Archives for posts tagged ‘hi-striker’

mustache-themed Hi-Striker


So Crushtoberfest is approaching again, and the party plans are in full swing. In case you missed it, Crushtoberfest ’08 was the house party that capped off a six week mustache growing contest among BDC employees and their friends and families. Last year’s feat-of-strength competition featuring the Captains of Crush grippers was a huge success, so we decided to step it up this year.

We liked the idea of a Hi-Striker, the classic carnival game where you swing an oversized hammer and try to ring the bell. But renting a Hi-Striker is not cheap, and we saw the opportunity to build something awesome. So going with the vague carnival theme (and the overt mustache theme) I generated this concept sketch for an electronic Hi-Striker, featuring a larger-than-life Tom Selleck head with light up eyes and fireballs shooting from his ears.

Here’s the plan: The contestant will strike the rubber pad with the hammer, compressing the sealed rubber hose under it. An air pressure sensor attached to one end of the hose will generate an analog voltage (up to 5v), the Arduino Mega will read the voltage and light up the LEDs according to a predefined scale. If the hit is a “ringer” then the LEDs will light all the way to the top, Tom Selleck’s eyes will light up, and fireballs will shoot from his ears. BTW the fireball effect is a flash paper/model rocket ignitor thing we worked out for last year’s party but never used. We also plan to have sound effects go with the LEDs, using the Adafruit Wave Shield for Arduino.

Stay tuned for more.

Hi-Striker construction begins

Construction on the Selleck Striker began without much detailed planning. I want to use as much scrap materials as I can, and luckily I have a lot of scrap wood lying around. The “striker” part is built around four 2x6s glued and screwed together to form a nice sturdy block, which will be topped with some thick rubber to cushion the hammer’s impact. The “sleeve” part holds the striker over the heater hose, which gets compressed when the hammer comes down.

The backboard is 8 feet tall, made with extra 1x and plywood. I drilled and countersunk holes in the front for the LEDs to poke through, and left some slots in the 1x cross-pieces for the LED wiring. I built a little “backpack” compartment for the electronics, and primed and painted everything white.

LED wiring

The Arduino Mega has 54 digital I/O pins, 50 of which are each driving an LED on the Hi-Striker. Each pin can drive up to 40mA, so the only additional components needed are one 100k current-limiting resistor per LED.

For testing, a simple cascading loop runs through the (first 16) LEDs one at a time:

const int ledCount = 16;    // the number of LEDs in the bar graph
int ledPins[] = { 2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17 };   // an array of pin numbers to which LEDs are attached

void setup() {
  // loop over the pin array and set them all to output:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    pinMode(ledPins[thisLed], OUTPUT);

void loop() {
  // loop over the LED array:
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    digitalWrite(ledPins[thisLed], HIGH);  // turn on the LED
    delay(20);                             // wait
    digitalWrite(ledPins[thisLed], LOW);   // turn off the LED

new paint job

The inspiration:

It’s a loose interpretation…

Hi-Striker control panel

Yesterday I finished the control panel for the Selleck Striker and started hooking it up:


reset button – Before a new contestant hits the striker, the reset button clears the LEDs, then checks the difficulty setting and applies any changes. It’s a SPST, switching 5V from the Arduino to one of its analog input pins. High on the pin = reset.

play/demo switch – Demo Mode plays a scrolling LED effect, Play Mode waits for a change in the pressure (like a hammer strike!). This is a SPDT (though I could have just used a SPST) switching 5V from Arduino to one of its analog input pins. High on the pin = Demo Mode, low on the pin = Play Mode.

analog_inputdifficulty knob – Just a 100K potentiometer that sends 0 to 5V to one of the analog input pins. This will allow us to adjust how much force is needed to get to the top.

score display – This 3-digit numeric LED display will show the “score” of the strike. I’m still not sure how I’ll calibrate it, but the idea is that you get a finer resolution score than the 0-50 LEDs in front. I’m thinking of having this also display the “difficulty” setting when you twist the knob.

striker connector – This is an RJ-45 connection for the striker portion, so that the two halves aren’t permanently tethered to each other. I’m only using three of the eight conductors.

audio out – This 1/4″ mono jack will send sound effects and other audio to the sound system.

Also note the the three Arduinos in the bottom of the photo. The Mega on the right will handle the LEDs and input elements, the NG in the middle drives the 3-digit LED display, and the Duemilanove with the wave shield on the left plays the sound effects. They’ll be communicating via their serial ports.

Selleck head

Sam is working on the Selleck head for the top of the Hi-Striker and it looks awesome!


The photo is deceiving… that thing is almost four feet high.

everything’s better with fireballs, part II

Three days left till Crushtoberfest, and I prepared a total of ten fireball launchers for the Hi-Striker. They’re used in pairs, so that gives us five “wins” worth of awesomeness. Here they are:

soldering the ignitors

First I cut the copper tubes to length, drilled each end cap and JB-Welded 1/4″ phono plugs into each one. Then I soldered model rocket ignitors to the phono plugs’ contacts inside the caps. The gray boxes are aluminum project boxes with phono jacks installed in one side. These will be mounted to the back of the Selleck head, but for now they were a good way to hold each cap as I was soldering. I then assembled the tubes to the caps and used a little electrical tape to hold them together.

cutting the flash paper

I cut each 8″ x 9″ sheet of flash paper into strips (across the short length),

twist it up

folded all the strips in half together and twisted them loosely,

stuff it in

then stuffed the whole thing into the end of the tube.

finished fireball launchers


topping off the striker

IMG_4935 Here’s how I added some padding to the top of the “striker” part of the hi-striker. I picked up a used tire from my local mechanic and managed to cut a couple of rectangular pieces out of the tread. After some trial and error I found the best way to cut through a tire with steel radials is with a sabre saw with a metal cutting blade. The shop stunk like burning rubber but it cut pretty quickly.


I used the nailgun with some trim nails to tack two layers onto the striker. It can probably use some trimming on the corners, but it will do the trick.

finishing the Selleck Striker

Just one more day till Crushtoberfest, and the Selleck Striker is ready to go. Last night I mounted the head (nice job Sam!) and drilled its eyes for LEDs. I also mounted the fireball launchers and wired everything up.

selleck head wiring the Selleck head

Crushtoberfest promo video!

A few photos from Crushtoberfest ’09


The Selleck Striker ready for action.


Lisa about to show it who’s boss.


Beer pong!


That’s a lot of facial hair.