Oh right... well when you put it that way i'm slightly scared
Printable View
Oh right... well when you put it that way i'm slightly scared
Actually I think it is everyone else that should be scared!
I worry what the spin up time will be on a bar that size. It could well be that it never gets up to speed if the ratio is wrong or your opponent can get in before it starts spinning. Will be very interesting to see though.
It's definitely a risk running such a long bar, the ratio is around 2:1 but the motor i'm using is rated for like 800w at 4s so it should hopefully have the grunt.
It will spin it up like it's not there. That's 4x more wattage to call on than I have and with more reduction. The issue will be start up current draw and cont. draw... you're going to need some very punchy batteries.
I'm definitely not going to scrimp on the battery or the esc, looking at possibly using one of these if they're really as good as they sound http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html I know Nick was running some tests on them so i'll see how they do. Esc wise i'll go for a 100a red brick which should be enough.
Battery looks good, be interesting to see how those perform. ESC might be overkill, a 70 or 80a ESC should be plenty. I have a 30a lol. Also, weight?
The Esc is probably overkill but i'd rather know it's definitely not going to blow up, It's a shame that's the lowest capacity version of that battery because 1800mah is way too much i think, might have a look at Optipower and see if i can get something smaller. Weight is going to be tight i think, the whole weapon set up alone is around 500g, and then the motor, battery and esc is going to be probably another 350/ 400g, the body is going to have to be super light methinks.
800W of pure power do i hold in my hand! unfortunately as is the way with Hobbyking they sent the wrong esc (50a instead of 100) so that needs to go back, i would do a quick test but i don't want to blow the esc and then be stuck with it. Still the motor looks nice! http://i921.photobucket.com/albums/a...ps623f6b33.jpg
100W?! Why have you done that. It max's out at 65W on 4S. I got one of the 70A OPTO's for that motor.Quote:
Originally Posted by mrsam
I may put an even bigger motor in at some point so it saves me buying another esc, What robot are you using it in?
I'm using it in my own undercutter beetleweight. It will be bolted directly to a 200mm Bar.
:eek: Direct drive!? what voltage are you running that at? at 4s that would be something like 26,000 rpm! surely you're not that evil
Of course its 4S. I have Anvil to avenge! I am just that evil/crazy/mental.Quote:
Originally Posted by mrsam
In reality I won't floor the weapon unless I have too. Doing around 50% throttle will be more than enough. It just means that I can crank it up if the need arises. Or it may turn out to be nice and stable at 26'000rpm so I will just go straight there!
Took a while to get this working but I finally managed it (turns out I had the low voltage cut off set wayyyyyy too high). Here's a nice little 3s spin up test of the black hole making motor http://vid921.photobucket.com/albums...ps1f83e92f.mp4
Been a while since I've posted on this thread but Lynx is finally underway, got everything but the drive motors and wheels so I have plenty to be getting on with. The chassis material is 6082 aluminium u channel ( 5mm thick for the main body and 3.5mm for the rear spar), I'm going to have to drill some weight out as it currently stands at 1.4kg, I think the last picture gives you an idea of how I'm going to lose the weight in style. http://i921.photobucket.com/albums/a...psf08fe7ce.jpg http://i921.photobucket.com/albums/a...ps90cf1d5b.jpg http://i921.photobucket.com/albums/a...ps3971dddc.jpg
Been a while since I've worked on Lynx but I completely forgot to post the latest progress I made, without drive motors, mounts, armour etc it was coming in at just over 1.4kg which was a major worry so some drastic weight loss was in order. After much centre punching and about 2 hours worth of drilling I managed to remove around 120g and I still had one side of the frame to drill. Since then I haven't touched it I'm hoping my next day off will be just solid building. Couple of pics just to keep you interested. http://i921.photobucket.com/albums/a...ps046020ea.jpg http://i921.photobucket.com/albums/a...psf814c4f9.jpg
And one more thing! Here's an entirely pointless test video of the weapon motor at 3s going to full throttle, for no other reason than it sounds like a freaking jet. http://vid921.photobucket.com/albums...psc0dlxhr9.mp4
BTW the noises in the background are my son.
Not posted any progress on Lynx in a while but I've done a hufe amount of work on it the past couple of days. Everything is mounted bar the armour and drive set up ( still waiting on my Chinese gearmotors) and i've even found the cojones to do a full speed spin test. The ticking noise is the blade scraping the motor pulley slightly, it only does it sometimes but it's something I'm going to address, a thrust bearing between the body and blade should remove any up and down movement without hindering the spin up.
http://i921.photobucket.com/albums/a...ps58c0cd07.jpg http://i921.photobucket.com/albums/a...ps8a9052dd.jpg http://vid921.photobucket.com/albums...ps4mkqmyzy.mp4
What is keeping the bar off the ground? Is the shaft just spinning on the ground or it it tapered to a sharp point? And how much does it weigh at the moment... there can't be much left!
Its a dead shaft so it probably just has a locking collar then that runs on the floor.
Spin up is real good for such a massive weapon. Colour me impressed.
Yeah, thats a 3S NTM 35-34... I think my 4S set up is overkill now... oh well, I have the parts may as well finish it.
Exactly what Harry said it's a 12mm dead shaft, a thrust bearing runs under the blade and then a locking collar runs on the ground.
The weight is just under 1.4kg without drive motors or wheels or armour but I have some weight I can still take out of the frame.
That motor is awesome btw Alex, if I gun the throttle it'll get the blade to full speed in around 5 seconds, the set up does get pretty warm though.
Put another thrust bearing on Lynx's weapon set up to stop it scraping the motor pulley, seems to have sorted it.....
Also has the added benefit of reducing friction making the spin up quicker. This is me pretty much gunning the throttle. http://vid921.photobucket.com/albums...ps0tbnh3e4.mp4
Almost done! Still needs a few bits doing, namely cutting the rest of the weight out of the rear spar and a new set of wheels. http://i921.photobucket.com/albums/a...psad73d58e.jpg Also managed a test at 1/4 throttle before it destroyed the old wheels....we won't go into that, that's a piece of 3mm Aluminium in the picture, threw it about 20ft away. http://i921.photobucket.com/albums/a...ps1320cf32.jpg
Grand, man. Hows weight looking?
Once the frame is finished it should be *just* under the limit, I had to downsize the lipo from 1300ah to 1000 so hopefully that stands up.
Pretty much finished, needs a bit more weight taken out of the frame to get it under the limit but nothing too major. Even managed a little drive test, the floor has no grip at all so it's struggling with traction. http://i921.photobucket.com/albums/a...pse8406996.jpghttp://i921.photobucket.com/albums/a...ps7cbbc14d.jpghttp://vid921.photobucket.com/albums...psuwnr80ga.mp4
Nice. Very F-Bomb esque
F-Bomb and Scissorhands were the main inspiration, here's hoping it works half as well.
One massive weapon and hardly any wheels. Should be interesting :D
It's a major effort I have to admit but I fear you'll end up shortening the blade and getting some more wheel like substitutes for those rubber bands. None the less, I hope it will work like a charm.
It doesn't seem to lack any driveability at this stage but i haven't tested it in an arena yet, i don't see it being a major problem but i'll see what happens.
Have you tried driving it while it's spinning?
A little yeah, it didn't seem too bad considering how large the weapon is, it has a little trouble turning in the direction the blade is going but nothing that's going to cause a problem. I'll know more when i test it in the arena next week, the floor i was driving it on here is laminate flooring so literally no grip.
Major update time!
Took Lynx down to Team Hell's workshop the other day to put it through it's paces, there are some problems that need addressing but overall the design seems fairly stable. I will however now be rebuilding the chassis to make the robot smaller and stronger and a new slightly shorter bar made from 4mm Hardox will be getting made seeing as the Lawnmower blade was not up to the task, even at half speed the tips sheared off and the bar bent and twisted. The machine definitely has plenty of power and it's not completely horrible to drive, the rebuild is already underway so it shouldn't be long before it's terrifying the beetle masses again.
I can't be bothered to post all of the videos from the day so i'll just post my favorite, this was the very last test we filmed against Utopia's old titanium shell, Lynx was pretty much on it's last legs at this point, the bar had twisted, the tips had sheared an the battery was dying but it still managed to cause some carnage. This test was still at half speed, scary to think there's still half to go right?
https://www.facebook.com/video.php?v...69629973768692
Some damage pics from the day, i didn't manage to get any of the targets Lynx hit but here's some of the damage it caused itself. Remember all of these tests were half speed so imagine the strengthening work i'm having to do for the rebuild.....shocking.
The pictures show the twisted and chipped bar and the bent weapon shaft.
http://i921.photobucket.com/albums/a...ps76a7416a.jpghttps://www.facebook.com/photo.php?f...7&l=3d89990a38http://i921.photobucket.com/albums/a...33819124_n.jpghttp://i921.photobucket.com/albums/a...42965398_n.jpg
And finally as an ending to this giant post to end all other's here's a sneak peek of the new chassis for Lynx V2, it's the same thickness (5mm 6082 Alu) but it's taller and will be shorter (the black shaded areas will all be cut away). The reason for the extra height is so i can stack all of the internal components on top of each other in one neat package, this saves space inside the machine meaning i can make it shorter overall by about 40mm. The new blade will be dropped from 350mm to 300mm and will be made from 4mm Hardox, hopefully it will weigh around the same or not too much more than the original blade ( 300g) but it should be much stronger. http://i921.photobucket.com/albums/a...81684670_n.jpghttp://i921.photobucket.com/albums/a...21300657_n.jpg
If you managed to sit and read through all of that i hope it was worth it, cheers people's.
Decided to post the rest of the video links if anyone's interested in them, they're alright, nout special.
https://www.facebook.com/video.php?v...45985440196197
https://www.facebook.com/video.php?v...71619323612949
https://www.facebook.com/video.php?v...82229061280157
https://www.facebook.com/video.php?v...07065144849117
Needs a new/borrowed RX and a lid but Lynx is basically finished and ready for Saturday, no idea how it'll perform as it's going in the arena untested but should be fun.
http://i921.photobucket.com/albums/a...pszqhhq4g7.jpg
Haven't updated this in a while, so Lynx has been to 2 events now and had mixed results. At the iron games in Wolverhampton it didn't work well at all, the grip was very poor and the weapon belt shredded every fight due to me stupidly using a timing pulley with a round belt (20,000+ rpm turns timing pulley into belt eating saw).
After it's disappointing first event it attended Whitwick over the weekend where it performed much better, unfortunately one of the drive esc's was playing up/half dead so it didn't really have completely free movement, the weapon however was working, very well in fact. In it's first fight with Limpet it managed to take out a wheel, a drive motor and bent his front scoop pretty badly out of shape but in the end still ended up in the pit due to having almost no grip and very little drive. well i say in the pit, it basically dug it's blade into the side of the pit and hung above it.
It's next fight was against the very heavily damaged Bork made out of wood, both robots had drive problems but Lynx was able to cause enough damage to win on a judges decision, there was sawdust everywhere. This put Lynx through to fight Headbanger, unfortunately the impacts from the weapon had broken a wire off the brushless esc board and with no time to fix it i had to withdraw.
All in all not a bad second event, the weapon is extremely powerful but the drive is an issue. The plan is to get some grippier wheels, replace the duff drive esc and possibly put some magnets at the back of the robot to compensate for the lack of weight over the wheels.
https://www.youtube.com/watch?v=SbbKhneW1XU
https://www.youtube.com/watch?v=UfRv-btues0