# 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)](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MOKBbDSS77qdWyw68PW%2F-MOKMpicRgVEJtLuD3av%2Fimage.png?alt=media\&token=cf122e37-686b-4638-95fd-aeab319f9996)

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](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MOKBbDSS77qdWyw68PW%2F-MOKNXP_I9JOcmRTOXan%2Fimage.png?alt=media\&token=ca4aae1e-80c9-4aef-9692-45c1df15c42e)

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](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MOKNdXaCNMCYcsh_4G0%2F-MOKQ0yOoiNBqQDb58bm%2Fimage.png?alt=media\&token=b5364fcd-1b25-4ad0-b0ca-d2e6c0cb9188)

Which may then be drawn up:

![Blind Miter Joint and hidden spline profile](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MOKNdXaCNMCYcsh_4G0%2F-MOKQy_rxSq1nLpKtWFr%2Fimage.png?alt=media\&token=9659657b-434a-4e92-902d-5fc82990b1c4)

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](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MOKNdXaCNMCYcsh_4G0%2F-MOKS2i6nZataefZnUo5%2Fimage.png?alt=media\&token=cd705fe8-793a-48eb-a299-bd36490c6fe7)

## Modeling the Box

![Box with parameters/dimensions](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MOMBLD2fj2wO-2AH6nv%2F-MOMCJmcXm8iFKU4Rsg5%2Fimage.png?alt=media\&token=3f3b05f7-8ad8-477f-8ee6-ec94acb5aea9)

## Cutting the Joint

![Box parts with side profiles](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MOMCSxxDJubxWCmAxDS%2F-MOMGDPXofeOXy9ks8w7%2Fimage.png?alt=media\&token=6b93d07e-7a84-4eff-8206-227c22b4a19c)

![Parts preview with miters](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MOMCSxxDJubxWCmAxDS%2F-MOMSgK9PkFNGaBNaUVD%2Fimage.png?alt=media\&token=7bddd5da-7ebb-4e9e-ba92-92eff7c8d94f)

![Pockets for hidden splines](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MOMCSxxDJubxWCmAxDS%2F-MOMSYaJyGV5Wf1ISfX7%2Fimage.png?alt=media\&token=5b976b20-4e3e-40f2-ae8b-8b1483f36367)

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MON2X7lqQgQSJmYU4Ci%2F-MON5_HD-clJeZHZ2WTn%2Fimage.png?alt=media\&token=69ed7b74-b875-4b6f-84d7-11a3bde305f7)

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MON2X7lqQgQSJmYU4Ci%2F-MON5dE2txvmzmoUWyLg%2Fimage.png?alt=media\&token=3fe6a907-77ba-4ef0-8f84-0d8db06002e6)

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MON2X7lqQgQSJmYU4Ci%2F-MON5NEmNZCFepcofehC%2Fimage.png?alt=media\&token=9453ee0e-e0be-4c79-88db-e570a7c53413)

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MON5f1WA5nhZoj1ir-F%2F-MON63dSdevxjULugNar%2Fimage.png?alt=media\&token=6e9859cb-e39b-4075-9b8c-0030ec5da1bf)

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MON5f1WA5nhZoj1ir-F%2F-MONEZ1rJ8-l65Rwu-DR%2Fimage.png?alt=media\&token=e12fcd9a-be0f-4a81-a509-4bf40ada69dc)

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MON5f1WA5nhZoj1ir-F%2F-MONEo4uA-QFbcAuTUwE%2Fimage.png?alt=media\&token=b773144e-377c-4f6d-a2ff-6ff971b9e963)

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MON5f1WA5nhZoj1ir-F%2F-MONEzzmkvsbjV6IylzH%2Fimage.png?alt=media\&token=2dcb5a80-d840-46ec-9cd2-7c634ace9e27)

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MON5f1WA5nhZoj1ir-F%2F-MONF7nvyU93zHiu1z2O%2Fimage.png?alt=media\&token=2bb12132-2a67-4df1-8ea0-01e225108ee8)

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MONFA1Fa1_-Kjbu_ix2%2F-MONFKB7u55bs1ygsFV3%2Fimage.png?alt=media\&token=d37041b7-c69a-4ba7-b719-72c1e97cbadc)

Cut the file:

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MRHfXwxg-i7u8gRBL0g%2F-MRHgXYdca2NODaaK9Zd%2F20210116_134633%5B1%5D.jpg?alt=media\&token=79b254ea-ff94-4a8b-9b28-84d461b952f0)

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MRHfXwxg-i7u8gRBL0g%2F-MRHgvfkEZcgmx6lsUMT%2F20210116_165842%5B1%5D.jpg?alt=media\&token=91f83ab4-e673-4907-88d0-fa4c238b842d)

With a downcut endmill the parts need minimal cleanup:

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MRHfXwxg-i7u8gRBL0g%2F-MRHh95LN0GANq0YbANC%2F20210117_122620%5B1%5D.jpg?alt=media\&token=e95c1e7d-3afd-42eb-973e-860136abc507)

And the box fits together, self-aligning:

![](https://235206304-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M2NwCQrLAFxezOUTC9_%2F-MRHfXwxg-i7u8gRBL0g%2F-MRHhMHLUwRqvZX0F5jA%2F20210117_123246%5B1%5D.jpg?alt=media\&token=9dce0279-eeec-469c-a5f3-b890a9b6b265)