LongMill CNC Routers: MK3 30×30 vs 48×30
The current LongMill decision is centered on two MK3 sizes: 30×30 and 48×30. Both share the same lead-screw, linear-guide and closed-loop-motor architecture, so the main question is whether the extra X capacity justifies the larger table and setup footprint.
Sienci's September 1, 2026 update says MK3 assembly began in August and the company is preparing to ship the first production units in September. We therefore keep these records as current/backordered rather than pretending routine shelf availability already exists.
LongMill MK3 size comparison
The motion system stays consistent across the two sizes
Sienci publishes T12 lead screws and 15 mm profiled linear guide rails on X, Y and Z, with 1.2 Nm NEMA 23 closed-loop stepper motors. The current control system is the SLB-LITE running grblHAL. That means the 30×30 versus 48×30 decision is primarily about envelope and shop space rather than buying a different motion generation.
The base machine is not a complete cutting setup
Sienci explicitly says the MK3 includes pre-assembled rails, electronics, power supply, drivers and motors, but does not include the computer, router, bits or work surface. A buyer comparing LongMill with a machine that includes a router or spindle should therefore use a complete-system budget, not just the advertised machine price.
The Setup Cost Calculator can include those missing items plus dust collection, workholding and any spindle upgrade.
65 mm and 80 mm cutting systems are both supported
Sienci publishes support for both 65 mm and 80 mm routers/spindles and warns that an 80 mm spindle reduces available cutting area. That is exactly the type of compatibility detail that should be checked before buying a spindle purely on power rating.
Material support is broad, but not unlimited
The current MK3 specification page explicitly lists softwood, hardwood, plywood, MDF, acrylic, PVC, HDPE, polycarbonate, ABS, carbon fiber, Dibond/ACM, aluminum, brass, copper and foams. Those claims establish manufacturer-supported material categories; they do not establish one universal feed, depth or finish.
Can the 30×30 become a 48×30 later?
Sienci says it plans parts that can increase the X size of an MK3 30×30 to 48×30. That makes the initial size decision more flexible than machines with no supported size-upgrade path, but the larger configuration still needs the larger table and shop footprint.
Compare both LongMill MK3 records
Compare 30×30 and 48×30 side by side, or use the Matcher when Shapeoko, Onefinity and other current machines should compete for the same project.
Manufacturer sources
LongMill setup has strong software, workholding and probing paths
Use the Software Finder to separate CAD/CAM from gSender machine control, the Workholding selector for T-track/fixture choices, and the Touch Probe guide for Sienci AutoZero.
Frequently asked questions
What sizes does LongMill MK3 come in?
Sienci currently publishes LongMill MK3 30×30 and 48×30 configurations. Their cutting areas are approximately 32×32×5.1 inches and 49×32×5.1 inches.
Is LongMill MK3 currently shipping?
Sienci's September 1, 2026 production update says MK3 assembly began in August and the company is preparing to ship the first production wave in September. CNC Router Match keeps the current records in a backorder/pre-shipment state until routine availability is confirmed.
Does LongMill MK3 include a router?
No. Sienci explicitly lists a computer, router, bits and work surface among items not included with the base MK3. Those should be included in total setup planning.
Can LongMill MK3 use an 80 mm spindle?
Yes. Sienci publishes support for both 65 mm and 80 mm routers/spindles, while noting that an 80 mm spindle reduces the cutting area.
Can LongMill MK3 cut aluminum?
Sienci explicitly lists aluminum, brass and copper among supported non-ferrous materials, along with wood, plastics, composites and foam.