Floors, walls, ceilings, doors, furniture, roof battens—interior finishing all in one case. The KSS 40 is the smallest and lightest miter track saw in the lineup: 3.6 kg with track and battery, operable with one hand, and it serves five functions—miter saw on the guide system, plunge saw, shadow gap saw, freehand circular saw, and guided saw on the rollable FLEXI track for cuts up to 1.4 m.
The shadow gap is its specialty: for joint widths of 13 mm and up—the flooring and drywall detail that no other saw in this class can handle cleanly. It cuts 40 mm on the guide rail and 42 mm freehand, and runs on the CAS battery system: one battery for Mafell, Metabo, Lamello, and Prebena; it is not compatible with Festool or Bosch. When sawing without a guide rail, the included rip fence should be attached for safety reasons, according to the operating instructions—we’re telling you this before you have to look for it in the fine print.
Buying the Mafell saw at RUWI isn’t a given: We’re manufacturers ourselves—tools for woodworking professionals from Fluorn-Winzeln, 4 kilometers from the Mafell factory in Oberndorf am Neckar. We carry only what we can recommend from our own experience—and below, we’ll honestly list the two areas where the “bigger sister” outperforms it.
Here's how to use it
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Cut on site: flooring, panels, trim, and battens—3.6 kg, can be operated with one hand.
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Cutting shadow joints: for joint widths of 13 mm or more, directly against the wall.
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Cutting long lengths: up to 1.4 m on the FLEXI track with casters—even in the middle of the room.
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Work cordless: 18-V CAS battery—in the warehouse, on a ladder, without a cord reel.
Does this fit in your workshop?
40 mm is the cutoff: 45 mm frame wood is a job for the KSS 50 18M bl; anything up to 61 mm on the rail is for the KSS 60 18M bl. And the clear distinction from the 50 series: The KSS 40 runs at a fixed speed, and you pull it back by hand after the cut—speed settings for the material and the automatic retraction feature start one class higher. The KSS 300 is the same 40-mm class model but with a power cord.
You can read about why your vacuum should be Dust Class M in the knowledge article on wood dust extraction —and the Machine Advisor will help you find the right saw by asking you two or three questions.
All the details
Function and Application
Design: Cordless miter rail saw – the lightweight interior finishing saw, 3.6 kg system with rail
Special Feature: Shadow gaps starting at 13 mm; FLEXI rail FX 140 with a guided cutting length of 1.4 m included
Battery system
Drive: 18 V DC, brushless
System: CAS (Cordless Alliance System), batteries compatible with Metabo, Lamello, and Prebena
Included in the set: 2 × PowerTank 18 M 99 LiHD and APS M battery power station
Performance and cutting data
Speed: 6,700 min⁻¹, fixed
Cutting depth at 0°: 40 mm on the miter rail, 42 mm free
Cutting depth at 45°: 27 mm on the miter rail, 29 mm free
Cutting length: 337 / 292 mm (for workpiece thicknesses of 12 / 40 mm)
Mitre angle on the guide rail: −60° to +45°
Saw blade: Ø 120 × 20 mm
Split wedge: 1.2 mm, swivels away automatically during plunge cuts
Brake: electric
Dimensions and weight
Weight: 2.8 kg with battery, 3.6 kg as a system with guide rail
Dimensions with guide device: 200 × 580 × 200 mm
Guide and system
Guide device: S, included
Electronics: Overload and jam shut-off, electrostatic protection shut-off, start-up lock
Dust extraction
Connection: Ø 28 mm
Chip bag: included
Safety and quality
Origin: Manufactured in Oberndorf am Neckar
Warranty: MAFELL-Complete, 36 months after registration
Spare parts: 10 years from the end of production (Mafell commitment)
