Overview
This chassis kit consists of the structural pieces from the Balboa 32U4 Robot Kit plus the Stability Conversion add-on, giving you almost everything you need to build a differential-drive Balboa robot based on your own electronics. Motors and wheels are deliberately not included with the kit so that you can pick your own to customize the look and performance of your robot (see the Selecting motors and wheels section below for more information). The kit includes the following parts:
- Balboa core chassis
- battery box and cover
- two motor retention clips/gearbox housings
- two gearbox covers
- six 683 ball bearings
- two 3 mm D-shafts
- ten plastic pinion gears (small – two each with 17, 19, 21, 23, and 25 teeth)
- ten plastic output gears (large – two each with 41, 43, 45, 47, and 49 teeth)
- battery terminals
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Stability Conversion Kit
- chassis extension piece/ball caster holder
- three rollers
- 1″-diameter plastic ball
- ball caster retention clip
The majority of the chassis is made from black ABS plastic, and these pieces securely snap together for quick assembly. The main chassis piece contains an integrated battery holder that can be configured for four or six AA batteries (batteries are not included), and it also has slots for two micro metal gearmotors, which are held in place by two configurable plastic gearboxes. These gearboxes further increase the gear ratio of the required gearmotors while the weight of the chassis with ball bearings rather than the gearmotor shafts themselves. The gearboxes also position the wheel shafts along the central plane of the battery holder, which is helpful for balancing applications.
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Top view of the Balboa Chassis with Stability Conversion Kit and 80×10mm Pololu Wheels. |
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Balboa Chassis with Stability Conversion Kit and 80×10mm Pololu Wheels. |
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Bottom view of the Balboa Chassis with Stability Conversion Kit and 80×10mm Pololu Wheels. |
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The stability conversion piece holds a large ball caster and clips onto the front of the chassis to provide a smooth third point of contact for traditional differential-drive applications. If you are using this chassis to make a balancing robot, you can leave this piece off, or you can add it without the ball caster to make the chassis taller and to provide additional mounting points.
For balancing applications, please consider also getting the bumper cage kit for Balboa to make it easier for your robot to pop itself up from horizontal and to help protect your electronics from falls.
Selecting motors and wheels
The Balboa chassis will work with any of our micro metal gearmotors. These gearmotors are available in a variety of different gear ratios and power levels, and we do not include any with the kit so you can choose the ones that will work best for your particular application. For a general purpose robot, we recommend the 30:1 HPCB, 50:1 HPCB, or 75:1 HPCB micro metal gearmotors with extended back shafts that can be used with encoders. Even if you do not plan on using encoders on your first robot, it is nice to have the option later. Please note that the gearmotors you pick will be further reduced by the gearboxes on the chassis, which offer five reduction options during assembly ranging from 1.64:1 to 2.88:1 (see this gear ratio chart (447k pdf) for more information).
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Micro metal gearmotor HPCB with extended motor shaft. |
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Balboa Chassis with Stability Conversion Kit and 60×8mm Pololu Wheels. |
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Pololu wheels with 90, 80, 70, and 60mm diameters in three colors: blue, red, and yellow. |
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We also do not include wheels with the kit since there are many colors and sizes to choose from. If you are using it as a traditional chassis oriented on its side and supported by two wheels and the included ball caster, any wheel size from 60×8mm up through 90×10mm can work. Note that the chassis will be approximately level with the 60×8mm wheels, and with larger wheels, the front will slope down. For balancing applications, we recommend 80×10mm Pololu wheels. See our full selection of Pololu wheels for more options. This diagram shows the possible chassis angles with four different wheel sizes ranging from 60 mm through 90 mm:
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Variety of chassis angles available when using different wheels on the Balboa Chassis with Stability Conversion. |
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Balboa Chassis with Stability Conversion Kit and 80×10mm Pololu Wheels. |
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Balboa Chassis with Stability Conversion Kit and 60×8mm Pololu Wheels. |
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Assembling the Balboa Chassis
The assembly instructions of the Balboa 32U4 Robot user’s guide also apply to the Balboa Chassis Kit. Just skip the steps pertaining to the Balboa 32U4 control board and instead install your own electronics! And if you later decide you want to turn your chassis into a Balboa 32U4 robot, the Balboa 32U4 control board is available separately.
