Festool FSK Cross-Cutting Rail System

The FSK rail system transforms your Festool circular saw into a portable cross-cutting station that rivals a miter saw for accuracy. The key is angular flexibility — cuts from -60° to +60° instead of being locked at 90°. This produces a portable and easy-to-use compound mitre saw system for accurate and precisely angled cutting.

Skip it if you own a TS 55 or TS 75. The system is specifically designed for Festool HK series carpentry saws and won’t work with standard TS/TSC plunge saws. The incompatibility isn’t a minor inconvenience — it’s a complete non-starter for most Festool track saw owners.

FSK Rail System Integration

The quick-fastener mechanism allows the rail and saw to function as a single unit. This isn’t just convenient — it’s the whole point. The built-in rubber spring automatically retracts the saw to the starting position after each cut is completed. No manual resetting between cuts.

The FSK 670 provides 26-3/8” cutting capacity — enough for most sheet goods and dimensional lumber. The quick-action screw clamp (4-11/16”) secures workpieces to the rail. Features include a splinter guard for splinter-free cuts and an adhesive cushion strip that protects the workpiece surface from being damaged.

Three lengths available: 250 mm, 420 mm or 670 mm. The 670 gets the most use for cabinet doors and wider panels. Some users find the length of the 670 bulky for small stock but essential for wider panels.

Specification	FSK 670 Value
Cutting Length Capacity	26-3/8” (670 mm)
Weight	3.59 lbs (1.63 kg)
Angular Range	-60° to +60°
Clamp Opening	4-11/16”

Compatibility and Angular Cutting

The compatibility list is short and specific. Compatible models: HK 55, HKC 55, HK 85, TS 60 K, TSV 60 K. That’s it. Not compatible with TS 55, TSC 55, TS 75, or non-Festool circular saws.

The angular cutting capability sets this apart from basic guide rail squares. The Woodpeckers Guide Rail Square offers a fixed 90-degree reference and does not offer the full -60 to +60 degree range of the FSK. The adjustable stop with scale enables repeatable angled cuts — critical for trim work where you’re cutting multiple pieces at the same angle.

Users in professional forums (Festool Owners Group) praise the FSK 670 for its ‘speed of setup’ and ‘accuracy for repeated cross-cuts’. It is often cited as a more portable alternative to a miter saw for on-site work. For finish carpenters working in occupied homes or upper floors where hauling a miter saw isn’t practical, the FSK/HK combo makes sense.

Standard rails (FS 1400, etc.) are better for long rips but lack the dedicated cross-cutting speed and attachment of the FSK. You’re not choosing between them — they serve different functions. Most contractors who invest in the FSK system still own standard guide rails for ripping.

Frequently Asked Questions

Can the FSK rails be used with the TS 55 track saw? No. The FSK system is specifically designed for Festool HK series carpentry saws and is not compatible with standard TS/TSC plunge saws. The quick-fastener mechanism only works with HK-series saws.

What’s included with the FSK 670? The package includes the FSK 670 Cross-Cutting Guide Rail, FSZ 120 Screw clamp (4-11/16”), and protective end caps. Saw sold separately.

How does the automatic return work? The built-in rubber spring automatically retracts the saw to the starting position after each cut is completed. Push through the cut, release, and the saw returns to start position for the next cut.

Is the FSK system covered under Festool’s warranty? Yes, it includes Festool’s All-Inclusive Warranty for 3 Years, which covers wear-and-tear and accidental damage with registration required. Additional benefits include 10-year spare part availability and a 30-day money-back guarantee.