LongMill Benchtop CNC MK2.5: Hobby CNC Router for Woodworkers and Makers
- Michael
- 5 hours ago
- 9 min read
Most benchtop CNC routers under $2,000 are compromises: undersized working areas, lightweight frames, or controllers that create more problems than they solve. The LongMill Benchtop CNC MK2.5 starts at $1,500 and has been through six hardware iterations since its 2019 Kickstarter to work through exactly that list. The current version ships with large extruded aluminum rails, 1/4" steel gantries on all axes, NEMA 23 motors, spring-loaded anti-backlash nuts, and the SuperLongBoard controller as standard.
Six years after its Kickstarter launch, the LongMill is still Sienci Labs' core machine. The original LongMill raised CA$436,197 from 324 backers on Kickstarter in 2019, the second successful campaign from Sienci Labs after the Mill One raised over $60,000 in 2016. Chris Halek and Andy Lee, who met studying mechanical engineering at the University of Waterloo, have shipped thousands of LongMills since across multiple generations. The LongMill Benchtop CNC MK2.5 comes in three sizes from 12x30 to 48x30 inches, cuts at speeds up to 150 inches per minute, and is available from Sienci Labs with a current price reduction while quantities last.
What it does: Benchtop CNC router cutting wood, plastic, foam, and soft metals on working areas up to 48x30 inches, with gSender control software and advanced controller included.
What changes: Industrial-grade aluminum and steel construction at hobby pricing, now with self-adjusting precision on all axes and a more capable controller than the previous generation.
What to know: Router not included. Spoilboard not included. Both must be sourced separately before first cut.
Track record: CA$436,197 from 324 Kickstarter backers in 2019. Sienci Labs has shipped thousands of LongMills across six hardware generations since.
From $1,500 (machine only), available from Sienci Labs
Quick Verdict
Who Is It For?
The LongMill Benchtop CNC MK2.5 is for woodworkers, hobbyists, makers, and small-shop owners who want a capable and reliable benchtop CNC for signs, furniture, engravings, guitars, and general wood and plastic work. The 30x30 is the most practical size for home workshops. The 48x30 suits anyone who needs to cut full cabinet panels or larger flat work. It is not the right machine for production shops or buyers whose primary use case is metal cutting.
Main Strengths
Three size options (12x30, 30x30, 48x30) with large extruded aluminum rails, 1/4" steel gantries on all axes, NEMA 23 motors, and MG-12 linear guides on the Z-axis: a construction spec that stands out at this price point.
SuperLongBoard now standard across all MK2.5 configurations: faster movement, anti-resonant motor drivers, high-grade EMI protection, Ethernet connectivity, and support for 4th axis cutting and RS485 VFD spindles.
Spring-loaded anti-backlash nuts on all axes, self-adjusting with no manual intervention required: a feature that typically adds significant cost on machines at this level.
gSender included at no extra cost: Sienci's free CNC control software with surfacing, calibration, and start-from-line tools, maintained by the same team that builds the machine.
Active community on Facebook and the Sienci forum, with lifetime technical support from Sienci Labs.
Main Limitations
Aluminum and brass are within the LongMill's material range, but Sienci is clear that soft metal cutting is possible and slow. If metal work is your primary use case, this is not the right starting point.
Assembly takes a few hours and first cuts rarely go perfectly. Budget a full weekend before expecting clean, production-quality results from the machine.
The LongMill MK2.5 is deliberately positioned below Sienci's own AltMill for complex or production-pace work. For most hobbyists that is fine, but buyers anticipating heavy use should evaluate the AltMill before deciding.
Is the LongMill Benchtop CNC MK2.5 Worth Buying?
For a woodworker or maker moving from hand tools to digital fabrication, the LongMill Benchtop CNC MK2.5 delivers a rigid, well-supported machine at a price that entry-level hobby CNC has not always managed to hit. Factor in the router and spoilboard before finalizing your budget, and the Beginners Kit removes the accessory guesswork for first-time buyers. Available from Sienci Labs.
What Is the LongMill Benchtop CNC MK2.5?
The LongMill Benchtop CNC MK2.5 is a kit-based hobby CNC router from Sienci Labs, built on large extruded aluminum rails, 1/4" steel gantries, NEMA 23 motors, and a lead-screw motion system with MG-12 linear guides on the Z-axis. It ships in three working area sizes: 12x30, 30x30, and 48x30 inches, with 4.5 to 4.9 inches of Z-axis travel. Assembly requires no soldering and takes a few hours. A router and a spoilboard must be sourced separately.
The MK2.5 builds on the LongMill MK2 CNC with two substantive upgrades. The SuperLongBoard controller, previously available as an optional upgrade, is now standard on every machine. Spring-loaded anti-backlash nuts replace the manual adjustment design of the MK2, delivering self-correcting precision on all axes. These are not cosmetic updates. The MK2 itself was already 2 to 3 times stronger than the original MK1 design at the same cost. The MK2.5 continues that trajectory with a modest price increase.
Sienci Labs co-founders Chris Halek and Andy Lee started with the Mill One CNC in 2016, launched the LongMill on Kickstarter in 2019, and have shipped machines continuously since. The 30x30 model started at CA$950 and by the MK2 was still only $1,350 USD, reflecting Sienci's stated goal of maintaining accessible pricing through iterative improvement rather than feature-driven price escalation.
What Can the LongMill Benchtop CNC MK2.5 Actually Do?
Wood is where the LongMill CNC lives. Any species of hardwood or softwood, MDF, plywood, and sheet goods are the everyday material for most users. Signs, engravings, joinery, guitar bodies, furniture components, and 3D relief carving are all within scope at cutting speeds up to 150 inches per minute, which Sienci describes as industry-leading at the hobby level. The 30x30 covers most individual workshop projects. The 48x30 handles cabinet panels and larger flat work without repositioning material.
Foam, plastics, acrylics, and machinable waxes are well within range. Acrylic cuts cleanly with the right bit and feed rate. Foam is commonly used for model making and casting patterns. For makers who work across non-metal materials in a single session, the LongMill handles the full range a home workshop typically encounters.
Aluminum and brass are possible. Sienci is direct about what that means: the machine can cut soft metals, but it takes time and requires conservative settings. The LongMill MK2.5 is not built for metal as a primary use case. For occasional aluminum plates or small brass components, it is capable. For anyone whose work is primarily metal, a more specialized machine is worth the additional cost.
Sienci describes the LongMill's market position the way a printer manufacturer might describe a home inkjet: capable of most things an individual would want to do at home, without trying to become an industrial press. The range of projects documented by the LongMill community confirms it: charcuterie boards, birdhouses, guitars, signs, furniture, toys. It handles a maker's or woodworker's project list thoroughly. It is not trying to replace a production CNC, and the design reflects that clarity of purpose.
LongMill Benchtop CNC MK2.5 Key Features and Specs: SuperLongBoard, Anti-Backlash, Software, and Working Area
LongMill Benchtop CNC Frame and Motion System: Rails, Gantries, and Lead Screws
The LongMill MK2.5 frame uses large extruded aluminum rails on the X and Y axes, fully supported Y-axis rails, and 1/4" steel gantries across all three axes. The Z-axis uses MG-12 type linear guides. Motion runs through lead screws driven by NEMA 23 motors, paired with spring-loaded anti-backlash nuts that self-adjust without manual intervention.
Lead screws are chosen over ball screws for lower maintenance requirements in dusty workshop environments. The spring-loaded system provides the zero-backlash precision typically associated with more expensive drive configurations, while retaining the low-maintenance advantage of lead screws. Previous LongMill generations used an OpenBuilds-based design requiring periodic manual adjustment. The MK2.5 eliminates that step.
LongMill MK2.5 SuperLongBoard: What the New Controller Adds
The SuperLongBoard (SLB) is standard on all LongMill Benchtop CNC MK2.5 machines. Anti-resonant motor drivers reduce noise and vibration, high-grade EMI protection reduces the risk of interrupted cuts, and Ethernet connectivity joins USB as a connection option. For users who want to expand their machine, the SLB supports RS485 VFD spindles, 4th axis cutting, and tool length sensor input.
The SLB is also the controller architecture Sienci uses on their higher-end AltMill CNC, meaning firmware development and feature updates benefit LongMill MK2.5 users alongside the broader Sienci ecosystem.
LongMill CNC Software: gSender, CAM Compatibility, and Assembly Manual
Every LongMill ships with gSender, Sienci's free CNC control software for Windows, Mac, and Linux. Built-in tools cover surfacing, calibration, and start-from-line, reducing reliance on third-party utilities for common tasks. The machine accepts standard G-code and is compatible with Fusion 360, VCarve, Carbide Create, Easel, and any other CAM software that exports standard G-code. Sienci's cloud-based CAMLab generates G-code directly from STL files for users who prefer a fully integrated workflow.
The LongMill Benchtop CNC MK2.5 assembly manual is available on the Sienci website alongside tutorial videos and webinar recordings. Sienci updated the assembly documentation with the MK2.5 release. For new users, the forum and Facebook community provide practical guidance on first setup, calibration, and early project work.
LongMill Benchtop CNC MK2.5 Specs: Sizes, Working Area, and Z-Axis Travel
The LongMill MK2.5 is available in three configurations. The 12x30 suits small workshops or limited bench space. The 30x30 is the most common choice for general woodworking. The 48x30 provides a 50x34 inch working area for full cabinet panels and larger flat projects. Z-axis travel is 4.5 inches on 12x30 and 30x30 configurations and 4.9 inches on the 48x30.
The machine mounts directly to a spoilboard or flat surface rather than a dedicated steel frame, keeping the footprint compact and allowing flexible integration with existing bench setups. Clamps and custom jigs can be integrated directly into the spoilboard. Maximum cutting depth on the Z-axis is 4.5 inches, and the machine accepts any CAM software that outputs standard G-code (.gcode, .nc).
LongMill Benchtop CNC MK2.5 Price and Configurations: Machine, Beginners Kit, and What's Not Included
The LongMill Benchtop CNC MK2.5 machine starts at $1,500 USD and reaches $2,150 USD for the 48x30, with current pricing reflecting a reduction that Sienci describes as while quantities last. The machine includes the CNC hardware, SuperLongBoard controller, and gSender software. A router and a spoilboard must be purchased before the machine can cut. Sienci recommends the AutoSpin T1 or Makita RT0701 for the router; both fit the included 65mm mount.
The Beginners Kit at $1,970 to $2,500 USD bundles the machine with a router (AutoSpin T1 or Makita RT0701C), AutoZero Touch Plate, Starter End Mill Set, and Magnetic Dust Shoe, saving approximately $110 USD versus buying items individually. For first-time buyers, the Beginners Kit removes the accessory guesswork and ships as a more streamlined order. Sienci notes a lead time applies to all orders, with current timelines listed on their site. US buyers ship via UPS only, and the LongMill qualifies under USMCA, exempt from the 35% tariff on Canadian goods. Ontario, Canada customers should verify availability due to a planned sales pause for ESA compliance.
Should You Buy the LongMill Benchtop CNC MK2.5?
The LongMill Benchtop CNC MK2.5 is the right machine for a very common buyer profile: woodworkers, makers, and hobbyists who want to move from hand tools to digital fabrication without industrial budgets or industrial footprints. At $1,500 for a rigidly built kit with a capable controller and free software, it is genuinely hard to argue against for that buyer.
324 backers put CA$436,197 behind the original LongMill on Kickstarter in 2019, and Sienci Labs has shipped thousands of machines since, improving each generation based on real user feedback. The 4.80 out of 5 rating from 475 customer reviews reflects a product that consistently delivers for its intended use. The MK2.5's upgrades are the result of that feedback loop, not features added to justify a new model number.
The 30x30 is the recommended starting point for most buyers, covering the full range of wood, plastic, and occasional soft metal work that fills a home workshop. The 48x30 is worth the additional cost if working area is a regular constraint. Both are available as machine-only (from $1,500) or as the Beginners Kit (from $1,970), which saves $110 and arrives with everything needed to start cutting. The LongMill Benchtop CNC MK2.5 ships from Sienci Labs.
FAQ About LongMill MK2.5 Kit
What is the LongMill Benchtop CNC MK2.5?
The LongMill Benchtop CNC MK2.5 is a hobby-grade benchtop CNC router from Sienci Labs available in three sizes (12x30, 30x30, 48x30 inches). It cuts wood, plastic, foam, and soft metals at speeds up to 150 IPM, ships with the SuperLongBoard controller and gSender software, and starts at $1,500 USD. Router and spoilboard are not included.
What is the difference between the LongMill MK2 and MK2.5?
The MK2.5 adds two substantive upgrades: the SuperLongBoard controller is now standard (previously optional), and spring-loaded anti-backlash nuts replace the manual adjustment system on all axes. The SLB adds faster movement, anti-resonant drivers, EMI protection, Ethernet connectivity, and 4th axis support. The price increase from MK2 to MK2.5 was approximately $110 USD.
What can the LongMill Benchtop CNC MK2.5 cut?
The LongMill MK2.5 is designed primarily for wood but also cuts foam, plastic, acrylic, and soft metals including aluminum and brass. Soft metal cutting is possible but slow, per Sienci's own specifications. The machine is not suited for hard metals or production-speed metal work.
Is there a LongMill MK3?
Sienci Labs has not announced a LongMill MK3 at the time of this review. The current generation is the LongMill Benchtop CNC MK2.5, released in 2024. Sienci has a track record of iterating when meaningful improvements are ready, as the progression from MK1 through MK2.5 shows, so future updates are plausible but unconfirmed.
Where can I find the LongMill Benchtop CNC MK2.5 manual?
The LongMill Benchtop CNC MK2.5 assembly manual is available on the Sienci Labs website at sienci.com, updated for the MK2.5 release. Sienci also provides tutorial videos, webinar recordings, and a community forum for setup guidance, calibration, and first-use troubleshooting.
Where can I buy the LongMill Benchtop CNC MK2.5?
The LongMill Benchtop CNC MK2.5 is available directly from Sienci Labs. A lead time applies; current timelines are listed on the Sienci website. US customers ship via UPS only. Ontario, Canada customers should check current availability. The LongMill qualifies under USMCA and is not subject to the 35% tariff on Canadian goods.
About the Author
Michael Green
Chief Editor at GizmoCrowd
Michael has been tracking tech and innovation campaigns on Kickstarter and Indiegogo for over 10 years, covering wearables, health tech, smart home devices, and audio-visual equipment.
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