Round Corner Templates in a Full Range of Radius Sizes

I designed an extensive set of round-corner templates for woodworking. They can either be used to mark corners with a pencil or as a template with a flush-trim bit. There is a wide range of radius sizes from 5mm up to 200mm and 0.5" to 8", all carefully optimized for best usage.

Update 2023-03-02: Added snap-in guides for the imperial unit guides.

About the Design

I designed all templates from the ground up, specifically to be printed on a 3D printer. The design is optimized to use all the strengths of this manufacturing method.

The templates have a height of 12mm (or 0.5"), to give a flush-trim bit a good surface area. Well-placed ribs give the template the required stability for an exact cut.

Plenty of slots and holes to fasten the template with woodscrews on the workpiece. All holes and slots have a diameter of 4mm and are designed to be used with 3mm or 3.5mm screws with a flat head.

If you use the slots, there is plenty of room for adjustments to place the template flush at the edge of your workpiece. The holes directly at the radius will provide the best stability.

The hexagonal hole in the side of the radius has an inner diameter of 6mm and is meant for extensions that can be aligned using a dowel or bolt of that diameter.

There are guides to attach to these extension holes (see “The Snap-in Guide Attachments”) to align the templates at the corner of the workpiece without screws.

The Centre Mark

Most larger templates have a centre mark with a cross, and line marks up to the endpoints of the radius.

If you draw two straight lines to the centre of the corner radius, it is easy to use the marks to verify the correct dimensions and location of the template.

Dimensions and Sizes

There is a wide range of metric corner sizes. You will find all available measurements in the following drawing:

I also created an alternative set of templates for US people working with imperial units. Not only the corner radius is in inches, but also most dimensions are adapted to this system. Only the screw and extension holes have regular 4mm and 6mm diameters.

You will find all available imperial sizes in the next diagram:

How to Print the Templates

If you use a Prusa Printer, there is an example project for PrusaSlicer ("LR2180-50 Print.3mf").

• Print the template with PLA (or PETG).
• Select 0.2mm layer height.
• Use the quality setting.
• Print with 3 perimeters for better rigidity (especially if you use PETG).
• The flat side of the model goes to the printer bed.
• Do not scale the model!

The Snap-in Guide Attachments

You can fasten the template to the workpiece with clamps or screws or print two guides you can attach to the templates.

The snap-in mechanism lets you quickly add and remove these guides to all templates. So you only have to print two you can use for all sizes.

How to Print the Snap-in Guides

The snap-in guides have tight tolerances (0.05) for a perfect fit. Therefore you have to print them as precisely as possible. If you use a Prusa Printer, there is an example project for PrusaSlicer ("LR2180-ST-M Print.3mf").

• Print the template with PLA (or PETG).
• Select 0.2mm layer height.
• Use the quality setting.
• Print with 3 perimeters for better rigidity (especially if you use PETG).
• The flat side of the model goes to the printer bed.
• Ensure there are no seams on the inner flat surfaces of the object!
• Do not scale the model!

You will find more details about my design on this page.

If you like the models, please rate them and comment below.

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