RogueTwo Robots

Update

Spent most of Hurricane Bawbag II in the shed today - or the Cave of Blunders as I'm now dubbing it - and made a bit of progress with Drumroll. First up was swapping out the existing drill motors for a pair of Gimson Robotics motors:

http://i31.photobucket.com/albums/c3...r2_build96.jpg

I've mounted them using the bottom inserts, but needed a 20mm HDPE spacer underneath to bring the shafts up to the same height as the old ones. Once bolted in, they're solid! So much more rigid than the old motors/mounts, although that bit of give in the old ones might've helped with shock absorption. Will soon find out if these being more rigid is a bad thing.

Then it came to making a bay for the lipo pack:

http://i31.photobucket.com/albums/c3...r2_build97.jpg

Advice from experienced lipo users (Dave, Kenny, Grant etc) would be appreciated regarding padding. It's currently sandwiched between two blocks of 15mm Nylon (perfect fit) and although there is left-to-right movement possible, this is eliminated when the top plate is bolted down. There's currently no foam in the bay but I plan on putting some underneath the battery and some between the battery and the white lid. Would this be sufficient? Or are there any parts of the bay you think I should consider remaking? I used to just bolt my Nimhs straight down but not sure what the best mounting practices are regarding lipos.

Starting to re-assemble the electrics:

http://i31.photobucket.com/albums/c3...r2_build99.jpg

The removable link mount has been moved over slightly so I can use wing nuts to hold the polycarb strip onto the mounting bolts. This is so I can easily unscrew and remove the strip in order to get access to the lipo for charging. The receiver will be getting moved to the other side of the second polycarb strip across the motors, as I realised just before heading in that it's currently going to be right next to the spinning can of the brushless. Power distribution bolts will be going somewhere on the front bulkhead, with better spacing and insulation compared to their old location.

Got some time tomorrow and most of Friday to do some more work on this. Hopefully getting the brushless mounted and some wiring done for a test drive. Also need to sort out a brushless ESC pretty soon...

Looks like it's going to be a serious contended at next years Champs. Also I can see a lot of the Gimson motors making an appearance.

Looks good Jamie... As for lipo mines just held down to the base with strap clips in 540, and 360 it sits in a box with foam... The best thing to do is use some hardish foam around it... The weakest point of a lipo is the front connection... Just put some form of protection around it... Not going to teach you to suck eggs mate you know what your doin :p

PJ, I thought it was going to be a serious contender at this year's champs, but it was a terrible failure. So I'm going to predict for the 2012 champs that it'll fail terribly, then I might stand a chance of doing well!
Yeah there'll be a fair few GR01s about. The fact that it's a drill motor but with a better gearbox housing, better bearings and multiple mounting options makes it an attractive package. Although they've yet to be proven in combat, I reckon they'll do fine.

Thanks for the info Dave. My battery securing methods have always been a bit cowboy in the past and while I know lipos aren't dangerous if treated right, I didn't want to risk it getting damaged as a result of shoddy bay construction. I'll stick some foam around the front area to offer a bit of support. Ta muchly.

looking good jamie :) that a 22v pack? thats what im going to be getting in the next few weeks for mine :)

Cheers. Nah it's just an 18.5V pack, keeps the voltage similar to what it used to be. I was originally still going to have 12V drills in it, so didn't want to overvolt them too much, especially since the robot is already pretty nippy. There's probably space and weight to go to 22.2V if I ever wanted to, but it's not something I'm considering right now :)

I'm going to use a 18.5v lipo in my bot, what's the size of the battery (dimensions)? or do you have a link where you got them from?

Those crews you used to hold the battery down, are they just screwed into HDPE? or did you place some sort of threaded insert into the HdPE first?

I take it your charging th ebattery whilst in the robot? would the foam around it not great a fire hazzard issue?

Can't charge Li-Po's in robot unfortunately, it's in the rules.

Lipos aren't allowed to be charged in the robot.

makes sence I suppose, just wondering how jamie will get his battery in and out quickly or easily in the bot. Something I'm thinking about for mine just now easy access.

The lipo access is not the quickest in the world admittedly. I looked at several different positions for the lipo that allowed the easiest access but there weren't a lot of options that didn't have the lipo covered by some sort of electrical connections or ESCs.

To remove: there are four M6 bolts in the base that I take off, which allows the outer and rear bulkheads to lift away, leaving good access to the innards. I then remove the two wing-nuts holding on the Scorpion and link and move it to the side. Then the four smaller M4 bolts holding the white cover on the lipo. So a bit fiddly, but with a screw gun and the right drivers, I imagine I will be able to remove it in just under a minute.

The lipo is a 'Gens Ace' brand I bought from Giant Cod. Not a well-known brand as they seem quite new, but have good reports so far so I'm trying my luck with them to see how they go.
Rough dimensions (from memory) are about 120mm long, 35mm wide and 25-30mm high and that is for an 18.5V, 2200mAh 40C battery. Not sure if that will be enough for a battle, will need to do some testing to find out. If not, Giant Cod now have a 5000mAh, 50C version that I could upgrade to, probably without having to worry about space or weight.

http://www.giantcod.co.uk/gens-2200mah- ... 06486.html (2200mAh battery)
http://www.giantcod.co.uk/cell-lipo-bat ... 1_130.html (5-cell packs, different ratings)

And the bolts holding the battery down are just tapped into the Nylon. It tends to hold threads better than HDPE so will suffice so long as I don't over-tighten them.

looks ok, id be abit worried only running 2.2amp though... how many amps does drumroll normaly pull? Will be more once uve gone brushless...

No idea what the usual current-draw per battle is, only recently got a charger that tells me how much it puts back in to the batteries. The 2200mAh battery was the one with the best 'C' rating they had at the time so I went with it, but the higher capacity ones are a more recent addition. I know over-discharging isn't good for lipos, so if the tests show that the robot is going to be draining the pack quite severely, I'll just get a bigger pack and put the current one into Carcinus, as it's not a current hungry bot.

Not much of an update, but just to display Kenny's handiwork before I shove them in a tube and weld them shut:

http://i31.photobucket.com/albums/c3...2_build104.jpg

8)

Coolio my noolio :P what are they made from?

Just stainless steel. Shiny stainless steel :)

Nice handy work

Looks excellent man, do they add any useful weight to the drum compared to the old style ones. Although most of the advantage will be the the speed increase/reliability i'm sure.

Technically they should, as the old ones were just flat circular discs, whereas these have the hollow innards and thicker outer rims. But any inertia increase will probably be minimal. Should be more reliable though yeah, and will spin much more freely compared to the old bearings.

Really need to get my drum made :(

Also, was just digging around photobucket earlier, once you have the end caps and brushless setup all fitted you need to have a Drumroll II vs LCD monitor round 2 :P

Update

Ah, the toxic aroma of welding and grinding fumes! Spent most of today welding the endcaps into the drum and making a mount for the brushless motor. My welding's getting better but the angle grinder is currently still my favourite welding accessory :proud:

Anyway, got the new endcaps welded into place on the drum. Bolted the timing pulley onto it too and fitted it into the robot. Just the perfect width:

http://i31.photobucket.com/albums/c3...2_build108.jpg

(excuse the lower quality photos, couldn't be bothered going back in to get my proper camera)
Spins much better and a lot more free than the old drum. Spent a bit of time trying to balance it too, and while I think I've made it better, I won't know for sure how good it is until I spin it up. But it seems pretty un-biased for now. With everything bolted/welded in place, the total weight is 2.35kg, which is a bit heavier than the previous assembly. Whether that will make much of a difference, again I won't know until I spin it up/fight it.
Once I've checked the balance, I'll give it a nice coat of paint and probably the spiral I had on the drum back at the 2009 tag champs.

Onto the brushless mount, I've probably went a little overkill with 5mm steel but nothing should be going anywhere!

http://i31.photobucket.com/albums/c3...2_build105.jpg
http://i31.photobucket.com/albums/c3...2_build106.jpg
http://i31.photobucket.com/albums/c3...2_build107.jpg

So there's the main faceplate that bolts to the chassis, to which the brushless motor also bolts. Then, heeding the advice of others, I made up a rear plate to lend some support to the back of the motor. I haven't used a bearing here, just a couple of zinc shaft collets that I had (one welded to the plate, one on the shaft). Despite not being bearings, the shaft spins in them nice and smoothly, so it's enough to make me happy.
I thought about making the mount as entirely one piece - in a U-shape - to have it as one solid unit but I quickly realised that once the motor was in, there would've been no way to get it out. So that's why I opted to do it in two pieces. They need to get tidied up a bit (cut the corners off/down a bit and grind everything so it's all nice and clean) and then I'll get them primed and painted and that'll be another thing ticked off the list.

And finally, made a start on getting the outer armour and wedge back together again. The first step was to alter the design so that rather than having two side pieces that bolted on, it would be one single piece that wrapped around the whole robot. The back panel is all that's done so far:

http://i31.photobucket.com/albums/c3...2_build103.jpg

It's the same 5mm mild steel as used in the brushless mount. Once the sides (4mm hardox) are welded on, I'll cut some pivot points for the rear wedge and weld them onto this back panel. Then hopefully the armour will actually protect the robot, as opposed to it falling off in almost every fight.

So that's that for a day. Should have more updates tomorrow, although not sure what I'll actually focus on, as Carcinus is at the stage of needing re-wired, which is tempting. Either way, at the current rate of progress I'll have both robots finished by mid-February, which will leave over a month for plenty of testing :twisted:

Looking good Jamie- what ratio you using for the drive on the drum?

Not 100% sure yet on the ratio Dave. The original small pulley I bought gave a 4:1 ratio but with the increased brushless shaft size of 8mm, that pulley is too small in diameter to fit grub screws into for securing in place. So I've yet to buy a new one (gonna have a look on Technobots shortly) but will probably aim nearer to a 2.5:1. Think Boner ran that ratio at the champs and seemed fine, and this drum is almost 2kg lighter.

You'll be just in time to do some more child educating then? :lol:

Looking good, will be very interesting to see what sort of power you can get with it now. Looks a lot more secure now too with the new fit, hopefully it runs the way you've wanted it to since you made it, and if it doesn't, you can't blame cutting corners any more :wink:

Looking good Jamie! Give us a spin-up vid soon!

Out of interest, what would you use on the shaft if you didn't have the collets?

I need something similar, that'll stop something moving along a shaft that also doesn't inhibit it spinning too much.

Umm, probably just bearings. I would have used bearings for the back end of the motor shaft but I wanted to weld it on and I didn't know how well bearings would hold their integrity when subjected to extreme heat.

The collets don't really inhibit spinning much. There's marginally more friction because the shaft is spinning in something that's not moving or has rollers or ball bearings, but it's not particularly noticeable and I'd be surprised if you saw a significant reduction in rpm as a result of using a collet. I was planning on using these 8mm collets as a form of bearing for Paws' spinning disc (although I'll have to buy some more now!)

The only issue I can think of is that to limit movement along the shaft, these collets need to be fixed in place with the supplied grub screw, which then obviously prevents the shaft from rotating in the collet. This can be avoided depending on the application though, so it would depend on how you plan on using them (or mounting them) really.

Hhmm something to think about. Way I see it your trying to reduce friction between the motor and the back mount, while staying fixed to the shaft to act as a spacer.
You need a bearing that has two independently moving faces while being able to spin freely on the shaft, but fixed in place also. :shock:

There must be such a thing. I'm thinking about my own robot design and just noticed your situation was similar.

The back mount of my motor doesn't actually need the additional collet fixed to the shaft to act as a spacer. The shaft is fixed to the can and a combination of the magnetic attraction and a circlip at the front holds the motor together. I could run the motor with just the front mounting plate holding it on; the back mount is just to add support to try and reduce motor movement during impacts. So there's no lateral movement that needs to be restricted. I just added the second collet to the shaft because there was space for it, and to make it look better :P

up at the higher end of the rpm range it could cause enough friction to cause damage to the motor. I'd coat the whole thing in grease to reduce this

Update

Ditched the rear brushless support for now. Something wasn't lined up/welded properly and it was hindering the motor rotation slightly as a result; could probably bore out the collet hole a little more but will just stick with the front plate for now and see what happens.

Done a few wee bits and pieces on Drumroll over the weekend and tonight, but not a lot has changed visually so not much in the way of pictures. I've re-jigged the internals a little; the lipo has been moved from underneath the Scorpion XL at the back to the front next to the brushless motor:

http://i31.photobucket.com/albums/c3...2_build112.jpg

Wasn't 100% happy with its original placement, plus the brushless ESC fits in better at the back than it does at the front. I've also fitted a foam-lined 3mm aluminium plate on top of it to hold it down, as opposed to the 1mm plastic piece I used previously. A decision somewhat triggered by the current discussions in the Lipo thread.

I can now also remove the lipo more easily by undoing the two socket screws that hold the ali plate down, whereas before I needed to faff about with wing nuts and four smaller socket screws to be able to take it out of the robot.
I've also got one of these:
http://www.giantcod.co.uk/power-battery ... 06643.html

that I'm planning on mounting in the robot so I can keep an eye on the total voltage and individual cell values. It's got a low-voltage alarm so should help with monitoring the state of the battery.

And finally, I've got the brushless ESC set up so the robot's now driving and spinning (just the motor). Still need to get a suitable belt to connect the drum as well as an inline fuse, but once I've got them then Drumroll will be ready to test. Then I can concentrate on re-fabricating the side armour and rear wedge (weight permitting) and paint it. Shouldn't be long now before it's finally finished again :)

Amazing you manage to fit it all in that kind of 3-storey-towerblock-of-parts assembly you've got going there. Keeps it all compact I suppose.

Next job is to get Carcinus and your flipper going then go to Barnsley with us :proud: :lol:

How do you still have spare space in there!

I've thought about getting a Li-Po alarm for Bitza, since we're using Electronize ESC's we don't have any of the built in Li-Po features of Sabertooth or Scorpion. Just don't know if I'll hear the alarm during a fight should our voltage drop that low.

You won't hear a thing in the arena. The best way to get around the issue is to oversize the lipo. I ran boner for three fights last comp before recharging because of a lack of time to get parts repaired between fights. This was possible because my lipo pack was oversized for safety sake. I do not recommend running a robot for several fights without charging though!!!!

The alarm on my monitor is pretty loud but, as Gary says, it won't be particularly audible in the arena. It'll be handy more when you've just come out of a battle to see what voltage you're sitting at.

I still have reservations about how long my battery pack will last. I'm limited by dimensions so will be hitting up teh intarwebz tonight to see if an increase in battery capacity greatly increases the physical pack size. If I can find something similar to what I've currently got, I'll probably upgrade before the champs just to make sure I won't be running low or cutting out in the middle of a battle. Hopefully testing will give me a better idea of how long the battery will last too.

No flipper chassis yet Tony, so little chance of getting it running before Barnsley. Not that I was planning on going anyway :P
Got those tank connectors unscrewed yet? :lol:

I bought that lipo alarm thing mainly for testing- I know the battery pack won't run out in a 3 minute battle but I would rather be ableto have as longer testing time as possible rather than having to stop and recharge the battery every 3 minutes.

What is the capacity?

2200mAh. Never used to pay attention to how much I used with the old setup in a fight, mainly because I didn't have a charger that told me how much had been put back in, plus the old batts were 3700mAh and the setup was less current-hungry, so a little top-up between battles was all that was needed. Will wait until testing to see what's what.

Tank connectors are still standing their ground, I have been trying too, strained a muscle in my hip the other day there trying to get them off and i'm still feeling it :lol: Now my workshop has been temporarily dismantled and a car has taken its place so can't really do anything for a few weeks.

Thats a shame, if you wanted a ride with us I would try to convince my old man to give me a loan of his car, just got insured on it today, so you wouldn't be subjected to the Chevy again :lol:

With Carcinus and Eric Jr we can send um hameward tay think again an aww that :rofl:

You should be fine. Remember we used to run feathers on 1.2Ah SLAs :)

The brushless whilst being more powerful draws nothing (a couple amps) when it's up to speed. So you get a huge current draw at the start which quickly tails off. Make sure that the drum spins as freely as possible. Make sure you put some 3 in 1 or WD40 in the bearings.