11. Open Source Hardware - From Fibers to Fabric¶

Research & Ideation¶

Traditional handheld punch needles are and industrial tufting guns used for small scale carpet manufacturing are limited in pile height and speed. This week, I wanted to hack a manual crank mechanism and a standard pile height punch needle to automate the punching motion using a servo motor, aiming for a 40-50mm pile height that exceeds standard manual tools. I love making art using my industrial tufting gun and hand held punch needles of various styles; however, theres a middle ground missing. My art would move a lot quicker if I had a mix between my hand held detailing punch needles and my large tufting gun.

Design & Fabrication Skills¶

3D Modeling: This customized 40-50mm pile height punch needle has a 20-tooth drive gear and was modeled in Fusion 360 to interface with a common servo. I also modified the original crank and rod within Fusion 360 to fit the sizes of my servo motor.

Digital Fabrication: Components were cut from acrylic using a 40W CO2 laser and 3d printed using a PRUSA MK3s.

Process Detail: Modified the original crank and rod geometry to accommodate the increased throw required for a 50mm pile.

References & Inspiration¶

Simji: Known for turning pet portraits into rugs, her process highlights the importance of perpendicular pressure and even tension.

Hess Jeon & Seo: Their "CnC Punch needle Machine MK-1" is an open-source collaborative project that uses automated hardware for textile art.

Sara Moore & Micah Clasper-Torch: These artists emphasize the tactile, 3D nature of punch needle work, where varying loop lengths create depth.

Two images side-by-side

Tools¶

Fusion 360
Prusa Slicer
Inkscape
KiCad
TinkerCad
Epilog 40w CO2 Laser
PRUSA MK3s

BoM¶

Materials¶

Qty	Description	Price	Link	Notes
1	Servo Motor : HK15178	2.00 $	unavailable	No longer manufactured
1	11 x 24 6mm Acrylic	15.00 $	FVSU Fab Lab	find alternative
1	Punch Needle	.50 $	FVSU Fab Lab	file included
1	Crank Mechanism	.50 $	FVSU Fab Lab	file included
1	M3 Heat Sink Screws	.50 $	Home Depot	source locally
1	3mm Screws	.00 $	FVSU Fab Lab	source locally
1	PLA Filament	.00 $	FVSU Fab Lab	source locally

Process¶

Step 1¶

The Math: To achieve a 40-50mm pile, my crank "throw" (the distance from the center of the gear to the rod attachment point) needed to be exactly half of my desired stroke.

Reference: I studied the original Printables Crank Mechanism to understand the pivot points.

Inspiration: I studied the industrial tufting gun I own and the needle is polished to a mirror finish to reduce friction.

Step 2¶

Punch Needle: Model a hollow tube with a beveled, sharp tip. Ensure the inner diameter is wide enough for your specific yarn.

The Gear: I created a 20-tooth spur gear designed to press-fit onto the HK15178 servo horn.

Modifications: After importing the Printables mesh/step file, I extended the connecting rod length to accommodate the new 50mm travel distance, resized all of the gear slots and pins that would fit the rod within inkscape. I then cut them out of acrylic on my lab's 40 watt CO2 laser.

Step 3¶

Material: 6mm Acrylic.Machine: 40W CO2 Laser.

Settings: Speed 10, Power 60-70% for cutting.

Task: Cut the main frame and height adjusters to match the height of the servo motor and adjusted crank, the 20 tooth gear to fit the servo motor's teeth, the modified crank arm, and the sliding rail that will keep the needle moving in a perfectly straight line. Also be sure to cut many 6mm vertical pins to use in step 5.

Step 4¶

Material: PLA (High infill for the gear to prevent tooth shearing).

Task: Print the modified Fusion 360 punch needle and the crank mechanism from printables base ONLY.

Finishing: Sand the needle tip with fine-grit sandpaper (up to 1000 grit) until it is buttery smooth. This is CRUCIAL for the part I mentioned in research about properly penetrating the fabric like a professional tufting gun would.

Step 5¶

Servo Mount: Attach the HK15178 servo into the laser-cut acrylic frame (I am still iterating this portion).

Drive Train: Press-fit the 3D-printed gear onto the servo (this worked great).

Crank Linkage: Connect the acrylic cut arm to the gear and the sliding component using the acrylic pins cut in step 3.

Needle Housing: Slide the 50mm needle into the laser-cut rails and snap the connecting rod from the crank to the base of the needle.

Step 6¶

Wiring for demo: Connect the servo to an Arduino Uno via a breadboard (Signal to Pin 9, VCC to 5V, GND to GND). I utilized TinkerCad to test out my connections to ensure I did not have any signal issues.

Code: See code section.

Dry Run: Observe the 50mm stroke. Ensure the acrylic doesn't flex and the gear teeth don't slip. My hand cranked dry run went great.

Code Example¶

/*
 * High-Pile Servo Tufting - Speed Control Interface
 * Project: OS Hardware Week
 */

#include <Servo.h>

Servo punchServo;  // Create servo object
int potPin = A0;   // Potentiometer connected to A0
int val;           // Variable to read the value from analog pin

void setup() {
  punchServo.attach(9);  // Attaches the servo on pin 9 to the servo object
}

void loop() {
  val = analogRead(potPin);            // Reads potentiometer (0 to 1023)
  int speedDelay = map(val, 0, 1023, 10, 100); // Maps it to a delay (10ms to 100ms)

  // Forward Stroke (The Punch)
  punchServo.write(0);                 // Move to start position
  delay(speedDelay);                   // Wait based on pot speed

  // Backward Stroke (The Retraction)
  punchServo.write(180);               // Move to 50mm extension position
  delay(speedDelay);                   // Wait based on pot speed
}

Final Thoughts¶

I'm proud of my prototype and look forward to reiterating until I have a fully functional handheld motor driven punch needle for heights and details that my industrial strength tufting gun can not provide.

Future Iteration: The next version will focus on increasing the torque of the servo or moving to a DC gear motor to handle the resistance of the fabric (monk's cloth).