After 11 hours of printing, the main body of the Theragun v0 is tangible and definitely looks like a boat. It’s relatively hollow as well because the infill is pretty low, so I’m 100% sure it would float. The motor and planetary gears fit nice and snugly into their respective positions, which is super satisfying.

The next thing to print is the cap that gets set onto the gear train and also holds the bearing. It’s going to be a nice a quick print, but because of the awesome change in dimensions that happens between CAD and 3D printing, I’ll probably have to do a lot of print-and-check.

Full On Theragun

Finally got the entire Theragun v0 CAD’ed out in Solidworks. At least for the most part. This does not include space for a trigger or any electronics that need to go inside, though I’m planning on the 12V power supply being external.


Here’s a transparent view so the insides can be seen. It’s a pretty simple mechanism, though I understand the pushrod thing that oscillates back and forth is going to need to be fixed so it can hold a soft massage-y thingy.


Over the next few days I’ll be 3D-printing, readjusting, and sanding the pieces to get everything snugly assembled.

PRS Begins

This marks the start of my endeavor to trick out a children’s toy to go fast, drive by itself, and maybe even become self-aware. I have begun to spec out a BOM for motors, speed controllers, steering and drive hardware, and other nonsense that goes into building a tiny car. More information about the competition is at the end of the table.

I’ve had a lot of ideas about how to make this car be human and autonomously controlled without removing or adding any parts, and the goal is to just flip a switch to go from human to autonomous control. I can’t help but fantasize about the style of the whole thing. Should it look like a sports car from the future? Should it be a movie or TV reference? Should it look like a giant toaster? The possibilities are endless.

This is my annoyingly misformatted list of initial constraints and criteria. As you can see, most of them are just rules from the competition, but you have to start somewhere. I’m sure more will come to mind as I continue designing.

Constraints and Criteria
Req. Num. Criteria Rationale Treshold Target Stretch
R1 Car dimensions shall be 62″ x 36″ x 72″ while containing driver [1.4] Stated in the rules Dimensions are exceeded Power Wheels Dimensions N/A
R2 Wheels shall have pneumatic tires [1.5] Stated in the rules Non-pneumatic tires Air-filled tires N/A
R3 Wheel base (axel-to-axel length) shall be at least 18″ [1.5] Stated in the rules < 18″ Power Wheels Dimension N/A
R4 Wheel track (wheel-to-wheel width) shall be at least 12″ [1.5] Stated in the rules < 12″ Power Wheels Dimension N/A
R5 Motor(s) shall be driven with at most 48V [1.7] Stated in the rules 12V 24V 36V
R6 Batteries shall not be LiPO/Li-Ion chemistry [1.8] Stated in the rules No batteries LiFePO N/A
R7 There must exist a throttle-controlled motor controller to transfer power from the batteries to the motor(s) [1.9] Stated in the rules No controller ESC Microcontroller with ESC
R8 A unique number must be visible on the side of the car [1.11] Stated in the rules No number Any Available Number 77 or 0x4D
R9 A 6″ x 1.75″ label shall be present for the Moxie Board [1.12] Stated in the rules No moxie tag Generic text Nice Photoshop logo
R10 Front and rear bumpers shall cover 75% of the width of the car [1.13.1] Stated in the rules No bumpers 75% coverage 100% coverage
R11 Front and rear bumpers shall cover at least 1″ of vertical space 4-6″ from the ground [1.13.1] Stated in the rules No bumpers Aluminum tube bumper Aluminum curved bar
R12 Bumpers shall be covered in an impact absorbing material [1.13.1] Stated in the rules No coating Pool noodle Rubber coating
R13 Bumpers shall not protect wheels of the car from side contact [1.13.1] Stated in the rules Wheels not exposed Wheels exposed N/A
R14 The car shall extend beyond the driver in every direction when viewed from directly above [1.13.2] Stated in the rules Any open sides Enclosed cockpit N/A
R15 The car shall provide front and side protection for the driver’s feet [1.13.3] Stated in the rules No protection Front and side protection N/A
R16 The car shall have mechanical disk brakes capable of a full stop [1.13.4] Stated in the rules No brakes Mechanical disk brakes Mechanical disk and motor braking
R17 Batteries shall be secured so that they remain in position in the event of a tip or roll-over [1.13.4] Stated in the rules Batteries not secured Velcro straps Metal tie-downs
R18 The car shall impliment a kill switch that stops all current flow from batteries to the motors [1.13.6] Stated in the rules No kill switch Kill switch N/A
R19 The kill switch shall be accessible from outside the car [1.13.6] Stated in the rules No accessible kill switch Accessible kill switch Easily removable and accessible kill switch
R20 The kill switch shall be easily identifiable as such [1.13.6] Stated in the rules Unobvious kill switch Red kill switch N/A
R21 The car shall implement a fuse with a value such that the maximum possible power output is 1440W [1.13.7] Stated in the rules No fuse Correct fuse size N/A
R22 The car shall implement front and rear LED lights [1.13.1(2)] (Optional) Stated in the rules. For illuminated driving at night No lights LED head and tail lights Functioning head, tail, reverse, and indicator lights
R23 The car shall be able to drive in reverse [1.13.2(2)] (Optional) Stated in the rules. For backing out of crashes Only forward drive Forward and reverse drive N/A
R24 The car shall implement a horn [1.13.3(2)] (Optional) Stated in the rules. For fun No horn Generic horn Selectable horn
R25 The cost of the car (excluding safety systems and power wheels toy) shall not exceed $500 (batteries are counted for 50% fair market value) [1.14] Stated in the rules > $500 chassis $500 chassis < $400 chassis
R26 The car shall reach a top speed of 20mph Competitive speed < 20mph 20mph 25mph
R27 The car shall play music Fun No music Music loud enough for driver Music loud enough for spectators


Here’s where you can find out more about Power Racing Series(PRS) and also the autonomous portion: A+PRS, which, to the best of my knowledge, is run by SparkFun and only takes place in Boulder, Colorado.

Can’t wait to get this one underway, stay posted for more brainstorming and hopefully tangible progress.

Theragun v0 Catch-Up: Drill Salvage and 3D Printed Gearbox

I’ve finally gotten back into documenting my projects and I’m hoping that I keep at it. My newest thingy was supposed to be a Christmas present, but this posting date is very obviously much past that. Oops. Anyways, I’m finally getting around to it, and this is what I had made up before Christmas.

A little background you should know: this device is not an original concept. There is already a Theragun out there that costs upwards of $600 and my goal with this devolution is to replicate the real thing for a fraction of the cost. The Theragun is a device used for relaxing muscles and easing pain by vibrating the affected muscle at a frequency higher than that of pain signals. This is supposed to block out pain signals to the brain and soothe muscles.

This initial gearbox was just a way to get the creative juices flowing and have something tangible to help visualize the rest of the gun. The motor and set of planetary gears came from a drill bought at GoodWill. Originally, the drill’s gearbox had three stages of gear reduction, but I didn’t really need to step down the motor that much so I just took out the first stage for use. Because there was no shaft conveniently jutting out of the sun gear I had to print out a shaft with a nice little toothed cap at the end to fit snugly over the gear. The shaft was stuck through a bearing set in the cap covering the whole gear train and screwed into a wheel so more mechanisms can be tacked on in the future.

Soon I should have the full gun CAD’ed out and ready for 3D printing. More to come.