We often receive inquiries about the difference between "stroke length" and "needle depth" as found in tattoo machine product names and descriptions. This article will explain these differences using illustrations and examples of pen-style tattoo machines.
What are "Stroke Length" and "Needle Depth"?
"Stroke length" is the reciprocating range of the drive bar (up and down)
"Needle depth" is the protruding length or depth of the tattoo needle
Simply put, that's what they are. Now, let's explain in more detail, summarizing the structure of cartridge needles and tattoo machines.
Structure of a Tattoo Cartridge Needle
When the cartridge bar, equipped with a safety membrane (usually made of elastic silicone that also acts as a spring), is pushed forward (up), the needle extends from the tip. When the pushing force on the cartridge bar is released, the cartridge bar returns to its original position, and the connected needle retracts backward (down).
Structure of a Machine (Pen-Style Machine for Cartridge Needles)
A tattoo machine is a product designed to move a tattoo needle back and forth (up and down).
The rotation of the motor inside the machine causes the drive bar to move back and forth (up and down), pushing the cartridge bar and extending the needle back and forth (up and down). As the motor continues to rotate, the drive bar repeatedly moves back and forth (up and down), resulting in the needle's reciprocating motion.
The range (length) of the drive bar's back-and-forth (up-and-down) motion = Stroke Length
Tattooing Techniques Based on Stroke Length Differences
Many tattoo machine manufacturers produce and sell machines with various stroke lengths. Some machines even allow for adjustable stroke length.
With 3.5mm as the standard, longer strokes are generally preferred for lining, while shorter strokes are suitable for shading, blending, packing, and solid coloring by most tattoo machine manufacturers.
・3.0mm or less: For shading and blending
・3.5mm: All-rounder, versatile type
・4.0mm or more: For lining
While manufacturers may intend specific uses for their machines, the actual application of a tattoo machine varies greatly depending on the tattoo artist and technique. For instance, stipple tattoos, which involve dot-like shading, often use longer-stroke machines typically meant for lining.
Stipple Tattoo Example
Needle Depth
Most machines allow adjustment by twisting the grip. Loosening the grip moves the cartridge needle forward (up), while tightening it moves it backward (down).
Even if the machine's drive bar is in the same position, adjusting the cartridge needle's position forward or backward (up or down) allows for adjustment of the needle's protruding length.
When the needle does not protrude at all from the tip, the needle depth is 0.0mm.
The protruding length/depth of the needle from the tip = Needle Depth
Recommended Machines with Selectable Stroke Lengths
■Cheyenne｜SOL Nova Unlimited｜Black｜2.5｜3.5｜4.0｜5.0mm Stroke
Cheyenne made｜Highly reliable tattoo machine manufacturer
Wireless machine powered by a rechargeable battery
Available in 4 stroke lengths
●2.5mm - The Beauty - Particularly suitable for delicate shading and careful work on sensitive body parts.
●3.5mm - The Generalist - Offers a perfect balance of lining and shading, the all-rounder of this series.
●4.0mm - The Specialist - Guarantees an ideal balance of lining and color packing.
●5.0mm - The Beast - Perfect for those who want to work quickly and most efficiently. The Beast elevates lining to a whole new level.
■CRITICAL｜TORQUE PEN MACHINE | FULL SET｜3.5｜4.2mm Stroke
CRITICAL made｜Machine by a highly popular power supply manufacturer
・Excellent operability with beautiful display
・Wireless footswitch and Bluetooth connectivity available
Next-Generation Machines with Adjustable Stroke Length
■Cheyenne｜HAWK PEN UNIO｜2.5-4.0mm Stepless Stroke Adjustment
Cheyenne made｜Pen-style tattoo machine with continuously adjustable stroke from 2.5 mm to 4.0 mm
■EQUALISER｜WIRELESS Neutron2｜Black
EQUALISER｜Freely adjustable stroke from 2.6 to 4.0 mm, allowing for precise work regardless of technique or style.
Conclusion
This has been a brief explanation of stroke length and needle depth in tattoo machines.
I am constantly amazed and delighted by the evolution of tattoo art and the overflowing ideas of tattoo artists that I see through SNS and other channels today.
I look forward to seeing the original works of artists who make full use of tattoo machines with so much potential.
Writer:
-Middle-aged tattoo lover-