Cutting PCBs down to size for each project has always been a problem for me. I don’t have a bench saw, so I’ve been doing this by hand until now. Despite the number of boards I’ve made, I still lack the dexterity to do perfectly straight cuts with a regular hacksaw, and my success with other manual methods has been equally limited. Like a year ago I stumbled upon a small a table saw on dealXtreme which I was tempted to buy but was kinda too expensive for me. My search continued until a few months ago, when I realized that I could make one myself, using a small motor I salvaged from a cheap $10 dremel-like tool that I once had. I wasn’t sure this was going to work, but decided to give it a go nonetheless.
I designed the whole thing from scratch around the motor and components at my disposal, but I integrated ideas I saw (heh) in similar projects online, like the adjustable cutting “guide” or the vent slots. It’s not a complex machine by any means so designing this didn’t take long.
Of course my design has its flaws; The pattern I followed to add bolts and nuts to the laser-cut pieces is pretty common and has been widely used in many projects. The problem is that in most of these projects, the bolts are placed in such a way that you can easily grip the hex nuts from both sides with pliers while tightening the bolt with a screwdriver. Since in my design the top deck is glued to the side walls, there’s no way you can get pliers from any direction to hold onto the nuts when you insert and tighten the bolts. You need to be very careful and hold them with tweezers or precision pliers from outside, which is incredibly frustrating and hard to do. To make things easier for me I ended up gluing nuts and washers inside the slots using a two-part adhesive so I don’t have to hold them in place myself when tightening the bolts. Surprisingly it works.
The pieces are quite self-explanatory but I’ve added some instructions in the SVG file. As usual I’ve included a DXF render too: DIY Table Saw (SVG, DXF)
Please bear in mind that I’ve still not decided on the electronics I’ll use for this. For the time being I’m using my lab power supply, but I will eventually either build a dedicated controller or just settle with a fixed power supply or an old laptop adapter. For this very reason you’ll find in the diagrams no holes for switches, cables, etc. Since most panel-mount components require simple holes, I’ll drill them as I need them, and according to what I end up using. What you will definitely need though, is a flyback protection diode across the terminals of the motor and a small ceramic capacitor for stability. I soldered both to the motor terminals before closing the whole thing.
Also check that you are providing enough power to the motor. I didn’t know the voltage rating of mine, so during my early tests I started with 6-8V and the motor began vibrating so wildly that the blade made small dents inside the slot. Taking the voltage above 12V reduced the vibration almost to zero and made the whole thing run smoother. At 18V I was able to cut through PCBs with no problem.
If you want to build one yourself I think you can use this motor I found on eBay, which seems to be designed for this kind of project and looks really close to the one I’m using.
I’ll leave you with a video now of the saw working:
— Elias Zacarias (@battlecoder) January 29, 2017
I’m quite happy with the result. I think the only modification it needs is a way to be clamped down to the table, but I think that I can do that without further modifying the design. I can -for instance- add a “bed” that runs under the bottom side (without obstructing the vent/exhaust holes, bolts, etc) that protrudes to the sides so I can put the clamps there. This piece could be attached to a couple of the existing holes in the bottom plate.
UPDATE: Several attempts later were made using the fold-able woodworking bench itself (whose surface can act like a clamp) with the plastic stoppers that came with it to keep the machine in place, and it worked amazingly well, so I don’t think I’ll modify my setup.
Another thing I forgot to mention: If you are going to cut PCBs I found that cutting the boards copper-side-up gave cleaner results.