Hammerschwanz 2.0 (6kg Raptor Thwackbot)

So, about one year after my first bot (oh, and what a funny but glorious failure that one was^^) i finally found some time to at least planning a second, much improved version of it.

Who want to see the old version: https://www.youtube.com/watch?v=eEPr...p90zvOmCdzzHWe "Hammerschwanz" in that playlist...
I managed to improve it from fight to fight (mostly making it somewhat maneuverable and stopping things from falling off).
But still, decided i better start over completely.

Internals stay (almost) the same, just switching the 18V motors for 12V ones (had to go with 18V motors on a 3S LiPo, since the post lost the package with the 12V motors and Raptors may only have 12V max).
So internals now:

Motors:
https://www.pollin.de/p/hochleistung...hc683lg-310695
ESC:
http://www.robots.ib-fink.de/fahrtre...tregler4_5.htm
Gearboxes:
Ranglebox Neptunes
Batteries:
http://www.mylipo.de/Lipo-2600mAh-11...5C-70C-kompakt

Not sure about the transmitter/Receiver combination yet, had problems with that on the event, couldn't make my transmitter connect... might get both new.

And this time, i'm doing the planning beforehand, not just lock myself into the attic for 14 nights in a row, and trying to get anything moving with just a cordless drill and a jigsaw and a load of HDPE.

So, planning looks like this so far (my first ever CAD):
https://cad.onshape.com/documents/f3...6649b613d2bb79

used the same (often wrong) screws for everything, because lazyness and i just wanted a rough estimation on weight.

For now i have 3900g used and 2100g left (always rounded up, so maybe a bit more) for:
- the missing/different screws.
- a useful wheel hub or whatever to attach it.
- receiver, link, cables, LED and such stuff
- something hammer-like to put on that tail to at least have the chance to do some damage
- something to make the wheels grippy
- whatever mistake i made and whatever i forgot or whatever doesn't turn out like it should.


Biggest changes to last version:
1. hopefully wheels won't fall off anymore. just pressing a nut into HDPE doesn't work on that size. will try to build a better hub in the next few weeks or so.
2. don't fall on one of the wheels and just lay there dead. HDPE triangle on the wheels seem to work for others, and since screw through the wheels didn't work, i'll try that one next.
3. V1.0 was actually a few hundred grams too heavy... but people let me start nevertheless, first event and not really a dangerous bot... gotta stay within the limits this time.
4. A more "sorted" inside. due to the "tail" sticking right through most of the bot, cable management and everything was a pain. even more since i miscalculated the space needed for cables. Planned for them from the beginning this time.
5. the screws last time didn't really work good. at the end, only 5 of almost 40 screws actually provided some hold, all the others were just for stabilisation while duct tape kept everything together. different screws this time, and more testing before just using what looks good.
6. make the weapon work this time. even if i would have been able to really drive, i couldn't make the weapon swing overhead, and sideways i just flipped myself. so lighter, sleeker weapon design this time, more weight in front or over the axis instead of behind it, and try to get the wheels grippier. also more attachment of the tail, to keep it from slightly rotate in the relatively soft HDPE. that (and having just one point of it on the ground) made the triangle always stuck in the wooden floor.
7. new form hopefully makes overhead weapon attacks easier, will keep my link out of reach of others, and the ESC more accessible between fights (less screws). Plus using a lot better tools and more time (as well as not doing it alone this time) will hopefully lead to overall everything fitting together better than it did.
8. Fitting motors -> more power, less smoke.
9. Somehow couldn't make the LEDs work last time... possibly smoked them while soldering. (bought the hottest soldering iron i could, thinking "bigger is better"... oh, i was so wrong...) Must change that this time, mount the LEDs properly and fix the link better, make charging more accessible. Handling in the pits really was only possible due to the wheels have fallen off anyway, so i could reach everything. (hopefully) without falling off wheels, i have to get there easier.
10. Test drive. Last event the wheels were build in the train at 5.00 am on the way to the event, just to get there, all "done", and realising the transmitter/receiver wouldn't work with each other. And not being able to drive, due to weight distribution. and... about everything. 90% of the damage i took i did on myself, so would have been avoidable with some testing beforehand. want to do a lot of testing this time.


So much for what i have done and have planned... any ideas how to improve before the actual build starts? (i know this likely won't be competitive in any way, but all expensive parts seem kinda secured from spinners (not many spinners can even reach that high chassis).
So this is somewhat a cheap-ish secure bot to get some experience and also something unlike all these boxes and wedges we see most of the time.

Looks good, I was always wondering what happened to this robot.
You don't necessarily need to make the weapon lighter, just make the shaft shorter.

Not much happened to it... that's the problem with too many hobbies and a job likely having 15 overhours per week or such. That's why we won't be in Dortmund this year, but hopefully can make it to an event later that year.

Well, the weapon definitely was a bit too big, my bot was too heavy, so saving some weight there won't hurt. even less since the old hat two design flaws i can't possibly change easily with my tools: it hat 1 "bump" on the flat end, and was meant to slide over the floor with that. only the hdp where the tail was mounted wasn't stiff enough, so it started to turn a bit each time the bot turned, making the sharp edges go down and get stuck in the wooden floor. tried to fix that with two additional bumpers of duct tape, but that was a workaround at best, no solution. plus it came from waterjet cutting with the mounting holes just a bit too small, so the screws i wanted to put there got sheared off, and i had to bend them on the other side to make it stay somewhat on.
Plus, i had a big problem with the grip on the floor. when i wanted the weapon go overhead, my wheels just skidded over the flor, providing zero torque to the weapon. so i think i'll go with something if not much lighter, at least a lot more balanced (getting it back at least worked once). the triangular shape was meant to push the plate in front of me towards spinners, so horizontals get deflected upwards on it, and verticals got nothing to bite into. i also wanted to be able to hit overhead or by spinning on the spot, ramming the triangle like a wedgeledge ramp unter the other bots.
But i simply realised:
1. there is no horizontal raptor spinner i am aware of, making triangular obsolete
2. my driving isn't good enough and the maneuverability is too bad to drive with that plate pushing. also get stuck on the floor a lot. with he tail even shorter, any sharp edge pointing downwards (maybe after a hit, before i find time to get back on the right side) would be like a plough to the floor, getting stuck on the tiniest bit. i'd like to avoid that ;)
3. i can't spin on the spot being that unbalanced and with the wheels so close together. (and with the weapon getting stuck).

I'll keep that plate and mount, and will try different weights and sizes anyway once the bot is driving to see what weapon could possibly work. I also have still around 3m of wood cored aluminium "tails" here to experiment with different lengths. Maybe i'll get back to it, wouldn't say no to it if it works.
Do you have any other ideas for improvement?

Slowly comes my night... or whatever.

"building" goes on, mostly in disassembling Hammerschwanz 1 to salvage the electronics and anything moving.
chassis is planned and materials are ordered, and in 2 weeks i'll hopefully find a bit of free time at work to start an experiment: casting hubs to mount the wheels better. i have no access to a mill or lathe or other cool stuff other than a ton of dremel tools, so making custom parts is not that easy for me. but i can cast small parts from Cobalt Chrome Molybdenum at work, so i'm gonna give that a try. no idea if it could actually work, but should be worth a try.

also managed to swap the pinion gears from the 18V motors to new 12V ones, since in the Raptor class only 12V is allowed. And 12V motors should work better with 12V than 18V ones, at least i hope so.

finally ordered a new transmitter (flysky fs-i6) since the other one i got cheap from ebay wouldn't work in any way...
And ordered some spares, screws and such small parts. now the waiting started, and maybe next week i'll be able to get some actual building done. the time after next week not so much, since work will be stressing a lot again.

Is that the same chrome moly as bike frames? Following the build eagerly, I enjoy watching a good thwackbot!

I'd be interested to see how you cure the weapon issues too.

It's the same Chrome Moly as in dental prosthesis, not sure how similar that is to the bike frame ones... would think not very, since bike frames usually should be less springy.

I hope many weapon issues will get solved by more grip combined with better fitting motors and putting the center of gravity closer to the wheels (so: lighter weapon/shorter "tail"). we will see... next week i hope to find some time to get the chrome moly things done, not sure when i might be able to test them. Also, at the end of next week most parts (or at least all important ones) should be here, so i can start to put everything together.