> For the complete documentation index, see [llms.txt](https://willadams.gitbook.io/design-into-3d/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://willadams.gitbook.io/design-into-3d/blind-miter-and-hidden-spline.md).

# Blind Miter & Hidden Spline

While modern adhesives are surprisingly able to allow one to simply cut and glue miters (esp. if one is willing to add a few nails), adding a hidden spline will create a much stronger joint (and one which has the added benefit of being self-aligning). 

## Drawing the Joint

The miter itself is of course simply a bisecting of the junction of the two boards:

![Basic Miter Joint (overhead view)](/files/-MOKMpicRgVEJtLuD3av)

In order to cut the miter and the void for the spline a V endmill which is narrower in diameter than the boards are in thickness will be necessary:

![Blind Miter Joint and profile of smaller V endmill](/files/-MOKNXP_I9JOcmRTOXan)

In order to leave a reasonable amount of material, the endmill should be used to cut so that it is positioned closer to the interior than the exterior of the box ― making the cuts for the spline equal in width to one-half the board thickness and positioning them one-eighth the board thickness in from the interior edge results in a reasonable arrangement which is easily calculated: 

![Blind Miter Joint with smaller V endmill positioned](/files/-MOKQ0yOoiNBqQDb58bm)

Which may then be drawn up:

![Blind Miter Joint and hidden spline profile](/files/-MOKQy_rxSq1nLpKtWFr)

Rotating the components and arranging them flat on the working area for cutting out shows them in profile as:

![Blind Miter Joint and hidden spline profile unfolded](/files/-MOKS2i6nZataefZnUo5)

## Modeling the Box

![Box with parameters/dimensions](/files/-MOMCJmcXm8iFKU4Rsg5)

## Cutting the Joint

![Box parts with side profiles](/files/-MOMGDPXofeOXy9ks8w7)

![Parts preview with miters](/files/-MOMSgK9PkFNGaBNaUVD)

![Pockets for hidden splines](/files/-MOMSYaJyGV5Wf1ISfX7)

![](/files/-MON5_HD-clJeZHZ2WTn)

![](/files/-MON5dE2txvmzmoUWyLg)

![](/files/-MON5NEmNZCFepcofehC)

![](/files/-MON63dSdevxjULugNar)

![](/files/-MONEZ1rJ8-l65Rwu-DR)

![](/files/-MONEo4uA-QFbcAuTUwE)

![](/files/-MONEzzmkvsbjV6IylzH)

![](/files/-MONF7nvyU93zHiu1z2O)

![](/files/-MONFKB7u55bs1ygsFV3)

Cut the file:

![](/files/-MRHgXYdca2NODaaK9Zd)

![](/files/-MRHgvfkEZcgmx6lsUMT)

With a downcut endmill the parts need minimal cleanup:

![](/files/-MRHh95LN0GANq0YbANC)

And the box fits together, self-aligning:

![](/files/-MRHhMHLUwRqvZX0F5jA)