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Author Topic: Team Ambient Chaos  (Read 8772 times)

AmbientChaos

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Re: Team Ambient Chaos
« Reply #15 on: October 17, 2015, 11:51:24 am »
Success!

The new Pololu motors that I found fixed all of my problems!  Just got finished testing them out and they seem to work with no stuttering on both 3S and 4S LiPo batteries, but I think I'll stick to 3S for now while I'm learning to drive. 

Unless something catastrophic happens at my first competition I think that I have found my choice for beetleweight drive motors from here on out.  They are the same size as the KitBots motors that were giving me all of these problems and they have the same type of all-metal gearbox case, but I have different gear ratios to choose from and they don't make enough noise to make the ESCs spaz out.  Then to top it all off, they fit nicely with a FingerTech mounting plate and a ServoCity power board to make a nice compact package that I hope will make them really easy to quickly swap out in between matches if necessary. 

I'm all out of excuses now, so I'll just have to finally get the aluminum plates cut, actually start fabricating this bot, and learn to tune and drive this thing!

FingerTech

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Re: Team Ambient Chaos
« Reply #16 on: October 17, 2015, 01:50:50 pm »
Glad you figured out the problem!
Kurtis Wanner
FingerTech Robotics

AmbientChaos

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Re: Team Ambient Chaos
« Reply #17 on: October 24, 2015, 07:50:01 pm »
It looks like my water-cut parts for Lapsed Pacifist should arrive some time next week, so I should be able to start building the final version of the bot and posting some pictures of the build progress.  I'm just a bit bummed that I couldn't get it all ready in time to debut at the Franklin Institute event today.

In the meantime, since I'm now getting some tiny amount of bot building experience under my belt I have started to entertain the thought of building a second bot, but this time making an antweight so that I can have a bot entered in both categories in competitions, and I think that I have learned enough that I feel more comfortable with the idea of trying to build a spinner. 

This is what I came up with over the last day or so.  I think that if I go through with it I would like to build it all myself this time.  That places a few limits on my designs since I don't yet have any experience with a mill or lathe, so I decided not to try to make something machining-intensive like a drum but to go with a simple horizontal spinner instead.  I thought about trying to make a belt-driven mid-cutter at first to try to minimize potential damage to the weapon motor, but after struggling to come to grips with all of the intricacies of belts, pulleys, axles, bearings, mountings, etc I defaulted to the KISS principle and went with the idea of just mounting the blade directly to the motor shaft, so the design wound up turning into an under-cutter.  I welcome any thoughts, critiques, or suggestions on the design.

On the subject of building it myself, I  ran across this page that goes with the Kickin' Bot book about cutting metal sheets with a jigsaw, which I think would be well within my ability.  Out of curiosity, what did anyone else on here do for cutting metal plates for your bots?
« Last Edit: October 25, 2015, 10:54:36 am by AmbientChaos »

Coboxite

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Re: Team Ambient Chaos
« Reply #18 on: October 24, 2015, 09:59:29 pm »
You might want to consider making your blade one toothed, that way you can get maximum bite at a higher speed. Otherwise, I can't see much wrong with the design.

I cut all of my metal with a dremel with a third party reinforced cutting disc, then clean up the edges with either a file or the sanding attachment for my dremel. It takes a awhile, but I find it the easiest way of cutting metals, even thick steel(About 3mm). Beyond that, aviation shears are good for thinner, weaker metals like aluminium and mild steel.

Badnik96

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Re: Team Ambient Chaos
« Reply #19 on: October 24, 2015, 10:13:45 pm »
If you have one, a bandsaw is perfect for cutting metal.
TEAM IGNITION
FireArrow (Antweight) 23-11
Nocturne (Beetleweight) 5-10 (Retired)
KnightShade (Beetleweight) 0-0
Landshark (Mantis) 1-2

Pennbots 2014 and Bot Blast 2014 antweight champion. Bot Blast 2013 Best Driver and antweight third place.

AmbientChaos

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Re: Team Ambient Chaos
« Reply #20 on: October 25, 2015, 10:54:06 am »
I was originally asking about cutting metal plates while thinking about a potential future bot, but now I'm thinking about the current one as well.  I have gotten most of the chassis plates (or templates for the UHMW parts) cut for me from my CAD files, but I have two pieces of 1/4" thick 7075-T6 aluminum that I'm going to make into a wedge and a spare by myself.  I have a bit of access to a machine shop where I was planning to use their drill press, band saw, press brake, etc to turn them into my wedges.  I was planning to use their band saw to cut the plates, but now that I've had a little bit of experience making a few cuts with the band saw on a piece of (6061 I think) aluminum plate a bit thicker than my plates and seeing how much more difficult it was than with wood, I'm wondering if I would get a cleaner/straighter cut with some method where I can have a guide for the cut like with a jigsaw instead of having to follow a line free-hand like with the band saw.  Would it even be possible to cut something as thick/hard as my 7075 aluminum plates with a jigsaw?  Or would it be easier to cut it with a dremel even if it is 6.35 mm thick?  I'm thinking that both methods would be more time consuming than using their band saw but might give me a straighter cut, I'd just have to buy either jigsaw blades or dremel cutting discs to get it done.
« Last Edit: October 25, 2015, 10:59:25 am by AmbientChaos »

AmbientChaos

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Re: Team Ambient Chaos
« Reply #21 on: October 29, 2015, 06:06:30 pm »
My water-cut parts finally arrived today!  Now I finally have everything that I should need, so I can get down to building this bot for real.

I'll post some more pictures when I have made some progress.

AmbientChaos

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Re: Team Ambient Chaos
« Reply #22 on: October 30, 2015, 12:35:30 pm »
So I've made a start on fabricating my UHMW parts.  I'm glad that I planned ahead and got more UHMW than I needed, because there was a bit of trial and error involved, and you can see in my last post that I already cut and bent some of it to make some wheel guards.


These are the first few parts I cut out.  I thought that I would cut them to shape and then drill all of the holes, but this wound up deforming the plastic for the holes near the edges, so I learned to drill all of the holes first and then cut it to shape.

These are my 4th and 5th attempts at making the outer walls of the bot, where I finally got them both finished where I'm happy with them.  The first two I will eventually finish up as spare parts if I need to swap them out after a fight, and the third one was almost completely finished when a slip of the hand turned what was supposed to be a counter-bored hole into a through-hole big enough for the screw to just fall through.

It still has a ways to go, but it is starting to look like a thing, and thus far all of my self-drilled holes are lining up with the water-cut holes.

AmbientChaos

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Re: Team Ambient Chaos
« Reply #23 on: November 03, 2015, 06:29:04 pm »
I didn't have any time to make a post earlier, but I got the last of my UHMW parts made a couple of days ago.

This meant that I could get the chassis totally put together and check the fit on the motors and servos.


Everything fit together like a dream.  I haven't had enough time to fit the rest of the electronics into the new chassis, but I did assemble the rest of the outside parts to see how it would look.


Coboxite

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Re: Team Ambient Chaos
« Reply #24 on: November 03, 2015, 07:28:55 pm »
Looking really good. Should be a strong contender with enough driving practice.

AmbientChaos

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Re: Team Ambient Chaos
« Reply #25 on: November 03, 2015, 08:21:00 pm »
I seem to have hit a snag.

I wound up deciding to make Lapsed Pacifist with 7075-T6 aluminum because it has strength close to steel at a lower weight, so I thought that it would be a simple way to make the bot sturdy while staying under the weight limit.  I don't have much experience fabricating with metal yet, so I just assumed that one metal would be about as hard to work with as another and it would just be a matter of using the right tools.  As I was thinking about fabricating my wedge today I wound up doing some research and discovered just how badly wrong I was.

I had originally planned to bend the edges of my wedge down to the sides to better combat horizontal spinners, but it seems that with 7075 aluminum (particularly this thick) I either wouldn't be able to bend the plate without breaking it or I would have to bend it with an absurdly large radius that wouldn't be useful here.

So it looks like my original plan won't work and one way or another I need to come up with an alternate plan.  If I want to be able to use the aluminum plates that I already have (assuming that I can get it drilled and cut), I think that my only option is to just leave it as a flat plate and cut the ends down at an angle.

I think that my other option would be to just scrap my aluminum plates and find some other material to make into a wedge more in line with my original design. 

So this leaves me with two questions.  Would a flat plate cut to angles like this still be reasonably effective?  What other materials could I use to still achieve a bent wedge like my original plan?  (According to my scale I still have about 13 oz of weight left to play with to make the wedge or any other additions.)

BranYoung

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Re: Team Ambient Chaos
« Reply #26 on: November 03, 2015, 11:26:17 pm »
13oz? That's plenty! Just find some .05in or .063 Ti and use it instead. It will last longer and if you use a heat torch you can bend it to a closer edge.

AmbientChaos

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Re: Team Ambient Chaos
« Reply #27 on: November 21, 2015, 06:01:48 pm »
I got a bit busy for a while, so I didn't have much of a chance to work on my bot until today.

Since I had the aluminum plates and nothing planned to do with them, I started doing the work to get them turned into some battle-ready wedges.  I was planning on having a big chunky wedge on the front to round out the weight on my bot, so until I figure out a redesigned wedge in a material that I could actually bend I figured that I would use the aluminum plates that I had so that I will at least have a complete bot.

Shortly after my last post I got all of the internal parts in place and wired up so that I could take it for a test drive.  At first everything seemed to be working great, but then the first time that I tried the lifting mechanism one of the servos seized up at full extension.  Unfortunately with the current design the servos are the hardest part to replace since I have to disassemble half of the bot to get them out, so I'll eventually have to do that to swap out my spare servo.  Then I'll get to take my servo apart to see what went wrong and whether it is fixable or just scrap at this point.

AmbientChaos

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Re: Team Ambient Chaos
« Reply #28 on: December 11, 2015, 09:47:00 am »
I finally got a bit of free time to do some more work on my make-do wedges and replace my broken servo.  I guess at this point Lapsed Pacifist is technically 100% complete and combat ready, even if there is some more work I would like to do before I am ready to throw it in the ring.  I still need to grind down the edges of the wedge to consistent flat angles rather than my rough job with a dremel.  I think I will keep my angled plastic wedge or even make another; while they definitely wouldn't hold up to a spinner I think that they could be tough/useful enough to swap out when I'm facing a wedge.


A future redesign will probably be in order to make it easier to replace the servos.  As it stands now I don't think that I could replace just a servo in the time between matches since I have to practically take half of the bot apart to get them in and out.  I think for my first competition I'm just going to have to cross my fingers that they're protected well enough.  The one servo that I had to replace is definitely shot, the middle axle in the servo's gear chain is only supported by plastic at the ends and apparently the plastic gave way.  I was considering keeping it for spare parts, but since this is probably the servo's weak link I expect that any other servo failures will be from the same issue.  I went for the cheaper servo to start out with, I guess if it actually turns out to be an issue during a match I'll wind up finding a tougher servo to replace it.

I guess now all I have to do to get ready for the debut at Motorama is finish up my wedges, finish making my spare parts, and maybe do a little decorating.
« Last Edit: December 11, 2015, 10:19:14 am by AmbientChaos »

AmbientChaos

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Re: Team Ambient Chaos
« Reply #29 on: December 16, 2015, 12:43:41 pm »
My wedge plates are finally finished. 
I drastically underestimated the amount of work that would be required to make a 1/4" plate of metal into the wedge with hand tools, I think that I probably spent about as much time cutting and grinding on these plates as I spent to make the entire rest of the robot.  If I knew all of this when I was still working on the design I might have gone a slightly less labor intensive direction, but in the end I'm still pleased with the results of my labor.  Now I just have between now and Motorama to practice my driving and decide whether or not I could put together an antweight in time.


« Last Edit: December 17, 2015, 10:35:22 am by AmbientChaos »