Looks good. Are you building anything around the outside to make the wheels a bit more spinner proof?
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Looks good. Are you building anything around the outside to make the wheels a bit more spinner proof?
If weight allows, we will put wheel protection around the sides. The rear wheels might be slightly exposed at the back but hardly, if we get flipped onto our back edge back we wanted a bit of clearance so we could do something about it. The front will be one big solid ramp style thing made of 20 or 25mm thick board, shielding the wheels from frontal assault, and from that front board we will come down the sides with 20mm stuff, but as I say, if weight allows. The weakest point will actually be the back bits we just made, since they're only 10mm thick.
10mm HDPE? That might be ok actually. Buzzbar didn't get through our 6mm HDPE this year on the back of our bot, just left a few cuts out of it maybe 3mm deep and its probably one of the more powerful spinners. Maybe it would have eventually got through (if it wasn't obvious from the start that he was going to win and kept going..) but it was cheap to replace after the championship and you ca always have spares pre cut if you're worried and swap them out after a battle that they get broken in.
Of course, my thoughts exactly. If it gets damaged, replace it. For the amount of material you get it's quite cheap. And the robot is made of varying thicknesses of chopping board, which if I remember right is low density polyethylene as against to high density? Either way it's tough!
Ahh ok, I think LDPE is more likely to crack than HDPE rather than bend so spinners might get through, not sure. I think the Bitza guys used LDPE and it got mashed by Little Hitter, but maybe it wasn't as thick as 10mm. Either way, if it does break you can always replace it with HDPE and see if that works better.
Yeah, all shall be revealed if we get to an arena! The material breaks cleanly, as in, it doesn't fold and discolour like some plastics. It can bend a ton but when it breaks it's quite violent. I guess you could call it brittle.
Yeh Bitza had Chopping Boards 13mm thick. They were very strong but also very brittle. None of the attacks, Little Hitter included managed to get through but after a while it just snapped into lots of little pieces.
Well if that happens then we know we need an upgrade. It hadn't occurred to me that the huge shocks that will undoubtedly go through the body of the machine could shatter the plastic. If they shatter, we will have learned something.
I while ago I was questioning this material but after finally sussing how to cut the stuff it's fantastically strong, s'for sure. :)
The chopping boards got us through the champs alright, but I wouldn't use them again. Plus given the price of HDPE sheet you might as well just get that.
I also found that when it was cold the boards were a lot more brittle and cracked while machining them in a cold workshop on several occasions.
That's interesting... we must have been lucky until now. If it goes, we now know why. Thanks for the info. :)
Yeh, nylon 6 also gets more brittle in the cold, we were makeing some new side panels last year, and huge chunks broke of, as we were using an electric planer on it...
Well, it's been a while! We're back at it again, now that my dad's work has opened up a little. We've spent the past few days designing and starting to build our lifter. We're going for a 4-bar, conventional drill and threaded rod, etc. We've cut some 2cm x 2cm box steel and got it into the right shape, welding (when I say welding I mean... uh :roll:) a little along the way. Tomorrow we'll do some more cutting and *cough* welding and gradually piece it together. Hard to explain what we're doing, I'll put pics up as we go.
Today we bought some bits and bobs to make the legs for the lifter, so once we have the design in place the actual build process shout be quite quick. Tomorrow we'll order the 15a Electronize ESC for the lifter motor (we thought it would be nice to have it proportional). Our motor mount is going to be quite interesting, it involves circles of wood/plastic, a T of PVC and rubber bands :rofl:.
The weight limit is slowly creeping up on us. The machines currently weighs a bit over 8kgs. We will probably have several kilos of lifter business, leaving us with not all that much to make it spinner and axe proof.
Will keep this posted. :)
I believe there are better options to control a lifter mech than a 15a ESC. Never built one so I don't know what it is, but thought I'd warn you before you fork out.
I've in the past thought about using car electric window relays, as these stop when a current past a certain amount is drawn (when the window can't go any further and the motor stalls) but that's me thinking with my Bitza hat on.....
i use a 15a electronize for my lifter, seems fine.
Aren't you worried about stalling it?
i used one for my claws, very reliable system, just a shame my claws were crap :lol:
lifted a heavyweight shell without blowing so its a pretty good system
If the lifter goes to plan it shouldn't stall when lifting an opponent. It will probably only lift half the weight of another machine in combat, and considering the motor unit can lift 60kgs comfortably at 12v without slowing down, it should be able to lift 8ishkgs in battle at 18v in its sleep, even with the ratios in mind. The only points at which it could stall are when it's fully extended or fully retracted, though with the precision of the proportional control and some practice that shouldn't be too much of a problem. Even if I do overshoot, the Electronize are tough little buggers, I think it'll be fine.
Hopefully some pics will come later today.
i use to run a lifter on an electronize switch smae principle as you are running on but the travel was stopped by limit swithces avoiding the possibility (in theory) of it ripping itslef apart
I don't quite understand how limiting switches can be setup. My mind immediately takes me to micro-switches that are activated by the arm when it passes them, killing the circuit and thus limiting its travel. Of course though, that doesn't work; the circuit is broken and the arm can't be retracted.
So, how do I do it?
I have a diagram for a limiter switch circuit at home, I'll post it tonight when I am home.
use diods and microwtiches. when the nut on the threaded rod hits the microswitch it will stop the motor going any further by cutting it off.
http://i46.photobucket.com/albums/f1...ave/limit2.jpg
The 'Ds' are diodes, and the info at the bottom there is the component you're looking for. Go you your local maplins and they'll sort you out, and also, the diodes have white lines on the which represent the lines on their symbols on this diagram.
Oh, of course! Brilliant! Makes perfect sense, haha. Well, ordered two large micro-switches, a pack of 12 1N5408 diodes and a 15a Electronize ESC.
Ended up not doing any buildy/designy stuff today, hopefully we will get to that tomorrow.
Thanks again.
Took us a bit longer to get going again than expected!
Diodes, microswitches and ESC have arrived, so all that's waiting for us to catch up.
I have some pics of the lifter arms in a mocked up position, latest 3 in the album - http://s1088.photobucket.com/albums/i32 ... elentless/
We just spent an hour planning our lifter's legs and the geometry of the whole thing. We're looking for a ratio of about 4:1, giving us a ROUGH lift time of 1.5 seconds. The travel is about 8-10 inches at the tip. Pretty nippy, certainly fast enough to be useful in battle. :)
Looks good, how is it at self righting?
It looks very nice indeed. Love all the toggle switches on it!
I'll have to come and have a poke around it at the champs :)
Thanks both! I will be returning the favour, Jamie, if you don't mind. :lol:
As for self-righting... well it... d-doesn't. :?
It will drive upside down, though, as the two back wheels still contact the ground when flipped. We were playing with the thought of an arm that comes out when the lifter is extended to flip it over (think razer-style) but we're going to be so close to the weight limit that that's unlikely.
Could always just add a bit to the highest point of the lifter to help it over, if it works either way up its not the end of the world if you don't though :)
Progress! The legs are more or less made, which involved lots of rough measuring and drilling with an angle-grind or two. :wink:
Pics of the setup held in the up position (by clamps, lol) here! - http://s1088.photobucket.com/albums/i32 ... elentless/
Good progress for an evening's bash. :)
Looking neat, are you coming to the UK Champs?
I am, yes. :)
Looking good! Hope it goes well at the champs!
It lifts, it lifts, it lifts!
Sort of!
Kinda!
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Well, it does what we wanted it to! Up and down and bloody fast too. Our setup works!
The motor has been mounted with a reinforced PVC T-joint (lol) and a strip of thin steel to hold it in place (hard to explain, pics will make more sense). Sounds weak, but I promise it's strong. Not sure how it will react to hard shocks; we mounted the motor in rubber to absorb any major blows.
The lifter arms are finished, save armour. The welds are.. interesting, but quite strong, plus they're braced. The legs are also complete. The geometry is quite good, if I may say so myself! It lifts really quite high for a 4-bar.
It took some thinking to get the threaded rod linkage business setup. We realised that our initial plan wouldn't work (desperately wouldn't), so we redesigned that and it works a treat. Wow, sounds so simple when you say it like that. Took us two evenings!
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As I said, the speed of the lift is fantastic. Comes up in a second or two. Very satisfying. However, we fear our lift ratio is too extreme. I think it's roughly 5:1 which on paper should work absolutely fine. Though, when I leaned on the tip of the lifter it struggled with just a few kilos on it. In fairness to the robot; its batteries were too dead to drive around, so maybe with a fresh charge it'll lift just fine. I really hope it will be powerful enough, as the current motion is just lovely! Once we get it speed controlled and radio controlled, we'll get a video up. Might be quite some time if we need to change the ratio.
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I feel like I'm babbling so I'll stop here. It's hard to put the amount of thought and work that each piece of the puzzle requires into text, so I'll stop here and save myself (and you guys) the hassle! Take a look at the pics, they're the most recent 9. :)
http://s1088.photobucket.com/albums/i32 ... elentless/
That looks like. Really nice macgine. Looking forward to seeing it running. Very nice shape!
Impressive, get a video up so we can see the mech in action.
Thanks both. We tested the lifter with freshly charged batteries, it lifted a 10kg dumbbell with relative ease. Considering the way we designed it the enemy robot can't sit entirely over the lifter, it should be fine. I reckon even if it had to lift 13.6kg it could do it.
Aside from some small motor mount issues, success! I'll get a video up once it's tidied up a bit and with proportional radio control.
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Having found out who we're fighting in our first battle we have tactically decided to leave roboteering indefinitely. :uhoh:
Bye! :rofl:
Limit switch business is now all done! Many thanks for the diagram, Dave, it works an absolute treat. I was dreading mounting the microswitches; part of me told me it was going to be a real fiddle. Thankfully, it went quite smoothly. Worked first time, perfect cut off timing!
After connecting the new ESC for the lifter and the rx, we've lost the use of our toggles (they allowed us to isolate drive and the weapon, for safety and convenience when testing). We can't tell at all why, if we unplug the channel again the toggles work as they always have. It's bizarre. So, instead of trying to fix it, we've decided to lose them. More things to go wrong in battle, so it's actually probably a good thing.
So, getting rid of those toggles aside, we've got to wire in a powerlight, tidy up the cables a little, and the wiring should be complete!
It weighs almost 11kg at the moment, it doesn't feel any less nippy for it, though. We spent a few minutes bashing about the living room. It lifted the sofas! Pushed them about a fair bit too. We may not be pretty, but we won't go down without a fight! NST, Inertia, you best be prepared! We might lift you to death! :twisted: :lol:
Will get a video up soon.
Next big job is the armour, and then it should be ready for the champs.
You'd be surprised how effective a lifter can be if well driven. Just look at the likes of Biohazard and Panic Attack.
Inertia XL and NST in one fight?! Bring plenty of spares!
Strangely, it might actually be good for you that you have Inertia in with another spinner rather than with a flipper/ram bot because he'll probably use his anti spinner creation rather than the disc.
It was something like this last year when Buzzbar was in town:
http://www.youtube.com/watch?v=EqLdrj2KpzQ