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PCB Cutting

Discussion in 'General Electronics' started by Jim Douglas, Mar 13, 2005.

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  1. Jim Douglas

    Jim Douglas Guest

    How do you guy's do this, I have bare PCB that is 6x6" and I am building a
    board of 2x3", what do you use to cut the boards. Before this I used the
    paper cutter at the office but got caught and don't want to get yelled at by
    the admin again! I am thinking a trip to Home Depot or ??


    Thanks!



    --



    Jim Douglas
    www.genesis-software.com
    Carrollton, TX USA 75006
    Latitude 32.9616
    Longitude 96.8916
     
  2. Bob Eldred

    Bob Eldred Guest

    For small quantities at home with hand tools, use a hack saw then file the
    edges straight and smooth with a file. I use a sheet metal shear but you
    probably don't have that available. A band saw also works, use a metal
    cutting blade.
    Bob
     
  3. Michael

    Michael Guest

    I've done that too. Works fine for phenolic boards. Glass boards can require
    DEEP scoring, otherwise the bending force required can be high enough to warp
    the board. Occasionally I use score-bend on smaller glass boards. Clamping
    board in a vise along the score while bending the waste results in less warpage.

    I used paper cutter many years ago and had the warp problem described above. A
    metal shear works beautifully ..... but don't let the machinists catch you
    cutting glass boards on one; I'm told that glass dulls a shear beyond all reason
    and that re-sharpening is very expensive.

    Not having a shear, a paper cutter, nor a bandsaw, I use a nibbling tool to cut
    boards and a file to clean edges afterward. Yes, it's slow and it wastes mucho
    board, but it's simple ... and cheap.
     
  4. Luhan Monat

    Luhan Monat Guest

    Hi,

    I score the board on the copper side with an exacto blade and then break
    it over a table edge. You need to first make a 2 inch cut making a 2 x 6
    and then cut that in half to make a 2 x 3.
     
  5. Rich Webb

    Rich Webb Guest

    Try a scroll saw. They're relatively inexpensive and much smaller than
    even the smallest bandsaw. A bit hard to make a perfectly straight cut
    unless you clamp an edge guide to its table. OTOH, it's useful to make
    oddly shaped board and cutouts.
     
  6. I wonder if anyone here has ever tried a scoring knife (essentially a
    single tooth file that you pull along a guide) as a way to make break
    lines in PCB material. I think I may have to get one of these and
    experiment with it. At least it is fairly easy to resharpen.
    http://www.epinions.com/Stanley_Scoring_Knife_Shop_Tools
     
  7. Karl Uppiano

    Karl Uppiano Guest

    I've always done this. I bought a knife 22 years ago, that was designed for
    scoring Formica. It has a carbide tip. A take few swipes with that thing
    along a straight-edge, and snap the board along the score. I score the metal
    side on single-sided boards. A little sanding smoothes everything right out.
    Works much better than sawing freehand.
     
  8. Drill a very small hole at each end of the score line and score both
    sides. The holes ensure that the two scores are closely aligned. This
    allows the inside of the bend to compress and the fibres at the outside
    are not there to stretch, so the force needed to break along the line is
    greatly reduced.
     
  9. Yukio YANO

    Yukio YANO Guest

    I use a "Jeweller's Saw" for smaller projects. A fugitive from my
    Lapidary days, perfect for cutting, sawing small objects like circut boards
    ..

    Yukio YANO
     
  10. Jim,

    I've used a table top jigsaw with reasonable results. Good points are that the
    saw kerf is really small so you don't waste a lot of board material. Bad points
    are that FR4 is a bit tough on the blades (at least they are cheap) and the
    small blade tends to want to follow the lay of the fiberglass which can make
    "straight cuts" difficult at times.

    While I've never tried it, I always thought the ideal way to cut PCB material
    would be a band saw with a fine tooth, carbide tipped blade. Using a panel
    cutting jig so you could clamp the PCB material down and cranking the blade
    guide down would make cutting even small PCB's pretty safe.

    As I have access to them, I also thought about using a table saw or power miter
    with a fine tooth carbide blade but never did due to the amount of waste in the
    saw kerf. FR4 is relatively hard and brittle so the chipping might be excessive
    even with a fine tooth carbide blade designed for cutting wood. Using a
    non-ferrous metal carbide blade with a negative rake angle might solve this but
    still removes about 1/8" of material. Table saw safety would dictate using a
    panel cutting jig with clamps for the PCB. With the power miter you could just
    clamp the PCB down to the saw table.

    I'd be interested if you figure out any better ways to cut PCB material. Good
    luck and be safe.
     
  11. I read in sci.electronics.design that James T. White
    There was a small PCB maker in UK who used these. The saws were less
    than 3 mm thick, but I don't know the thickness. Proper guarding is
    essential because the odd blade can disintegrate suddenly.
     
  12. Jim Thompson

    Jim Thompson Guest

    Reminds me that friend DOES use a small-bladed, carbide-tipped, table
    saw to cut FR4.

    I've also, on rare occasions, used a small hand-held rotary tile saw
    (Makita) with a diamond blade. Cuts the FR4 cleanly, but tends to
    "mooosh" the metal edge when you cut across a ground plane.

    ...Jim Thompson
     
  13. Jim Douglas

    Jim Douglas Guest

    I found heavy duty scissors at WalMart for $6.00 that cut right through the
    stuff. The are made by RubberMaid, go figure. I went shopping with board
    material in hand and tested alot of different products, this was the least
    expensive tool I found that worked easily. The ones made for metal did not
    do good cutting the PCB material.

    I like the score and snap idea and will try that next time, I do have one of
    those scoring type knifes! Thanks for all the input!
     
  14. Excellent! I didn't find one with a carbide tip, but just bought one
    with a replaceable steel tip.

    Now I have to make a cutting board out of a square of plywood with a
    strip of laminate glued to the near edge as a board stop and a second,
    narrower strip glued on top of that as a guide for the steel square
    (set back a bit so that the knife doesn't have to hit it when it
    reaches the edge of the board) and I will ready to clamp that to the
    work bench the next time I need to cut a board.
     
  15. JeffM

    JeffM Guest

    I bought a knife 22 years ago, that was designed for scoring Formica.
    http://www.google.com/images?q=carbide-tipped-scribe ?
     
  16. keith

    keith Guest

    What about a table-mounted router (or roto-zip)? AFAIK, the biggies use
    such high-speed widgets to cut FR4.
    Wrong direction of cut. The bit should "rout", rather than "saw".
     
  17. Brane2

    Brane2 Guest

    keith wrote:

    I have tried with tabletop scrollsaw from Proxxon-"DSH" (No:28092) and I
    can say that it works very well, but not with blades that are meant for
    it (No:28740-No:28744).

    I had to use harder blades (No:28106) that are pain to mount in the saw,
    but they work very well and seem to take FR4 abrasion much better than
    serial ones. Quality of the cut is perfect and blade cuts closer to
    straight line, so there is much less need for "course corrections".


    Regards,


    Branko
     
  18. Guy Macon

    Guy Macon Guest

    I just use my lightsaber to cut PCBs...

    This shouldn't be a problem; copper shouldn't be allowed to reach
    the edhge of the board.
     
  19. Barry Lennox

    Barry Lennox Guest


    Depends on the size and accuracy required. Options I have used are:
    (#3 is the current choice)

    1. Scoring both sides with a custom tool, basically a hook in an old
    piece of heavy-duty bandsaw blade, then snapping it.

    2. A metal shear, but I understand it does the blade no good.

    3. A scrollsaw then clean up the edge with a light touch on a belt
    sander. Odd shapes I cut out with a cheap air-nibbler.

    Barry Lennox
     
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