--- title: 4mm x 15mm Up-Spiral Flat Router Bit description: Despite its small diameter, the 4mm x 15mm Up-Spiral Flat bit is able to cut up to 30 mm depth. Two sharp cutting edges offer several advantages in a wide range of materials, from foam to hardwood. Th --- [Skip to content](https://support.shapertools.com/hc/en-us/articles/14091261517339-4mm-x-15mm-up-spiral-flat-router-bit#main-content) - [English](https://support.shapertools.com/hc/en-us/articles/14091261517339-4mm-x-15mm-up-spiral-flat-router-bit) - [Deutsch](https://support.shapertools.com/de/hc/de-de/articles/14091261517339-4-mm-x-15-mm-spiralnutfräser-zweischneidig) - [Français](https://support.shapertools.com/fr/hc/fr-fr/articles/14091261517339-4-mm-x-15-mm-fraises-à-rainurer-hélicoïdales-à-deux-tranchants) English Show submenu for translations [Contact us](https://support.shapertools.com/kb-tickets/new?hsLang=en) ![Shaper-KB-Logo.svg\]](https://support.shapertools.com/hubfs/Shaper-KB-Logo.svg) Open main navigation Close main navigation - - [English](https://support.shapertools.com/hc/en-us/articles/14091261517339-4mm-x-15mm-up-spiral-flat-router-bit) - [Deutsch](https://support.shapertools.com/de/hc/de-de/articles/14091261517339-4-mm-x-15-mm-spiralnutfräser-zweischneidig) - [Français](https://support.shapertools.com/fr/hc/fr-fr/articles/14091261517339-4-mm-x-15-mm-fraises-à-rainurer-hélicoïdales-à-deux-tranchants) English Show submenu for translations - [Contact us](https://support.shapertools.com/kb-tickets/new) - [Go to shapertools.com](https://www.shapertools.com/) [Go to shapertools.com](https://www.shapertools.com/) Shaper Support - There are no suggestions because the search field is empty. 1. [Help Center](https://support.shapertools.com/?hsLang=en) 2. [Accessories](https://support.shapertools.com/accessories?hsLang=en) 3. [Specialty Router Bits](https://support.shapertools.com/accessories?hsLang=en#specialty-router-bits) # 4mm x 15mm Up-Spiral Flat Router Bit Despite its small diameter, the [4mm x 15mm Up-Spiral Flat](https://www.shapertools.com/store/product/4-mm-x-15-mm-up-spiral-flat-router-bit) bit is able to cut up to 30 mm depth. Two sharp cutting edges offer several advantages in a wide range of materials, from foam to hardwood. This bit is perfect for finish passes when a larger diameter is too big. Its two-edge geometry cuts fast and clean and can handle large feed rates compared to bits with similar diameters. This bit requires special attention to the points and table below, since it can break if used incorrectly. #### Notes - Cleaning from time to time will considerably increase the service life of this bit - Don‘t exceed a step size of 8mm per pass. This bit is not designed for deep rough cuts and may break if cut pressure is too great - The long edge combined with the small diameter can create a lot of downward pressure on the bit, so tightening the collet harder than normal may be necessary - Use small offsets when cutting with the grain, especially wood types with long fibers and large pores such as Oak or Ash. Cutting against the wood grain can cause chatter and significantly decreases the cut quality - The cross **×** in the table below indicate that a different router bit may be more suitable to prolong the life of the bit. - All values are in mm. Plunge and Auto Speed are in mm/min. | **Material** | **Pass Type** | **Depth/pass ** | **Plunge speed** | **Auto Speed** | **Spindle Speed** | | --- | --- | --- | --- | --- | --- | | Foam | Rough | 15 | 350 | 500 - 600 | 6 | | Acrylics | **×** | **×** | **×** | **×** | **×** | | Soft Plastics  | Rough | 8 | 350 | 450 - 600 | 6 | |   | Finish | - | 300 | 350 - 400 | 6 | | Solid Surface (e.g. Corian) | Rough | 4 | 250 | 250 - 350 | 6 | |   | Finish | - | 300 | 200 - 300 | 6 | | HPL | **×** | **×** | **×** | **×** | **×** | | MDF | Rough | 8 | 350 | 400 - 550 | 5 - 6 | |   | Finish | - | 300 | 300 - 500 | 6 | | Softwood, Plywood | Rough | 8 | 300 - 350 | 400 - 600 | 5 - 6 | |   | Finish | - | 300 | 300 - 500 | 6 | | Hardwood | Rough | 6 | 300 - 350 | 400 - 600  | 5 - 6 | |   | Finish | - | 250 - 300 | 300 - 500 | 6 | | Chipboard | **×** | **×** | **×** | **×** | **×** | | Non-Ferrous Metals | **×** | **×** | **×** | **×** | **×** |   - [Origin](https://support.shapertools.com/origin?hsLang=en#main-content) - 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