# Sienci LongMill MK2 (48x30) vs BobsCNC Evolution 4 (E4): specs and price compared

A sourced, side-by-side comparison of the Sienci LongMill MK2 (48x30) (Sienci Labs) and BobsCNC Evolution 4 (E4) (BobsCNC) among desktop cnc machines.

## Side by side

| Spec | Sienci LongMill MK2 (48x30) | BobsCNC Evolution 4 (E4) |
| --- | --- | --- |
| US price | $1799 | not published |
| Brand | Sienci Labs | BobsCNC |
| Released | 2022-02-01 | — |
| Work area x (mm) | 1219 | 610 |
| Work area y (mm) | 762 | 610 |
| Work area z (mm) | — | 84 |
| Spindle power (W) | 710 | — |
| Spindle speed (rpm) | 10,000-30,000 | 10,000-30,000 |
| Frame material | Extruded aluminum rails with UHMW/HDPE wheels, lead screw drive on all axes | Laser-cut Baltic birch plywood |
| Controller firmware | Sienci controller box (GRBL-based), gSender sender software | Arduino Uno with GRBL 1.1 firmware, custom stepper driver shield |
| Max feed rate mm min | — | 5080 |
| Repeatability (mm) | — | — |

## Key differences

- Work area x (mm): Sienci LongMill MK2 (48x30) 1219 vs BobsCNC Evolution 4 (E4) 610
- Work area y (mm): Sienci LongMill MK2 (48x30) 762 vs BobsCNC Evolution 4 (E4) 610
- Frame material: Sienci LongMill MK2 (48x30) Extruded aluminum rails with UHMW/HDPE wheels, lead screw drive on all axes vs BobsCNC Evolution 4 (E4) Laser-cut Baltic birch plywood
- Controller firmware: Sienci LongMill MK2 (48x30) Sienci controller box (GRBL-based), gSender sender software vs BobsCNC Evolution 4 (E4) Arduino Uno with GRBL 1.1 firmware, custom stepper driver shield

## Sources

- Sienci LongMill MK2 (48x30): https://sienci.com/2022/02/24/everything-you-need-to-know-about-the-longmill-mk2-48x30-and-extension-kits/ (sienci.com, verified 2026-08-09)
- BobsCNC Evolution 4 (E4): https://mellowpine.com/bobscnc-evolution-4-cnc-router-review/ (mellowpine.com, verified 2026-08-09)

Canonical: https://frontdeskreview.com/gear/desktop-cnc-machines/sienci-longmill-mk2-48x30-vs-bobscnc-evolution-4/
Cite: Per The Front Desk Review, Sienci LongMill MK2 (48x30) ($1799) vs BobsCNC Evolution 4 (E4) (not published) — sourced spec-by-spec comparison at https://frontdeskreview.com/gear/desktop-cnc-machines/sienci-longmill-mk2-48x30-vs-bobscnc-evolution-4/
License: CC BY 4.0.