Micro Table Saw
For years, I've been cutting PCB's freehand using a dremel tool and a cutting disc. It works well but the dust and less than perfect edges bothered me.
An option was a PCB guillotine but it costs a fortune and the resulting cut edge is still rough.
An idea that has been floating around in my head for quite a while now but did not have the time or motivation to build one: A micro table saw with a diamond cutting disc for cutting PCBs.
There are a lot of miniature table saws that you can buy but most use teethed saws which I think would not cut cleanly through FR4 (I haven't tried it so I don't know for sure) plus if it isn't carbide tipped, would be blunt in a few passes of the abrasive fiberglass PCB material so I decided to make one that used a diamond cutting disc. This was the result of an afternoon's work.
The "underchassis" of the table saw. An MDF base, two sealed bearings and steel shaft from torn down copier, chuck from some old burnt out AC powered Dremel knockoff and some alu brackets to hold the work surface:
Detail of the bearing pillow block machined from polycarbonate:
The heart of the table saw. This is a fairly old Dremel "chainsaver" used for resharpening chain saw chains. It runs on 12V and is powered off my renewable energy system in my workshop:
A grinding bit used as a convenient shaft for the flexible coupling:
Flexible coupling using a silicone tube:
Cutting disc spinning at about 15,000RPM:
The bottom side of the plexiglass work surface milled to clear the chuck, and holes milled to clear the blade and bearing:
The cutting disc protrudes exactly 2.5mm above the work surface so that dictates the maximum thickness of material that can be cut in one pass, the yellow-green material is 1.6mm thick FR4 PCB:
Test cutting various 1.6mm blank FR4 PCBs and the makeshift 'fence':
I tried cutting 3.5mm thick plexiglass sheet. One pass isn't enough but it worked well when the piece was turned over and run a second time:
The complete micro table saw clamped on the work bench, work surface is 10 inches by 5 inches:
Rotary tool placed on top of a piece of alu extrusion simply held by gravity:
Later added a foam cap on the end to keep dust contained under the work surface:
The test cuts showed promising results. Now, I can make PCBs with nice edges and little waste. My next plan is to make a simple adjustable fence that can be clamped easily to the table. Stay tuned!
07 Sept 2012:
The alu extrusion wasn't all that effective as a motor mount so I made a new one from acrylic and M4 allthread:
The flexible coupling also had the habit of vibrating then jumping out so I added an aluminum sleeve to keep it centered:
Dremel in place on the motor mount:
View of the cutting disc:
Also added a spring under the motor to provide some forward pressure to prevent the motor moving backward:
08 Sept 2012:
I had an idea of how to make a chamfer using the micro table saw. Add a guide along the axis of the saw:
...and let the blade protrude just enough:
Then slide the workpiece along the guide and you get a nice chamfer:
Dust collected from cutting circuit boards and acrylic sheets:
20 Jan 2013:
The flexible coupling keeps on failing when I'm cutting material that requires a bit of torque from the motor so I made a hard coupling from polycarbonate:
First thing is to drill a hole on the side of the grinding bit that is used as a shaft:
Here are the parts needed for the coupling. A donor grinding bit used as a shaft, a short piece of paperclip wire, the polycarbonate coupling, the setscrew and a piece of silicone tubing as a cushion between the two shafts:
All together on the table saw. The short piece of paperclip wire is used as a pin to prevent the shaft turning in the coupling but allows some play:
A bit of heatshrink tubing holds the pin in place and prevents it from flying off and hitting someone in the eye while spinning at 15000RPM:
Here it is spinning with very little vibration:
The dust that has been collected since I've built this thing. I've used this table saw to cut PCBs, acrylic sheets up to 5mm and 1mm aluminum sheet (with lubrication):
With the new coupling, the spring under the motor holding the Dremel in place is no longer needed so was removed.:
Page created and copyright R.Quan © 02 Sept 2012.