LMT Onsrud 52-360BL 1/2" Solid Carbide 2-Flute Upcut Ball Nose Router Bit – Extended Length, 1-1/2" Cut, 1/2" Shank, 5" OAL

The LMT Onsrud 52-360BL is the extended-length version of Onsrud's 1/2" solid carbide two-flute upcut ball nose. With a 1-1/2" cutting edge, a 3-5/8" neck, and a 5" overall length, it reaches into deep 3D carvings, mold cavities, signs, and model work that a standard 3" ball nose cannot touch without the collet nut hitting the part. The ball tip geometry is ground for carving and modeling, leaving a smooth scalloped surface on finishing passes, and the upcut spiral keeps chips clearing out of deep pockets instead of packing in behind the tool.

LMT Onsrud 52-360BL specifications

What the 52-360BL is designed to cut

• Hardwood and softwood 3D carvings, reliefs, and signage
• MDF, plywood, and other wood composites for molds, plugs, and patterns
• Hard and soft plastics, including HDPE, acrylic, and modeling board
• Aluminum at light engagement for 3D surfacing
• Foam and tooling board where deep reach is needed

When you need the extended-length version

A standard 1/2" ball nose (Onsrud 52-360B) has about 1-1/8" of cut and 3" of overall length. On a deep relief, a bowl, or a mold half, the collet nut arrives at the top surface before the tip reaches the bottom of the cavity. The 52-360BL's 3-5/8" neck gives you that extra reach while keeping a full 1/2" shank in the collet for rigidity. Run the roughing pass with a flat end mill and leave this tool for the semi-finish and finish passes; its extra length means you should keep stepovers and feeds conservative to avoid chatter.

Fitment

The 1/2" shank requires a 1/2" collet: ER20 (1/2" is the largest ER20 size), ER25, ER32, or a 1/2" collet on a handheld or table router. It will not fit ER11 or ER16 spindles.

Frequently asked questions

What stepover should I use for a smooth finish?
For a 1/2" ball nose, a 10% stepover (0.050") leaves a scallop height of roughly 0.001", which sands out easily. An 8% stepover is a common choice for paint-grade signs and molds.

Is this the same as the 52-360B?
No. The 52-360B is the standard 3" overall length version with a 1-1/8" cut. The 52-360BL adds reach with a longer neck and a 5" overall length.

Will it work in a 1/4"-collet trim router?
No. The shank is 1/2". Use a router or spindle with a 1/2" collet.

Genuine LMT Onsrud tooling, manufactured in Waukegan, Illinois, USA.