SCARAB Hubmotor Drum (Beta)

Modular Hubmotor Drum for Combat Robots!

The SCARAB is an experimental, one-of-a-kind weapon system for combat bots. Featuring a 2200kV 22mm x 22mm stator size fully custom motor, replaceable magnet rings, and replaceable AR600 sharpened teeth, this is unlike anything the world has seen before. Forget using countersunk screws as impactors! A handful of top builders have made hubmotor beaters and drums, but nearly all are custom-tailored to a single bot, and usually cost hundreds of dollars and dozens of hours of work to design and create. There are a couple of other drum spinner options you can buy, but all have magnet rings epoxied in and are impossible to replace. This is the first to use a completely custom motor rather than modifying an existing one, and the first to have a cheap and easy-to-swap magnet ring insert. 

For this beta batch of 50 units, the price has been reduced by almost 33%! As this is a beta product, the final dimensions may change for future batches. Notably, the drum width may get narrower to allow for a right-angle wire exit, which will be easier to mount on most bots. However, you shouldn't need to change your bot design much to accommodate this change, and the distance between uprights will remain the same. 

CAD model here!

Specs and Usage

The SCARAB drum system with its shaft, bearings, spacers and all weighs just under 1lb (450g), with spinning mass of 330 grams or 0.72 pounds, an immense amount of stopping power! Perfect for beetles looking for crazy weapon power in a tiny package. The effective diameter is 65mm (2.559") with stock teeth, and the drum fits onto a 125mm long shaft, with 102mm between uprights. Use with a 4S LiPo for best results and 268 mph theoretical tip speed. 6S is not recommended. 

To assemble your SCARAB for use, you will find in the hardware package 3 aluminum spacers. Two of these should go between the stator and drum body to prevent the coils from rubbing on the spinning drum, and one on the outside of the drum opposite the stator to prevent the drum from rubbing on your uprights. 
The stackup order should be: (Upright), Stator, Spacer, Spacer, Drum, Spacer, (Upright). The bolt shaft can go through from either side, but it's easiest from the drum side.

Every SCARAB Hubmotor Drum includes:

• 1X SCARAB Hubmotor Body + Magnet Ring Assembly
  • 7075 anodized aluminum drum body with magnet ring installed
  • 2X 12 x 12 x 8mm needle roller bearings installed
• 1X 2222 Drum Stator
• 2X ~48 gram AR600 hardened steel teeth with 52-degree sharp beveled edges (10-degree positive rake angle)
  
  • Works effectively like a single tooth drum with 1 center and 2 outer teeth
• 8X M5 x 10mm button head class 12.9 tooth mount bolts
• 3X 1mm thick Aluminum spacers
• 1X custom shoulder bolt shaft with low profile T25 torx head, 125mm long, 8mm diameter
  
• 1X M6 nylock hex nut

Measured peak current draw up to 100A on spinup, continuous 18-22A at full speed on 4S LiPo. Size your battery accordingly, at least 4S 1100mAh for 3 minutes at max throttle. Pairs well with our RevvitRC AM32 ESC with BEC. Kinetic energy stored is 880J theoretically at max speed!

Due to the location of the magnet ring and weight-reducing cutout, 4X M5 x 10mm bolts per tooth will fit just fine, but if you wish to use longer screws, you can only fit them into two of the holes. DO NOT insert a screw longer than 10mm into the hole above the magnet ring!

With this BETA version, there are three wires that exit at different locations, which will be fixed on the production motors. However, you do not need to have all 4 mounting screws used, just 1 or 2 is fine, as the 8mm shoulder bolt is the main mechanical connection and the M4 screws just prevent the stator from spinning inside the motor. I recommend using just 1 or 2 mounting screws and then 3 holes or a large slot/channel for the wires in your uprights. Use ~3.5mm bullet connectors on the wires and ~5.5mm holes in your frame rail so they fit through.

BETA FEEDBACK NEEDED!

We may reach out for feedback on the use of this weapon system so we can make changes and improvements on the production versions! Your feedback is invaluable to help us make the best products on the market for robot combat. 

We are already finalizing the design of production versions of this product so that it will be compatible with a bot designed for this beta unit, so rest assured, only minor changes should be needed to your bot! The swappable magnet rings will work on beta and production motors. The stator will also remain the same size and KV. 

The next motor batch will likely use a right-angle wire connection to a PCB with an optional MR30 connector to the motor. Making your uprights about 8-10mm further apart, you should be able to fit the production stator onto an existing BETA SCARAB drum, and we will sell the stator separately to allow for this. 

Safety Disclaimer

Warning: combat robots are not toys! They can be extremely dangerous. Click here for a safety video.

Testing a robot with an active spinning weapon should never be done while maintaining a line of sight with the robot. Ideally, you should be testing inside an enclosed box or arena with at least 1/4" thick polycarbonate windows or top to see through, and 1/2” or thicker plywood or MDF construction. Operation (Including testing) outside of a suitable arena or test box could cause serious injury. By purchasing this product you acknowledge that you are responsible for the safe use of this product and that Just ‘Cuz Robotics or its employees are not liable for any injuries or damages.