AmbiSinister: The Early Years

Hey there! So you’d like to know how I first got started way back when? The first time I threw caution to the wind and built one of these crazy robotic combat creations? Well, I’ve got a few pictures of the finished thing. Nothing in progress though. But here it is. I’ll go through and talk about what I learned and what worked and such as we go! Here’s the first several iterations of AmbiSinister.


Overview shot. There are two Fingertech Gold Sparks under there for drive. Not as sought after as the Silver Sparks, but I was new and didn’t know any better. They survived perfectly fine in this bot though! It’s just a short piece of angle iron I bought from Home Depot and a piece of Green House spars. I had bought the latter off of Amazon to build a desk. I cut the top piece off and it gave me a little drop down to mount the motor on. That’s a Baby Beast from Hobby King. I still use these motors in AmbiSinister. I’ve loved them. Very compact and seem to have plenty of power. The new ones only come with a 5MM threaded end though, not the tiny 2mm shaft with mounting holes as the old ones.


SIDE SHOT! You can see how the Spar piece was like a flat with two small L’s. Cut the top off one and the bottom off the other and mounted everything up. At this point I started wiring everything in and think I drove it around a bit just for shits and giggles. It did move!


Another back side shot. The mounts are from Fingertech as well and the hubs/wheels too. Same as the mixer and ESC’s. My bot’s motion was 100% Fingertech at this point and worked flawlessly.


That’s all I have from the first iteration. It fought at the Inaugural MassDestruction hosted by Artisan’s Asylum. Was a blast. And many, many thanks to Robert Masek for making me feel welcome to the sport. I am a solitary guy by nature and prefer to watch and browse and not join in with things. But I showed up with basically a pile of parts after having to take the bot apart to get it underweight. And he didn’t mind sliding me in late and seeing if I needed any help. It also helped that he was my size so I didn’t feel as out of place as well.


About as well as I expected. It flipped. Every. Hit. However, it miraculously was able to flip back onto it’s wheels! YAY! I lost three and won one match by knocking a power cord out. I got it to spin and it looked bad ass. But hey, didn’t work as well as I hoped. But it was a great learning experience and let me to try making some changes going forward.

ITERATION 2! Here we go. I actually downloaded Fusion360 and gave it a run. I wanted to try and belt drive this version instead of the friction drive on the last one. So I planned everything out. Still the Baby Beast. Now improved to Silver Sparks and the Bearing mounts. I cut out two of the plates, top without the weapon motor covered, and bolted through the mounts to hold them together. Worked fantastic. Though I did not give myself NEARLY enough room inside for electronics. Word to the wise, always, always, always make a tons more space than you’d ever think needed.


The weapon motor. With the tiny shaft. 2150KV means this thing spins massively fast on 3S and always needs to be geared down on a shell spinner.


But… but… but… belts…. Yup. I couldn’t find a way to feel comfortable with a way of getting a pulley onto the tiny shaft so I just went back with the old stand by. Took the prop adapter from the Baby Beast and put a couple washers and a Fingertech foam wheel on. The shell then pushes onto this contraption and as it spins it spins the shell the opposite way. It worked perfectly fine. That’s why I stuck with it when I started having issues figuring out a pulley system. Fingertech sells fantastic pulleys and belts, but they have a 3mm bore that can be made bigger. So keep that in mind when picking out motors and such!

How well did this iteration do? Worse than before. Flipped itself constantly. This one had no propensity to flipping back onto it’s wheels though. So once turtled, it just spun around aimlessly. *Shrug*


Third times the charm! Pfft. Perhaps for most people. This one I switched drive motors to Pololu micro gear motors. They are about half the weight of the Silver Sparks and tiny. They are much more fragile though. But for me, they are perfect. If I’m trying to push the enemies, I’ve probably already lost. Same Baby Beast up front, and it was friction driven one more time.


The battery is tucked up underneath the top framework you see here. This frame was 3D printed by Shapeways. It worked well. Held up fine and everything mounted as expected. Again, I think I didn’t leave quite enough space for the battery, but I got a slightly smaller one and slid it in instead.


SHELL! First time I’ve showed you fine folks the shell. It’s a mixing bowl upside down. The teeth on this version are Felling Dogs from a Stihl MS 200 T chainsaw.



Here’s the last picture. Shell again. The orange plate on the top was made to help keep the paper thin center more rigid. Before spinning it up would cause instability. The plate helped immensely. It was massively smooth. And how did it do? Meh. Same issues as before. Won zero fights.


There is a fourth version that had a 3D printed shell graciously provided to me by Jamison Go of Team G3 Robotics. He designed and printed it for me and waterjet a toothed ring underneath. It looked amazing. It performed the same. Why? I am not fully sure. I’ve been told having the weight focused on the rim down low is actually negative because it has a tendency to be unstable when taking a hit. Having weight more evenly balanced makes it less likely to flip. I was working on a new shell and design that would more evenly balance the weight. I will be putting up CAD and my thoughts and musings on a new page shortly. Stay tuned!