3D Printing – Where the Z Axis get Techinal. Trade-offs for ultra Precision.
Why We Slowed It Down to Speed It Up
In 3D printing, the Z axis is rarely the star of the show. People obsess over toolheads, hotends, belt paths, and accelerated motion on X/Y — all the flashy parts of a high-performance CoreXY. But if your goal is precision, if your goal is reliability, if your goal is the kind of microscopic repeatability that makes prints look indistinguishable from resin… everything begins with the Z axis.
For the NorthForge3D Trident development mule, we made a series of deliberate engineering decisions that slowed the Z axis down dramatically on paper, increased its resolution far beyond what current filament science even requires, and then regained the lost speed by moving to higher-voltage motion control.
This article walks through that trade-off — why we slowed the axis down, how we gained precision, and why higher voltage lets us “speed it back up” without ever giving up accuracy.
1. The Three Knobs of Z-Axis Precision
Every Z axis is defined by three major factors:
- Motor step angle
- Lead screw pitch
- The voltage driving the motor
Most printers today use 1.8° stepper motors and a T8×8 lead screw. That gives you 200 full steps per rotation, and each rotation moves the bed or gantry 8 mm. It’s fast, it’s cheap, it’s fine… and it’s nowhere near the precision a next-generation machine should have.
We changed both of the mechanical variables:
• 1.8° → 0.9° stepper motors
(200 → 400 full steps per revolution)
• T8×8 → T8×2 lead screws
(8 mm per revolution → 2 mm per revolution)
These two changes increased our Z-axis steps per mm by a factor of 8×.
A typical Z axis has about 400 microsteps per millimeter.
The NF3D Trident mule has roughly 3200.
That is far beyond the minimum surface resolution filament can currently express — and that’s exactly the point. It means the mechanics no longer limit the quality of the print. The limiting factor becomes the consistency of molten plastic flow… which is exactly where a precision-focused platform should be.
2. The Trade-Off: Slowing the Z Axis Down
When you increase steps per millimeter by eight-fold, you also reduce mechanical speed by eight-fold.
Two things happen immediately:
- A full rotation of the motor now moves the axis only 2 mm (instead of 8).
- The motor needs twice as many electrical steps per rotation.
If nothing else changes, your Z axis becomes very slow in terms of maximum mm/s.
For printing, this doesn’t matter — the Z axis barely moves during printing. But it does matter for:
- Bed leveling
- Probing routines
- Quad Gantry Level
- Z-hops
- Homing
This is where you feel the trade-off.
So the question becomes:
How do you keep all the precision… and keep the Z axis feeling fast?
The answer is voltage.
3. Regaining Speed the Right Way: Moving to 48V
Most hobby printers run their stepper drivers on 24V. That’s fine for light axes and low resolution. But once you dramatically increase steps/mm, the motor hits a new limit: inductance.
At high step rates, the coil simply cannot pull current fast enough when driven at 24V. Torque collapses. Speed collapses. And skipped steps become a real possibility.
By moving the Trident mule to 48V on Z, we regain the lost speed:
- The motor reaches its current setpoint much faster
- Torque stays strong at higher RPM
- Step frequency limits increase
- The axis accelerates more crisply
- Leveling and probing feel fast again
- You preserve every bit of the mechanical precision
So we slowed the axis down mechanically (for the right reasons), and sped it back up electrically (also for the right reasons). That’s real engineering — not marketing.
And this raises the natural question…
4. Are We Stopping at 48V? Probably Not.
Once you go down the path of higher resolution and higher precision, the next steps become obvious.
If 48V helps us recover speed on a dramatically slowed, ultra-precise Z axis…
what would 60V do on X/Y/Z in a future machine?
Right now, the Trident mule is the test platform — the place we validate ideas, measure real-world benefits, and push the envelope. But the philosophy guiding the Deuce is already clear:
- More precision
- More headroom
- More stability under high acceleration
- Industrial control behavior
- Voltage used intelligently, not recklessly
48V isn’t a gimmick. It’s the entry point into a different class of motion system.
5. Why This Matters for the Trident and the Deuce
This isn’t just about the Z axis being “really accurate.”
It’s about building a foundation for everything that follows.
The Trident mule needs:
- Rock-solid Z offsets between two independent gantries
- No banding
- No Z wobble
- No non-linearities
- Insanely consistent first layers
- A platform that reveals the true limits of molten plastic, not the limits of mechanics
The Deuce needs all of that and more — and it needs it at speeds that most printers never reach. It needs a Z axis that is no longer the weakest link. It needs a motion system with enough precision and enough voltage headroom that the mechanics disappear as a limiting factor.
The Trident mule is where we test that philosophy.
The Deuce is where we take it to its logical conclusion.
6. And Next Time: The X/Y Axis and the Frame Itself
Resolving Z to this level is only the beginning.
The next Technical Notes article will look at the X/Y axis and the frame — and why precision means nothing unless the entire machine holds its shape under load. We increased Z resolution by a factor of eight. Now we need to reduce frame motion by the same magnitude.
A printer that is only square when idle isn’t a precision tool.
A printer that stays square even if you dropped it off your roof — that’s where we’re heading.
And that’s how the next chapter begins.