Wednesday, May 18, 2016

Denise - My first Fairyweight (and future Denise-related plans)

First off, shout out to Xo Wang for linking my blog on his. I will do the same for his blog. 

Second, the first part of this was originally a SERVO magazine article I submitted a few days ago.

The 150 gram Fairyweight class (also known as the UK Antweight class) has unfortunately been on a decline in the Northeastern United States. After talking with several UK Antweight builders, I decided to build one in order to increase the amount of bots at Motorama 2016.

The method I was going to use is one utilized by UK Antweight builder Rory Mangles (his build diaries can be found here). His robots are made from a folded piece of Lexan, usually 0.08 inches (2mm thick). They have proven to be quite durable in battle throughout his fighting robot career. At my local hardware store I picked up some 0.098 inch (2.5mm) Lexan sheet. I also had some leftover 0.0625 inch (1.5mm) Lexan sheet that I used for a previous bot, perfect for the top cover.

I began by using cardboard to mock up the robot’s body, and traced the design onto the Lexan. The body was cut out with tin snips and holes for mounting the motors and wedge were drilled. (the latter holes weren’t added immediately, which let to some “interesting” drilling methods to say the least) When it came time to folding the body into a “shell”, a pair of locking pliers designed to bend sheet metal allowed me to easily fold the Lexan.  The locking pliers were also used to make the bot’s wedge. 

A fresh Lexan sheet for my new bot

Almost there...

The receiver/ESC/motor combo came from the UK, in the form of the NanoTwo kit. It contains a DSM2 LemonRX receiver, an ESC, and two gearmotors pre-soldered (it also contained motor mounts and 3D printed wheels, but I chose to use different ones because of how I designed the robot). All I needed to do was bind it to my transmitter.

All that was left to be done was to fully assemble the robot. I used two FIngertech Bearing Blocks to mount the motors, and attach the top and base of the bot together.. Since the Bearing Blocks are designed for the Spark motors, they needed to be modified to fit the smaller gearmotors. I sent them off to another builder to mill a slot .04 inches (1mm) deep. 

My bot was finished a day before the event, with a little under 20 grams to spare. I had previously given it the name, “Denise” because of an inside joke that occurred in a Facebook chat with some of my UK builder friends. One of them referred to Demise, the scary Fairyweight spinner that had won the past three Motorama events undefeated, as “Denise”. I thought it was funny and the name stuck (I could have been an awful person and told the event organizer to pronounce it the same way, but I decided not to!). 
At Motorama, there were only two other Fairyweights, so the event would be in round robin format. I ended up fighting Demise first, and lost. The fight went the full two minutes, the only damage to the bot were some cracks on the front wedge and the loss of a wheel.  I managed to win my second fight against Mike Jeffries' 3D Shockbots lifter, called 'Bia' (he won it at Motorama last year). Bia would later get shredded by Demise in its next fight This meant Denise came home with second place.

Denise and Demise
Denise and Bia
Bia after facing Demise

Building Denise made me appreciate the Fairyweight class even more. As soon as my fighting was done I already thought of more ideas for new bots and how to improve Denise. Hopefully the Fairyweight class will boost in numbers in the Northeast, and Denise will reign supreme (I can hope, can’t I?).

Following the event, all I've been thinking about recently are (UK) antweight designs. Aside from Denise 2, (which I will go into detail about in this post), I've thought of two other ideas for future 150g bots.

1. A horizontal undercutter originally similar to Dark Blade, but thanks to advice from Rory and Shakey, I'm leaning more towards something like Anticyclone
2. A vertical spinner similar to Why Wait (no image/video at the moment)

For Denise 2, I have several design goals (besides the obvious goals of working properly and being invertible):

1. 4 wheel drive (4wd Nanotwo ESC/receiver combo with 4 3d printed wheels from Shakey and standard micro gearmotor mounts)
2. Wheelguards (most likely 1.6mm Lexan)
3. A flush enough wedge (the wedge on the original Denise was messed up due to my imperfect bending, which meant that it had a hard time getting underneath other bots)
4. Durability (especially since I'm going to be fighting in an arena without push-outs)

The wedge will most likely stay at 2.4mm Lexan unless I am able to make weight for something thicker. At the moment, my material ideas are as follows:

1. 2mm base with 1.5mm top, sides and back, and 2.4mm wedge
2. All 2mm body and 2.4mm wedge
3. 1.5mm body and >2.4mm wedge

Of course, Bot Blast is the next on my agenda, so preparation for that comes first.

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