Homebrew PCBs

javaguy11111 wrote:
> Any suggestions on cutting circuit boards. I have used a bandsaw, but
> it tends to be slow, dusty and inaccurate. I have tried paper shears,
> but the board tends to get warped and is only good for about two
> inches and it is too hard to cut any further.
> 

   Dremel, really requires the flex shaft to do it so the handle can be 
within the diameter of the cutoff disc.  Use the THINNEST discs, they 
will break a bit more often but are cheap and cut faster due to less 
material removal with the same power from the tool.  Actually use the 
cheap $20 hand tool from Walmart, it's amazingly high quality for the 
price and will also take the dremel flex shaft.

   Get two of the high quality drawer slides from Lowes ($15 or less). 
Remove the outer 3rd section and just use the inner more bearinged two 
sections for less play, requires drilling holes in the middle piece for 
mounting though.  Mount a piece of wood between the rails, and tool to 
the wood with hose clamps.  Align accurately so that the rest of the 
disc travels exactly through the slot the edge cuts and the discs will 
last longer than you'd think.  Set it up so you can mount the boards 
securely, and have the tool travel on the rails and slice the board. 
Then, build a simple stepper motor controller and attach a 1/4"-20 
threaded rod to the shaft, a coupling nut to the board, and set it up to 
travel automatically at a reasonably slow rate.  Adjust speed to have a 
reasonable rate without too much loading on the tool.

   Coat hanger wire.  Build a box frame around the whole cutting area, 
but not the dremel motor.  Point the wire ends in so they don't cut the 
bag.  Wrap a garbage bag around the frame with the sliding tool plate 
moving along a slit in the bag.  Knock your boards off before removing, 
and throw the bag away now and then to get rid of the dust.  A design 
that keeps the rails and the flex shaft handle (bearings) outside the 
bag will be best.  Helps if you hunt down some good clear bags, although 
you can flip the front up when loading a board easily enough.  Small 
slits in the bag don't let out too much dust, one on the other side will 
let you get a hand and screwdriver in for changing the wheel etc.

   Note that this can be scaled up to more drill sized cutoff wheels and 
motor systems.  But you still want to seperate the boards not grind a 
bunch of fiberglass dust, so the thinnest wheel you can use will be the 
best.  Anything more is just wasting grinding wheel money and making 
more dust.

   Actually just thinking more about it, some spring snap clips like the 
ones to hold tool handles on the wall but small enough to hold the flex 
shaft may be good enough to let you pop the handle in and out so it's 
not tied to the machine.  If not that some other quick removal system 
would be a good idea, no sense having a dremel and flex sitting around 
for a single purpose if not necessary.

   Maybe $80 or so if you have to buy the tool and flex which will come 
in handy anyway.  Only does straight cuts but could be modified for 
more, and worth it if you do more than a few boards.

Alan