View Full Version : Introducing .. "Maggot Mk.3"..

06-28-2011, 04:23 PM
When I first started building for Battlebots back in 2001, my first robot was named "Maggot" and the team became Team Maggot. Since then, all of our bots have been named something to do with flies. Except for Bheka. We had Maggot, Micro Maggot, Fly Speck, Botfly, and some others.

It's time to return to our roots..

This Mech, is being designed and built from the center out. Instead of starting with a robot, and adding a turret for guns and stuff, I decided to build the turret first, then the rest of the robot around it. I also wanted to get away from gravity feeding the BB's to the airsoft guns.

First I got some high capacity BB magazines, removed the metal case, and cut down the mechanism. Made some new housings from Styrene, and added some full rotation servos to wind the springs in the mechanism.

The final product is even smaller than in this picture. But I used a larger servo.
I bought a factory hopup to use for measurements, and ideas. The hopup is not needed for the ability to add spin to the BB. but makes a dandy method of feeding the BB's from the magazines and holding them while the guns cycle.


I made some hopups from Delrin, but they were somewhat rough. Then made new ones from aluminum.
Made a mount that would serve as a base for the guns, magazines, camera, and tilt servo. The guns and hopups were mounted as were the magazines.




The curved tube between the magazines and hopups, are springs. Heated to soften, shaped, then quenched to put some temper back in.

A hopper to feed the magazines will be added, but will be no taller than the top of the guns.
There will also be a tilt mechanism, and rotate for the turret added. The turret will be embedded in the body of the robot to keep the COG as low as possible.

More to come as it develops..
Thanks for tuning in

06-28-2011, 05:17 PM
I'm already afraid of the robot that's not yet built around that.

Awesome work gdubb2!


06-28-2011, 05:19 PM
Love the path you're taking, simple and efficient! and I cant wait to see it since you mentioned trying to keep the COG low. Also awesome idea using springs for managing the feeding line. +1 rep

06-28-2011, 05:38 PM
Very cool looking Gary! A little tough to say for sure but it seems to me that Maggot Mk.3 is going to be considerably bigger than Bheka? Are the AEG's significantly more accurate than the Defenders - aside from being more powerful I take it, or is that more a factor of the barrel configuration?

And, BTW, how's that saying about minds working alike? Unlike you I haven't built any sort of robot as yet, but I'd picked up some 3/8" I.D. polyethylene tubing two or three weeks ago to use as a feeding tube from a remote bb reservoir I'm considering for my turret gun. The polyethylene (whitish) tubing holds it's shape much better than the vinyl (clear), but hand-in-hand with that it's less flexible and therefore needs larger radius turns. I had tried the 3/8" O.D. (didn't note the I.D.), but that's too tight - ideally I'd use 7mm I.D. polyethylene.
http://img192.imageshack.us/img192/9246/dscf012425.th.jpg (http://imageshack.us/photo/my-images/192/dscf012425.jpg/)


06-28-2011, 06:16 PM
Thanks guys,

Stobs, I think you will find that poly tube may deforms bit too much if over bent (tried it), I tried bending aluminum tube after filling it with sand. Sometimes it worked, sometimes it just broke. Without the sand, it was sure to fail every time.

So with tears in my eyes I went the spring route. It's heavier, but can make pretty tight bends without deforming if you heat it red hot with a propane torch then shape it and quench. It springs back a bit, but not too much. I shoved an elbow of bent soft copper tube through it before heating.

one could also just use the springs for the bends and fill in the straight runs with aluminum tube. 9/32 alum tube from the hobby store screws into the springs I used nice and tight. The springs I used are from a hardware store. 3/8 dia with .047 wire.

Poly might be the answer though.. different applications and all.


06-28-2011, 06:27 PM
Nice work, really smart and thought out

06-28-2011, 08:57 PM
Awesome turret Gary, you gave me an idea on how i can make my magazine work by using a tube to connect it to the gun. What kind of leg setup are you thinking of using?

06-28-2011, 09:18 PM
Hey Cire,
Hmmm... legs.. uh well, I guess I'll have to think about it. Oh yeah I remember now..Quad with 3DOF legs. Very similar to Bheka, except more symmetrical. I sort of envision a crab looking thing with 4 legs. The legs will be all Hitec 5980 and 5990 servos. If I can do it, it will just be a turret with legs, and not much more.


06-29-2011, 09:17 PM

Brake line tubing bends pretty easy. 3/16 and 1/4 inch are probably the most common. This is the OD so the 1/4 is still probably too small for the BBs. There is also a 5/16 that would probably work. Here is a video that shows how easy it is to bend.


BTW, I like the look of the springs. Looks more mechish than smooth tube

looks like an option - http://cgi.ebay.com/Soft-Copper-Tubing-5-16-x25-Tube-cobre-ouen-cuivre-/180670762112#vi-desc

09-16-2011, 02:43 PM
Small update,

I have the turret rotation working. Not real sure that I totally like it though. The rotation setup is simply a 94T gear on a HSR 8498 servo driving a 44T gear mounted to the base. The servo is attached to the gun/camera platform. There is a lot of reduction in resolution, but that's the down side to the gain in rotation.

There is also a .75" hole through the center hub, which allows for the passage of servo leads, and power wires to get from the body of the bot to the turret. This will be a nice clean way of powering the guns, camera, and targeting system.

This is a video of the thing rotating, I haven't got around to the elevate part just yet... That's next..:o


Maybe this link will work..

09-16-2011, 04:18 PM
I gotta tell you I'm getting tired of the things you make being so freaking cool. Leave some for the rest of us! :p

10-19-2011, 01:54 PM
Small update.. made some brackets and servo horns.


11-29-2011, 03:07 PM
Update.. Made a bit of progress. The frame is wired, but the turret is not totally done yet. I still have to make the gun hoppers, and armor for the entire bot.

The legs are 3DOF, consisting of (2) Hitec 5990 servos and (1) 5980 per leg.
Turret rotate and tilt are Hitec 8498 servos.
Camera is a Trendnet.
Servo control is via a SSC-32 connected through an Xbee radio.

3642 (http://forums.trossenrobotics.com/gallery/files/2/0/3/3/frameturret_3.jpg)





11-29-2011, 11:39 PM
Whoa low and wide, kind like a sports car. Can't wait for 2012!

12-31-2011, 10:04 AM
Well, in a fit of frustration,and not being satisfied with my progress, Maggot has been rendered into a pile of parts.

I'm going to start all over again.. I'll most likely drop 1 gun/magazine setup to gain some weight back, and try to get it a bit smaller.


12-31-2011, 09:27 PM
Can you elaborate on what frustrated/unsatisfied you?
Anyhow I hope this new year brings you good fortune on your robots! HAPPY NEW YEAR!

12-31-2011, 09:33 PM

It just got too large and heavy as it evolved. The last few days, I was fighting with the walk sequences and just not having much success. I've been leaning towards a rebuild for a while, and this just pushed me to it. Hopefully the next version will be more of a fusion of the old Bheka and the new Maggot, rather than a complete from the ground up build.

Happy New Year to you too.

01-15-2012, 04:09 PM

New version of Maggot Mk.3(A)

New frame that is slightly longer, but quite a bit narrower.

Single gun with spring wound magazine instead of duals.


01-17-2012, 12:22 AM
Looking good gdubb...Can't wait to see maggot walking around.

01-18-2012, 03:51 PM
Video of Maggot on the move,,


01-21-2012, 05:03 PM

This is a video of the target during a live fire test of the AEG and magazine setup Maggot. The gun was operating at 7.2 volts, and the winding servo was keeping the magazine wound up and feeding BB's.


The targeting from the onboard camera was even pretty close..


02-13-2012, 08:03 AM

Would you mind going into a little more detail about how you are using a servo to wind the feeding spring on your magazines? I have been thinking about using a similar method, but I am curious as to how you are doing it.


02-13-2012, 11:08 AM

These aren't pretty, but work well, so far.

I'll run through the whole process. I started with some magazines from an M-14 Airsoft gun. They were big and heavy due to the metal case. So I removed the metal case, made the mechanism shorter, and made new cases from styrene.


There was an early version that didn't work very well. Picture in my gallery as (Prototype1a). It used an HS-55 servo which was underpowered and the T-bar connection to the mechanism gear was weak.

The next version Uses an HS-85MG servo hacked for 360 rotation with a more solid connection.. This works well.


Here is the styrene case and a view of the shortened mechanism. Notice the 3 holes in the gear/sprocket on the mechanism. This is where the servo connects.


I made a cheesy aluminum plate to interface between the servo horn and the 3 holes in the mechanism gear/sprocket. It has 3 machine screws the extend out and insert into the 3 holes.


Here's the complete unit. The gear/sprocket on the mechanism only allow for 1 way rotation, so care must be taken when setting up the operation of the servo. I run the servo for a few seconds before firing the gun the first time to preload the the magazine and get BB's feeding to the gun. Then every time I fire the gun, I run the winding servo to keep the spring wound. It seems to work pretty good so far.

I haven't come up with a good way of releasing the tension on the spring just yet. At the moment, I just dump the BB's out of the feed hopper, and shoot the BB's that are in the feed tube. When it goes empty, the spring releases. Don't know if this is good or bad on the mechanism. Might be better to leave the thing wound up.

Hope this helps
Good Luck

02-13-2012, 12:34 PM
Thank you Gary! You have been a great help!

I haven't come up with a good way of releasing the tension on the spring just yet. At the moment, I just dump the BB's out of the feed hopper, and shoot the BB's that are in the feed tube. When it goes empty, the spring releases. Don't know if this is good or bad on the mechanism. Might be better to leave the thing wound up.

BTW, from everything I have read about these airsoft spring loaded magazines, my understanding is that you should always relieve the tension in the spring when possible. Apparently leaving it in tension destroys the spring after a while (metal fatigue maybe? I'm not sure). Sound like you have a good method for clearing the magazine though just by shooting until dry.

03-13-2012, 04:11 PM
Some pics of Maggot with the armor on.. The top is plain as the targets will mount there somewhere.


Batteries are under the front cover, Electronics under the back cover.


03-13-2012, 10:20 PM
Looking really cool Gary. I should have gotten you to paint my robot!

03-18-2012, 05:06 PM
As always your work looks great! Looking forward to seeing Maggot in person this year.

05-06-2012, 02:44 PM
Post Robogames update..

Well, Maggot won a few, lost a few, and a good time was had in the process.

There were a few issues, some I anticipated, others I hadn't..
1: Camera lag.. better this year, but still a problem for me. It would seem that the D-Link cameras performed better than the Trendnet in the noisy environment. I'll probably change over. Been using the same Trendnet for 3 years now.
2: Occasionally, the turret rotate servo would just take off doing it's own thing. It was an intermittant problem that had surfaced a week or so prior to Robogames. I thought I had fixed it, but It came back. I suspect some interference induced into the servo lead. Looks like shielded cable time for a couple of servos.
3: Other control issues.. self induced.. I reprogrammed some sequencer calls, and I am an absolute terrible mech pilot. My wife has been hounding me for 4 years to practice..practice.. practice. But I'm afraid of breaking something so I don't.. Maybe I should listen to her..
4: Target panels and electronics performed flawlessly, I believe that having the entire targeting system isolated from all other power and wiring was the secret.
5: My force fed BB system did pretty well for the most part. It seems that if it gets wound too tight, the BB's don't feed through the feed springs very well, and I had a couple of jams. Need to get the winding mechanism speed closer to the gun firing rate, to avoid over winding the magazine.

For next year, I plan on attacking the known issues, practice driving..(Really I will), and maybe change the armor color from white on black to black on white.