Fret Slotting Mitrebox

This is a 3d printable slotting mitre box designed for cutting fret slots for stringed instruments by using an indexable template.

See separate listing for 25.5" and 24.75" Templates, these have been modified for use with a drilling template - that will align the fretboard with the slotting jig.

This design has a feature that most commercial mitre boxes to not - it can cut angled slots - for multiscale fret boards etc.. Its experimental right now but will be documented in the near future, if any commercial makers want to know how it works - get in touch. For now this is a solid slotting mitre box at a finished cost of less than half the price of commercial examples.

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NEW *** Make your own custom templates ***

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Version 2.0 - Redrawn  12/2025 - insert holes are now Ø8.1 X 13 deep, sized to suit more common M6 inserts. Treat this one as a work in progress as I have not actually made one of this iteration but many people are having issues finding the correct inserts,  Version 1 files still available if you have the original inserts. The only inserts that require to be shorter than the common 12.7 long ones are the roller holders and you can either source shorter 9.5mm or 8mm inserts for these or file down the longer ones.

V2.01 - Revised The Screw Lengths - New non printed parts  BOM

• 1M2X10 Cap Head Screw

• 28M6 x 12.7mm Heat-Set Insert

• 8M6 x 9.5mm Heat-Set Insert

• 1M2 x 4mm Heat-Set Insert

• 2M6X50 Hex Head Screw Full Thread

• 8M6X14 Button Head Hex Drive Screw

• 12M6X20 Button Head Hex Drive Screw

• 8M6X16 Button Head Hex Drive Screw

• 8626ZZ Bearing 

Should now work with CNC Kitchen inserts and those available from McMaster-Carr amongst others, for example. See inserts.txt for links.

• https://www.accu.co.uk/brass-threaded-inserts/849042-HTBTEI-M6-BR

• https://www.amazon.co.uk/HANGLIFE-Threaded-Inserts-Printing-Components/dp/B0CS6YCWHD

• https://cnckitchen.store/products/heat-set-insert-m6-x-12-7-20-pieces

• https://www.mcmaster.com/products/inserts/threaded-insert-type~heat-set/system-of-measurement~metric/

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Version 1.04 - now with STEP files so you can make your own modifications. It has been noted that the inserts I originally specified may not be easily available so the STEP files will allow you to dimension the holes to suit any insert.

Full instructions are contained in the pdf attachment.

Bill Of Materials
3d printed parts, Approx. 400g material required, Print Time 14Hr.
• Base, Qty 1 225mm Long
• Side Plate, Qty 2
• Side Mirror, Qty 2
• Roller Holder, Qty 4
• Roller Holder Clip, Qty4
• Side Plate Clip, Qty4
• Clamp (Optional Experimental for angle cutting, Qty 2)
• Clamp Fixed (Optional, Qty 2)
• Clamp Face, Qty 2

•  Base Shorter (215mm)  V1 - Qty 1 Req (alternate for smaller printers)

All Printed parts can be made from PLA its stiffness is a benefit.
Sundries - Approx. Cost £20-27
Screws

• M6 X 14 Button Head Hex Screw, Qty 8
• M6 X 16 Button Head Hex Screw, Qty 8
• M6 X 20 Button Head Hex Screw, Qty 12
• M6 X 60 Button head Hex Screw, Qty 2
• M2 X 20 Cap Head Socket Screw, Qty 2
Other screw types of the right length can be used.
Inserts
• M6 Brass Push In Flanged Insert, Qty 34 – See Drawing for dimensions, source these from ebay or amazon
example 1
example 2
• M2 Brass Push in Insert, Qty2 (Option Qty 4) – Expected OD Ø3.6
example

Bearings
• 626ZZ Roller Bearings, Qty 8

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3D PRINTING SETTINGS

Print from PLA or other stiff material - default settings work but ensure minimum 3 perimeters.

The mitre box is 75mm wide but you can increase this width using the scale command in your slicer if you require a wider box a scale factor of 130% will give a width of 85mm. This will work fine with parallel fret templates as well.