In-Between a Rock and a Hard Space

Project By: ThomasLove

puzzle box toys games

The goal of the project is to remove the key from the base by aligning the hidden sliders. with a twist at the end ;) There is a very satisfying clunk and swoosh when you solve it. (You will hear what I mean once you build it)
This is a very fun project to build and is a awesome puzzle to watch your friends and family struggle to conquer.

I would say this is a mid to advanced level project. It was certainly a challenge for me


Type Length Width Thickness Origin
Name Type Tool Feedrate Plungerate Cut Depth

I cannot add the second link to my fusion file for the exterior shell so I'll put it here for now; until I figure out how to add it

I designed this project for certain materials.
HDPE for the sliders and the inner sanctum.
Aluminum for the key.
3/4 Plywood for the outer shell. (NOTE that 3/4 ply is not actually 3/4'' its closer to .724'' so I have adjusted the models for this thickness.)

I generated these files with a shorter end mill for some of the pieces because that is what I had. HOWEVER I went back and edited the files for the CORRECT end mill length so you need to simply put in the correct end mill into your CNC and the file will work.
The files for the .125” end mill for the wooden exterior shell should have a flute length of .75” because of material thickness.
And the files for the .125” end mill for the aluminum Key should have a flute length of .5” also because of material thickness.

For the key and the bottom cap of the exterior shell you will need to make a fixture to machine this. I used a piece of three-quarter plywood and attached it to my waist board to cut in my alignment holes. And then tapped each hole for quarter by 20 bolts which worked very well. You can adjust this after the fact for dowels by simply drilling the holes out for the correct size dowel.(although note that I used these alignment holes on the cap to attach it to the inner sanctum.)

To assemble the inner sanctum sides I used six screws per side and I pre-drilled the holes. Six screws may sound like a lot, but there’s no kill like over kill.
I then screwed all the pieces of the top together by aligning them with the key to make sure a smooth action of the key. From here I bolted the bottom cap on to the top piece from the inner sanctum with ¼ by 20 into the alignment holes with a little glue so they don’t wiggle loose. Adjust the bolts as necessary to provide a smooth action that isn’t too loose. Then I screwed this assembly to the rest of the sides of the inner sanctum with 4 screws.
To attach the exterior shell to the inner sanctum I used PL construction grade adhesive this worked exceptionally well. While glueing I used the sliders to align the pieces and then clamped them down, before clamping them down all the way I played with the sliders to make sure that they had a smooth frictionless action to them. I then removed the sliders just in case there was any squeeze out from the glue. I left the bottom piece with a friction fit so that you can take it off to adjust the bolts holding the cap in place.

That’s all of the info that I can think of that will help you along on this project. Feel free to drop some questions and tell me if a file is corrupted!

Happy cutting my dudes!


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