Introduction: 30lb Fighting Robot-Nyx

Picture of 30lb Fighting Robot-Nyx

I recently built a new 30lb fighting robot for the NERC Sportsman class and Dragon*Con Robot Battles events. This instructable will follow the build process and will include links to parts suppliers, machining resources and .dxf drawings of the custom components used to make the robot.

If you are serious about building your own version of this robot, contact me and I'll be happy to help where I can.

Step 1: A Pile of Parts and the First Day of the Build

Picture of A Pile of Parts and the First Day of the Build

The pile of flat stock was waterjet cut by Westar Mfg. out of 6061 aluminum and 4130 steel.

Drawings for this collection of parts along with materials, thicknesses and quantities can be found here.

The top armor and two supplimental weapons were not included in that collection to allow modifications to be made for weight purposes. Those files are located here.

These drawings were done with the intent that most would be made on a waterjet, and as such did not require dimensioning. Each of the drawings that was meant for waterjet cutting has a 1" reference square on the sheet.

With the great deal of interlocking components, the order of assembly is important. The first components to be assembled are the weapon hub, support hubs and weapon sprocket. Doing this first also showed the first issue in the build. The sprocket model on did not have the correct hole spacing which meant only 3 of the 6 planned bolts would fit. These holes are all meant for a #10 bolt, and without a clearance hole bit on hand, one had to be ordered.

The other main piece of the day was countersinking the holes on the inner rails to ensure there would be no contact between the moving roller chain and the bolt heads. The front threaded spacers also needed to be added and loctited as the bolt heads will be covered by the D shaped bearing blocks during assembly. A product called Nutstrip is used to connect the panels together, allowing for quick assembly.

Step 2: Day 2, Padding and Keyway Modification

Picture of Day 2, Padding and Keyway Modification

At this point the build was stuck since it would be another day before the 0.201" drill bit would arrive from McMaster-Carr, so I tackled two of the smaller projects.

The first was adding padding to the area the flipping attachment would contact the front panel. I used some 3/16" thick rubber cut into a hollow square shape and glued to the aluminum plate. The small pocketed area was added to allow the use of the optional low rpm dual grinding disks, as the main weapon hub would brush against the aluminum plate when spinning continuously.

The weapon sprocket needed to sit closer on the weapon motor shaft than the existing keyway allows and without a broach available, I chose to use a mini-mill with a 1/8" endmill to expand the keyway area. The shaft was clamped to the table with the existing keyway sitting roughly level. The endmill was then brought into the keyway slot and aligned with the vertical walls of the keyway. Using low spindle speeds and some cutting fluid it was easy to expand the keyway. I've also included a picture of the modified shaft next to a stock shaft for comparison.

Before calling it a day, I used some Goop adhesive to glue the bearings into the bearing blocks and the weapon hubs to keep them from sliding around while I was assembling the weapon rack.

Step 3: Day 3, Weapon Rack Completion and Initial Chassis Assembly

Picture of Day 3, Weapon Rack Completion and Initial Chassis Assembly

The first task of the day was drilling the new mount holes in the weapon sprocket. I used the steel weapon hub as a guide for the drill bit and quickly added three new holes to the steel sprocket.

The weapon hub was bolted together and the 3/4" tubular steel shaft (1/8" wall, 9.875" long) was slid through the assembly. Two shaft collars were added to each side and the two bearing blocks were slid on the ends of the shaft. These bearing blocks were bolted to the front armor panel locking the assembly together. The weapon hub was centered on the shaft and the shaft collars were locked down at the hub and bearing blocks to prevent it from moving side to side.

The two inner side rails were slid onto the rear armor panel and the weapon rack was slid into the front. These four sections were then bolted together.

The last part of the day was the addition of the remaining hex standoffs and the baseplate. For the initial build the holes were mistakenly drawn to 0.250" diameter when they should have been 1/4" clearance holes. (0.266" diameter) This has been fixed for the posted drawings.

Step 4: Day 4, Drive System Install

Picture of Day 4, Drive System Install

First, the dewalt powerdrive kits were bolted to the baseplate. I'm using the optional motor retainer kit with the stock steel threaded rod replaced with aluminum for a 3.6oz weight savings. After that, the outer side rails were bolted to the frame. 1/2" shoulder bolts were added with the threaded end on the outside of the outer wheel guards. Once they were added, measurements were taking to figure out how many washers needed to be added. The outer wheel guards were removed, allowing for the addition of washers, wheels and the drive shaft, which itself had washers, shaft collars and keyed sprockets on it. Once all of this was added the outer panel was reattached. The weapon motor shaft goes into an aluminum pillowblock made from scrap, the exact design will be up to you if you replicate it, the only important part is the bushing or bearing used in it must be 1" above the baseplate.

The next step was measuring and cutting the chain. First I aligned all of the sprockets with the wheels and weapon, then I took the length of roller chain I had and wrapped it around the section to determine where I needed to break it. Once the chain was broken at the proper length, I wrapped it back around and added the master links. At this point, the mechanical assembly is complete.

Step 5: Day 5, Wiring and the First Test Drive

Picture of Day 5, Wiring and the First Test Drive
The final day of the build consists of a great deal of cutting, crimping and soldering with a bit of gluing and velcroing thrown in for good measure.

The electrical system consists of the following components:
1 Hobbyking R610 receiver
1 Team Whyachi MS-1 switch (discontinued, MS-05 should be adequate)
1 Turnigy Nano-tech 6s1p 2650mah Lipoly pack
1 Digimix V-tail mixer
3 Holmes Hobbies BR-XL motor controllers
A small pile of deans connectors, wire and bullet plugs

The three BR-XL controllers are velcroed to the baseplate between the three dewalt powerdrive kits. The motor side of the controllers each  connects to 1 motor, the positive lead on the battery side runs to the MS-1 switch, which has the positive battery lead connected to the other terminal. The negative lead for each controller connects directly to the negative battery lead. The drive PWM cables connect to the V-tail mixer, which then connects to the Ail/Ele ports on the rx. The weapon controllers PWM cable goes directly to the rudder port on the rx. A power light built using a high output LED and a resistor is connected in the same fashion as the power leads for the motor controllers.

The foam padding that the battery is resting in is to minimize the risk of shock damage in combat.

Once all of the systems were hooked up and calibrated (full calibration instructions come with the BR-XL controllers, only calibrate one at a time to avoid issues) the robot was ready for its first test drive.

Step 6: Final Touches

Picture of Final Touches
The top armor and the alternate weapons are the last parts to be added to the robot before it is ready for combat. I personally like to add some paint to my robots because I think it makes it more fun for the audience, however that is entirely optional.

After doing some testing, it appears that the weapon drive will need a torque limiter for the flipper attachment. For now, the dual disks are working very well:


MikeNCR (author)2012-04-17

I've added a torque limiter to the weapon drive. This seems to have eliminated the shaft snapping issue. Video of the test can be found at:

MikeNCR (author)2012-02-14

Motorama is this weekend, look for video early next week.

MaxP22 (author)2015-10-04

How did you attach your sprocket to the weapon motor?

aaron0127 (author)2015-04-20

Can some one link me to the wheels i used Banebots 3/78 wheels but no on int the world has them in stock any other ideas?

Sitherus (author)2014-11-12

the most expensive part of this is the 250 dollar motors you need 3 of do you know of an alternative. that i could get for chaper i was thinking of using windshield wiper motors but they are gearboxed. and wouldnt fit.

MikeNCR (author)Sitherus2014-11-13

Your best bet is to look at other cordless drill motors. You'll need to find ones that will fit within the profile of the bot (or modify some elements of the design) and make mounts for them, but with the right gearing alternatives should work.

Sitherus (author)2014-11-12

I want to Make this and was about to lazercut some parts then i added the cost. Im sorry I love bots but I dont see the point in building a 950 dollar bot that smashes other bots. I have built many other bots out of cheaper prices. that cause more destruction than this.

N.fletch (author)2014-05-12

Great Instructable, I really like the level of quality and professionalism that went into the design. What CAD SW did you use when developing, or which would you recommend?

MikeNCR (author)N.fletch2014-05-12

I prefer Solidworks, though this sort of design could just as easily be done in Inventor or ProE. It's mainly down to which package you're familiar with.

ggrock (author)2013-09-12

Plz Give me full over view of make this Robot>>>>>>>>>

TINY 10304 (author)2013-07-01

Can I get some blueprints pleaseee

xXCrazyEyesXx (author)2013-01-01

Nice :D Im trying to make a battlebot too.. but i must wait to get the receiver & transmitter...

pokemonjarrod (author)2012-12-14

Can you give me instructions on how to do this robot with a hammer and a saw?

MikeNCR (author)2012-10-01

Nyx went 6-1 at Dragon*Con Robot Battles and won the 30lb championship. Video is on my youtube channel.

1 and 3lb:

12 and 30lb:

Near Chaos Robotics:

MikeNCR (author)2012-02-22

Nyx finished with a 2-2 record at Motorama. The video can be found at

One loss was due to the motor wires unsoldering themselves. Trims on the radio were turned down to 75% and that functioned as a temporary fix to the issue. The other loss was due to Nyx ending up in a position it couldn't get out of which resulted in a loss by countout.

I'm very happy with performance and I think the addition of a torque limiter to the weapon system will be the final touch the robot needs to start winning tournaments.

DoKToR2006 (author)MikeNCR2012-02-24

Really well done combat bot!
I've seen the videos and i must admit, your robot massive as hell!

Have Nyx suffered serius injuries from the confrontation with Enforcer?

MikeNCR (author)DoKToR20062012-02-24

Nothing serious, the only damage was cosmetic. It stopped driving because the drive motors got hot enough to unsolder the wires connecting them to the speed controller. I turned the trims down to 75% power and it seems to have fixed the issue for the moment.

rocketman7 (author)2012-02-11

Great Robot! My friend builds fighting robots too! He is in the Combot competition... He says that you have to hit it with a sledgehammer and drop it off a high building. If it breaks, then it will certainly break in the competition.

graydog111 (author)2012-02-05

What happened to "Battlebots" on TV? That was one of my favorite shows.

MikeNCR (author)graydog1112012-02-05

They had some issues with advertisers that led to the show being cancelled. They've put on a few non televised events since then, but the main events are now no longer affiliated with Battlebots.

On the west coast, the big group is Combots ( )

On the east coast, NERC puts on some of the biggest open events ( ) and has an event coming up at Motorama in Harrisburg PA in a few weeks.

Robot Battles ( ) puts on some good events as well in the southeast. Their biggest event is each year at Dragon*Con.

Most events around the US use to manage registration.

graydog111 (author)MikeNCR2012-02-07

Thanks Mike. I'd love to see them back on the air every week. It would sure beat basketball.

dustinnewton (author)MikeNCR2012-02-06

I always wondered who had control of the episode rights. That's one series that I would gladly buy on DVD in a heartbeat. I always enjoyed watching them.

MikeNCR (author)dustinnewton2012-02-06

I'm guessing some combination of Comedy Central and Battlebots, which means it probably won't happen any time soon.

Kelpbot (author)2012-02-02

It seems like a very solid robot! Very nice job. Im not sure about what you want from this robot, but it seems that it has almost more speed than it needs. I would consider using a 1:3 or more gear ratio for the drive system. Although some speed would be sacrificed, the control over turning would increase, and there would be less stress on the motors (although they are very durable). I personally would prefer this to lowering the motor power to slow it down.

MikeNCR (author)Kelpbot2012-02-02

With most modern radio systems you can adjust steering sensitivity to make it easier to drive. The high speed allows me to out maneuver the opponent and control the match, or at least that's the idea.

lawsonuw (author)MikeNCR2012-02-05

A better idea is to keep the speed and install a tail-rotor gyro between the receiver and the v-tail mixer. Even the cheapest gyro will let you power-slide around the arena like a god. (works great on ice too :D ) The Holmes Hobbies controllers look like they do synchronous rectification so they're better than the Victor 883's my first bots used, but a gyro is the best.

Also, the side plates holding your wheels look fairly weak. A spinner hit to the corner of the bot and the long spacer bolts will bend right off.

P.S. My most successful bot is Micro Vice uses a steering gyro and is a blast to drive.

MikeNCR (author)lawsonuw2012-02-06

A gyro would likely make the bot easier to drive, but I'm pretty happy with the handling as it is.

This bot was built for the NERC sportsman class and Dragon*Con robot battles. Neither event allows high energy spinning weapons, so they're not a major concern for this build.

MV looks pretty good, same with Vice and Insomnia. Planning to take any of them to events again?

lawsonuw (author)MikeNCR2012-02-06

Ah, a no spinner class. In that case you're armor's too heavy :P

No plans to compete right now. While Insomnia had a wicked weapon, it was lightly armored, so it got "retired" in it's last battle. (certainly still competitive with enough spare parts) I botched up the execution of Vice, so it's mostly a sculpture now. Micro Vice was born as a test-bed for a rebuild of Vice, but is FAR more effective than I expected.  I was slowly iterating the design when I got a good idea how to make an AWDmotorcycle.  The motorcycle has since chewed up all my time.

P.S. the GWS P-03 was my gyro of choice.  Cheap, fairly symmetrical CW to CCW, and a minimal dead zone. 

Kelpbot (author)MikeNCR2012-02-02

Valid point. Just an idea. Good luck with your battles!

thrashermanTotalDIY (author)2012-02-05

nice! check out my contest for this. Battle bots Contest. Please Enter

frank26080115 (author)2012-02-02

That's awesome.

How much did this cost?

I saw your other robot, what lessons did you learn from the other robot that you applied to the design of this one?

Do the "nano-tech" batteries really make a difference over traditional Li-poly?

MikeNCR (author)frank260801152012-02-02

A good portion of the parts were recycled from old projects, but to build this new with all new parts the cost would be around $2000.

I'm trying the nano-tech batteries on this robot and won't know what differences there are besides cost for a bit, as the first event it will attend is in a few weeks.

Giesterfarher (author)MikeNCR2012-02-05

As to batteries. I'm not too familiar with the voltages required for your robots, but for weight savings, you might look into these Shorai Lithium/Iron batteries.

Yes. I said Iron. :)

They have a carbon fiber case, and the one I bought for my Sportster weighed less than 1 lb. and was half the size of my stock battery. The neatest thing about them is, the hotter they get, the more efficient they are, so in an enclosed space with hot motors running right next to it/them, voltage losses should not be an issue.

Good luck with your competition!

MikeNCR (author)Giesterfarher2012-02-05

They don't seem to carry anything in the right size/capacity/voltage combination I'd be looking for.

The current pack is 2.65Ah and provides a nominal 22.2v

Kinnishian (author)Giesterfarher2012-02-05

Hmm, your battery is most likely Lithium Iron Phosphate, also referred to as LiFePO4 and LiPO4. I tried to find more information on the website about the battery type, but couldn't. I am actually very skeptical of battery resellers who don't include more information about their product.

That said, LiPO4 can offer a lot of energy/kg. It's not particularly volumetrically dense, though, and can take as much as 1.5 or 2x the space of bare LiPo packs. Overall, nanotech beats LiPO4 in almost all measures except 1) safety and 2) lifespan.

Anyway. I also wanted to comment in case someone pops up and says "no, you're wrong. Lithium/Fe is _____ type of battery." Because i'd love to hear about something new.

MikeNCR (author)Kinnishian2012-02-05

I actually use LiFe batteries in my two other large robots Apollyon and Moros. They're using 5s and 6s A123 systems packs.

As far as I can tell these are just relatively new LiPo's that seem to have decent performance.

Giesterfarher (author)Kinnishian2012-02-05

You are correct about them being LiFePO. There is a FAQ section on the site, and there used to be a technical section there as well that was way over my head, but I can't find it now. It's possible it gave away too much and they took it down to protect proprietary secrets?

I'm not familiar with nanotech batteries, but if there is a safety issue, or for that matter a cost issue, then maybe the LFX batteries ARE worth a look. It wouldn't do to have the robot explode when a titanium spike pierces it resulting in mass destruction and death of the audience, would it? ;)

Here's the FAQ section, in case you didn't see it before.

lewisb42 (author)2012-02-02

Regarding cost, I'd particularly like to know how much the waterjetting was, in case it might just accidentally fit my budget. :)

Also, I like the way you offset the wheels in order to fit the drive chain and sprockets in. That's an great potential solution to a problem I've been mulling over for my next 3-lb robot. (Though I'd be doing it with timing belts, not chain.)

MikeNCR (author)lewisb422012-02-02

The waterjetting ran $374 + materials and shipping.

dausmus (author)MikeNCR2012-02-05

How does that waterjetting cost compare with laser cutting the same parts?

MikeNCR (author)dausmus2012-02-05

I haven't done any laser parts. I'm a fan of waterjet because you don't get any heat affect zone issues and it can handle a much wider range of materials.

VinceJDJ (author)2012-02-04

I logged in just to favorite this. Nice work dude!

LanceMakes (author)2012-02-03

Wow, way to set the bar high! Good luck in the Make it Real challenge

ad895 (author)2012-02-02

very cool i like the design. i too build battle bots, but mine is though my school. we have a weight limit of 15 lbs our designs look alot like yours but with a different weapon ours is like a 3-5 pound beater bar

MikeNCR (author)ad8952012-02-03

Nice. I'm a big fan of the BotsIQ/NRL programs. My 12lb bot Apollyon ran in the 15lb college class as Interstellar Overdrive when they did the big event with Battlebots in CA a few years ago. Ended up placing 4th and winning best engineered.

black hole (author)2012-02-02

Is this named for Nyx, the Greek goddess of the night?

MikeNCR (author)black hole2012-02-02

Yeah, I've been using a general greek theme for names. Some of my other bots are Moros, Kobalos and Apollyon.

black hole (author)MikeNCR2012-02-03

Have you used Enyo (i-nye-oh), the war goddess? It would be fitting.

MikeNCR (author)black hole2012-02-03

Not yet, but it's on the list of potential names.

black hole (author)black hole2012-02-02

Great job, by the way. I voted and I hope you win!

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