would seem that I left the baseplate at home, so I've had to throw something together using a rather flimsy piece of chipboard I found... Not really ideal, but should hold; It's only really there to keep the dust out.
Here's a pic of the current setup:
Attachment 5187
You know your heavy esc? If it got damaged at an event do you think it would be possible to return for repair? Assuming you start selling them and everything?
Considering the low volume that would be sold then that would probably be fine, though I'm still not planning on selling them just yet... If I get some home PCB manufacturing going on then I might look into it again..
So, having completed an event with the Johnson 600 fitted instead of 550s, I have to say they're actually pretty good! My lifter died early in the day, meaning I had to resort to being just a rambot, so the drive got some thorough testing and I was very glad they were fitted; very noticeable increase in speed, I'd say around 50%, and I was able to push people around quite nicely, which is never normally something Richie can do. The motors were rather hot at the end of the two fights I lasted the full 3 minute for (you could almost burn your hand on them), but they're 9.6v motors overvolted to 12v so that wasn't too surprising. Both were still working fine at the end of the day though, and at £3.50 each, if one does burn out eventually, I'm not gonna be too upset :L
Fitting them to the drill gear boxes only required cutting a few mm off the end of the shaft, and then grinding a flat on it to fit the cog from the 550, all of which took about 5 mins with a dremel. After that it just screwed straight in to the drill gearbox as a 550 would. All in all took about 15 mins to fit each motor in the robot. Very worth while upgrade for the money and effort required.
In other news, the new Heavyweight speed controller I had fitted in Richie for testing worked flawlessly all day without getting even slightly warm, which means I can go ahead with building my heavyweight over Easter (This was hopefully the last event I do without a heavy).
As was mentioned earlier, Richie's lifter broke. This was courtesy of Battleaxe putting me on the floor flipper in just such a way that it hurled me into the steel wall of the arena. This bent the lifting forks, arm, and linkage, and the lifter drive circuitry also burnt out (Damn you Battleaxe! *shakes fist*). Managed to get things straight enough to be used, but with the lifter circuit gone and not enough time left to fix it, the lifter was out of action for the rest of the day. I'm planning a much neater solid state switching circuit that should be much more reliable.
Glad you've got it sorted and think you should build a beetle :)
I did; I had Bork in the Beetle competition at the weekend, and it even won a fight! :P
Attachment 5214
Nah, I'm going to build a "serious" (or as near to serious as I get) beetle soon hopefully; got all the parts, just not all at at uni so'll have to wait until at least the easter holiday.
Oh wow do you mean at the feather and heavy event you went to
Yeah; the Beetle arena was there and we had a bit of a tournament in the break between the shows:
https://www.youtube.com/watch?v=jKzz...1Vj9zjdKmF3txv
Just finished off the new ESC for Richie: ~150A per motor at up to 40V (though the capacitor ratings limit it to 25v atm), with a total build cost of £7 for components.. Should be good enough for driving drill motors :P
Attachment 5254