IGM M138 is a rounding-over router bit with 2 carbide cutting edges (HW) and an integrated guide bearing for rounding sharp edges on solid wood, MDF, laminate, plastic and artificial stone. It is available in 9 versions with radii from 1 to 16 mm. For use on handheld routers only. Distributed in Italy by Krollit, official IGM distributor since 2007.
- Available radii: 1, 2, 3, 6.3, 8, 9.5, 12, 16 mm
- Cutting diameter: from 11.5 mm (R1) to 44.7 mm (R16)
- Cutting height: from 9.5 mm (R1–R3) to 22 mm (R16)
- Shank: 6 mm (R2 and R3 versions) or 8 mm (all other versions)
- Guide bearing: included in all versions, positioned at the tip
- Cutting edge material: micro-grain HW carbide, hardness 93.5 HRA, thickness 2 mm
- Red PTFE Teflon coating: protection against corrosion, resin and burn marks
- Anti-kickback technology compliant with EN 847
- Laser-marked shank with parameters and “K” point for optimal positioning in the collet
- Exclusive use: handheld routers
Who uses the M138 and what it is used for
The IGM M138 router bit is used by carpenters, furniture manufacturers and edge-banding installers to round sharp edges on panels, worktops, doors and frames. Small radii (R1, R2, R3) are chosen for finishing ABS edging on kitchen doors and furniture, where the sharp edge left by the automatic edge bander needs to be softened with a minimal radius. Medium radii (R6.3, R8, R9.5) are the most commonly used for decorative edges on solid wood and MDF worktops. Large radii (R12, R16) produce wide decorative profiles on frames, panels and artificial stone surfaces. The bearing at the tip guides the bit along the edge of the workpiece, ensuring uniform material removal along the entire length.
Who the M138 is suitable for
| Profile |
Compatibility |
Reason |
| Carpenter and custom furniture manufacturer |
Suitable |
9 radii cover everything from ABS edge finishing (R1–R3) to decorative profiles on solid wood (R8–R16) |
| Craftsman working on worktops, frames and decorative panels |
Suitable |
The bearing at the tip ensures precise guidance and uniform removal on long, straight edges |
| Operator using a CNC router table |
Not suitable |
The M138 is designed exclusively for portable handheld routers |
Not suitable for: rounding internal edges and inside corners, where the bearing cannot follow the profile — in these cases, use router bits without bearing with a guide bushing or template.
IGM technology and build quality
The micro-grain carbide cutting edges are brazed and sharpened on 5-axis CNC centers with automatic balancing. Hardness is 93.5 HRA, thickness 2 mm with a minimum of 1 mm for reduced-diameter versions. The increased thickness allows multiple resharpening cycles. The red PTFE Teflon coating reduces friction and protects against resins and adhesives. Each router bit passes an automated quality control. The anti-kickback technology complies with the European EN 847 standard.
Technical specifications — all variants
| Version |
Radius R (mm) |
Shank S (mm) |
Diameter D (mm) |
Length L (mm) |
Cutting height I (mm) |
Ø Bearing B (mm) |
| M138 R1 D11.5x9.5 L59 | 1 | 8 | 11.5 | 59 | 9.5 | 9.5 |
| M138 R2 D17.34x9.5 L61 | 2 | 6 | 17.34 | 61 | 9.5 | 12.7 |
| M138 R2 D17.34x9.5 L61 | 2 | 8 | 17.34 | 61 | 9.5 | 12.7 |
| M138 R3 D19.15x9.5 L61 | 3 | 6 | 19.15 | 61 | 9.5 | 12.7 |
| M138 R3 D19.15x9.5 L61 | 3 | 8 | 19.15 | 61 | 9.5 | 12.7 |
| M138 R6.3 D25.3x12.7 L64 | 6.3 | 8 | 25.3 | 64 | 12.7 | 12.7 |
| M138 R8 D28.7x12.7 L64 | 8 | 8 | 28.7 | 64 | 12.7 | 12.7 |
| M138 R9.5 D31.7x15.88 L68 | 9.5 | 8 | 31.7 | 68 | 15.88 | 12.7 |
| M138 R12 D36.7x19 L71 | 12 | 8 | 36.7 | 71 | 19 | 12.7 |
| M138 R16 D44.7x22 L74 | 16 | 8 | 44.7 | 74 | 22 | 12.7 |
Common specifications for all versions
| Number of cutting edges (Z) | 2 |
| Geometry | Straight cutting edge |
| Rotation | Clockwise, right-hand rotation |
| Cutting edge material | Micro-grain HW carbide |
| Cutting edge hardness | 93.5 HRA |
| Cutting edge thickness | 2 mm |
| Coating | Red PTFE Teflon |
| Anti-kickback | Yes, compliant with EN 847 |
| Guide bearing | Included, positioned at the tip |
| Shank marking | Laser: code, D, I, S, max RPM, K point |
| Packaging | Resealable case with specification label |
| Workable materials | Softwood and hardwood, plywood, DTD, MDF, laminate, plastic, artificial stone |
| Use | Handheld routers only |
Frequently Asked Questions
Which radius should I choose for finishing ABS edging on kitchen doors?
For finishing the sharp edge left by the automatic edge bander on ABS edging, the smallest radii are used: R1 mm for a barely noticeable rounding and R2 mm for a slightly softer profile. R3 mm is the maximum recommended radius on standard 1–2 mm ABS edging without risking cutting into the underlying panel.
What is the difference between the 6 mm and 8 mm shank versions?
The R2 and R3 versions are available with both shank sizes. The 6 mm shank is compatible with light and compact handheld routers with a 6 mm collet. The 8 mm shank offers greater rigidity and is preferred on medium- and high-power routers. All other versions are available only with an 8 mm shank.
Is the bearing positioned at the tip or on the shank?
In the M138 series, the bearing is positioned at the tip, below the cutting edges. This position allows the bit to be guided along the lower edge of the workpiece, with the bearing resting on the panel face or on the already trimmed edge. To work with fixed templates above the workpiece, a router bit with a bearing on the shank is required, such as the M107 series.
Does the bit also work on artificial stone and plastic?
Yes. The micro-grain HW cutting edges with PTFE Teflon coating are compatible with plastic and artificial stone, such as Corian and similar materials. PTFE reduces material build-up on the cutting edges when machining synthetic surfaces. For artificial stone, a lower speed than for wood and light passes are recommended to preserve the cutting edges.
Can the router bit be resharpened?
Yes. The HW cutting edges are 2 mm thick, sufficient for multiple resharpening cycles. For reduced-diameter versions (R1), the minimum thickness is 1 mm. Resharpening is recommended at a specialized center to maintain the correct rounded profile and original balance.
What are the recommended maximum RPM values for larger-diameter versions?
The maximum RPM values are specific to each version and are laser-marked on the shank. Larger-diameter versions (R12 D36.7 mm and R16 D44.7 mm) require lower RPM than smaller versions to maintain the correct peripheral cutting speed. Always check the marking on the shank before use.
