FingerTech Nightwing 3lb Undercutter Assembly
FingerTech NightWing Undercutter Weapon Assembly
The FingerTech NightWing undercutter is the same battle-tested weapon system at the heart of the NightWing 3lb kit — now available on its own. FingerTech refined this assembly over years of competition, and it’s proven itself extremely robust without breaking the bank. It’s built around a 3/4″ weapon shaft, high-performance roller bearing, and a custom 42T threaded-bore pulley — everything you need to drop a devastating spinning weapon into any 3lb horizontal or vertical build. Disc not included.
$56.99
3 in stock (can be backordered)
FingerTech NightWing Undercutter Weapon Assembly
The FingerTech NightWing undercutter is the complete weapon assembly mechanical stack from FingerTech’s renowned NightWing 3lb kit — sold separately so you maintain your bot, or so you can drop a proven, competition-ready spinning weapon into any 3lb build. Whether you’re building a NightWing from scratch, designing your own custom undercutter chassis, or replacing a damaged weapon system, this assembly kit gives you everything you need to get spinning (electronics and blade not included).
A Weapon System Refined in Combat
FingerTech has refined this undercutter weapon system over years of competitive combat. The 3/4″ weapon shaft is supported by an SCE128 high-performance roller bearing that dissipates impact forces over a large area, keeping the weapon spinning reliably hit after hit. A flanged bearing at the opposite end of the shaft completes the support stack. The result is a weapon system that’s extremely robust without being overbuilt or overpriced.
How It Works
A Grade 8 hex bolt transmits torque and clamps the entire weapon stack together through a threaded bore in the custom 42T timing pulley. The pulley is custom-made for this assembly with a 5/16-24 threaded bore — it’s not a standard pulley swap. Note that the standard FingerTech 42T pulley will not work in this application! UHMW spacers and a bearing block keep everything aligned and absorb shock, while a lasered steel hex star and aluminum disc hub provide a solid, repeatable mount for your weapon disc.
What’s Included
- SCE128 high-performance roller bearing
- FR1810zz 5/16″ flanged bearing
- Custom 42T-5/16-24 threaded-bore pulley
- Lasered steel hex star + aluminum disc hub
- Aluminum tube spacer, UHMW thick + thin spacers
- UHMW bearing block + four #6×0.75in thread-forming mounting screws
- 5/16 x 2.00in Grade 8 hex bolt + flat washer
- Four 6-32 x 3/8in button head screws
- 5/64in hex key
Total assembly weight: 133g (4.69oz). Weapon disc and electronics not included.
Disc Options
This assembly is designed to pair with a 10in weapon disc. The FingerTech NightWing AR500 Weapon Disc is the standard pairing — AR500 steel for maximum momentum and big hits. On a 3S LiPo this weapon supports up to 8,000 RPM, delivering a tip speed of 240mph. It can also run on 4S if you’re using a smaller diameter disc for faster spin-up and more control.
Custom Chassis Builders
Want to design your own undercutter around this weapon stack? Use 3.18mm (1/8in) top and bottom plates with 30.35mm (1-3/16in) tall walls, and space the motor axis 46.13mm (1.82in) from the weapon axis. Pairs with the FingerTech 3lb Undercutter Electronics set for a complete drivetrain and weapon power solution.
Safety Warning:
Spinning weapons generate extreme kinetic energy. Always engage a weapon lock and test only within a secure arena or test box. Never operate a spinning weapon in an unsecured area.
Features
- Battle-tested FingerTech NightWing undercutter — the same weapon stack from the NightWing 3lb kit
- SCE128 high-performance roller bearing — dissipates impact forces over a large area for hit-after-hit reliability
- Custom 42T-5/16-24 threaded-bore pulley — torque-locking bolt clamps the entire weapon stack together
- Supports up to 8,000 RPM on 3S — 240mph tip speed with a 10in disc (your weapon performance may vary)
- Works in any 3lb horizontal or vertical spinner — not just the NightWing chassis
- 5/64in hex key included — everything you need to assemble right out of the box
Specifications
| Specification | Detail |
|---|---|
| Weight | 4.69oz (133g) |
| Weapon Shaft Diameter | 3/4in (19.05mm) |
| Shaft Tube Length | 1.21in (30.81mm) |
| Main Bearing | SCE128 — 3/4in bore, 1.00in OD, 1/2in width |
| Flanged Bearing | FR1810zz — 5/16in bore |
| Pulley | 42T, 5/16-24 threaded bore (custom — not standard 42T) |
| Bolt | 5/16 × 2.00in Grade 8 hex bolt |
| Mounting Screws (bearing block) | 4× Phillips #6×0.75in thread-forming |
| Assembly Screws | 4× 6-32 × 3/8in button head |
| Tool Required | 5/64in hex key (included) |
Frequently Asked Questions
Can I use this assembly in a custom 3lb build — not just the NightWing?
Absolutely. While this is the weapon stack from the NightWing kit, it's designed to work in any 3lb horizontal or vertical spinner. If you're building a custom chassis, use 3.18mm (1/8in) top and bottom plates with 30.35mm (1-3/16in) tall walls, and space the motor axis 46.13mm (1.82in) from the weapon axis. The assembly handles the rest.
Can I use the standard FingerTech 42T pulley with this assembly?
No — and this is important. The pulley in this assembly is a custom 42T-5/16-24 with a threaded bore specifically made for the undercutter weapon shaft. The standard FingerTech 42T timing pulley has a 3mm bore and will not work here. Do not substitute the standard FingerTech 42T pulley in this assembly — it is not compatible and the weapon stack will not function correctly.
What electronics do I need to power this weapon system?
This assembly is the mechanical weapon stack only — electronics are not included. It's designed to pair with the FingerTech 3lb Undercutter Electronics set, which includes the F4006 weapon motor, ESC, and supporting components. If you're building a complete NightWing, the full electronics set is the recommended pairing.
What disc works with this assembly?
This assembly is designed for a 10in weapon disc. The standard pairing is the FingerTech NightWing AR500 Weapon Disc — cut from the same AR500 steel used in 250lb BattleBots™ weapons. A smaller diameter disc can be used on 4S for faster spin-up and more control.
Where can I find assembly instructions?
Full assembly instructions are available in the FingerTech NightWing Kit Instructions (PDF) on the ItGresa site. The undercutter assembly process is covered in detail there.
