Laser cut boxes for project boxes are all over the place lately, but I've found that they often need a fair amount of hardware and complex designs to make them solid. This Instructable will show you how to make attractive and structurally sound project enclosures held together with dove-tail style joints and a just a few machine screws.
The trick to making these dove-tail joints is an emery board, the kind for filing your nails. The joints of the project box are laser cut with a "V" shape on one side and a smaller, rectangular hole on the other. The receiving rectangle cut is then sanded down to fit the V shape using the emery board. When assembled, the dove-tails hold the sides together tightly. Screws are added to hold the top and bottom in place, securing the enclosure. I used 4 (one for each corner,) but the box could easily be held together with just one.
The project that I'm making a case for is a modified Sparkfun single cell, lithium-polymer battery charger. The charger comes as a kit for charging li-po's at 100 or 500mA, but with a little bit of tweaking and a few components it can be made into a variable charger.
Materials
1/8th inch acrylic plastic. It will work with thicker plastic, you'll just need to do more sanding.
Machine Screws such as 1.25" Length 2-56 Thread from Ponolu
A project to put in the box
Tools
Laser Cutter
Emery Board. These can be found at drug stores and mini-marts.
The trick to making these dove-tail joints is an emery board, the kind for filing your nails. The joints of the project box are laser cut with a "V" shape on one side and a smaller, rectangular hole on the other. The receiving rectangle cut is then sanded down to fit the V shape using the emery board. When assembled, the dove-tails hold the sides together tightly. Screws are added to hold the top and bottom in place, securing the enclosure. I used 4 (one for each corner,) but the box could easily be held together with just one.
The project that I'm making a case for is a modified Sparkfun single cell, lithium-polymer battery charger. The charger comes as a kit for charging li-po's at 100 or 500mA, but with a little bit of tweaking and a few components it can be made into a variable charger.
Materials
1/8th inch acrylic plastic. It will work with thicker plastic, you'll just need to do more sanding.
Machine Screws such as 1.25" Length 2-56 Thread from Ponolu
A project to put in the box
Tools
Laser Cutter
Emery Board. These can be found at drug stores and mini-marts.
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Signing UpStep 1: Designing the Joints
First, find some machine screws of a suitable length, longer screws will allow for more room in the project box. I used 1 1/4" long, 2-56 thread screws from Polulo; my project box needed to be exactly 1 1/4" tall for the screws to reach from one side to the other.
Design the enclosure with rectangular finger joints as per usual. This project was designed with 123D and then cut into slices using 123D Make for laser cutting. Another option would be to use the web based BoxMaker tool by Rahul Bhargava to automatically create a finger joint box design, and then use a vector editor (Illustrator, Inkscape, Corel) to add the dove-tails.
Based on the length of your machine screws, choose two opposing sides (top-bottom, left-right, back-front) and add 70 degree angles to the joints by making the outer edge wider. Here I've made all the tabs on the top and bottom into dove-tails and left everything else as it was.
Design the enclosure with rectangular finger joints as per usual. This project was designed with 123D and then cut into slices using 123D Make for laser cutting. Another option would be to use the web based BoxMaker tool by Rahul Bhargava to automatically create a finger joint box design, and then use a vector editor (Illustrator, Inkscape, Corel) to add the dove-tails.
Based on the length of your machine screws, choose two opposing sides (top-bottom, left-right, back-front) and add 70 degree angles to the joints by making the outer edge wider. Here I've made all the tabs on the top and bottom into dove-tails and left everything else as it was.
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You are 100% correct, in fact I can't remember why I choose to do it that way in the first place. I think I only had heavy gauge wire at the time and I didn't feel like I had the room to solder it to the center jumper pad. If I had it to do over I would use a thinner wire and solder to the pad like you're saying.
Good luck with your project!
Great little project, I was wanting to mod this board in a similar way for very small lipos and came across your project. I have a question. Having scraped away the 500mAh jumper pad link to the central pad, cannot I just connect to that central pad to get my PROG tab connection to the MCP73831? Seems an easier, neater and safer way of doing it, or have I misunderstood where the PCB traces go?
Patrick
I have really small IR system that I made long time ago from one Japanese guy's website, the thing is that it could only work with small airplanes, would be cool to make it work with cars and boats and all kinds of robots!