Stitch Regulator for Juki TL Machines

This is a stitch regulator that can be used with Juki TL machines. Commercial versions of these are very expensive ($700 - $1,000 USD), but the way they work is fairly simple. You can build a DIY version using an Arduino microcontroller, an old PS/2 optical mouse, and a handful of inexpensive electronic components.

Table of Contents

• How It Works
• Building One
  • What You Need
  • Schematics
  • Instructions
• Code
• Frequently Asked Questions

How It Works

StitchReg works by using the optical sensor from a mouse to calculate the speed of the machine/fabric and control the speed of the machine by acting as the foot pedal with a digital potentiometer.

The Juki foot pedal is basically a resistor and there are 3 states we need to care about:

• idle - when the foot pedal is not depressed forward or backward it sits around 140k ohms
• thread cutter - to trigger the thread cutter the pedal drops to around 44k ohms
• sewing - sewing happens, slow to fast, from around 20k ohms to around 500 ohms

Building One For Yourself

What You Need

Currently this is just breadboarded with an Arduino Uno Rev 3. Once the design is final I’ll create a PCB and enclosure.

• PS/2 Optical Mouse
• Arduino kit
• MCP4131-104E/P
• Momentary switch

The parts below are in the linked arduino kit, but I’ll find better options.

• PN2222A transistor (in the above arduino kit)
• 1k ohm resistor (in the above arduino kit)
• 10k ohm resistor (2) (in the above arduino kit)
• 100k ohm resistor (in the above arduino kit)
• Buzzer (in the above arduino kit)
• Barrel Jack (cut the one off the battery connector in the arduino kit)

Schematic

Instructions

Coming soon!