Smokescreen V2.0

Smokescreen also got another major revision. As with all of my major revisions, I made some major architecture changes to resolve issues I’ve had previously.

After testing in Vegas, I confirmed a couple of issues with Smokescreen 1.0 and found a couple of new ones.

Pre-event issues:

Issues encountered at the event:

Whenever I design a new major revision of a robot, I make a strong effort to try to design out the major issues that existed in any previous iterations. Otherwise, why would a redesign be worth the time?

Doing a ground-up architecture change is always risky, but after testing the T-configuration on Sandstorm and Mirage, I decided to roll with it on Smokescreen.

I decided to address these two main drive issues with the drivetrain redesign:

To address propulsion and drive power issues, I decided to eat the weight and volume difference and use Silver Spark 16mm gearmotors. these are almost triple the max power of the N20s I was using. Since motor power in watts is proportional to torque times speed, I was able to get more torque at the same speed of the old setup. Since I’m running the motors closer to their peak efficiency, I was able to net a faster robot at similar torques.

And to fix the ground clearance woes, I simply added more ground clearance. I designed the frame to not restrict me to using a very specific wheel diameter. The smallest diameter I could use is about 1.75" with 1/4" of ground clearance, but after assembly I leaned torwards 2.25" wheels for 1/2" of clearance. This is a massive improvement over the fixed 1/8"ish ground clearance of 1.0.

The two issues I needed to address in the new weapon module were balance issues and motor torque. I was able to find a much higher power motor which let me dump more torque into the weapon for good startup and have a much higher tip speed at a whopping 130mph peak.

To test a few different motors before arriving at my final choice, I printed a TPU timing belt and PLA hub to test spinup with an old weapon disk from another robot.

To fix weapon balance issues, I designed the disk to be manufactured in as few parts as possible. This puts the task in balancing firmly in the CAD phase rather than the assembly phase. I’m far more comfortable with ensuring a design is balanced and can be assembled as balanced than balancing after the fact.

Once I arrived at a few designs that I wanted to roll with, I submitted them to SendCutSend.

SendCutSend is a metal laser cutting service that really puts quality and customer service first. I’ve used them for parts on Sandstorm previously, but have since started sourcing parts for all of my robots through them.

I’ve talked about their ordering system before, but another reason I love them is their speed and service. From submitting my order to receiving the parts took less than a week. Throughout the process, they have this slick dashboard that lets you track your order as it moves through the system from prep, cutting, finishing, and finally shipping. They work around the clock to ensure parts are cut accurately and quickly.

They have tons of different materials and thicknesses like titanium, aluminum, AR steels, and more. They really have the best selection for combat robot parts.

SendCutSend is laser focused on quality and customer service and they come highly recommended from me. Plus, they cut metal with friggin laser beams. That’s pretty damn cool.

The final weapon profile varies between the configurations, but they all share a common feature. I’m borrowing the hex bore from the FIRST Robotics competition ecosystem of parts to transfer torque between the pulley and the weapon. These all ride on oilite bushings pressed into the center of the hex shaft and a steel clevis pin. The whole setup rolls more smoothly than I expected with my lathe ability.

The new Smokescreen accessory package covers the rest of the issues I’ve had previously.

Astute readers will recognize that these parts are awfully similar to Sandstorm’s defensive accessories.

V2 drives about as well as I’d want a robot to drive and the weapon works better than most of my past robot weapons. I’m going to play with a few different gearing/wheel sizes over the next couple of weeks.

I’m excited to test it against other 1lb robots at November Necrosis in a few weeks. After doing some test runs with it, I’m very happy with the energy transfer from the weapon.

Another huge thanks to SendCutSend for sponsoring Smokescreen and my other builds. I’ve made a lot of competitive strides lately and I’m excited to go even further beyond with their help.

In the mean time, check out this overview/reveal video I created for my fall 2020 fleet:

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