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Messages - AmbientChaos

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Who is the one running the BotRanks?  It looks like there hasn't been any event results added in over a year now.

Event Results / Re: Motorama Beetles 2020
« on: April 23, 2020, 09:38:54 am »
Missed one:


Progress Reports / Re: Team Tamper Resistant
« on: April 03, 2019, 08:40:56 pm »
It looks like we both got some inspiration from Silent Spring and wound up with some strikingly similar bots. 

Maybe if all 3 of us make it to Franklin this year we can have a battle of the 3D printed undercutters!

Questions / Re: Tools and materials for a beetleweight?
« on: January 25, 2018, 01:09:23 pm »
American here, so my preferred sources might be different than those across the pond, but here are my thoughts.  If you're looking for armor in the strictest sense (particularly for wedges), grade 5 titanium is what is most commonly used in beetleweights since it is strong/flexy to take impacts while being lighter than steel.  For frames, many people use impact resistant plastics like UHMW polyethylene because it helps to absorb impacts and tends to flex/scratch when hit rather than breaking (one experienced builder recently built a 30 pound bot out of a slab of the similar HDPE that the Brits seem to prefer).  For lids/baseplates there is much wider variety with everything from aluminum to polycarbonate to garolite seeing frequent use.

Weapon motors very commonly come from HobbyKing, with the Propdrive series seeming to be notably popular at the moment.  For drive motors I would recommend Pololu, ServoCity, and FingerTech.

As far as tools go, I've been doing fairly well with basic tools like a drill, jigsaw, dremel, sander, and metal shears supplemented by having a couple more difficult parts cut by waterjet.  You don't have to have a fancy CNC mill or lather to be able to make a cool bot, you just have to be able to design around your tool limitations.

As an aside, this forum has become much less active than it used to be, but there is a very large and active group on Facebook that you could join.

Progress Reports / Re: Revelation Robotics
« on: October 04, 2017, 06:50:48 pm »
When I was trying to figure out how to set up the dead axle for my current antweight horizontal spinner I wound up looking at the pictures in Jamison Go's build log of DDT for inspiration. Since I was trying to accomplish this with all off-the-shelf parts, here's a rundown of what I've wound up using:
  • Flanged sleeve bushings pressed into the top and bottom of the frame to provide a larger contact area with the plastic of the chassis as well as some compressive force
  • Shoulder screw through the bushings to act as the dead axle
  • Blade screwed to a 3D printed pulley (I used a Fingertech blade and a ServoCity screw plate since they went together easily)
  • Bearings in the center of both the pulley and the blade
  • Shim washers between the bushing/screw head and the bearings so that tightening down the screw only prevents the inner section of the bearing from moving
Granted this was all completed just a few weeks ago and has yet to be tested in a competition, so your mileage may vary.

Questions / Re: What Dream parts would you choose for a heavy weight?
« on: August 17, 2017, 06:47:42 pm »
This forum isn't especially active all the time, it mostly gets busier right before one of the bigger competitions.  You might try the Facebook Combat Robotics group, it's pretty active and helpful.

Progress Reports / Re: Team AstroBot
« on: July 01, 2017, 11:12:07 pm »
I may have only found this hobby about a year ago, but I definitely understand how you feel.  For both the Motorama and Franklin Institute events this year, despite my frequent checking of BuildersDB I only got online in time to find that the events had filled up almost instantaneously before I even knew registration was open.  I only managed to get my beetle into Motorama by showing up at the event with my bot and taking the place of someone who dropped out at the last minute, and I think that might be the only way that I could get entered into the Franklin Institute as well.  I'm not really sure what the solution to the problem is, but it seems that in our neck of the woods there are currently more builders with insect weight bots than the established events can handle. 

Questions / Re: Steering help on Viper Kit
« on: March 17, 2017, 07:52:08 am »
The issue here is that you have two separate channels on the transmitter (left-right/aileron and forward-back/elevator) that you need to act as two combined channels for controlling your drive motors.  As Coboxite said, the two ways to do this are to mix the signals at the transmitter end or to mix the signals at the receiver end.  For the transmitter end I think that most people have transmitters that are intended for planes or planes/helicopters, but it seems that you have a transmitter that is intended solely for helicopters.  I have much less experience with setting up controls for that type of control scheme, but I think that it may be do-able if more difficult than with a transmitter meant for planes.

For plane transmitters, elevon mixing is convenient because pushing one direction on the stick can give you an equal output on on two channels.  For a helicopter transmitter (and anyone that has actually tried this can feel free to jump in and correct me), I think that you would want to set your swashplate type to 3-S (this being a type of mixing for helicopter inputs), and then I think that you would want to change the AFR to set the aileron and elevator channels to +/- 100%.  I think that this could give you something that is functionally similar to elevon mixing, but I could be entirely wrong. 

If it does seem to work at least as far as motor direction goes, (assuming you have fingertech tinyESCs to go with the silver sparks) you can run the calibration on each ESC so that the maximum input it sees from each direction on the stick gets translated to maximum output for the wheels.

If it turns out that this idea doesn't work, I think that your options would be either to get a different transmitter that allows you to do elevon mixing or to add a receiver-side attachment to do the mixing for you as Coboxite said.  If you're sure that you're getting into this hobby for the long-term it might make more sense to invest in a transmitter with elevon mixing, otherwise it might mean having to add a standalone mixer into every bot you build/drive in the future.

Progress Reports / Re: Team Ambient Chaos
« on: February 27, 2017, 11:52:01 pm »
Glad to hear it. I have a idea for a bot that just might be crazy enough to work, but it is based upon the blade hubs. I was worried about going for the idea due to the hubs popping of easily, but it sounds like it might be worth a try with the new hubs.

Progress Reports / Re: Team Ambient Chaos
« on: February 23, 2017, 10:31:52 pm »
Motorama has come and gone for this year, so it's time for the post-mortem.

Angry erector set managed 1 win and 2 losses, and the electrical issues from its first event have been fixed, so I was in control the whole time and performed much better.
The first match against Commander Doom went in my favor, but the weapon blade was barely hanging on by a thread by the end of the match. 
For the second match against The Cuban, he came over before the match to pick out a blade that was longer than mine to use for the fight.  The result was that he was able to take off first my weapon blade and then my wheel before I could to much to him in return.
In the third match against Odium one of the first hits broke the gearbox for my right wheel, leaving the wheel inoperative and leaving me stranded, but when the wheel fell completely off a little bit of magic happened.  With the blade dragging me forward I suddenly found that I was more mobile with one wheel than I had been with two wheels.  It only lasted a few seconds before the blade came off, and I might have only gotten one hit off at best, but it brought a huge grin to my face while it lasted.  Now I have crazy ideas rattling around my head about trying to create a one-wheeled horizontal spinner a-la No Fly Zone where the weapon is the propulsion.   :o

I think that I learned several important lessons from these three fights that I can carry forward.
The weapon blade came off or nearly came off in every fight.  While the new clamping style of fingertech hub seems to be an improvement over the old set-screw style hub (in that it no longer comes off after the first hit), I think that it winds up that the metal is too soft so that each hit winds up enlarging the hole and slowly working the hub off of the shaft.
Instead of using the battle-tested Spark motors, I went with a pair of motors that were smaller/lighter in order to make the weight limit (an all-metal frame is not light).  The gear boxes wound up breaking on the first significant hit to the wheels, and eventually the front plate of the gearbox shears off completely.
The second fight bend the shaft on my weapon motor, and the third fight bent the mounting bracket for the motor.  I think that these parts just weren't meant to take these types of loads, so I need to look at doing a better job of channeling the forces from my own weapon directly into the frame instead of through the weapon motor.
I went with the titular aluminum extrusions because they were practically ready off-the-shelf to be a frame, all I needed to do was enlarge a few holes and bolt everything together.  I think that having an all-metal frame for an antweight was overkill, since it wound up leaving me without enough weight to put into the other necessary components as I should (like the drive motors).  Also, while I think that it serves reasonable well as a frame material, the two fights with the spinners showed that it doesn't fare well where it can come in direct contact with an unfriendly blade.
Overall I think that this is more than I can fix with a few tweaks to the bot to make it more competitive, so I think that I will either wind up making a large enough re-design that it will warrant a new name, or I will wind up replacing it with another type of bot completely.

Enraged Erector Set also managed 1 win and 2 losses, but I feel like it was more successful overall.
The first fight against Mombot went in my favor, but I feel like I could have performed better.  Because I went into the event with the weapon blade unbalanced, I couldn't put the weapon throttle above 25% before it vibrates enough that the wedge wouldn't get under much of anything, and I was experiencing some traction problems that I slowly learned to compensate for over the course of the match.
The second fight against Sparky was over in seconds.  It looks like his wedge was lower than my wedge, so he got in the first good hit, and this revealed a big flaw in my wedge.  I had countersunk the holes in the wedge to have flat-head screws that would be flush with the face of the wedge, but I didn't realize that the heads of the screws would be taller than the thickness of the wedge, so I wound up using button-head screws instead.  It turns out that these screws were holding on to practically nothing, so the one hit tore the wedge right off with no significant damage, and with the wedge and one wheel already gone I decided to tap out before he hit my now exposed battery or electronics.
The third fight against Wedge of Allegiance came down to the fact that he had a lower wedge that I did, and he did a good enough job of driving that I only got one or two chances to hit him from the side or back, otherwise his wedge just kept getting under me.

Overall I think that Enraged Erector Set did reasonably well, and the biggest issues with the current iteration stem from my rush-job to get the last few pieces built in the week before the event and can be improved on before it sees another event.  The weapon blade I'm hoping will be as simple as grinding one side down so that I can spin it at full speed without major vibrations.  The aluminum frame seems to be a much better fit to the beetleweight weight class than to an antweight; I still have a couple of ounces of leftover weight to play with, and some plans for possible ways to use it.  Once I fix the wedge so that I can use the flat-head screws as intended, the most vulnerable parts of the bot will be the wheels and the flat back section of aluminum extrusion.  I'm going to resurrect the style of wheel guards that I tried on Lapsed Pacifist to try to protect my wheels, and I'm going to add a strip of poly-carbonate to the back to make it more resistant to other spinners.  The wedge should be pretty good once I get it back to using the correct screws, I just need to sharpen the front edge so that I can do a better job of getting under other bots.  The weapon motor seems to have held up pretty well to the abuse of the weapon being used, much better than AES.  I already had two ball bearings to transfer force directly from the axle of the weapon motor to the frame, but I have a couple of ideas to reinforce the mounting of the motor and weapon arms to make it all as rock solid as I can get with an in-weapon motor without going to a more extreme overhaul of the weapon.  Finally, I believe that the problems I had with traction is actually that I had too much power.  I have motors that run at 1,000 rpm at 12V, but I threw in a 4S battery that jacked up the speed even further.  After the first fight I had the impression that my issue was that I was making too-large movements with my stick and losing traction as soon as the wheels started turning, so I turned the max throttle down to 75% for the later fights and felt like I had much more control.  Now I just need to decide whether I would be better off dropping down to a 500rpm motor, dropping down to a 3S battery, or just limiting the throttle in the transmitter.  In any case,  I look forward to getting the chance to give the bot another workout once I finish with the improvements.

Progress Reports / Re: Team Ambient Chaos
« on: February 17, 2017, 12:14:10 am »
I got the weapon blade from the local machine shop today and got it mounted to the motor, so now Enraged Erector Set is complete!

While it came out more-or-less okay, the bore hole at the center of the blade wound up being a bit off-center.  The result is that I can't put the throttle above about 25% before the vibrations really start to make it lose traction.  Thankfully it sounds like I might have one more day to try to get it balanced before it has to compete.

Does anyone else have any experience/tips for trying to balance a blade like this?  My approach so far has been to place the blade with a ball bearing holding it up on either side, give it a spin and let it come to a rest, and then shaving some metal off on the side that stops on the bottom (always the same side so far).  Is this the proper way to do this, or is there a better way?

Progress Reports / Re: Team Ambient Chaos
« on: February 14, 2017, 11:19:19 pm »
After a few hours of work, the only things that Enraged Erector Set needs to be functionally complete is the weapon blade.  There are still a few finishing touches I would like to put on it tomorrow, but otherwise it is good to go.

The weapon blade should (hopefully) be done and ready for me to pick up on Thursday afternoon, so hopefully I can get it mounted and balanced Thursday night.  I'm certainly going to be cutting it close!  If all else fails, I'm considering 3D printing a solid PETG plastic blade just so I can have something to put in the competition.  Now I just hope they will let me in as a last minute addition!

I got my titanium wedge and a backup wedge made, but I think that I underestimated how difficult it would be to work with titanium.  I started out treating it like aluminum and just trying to cut out the basic shape of the wedge quickly, and I soon learned how much harder titanium gets when you get it hot, so slow and steady is the better course.  I still managed to blunt a few (admittedly cheap) drill bits before I fully learned my lesson, but I finally manged to get everything cut and drilled just the way I wanted it.  Then all I had to do was bend the first side, bend the second side, and *SNAP*.  The side of the wedge snapped clean off, so I had to start all over.  But in the end I managed to get it made, so now I have two (mostly) complete bots ready to  compete at Motorama!

Progress Reports / Re: Team Ambient Chaos
« on: February 10, 2017, 07:45:34 am »
So it sounds like using adhesive to hold it on is the way to go (particularly with trying to get things done at this late stage), and I might not even need something as strong as epoxy.

Progress Reports / Re: Team Ambient Chaos
« on: February 09, 2017, 08:50:35 pm »

I have made some more progress with Enraged Erector Set.  All I need now to have a complete bot is to finish the titanium wedge, add a master power switch to complete the wiring harness, and get the drummette made.  I am going to go talk to one or more of the local machine shops within a few miles of me tomorrow, and if they say that they can get my drum made by the end of next week I just may be able to get my beetle entered into Motorama after all!

As far as the drumette design goes, I have one question for the more experienced builders/machinists.  If I'm attaching the drummette directly to the can of my weapon motor, would I be better off keeping things tight and press-fitting it to the motor, or would it be better to go with a looser fit and use epoxy to hold the two together?

Progress Reports / Re: Team Anarchy Robotics
« on: February 07, 2017, 07:02:25 am »
I'll be there on Friday morning, and I have a few spare 6ch receivers with proper failsafe that work with a dx6i that you could use.

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