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Thread: Mr. Krippling - Exceedingly Good Breaks! - Team Manuva's Heavyweight Build Log

  1. #1
    So I mentioned I had some big news to share soon....


    All of this happened quite quickly, so I can't exactly say I was planning it. The opportunity came around and I had to take it. I've bought a heavyweight!

    Well, the chassis anyway. There was a choice between a hammer and a lifter, so I went with the lifter as I felt it would be a more versatile platform.


    IMG_20200603_201140_308.jpg

    IMG_20200603_182915.jpg


    Originally built by Jack Tweedy, the chassis is 6mm mild steel in most places. I think the top panel is 4mm, but it doesn't fit in to what I have planned anyway, so will likely be either replaced or repurposed. The weapon arm will need reinforcing with Hardox eventually.

    The chassis itself has mounting points for Ampflow motors and gearboxes for both the drive and the weapon, but I'm not sure I will go for that as it will cost ~£1000 for 3.

    With regards to the drive, I'm still weighing up my options. I like the idea of brushless (Maytech look super tempting, but expensive) and they seem to be easier to get hold of ESCs for that amperage at a reasonable price, but are less likely to include gearboxes. On the flipside, it's easier to get brushed motors with gearboxes, but high amperage ESCs are less common and more pricey.

    Same goes for the weapon really. I was looking in to wheelchair motors to power the lifter as they provide quite a bit of torque, but after a few discussions with friends we worked out it would require an ungodly amount of further gear reduction to get it to lift 110kg. Therefore, I'm looking in to low pressure pneumatics as you can get a lot of the parts off the shelf from Amazon. Not going to lie, this scares me quite a bit because I have the capacity to be an idiot at times. However, you don't learn without actually doing things, building robots has definitely pushed me out of that comfort zone a few times already.

    To sum it all up, I have no concrete plans yet.

    And yes, the most important bit: the name. Mr. Krippling was originally reserved for my upcoming beetleweight that is currently in CAD, but I figured it was more of a flagship name for the team. It continues the baked goods theme nicely, expanding out from bread to wider bakery themes. The plan is to paint the robot like an Angel Slice, with the white and pink icing.

    That's the most important bit.


    Anyway, this is where we are at. This is the big one. If anyone could offer any advice or ideas, then it would absolutely be much appreciated.

    Cheers,

    Andy

  2. #2
    Very nice. It can be a bit daunting first going into heavyweights but you gradually get used to them (except their weight, you'll always hate how heavy they are!)

    Drive wise, you're right that Ampflows are expensive and brushless would be more complex for a drive train. An alternative option might be electric scooter motors, running through spur gears, onto the wheels. Not the most powerful setup compared to the above options but plenty to get you moving, and very similar to what a lot of UK heavies run with their Bosch 750s. Motors are about £40-60 each and you could run them off a RageBridge (~£200 I think) although I think a fellow roboteer is designing a similar brushed controller that might work out cheaper than a RageBridge so depending on what your timeline for this is, that may be available to you.

    I run scooter motors in Shunt and Coyote and they're perfectly capable of shifting them; they're also quite rugged with some basic battle hardening. They wouldn't fit the brackets that are in the robot, but if you have access to CAD, it would be simple enough to design some new mounting brackets which you could then either cut by hand or get waterjet/laser/plasma cut. That would allow you to get holes lined up right for gear spacing etc. Let me know if you want any more info or links for the motors.

    As for weapons, you'd again need quite a powerful/expensive motor and a lot of gearing to drive it. Pneumatics would certainly be a decent alternative. As it's quite a shallow bot, you could have the rams protruding out the top towards the rear, so you can get more stroke and travel on the lifter/flipper arm. Ripper had a similar design in Series 7:

    Ripper.jpg

    The only thing might be that the chassis is also too shallow for the traditional 2kg CO2 bottles, so you might need to slave smaller 600g ones together, which presents issues with arming up, or alter the shape of the bulkheads or top armour to give extra height. I think there are also 1kg bottles around but are more rare, however they might fit the chassis better. I'd recommend a buffer tank(s) too to help prevent regulator freezing and increase the speed of your rams firing.

    If you go the pneumatics route, see if you can find any fire extinguisher servicing/refill places near you. I found one not too far from me that refills a 2kg bottle for £5 and has loads of bottles on their premises, so they're a good option if I ever need to change bottles or get advice.

    Hope that helps, but any more questions, just ask.

  3. #3
    Ocracoke's Avatar
    Team Kaizen

    Neat. As Jamie mentions, the logistics of moving a heavy robot can be a challenge all on its own so make sure you have folks around who can help lift and shift the thing. How heavy is the shell at the moment?

    800W scooter motors would indeed work but you'll still want ESCs capable of taking the pounding. Ragebridges would indeed work though you could use a Cytron 60A like Kaizen, Jibril 1.x and Mean Machine have used in the past if you go for the Scooter optionn. The fans on them are a weak point as is a dodgy capacitor but I can testify that they work. I wouldn't want to drive Ampflows with them but they are an option.

    Worth considering a pair of linear actuators for the lifter if the pneumatic option doesn't pan out? I am sure the HW version of Luna-Tic did use some.
    Team Kaizen - Build Diary for all the robots

    AW: Amai, Ikari, Lafiel, Osu, Ramu
    BW: Shu!, The Honey Badger
    FW: Azriel
    MW: Jibril, Kaizen

  4. #4
    I forgot to mention, 800W scooter motors are impossible to get at 24v now, the minimum voltage they're available in is 36V. Highest power 24V scooter motor now is 500W, but I believe the dimensions are the same so it could well be that they've just downrated them. They'd still be plenty of power, and would probably cope with an over-volt to 8S if you wanted to eke out more power.

  5. #5
    You are in the big league now Andy, now I get the chance to fight you at the highest level-keep us

    updated on how you are getting on with the Robot.

    Heavyweight builds are very rare on the forum so well done in buying Mr Krippling and I know you can bring it

    to fruition.

  6. #6
    Haha. Yes Heavy Luna-Tic had a 4000N linear actuator. 12v but ran it on 5s. It worked okay, cheap n easy to set up, but slow. A single Ragebrigde will run 2x 800w scooters. But will hit the 45amp limits (per side) and you will have zero pushing power. Learnt the hard way. But it ment I could get it built and start fighting. I later upgraded to an old sidewinder, much better. but then the 2018 champs..... Happened..... RiP...

  7. #7
    Love the name Andy. Congrats on your new project, that'll be plenty to keep you busy in lockdown.

  8. #8

  9. #9
    Thanks to everyone for your kind words and advice! I wanted to leave it until I had some concrete plans in place before I updated again. As people have mentioned, HW build logs are very rare on here, so I feel obligated to make this build log the best resource I can.


    I've made quite a bit of progress on buying parts for the drive. This has always been part of my build philosophy, because as long as you can still drive and push, you still have a chance. A strong drive system was priority number 1.


    ESCs

    I have managed to get my hands on 3x second hand Robot Power Vyper 120A brushed ESCs from a listing on here. Two ended up being just under the cost of a Ragebridge, plus a spare. Given the amperage is much larger, I'm very happy with that.

    Vyper-1.3-iso-sm.jpg

    Motors/Gearbox

    Also, much to the dismay of my wallet, I went with 2x Ampflow E30-400 motors with the gearbox from Rapid Online. There were a couple of reasons for this. First was that there is not much price difference (relatively speaking) between the basic Ampflow E30-150 motors (£85) and a decent scooter motor (~40-60 as Jamie said). Given that the ampflows are 1.6kW compared to the 500W 24V scooter, the difference in quality was well worth it in my opinion.

    I then chose the E30-400 over the E30-150 because it has a much higher stall torque. Also, my Dad always said "Choose what you want, then buy the next one up instead". That advice hasn't failed me yet.

    unnamed.jpg

    The gearboxes were a harder sell as it is possible to do this myself. However, my decision was swayed by the lack of space inside the robot. As Jamie has already mentioned, it is a relatively small chassis (~750x600x250mm), so anything I built would be:


    • Larger
    • Less precise
    • Require modification to the existing chassis.


    After some calculations, building a gearbox of similar size and gear ratio would cost about £70 less than the off-the-shelf variant, with all the issues above added on. At the very least, I can use these as a learning resource to make my own gearboxes in the future.

    The precision downside that I mentioned above is also claimed by Team Riobotz, who say in their combat robot tutorial book that the Team Whyachi variant of these "are worth every penny" just so you don't have the hassle.

    So build progress-wise, that's where I'm at.

    -----------


    The only thing might be that the chassis is also too shallow for the traditional 2kg CO2 bottles, so you might need to slave smaller 600g ones together, which presents issues with arming up, or alter the shape of the bulkheads or top armour to give extra height. I think there are also 1kg bottles around but are more rare, however they might fit the chassis better. I'd recommend a buffer tank(s) too to help prevent regulator freezing and increase the speed of your rams firing.

    If you go the pneumatics route, see if you can find any fire extinguisher servicing/refill places near you. I found one not too far from me that refills a 2kg bottle for £5 and has loads of bottles on their premises, so they're a good option if I ever need to change bottles or get advice.
    Thanks Jamie for all of your advice! I've already extensively studied your videos on the pneumatics setup of both Shunt and Renegade, so your advice is super helpful. I will definitely be asking a few questions as I go along, if you don't mind?

    Having done some measuring, you are unfortunately correct, it is too shallow. You can get 1kg bottles, but mostly for powder and not CO2. Would these still be suitable?

    I've had a look and Lancashire Fire Protection are very close to me, so that's great advice. I shall get in contact with them should I pursue pneumatics further.

    Neat. As Jamie mentions, the logistics of moving a heavy robot can be a challenge all on its own so make sure you have folks around who can help lift and shift the thing. How heavy is the shell at the moment?
    Cheers Lucy. Chassis is around 45kg according to Tweedy and the measurements we gave to the courier.

    Worth considering a pair of linear actuators for the lifter if the pneumatic option doesn't pan out? I am sure the HW version of Luna-Tic did use some.
    Linacs were a consideration and definitely still remain a backup if pneumatics don't work out. The downside would be the payoff between speed and lift. I've already done some calculations with a friend:

    Using a heavy duty 12v Gimson linac at 24v, this would give an extension of 22mm per second.
    The arm itself is 700mm from the pivot in a class 3 lever. Positioning the linac at 100mm from the pivot would give a 620mm circumference, of which we are using 1/3rd-ish. That gives a full extension time of around 9 seconds, which is slow. However, 45 degrees should be enough to topple an opponent, which would be about 3 seconds.

    Still slow and not ideal, but manageable.

    The force to lift 110kg at 700mm gives a mechanical advantage of 7, meaning that we need 770kg of lifting force with the linac at 100mm from pivot. This means a pair of 4000N linacs should be enough.

    As far as I can tell, this would be the best situation in which linacs could be effective in this configuration, so I would rather avoid it unless I could sub out the 12v linac motors for some 24v ones.


    You are in the big league now Andy, now I get the chance to fight you at the highest level
    Bring it on, Colin! Looking forward to it!

  10. #10
    Ocracoke's Avatar
    Team Kaizen

    Cheers Lucy. Chassis is around 45kg according to Tweedy and the measurements we gave to the courie
    Wow. Jibril 1.6 ended up being under 45kg at the MW championships at EXR Cheltenham 2019. Big solid lump you have there

    I have managed to get my hands on 3x second hand Robot Power Vyper 120A brushed ESCs from a listing on here. Two ended up being just under the cost of a Ragebridge, plus a spare. Given the amperage is much larger, I'm very happy with that.
    Ah ha! You're the person who snagged them! I was toying with the idea of getting those myself for a MW or potential HW project. They should serve you well... I'll find alternatives :P
    Team Kaizen - Build Diary for all the robots

    AW: Amai, Ikari, Lafiel, Osu, Ramu
    BW: Shu!, The Honey Badger
    FW: Azriel
    MW: Jibril, Kaizen

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