avoiding chipped FR4

Discussion in 'General Electronics Chat' started by StephenDJ, Feb 12, 2009.

  1. StephenDJ

    Thread Starter Active Member

    May 31, 2008
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    A hacksaw causes chiped edges when trying to use it on pcb. I find that the copper has a tendency to chip up and break loose from the FR4 material at the edges when sawing. Tell me, what kind of cutting device should I use?
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    A shear works, but the blades are dulled quickly for other, demanding metal work. Some people use the miniature HF shear and report good results. Others report using a pointed carbide bit in a mill.

    I used to use a hacksaw blade in a scroll saw and a belt or disk sander to get the final dimension. The hacksaw blade also dulls quickly. I got tired of the fine fiberglass dust.

    Now I use a miniature table saw with a carbide blade (about 4" diameter). I cut most of the way through, leaving about 10 mil. Then, I simply snap off the thin flashing that is left. If you cut entirely through, you get chipping. I design my boards so I am not cutting both copper and FR4. I leave a narrow (5 mil or so) etched space between the copper ground pour and the edge.

    John
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
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    I use a cheapo 4" table saw with a dry diamond blade. Lots of dust and stink, but no chips and a narrow kerf. Motor bearings leave a lot to be desired, though.
     
  4. StephenDJ

    Thread Starter Active Member

    May 31, 2008
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    Hehee, thanks... this is great advice, I appreciate. It looks like you both have suggested the 4" table saw. I also have the idea of building a small saw that uses a verticle band saw blade running down through an opening in a table. Thanks
     
  5. StephenDJ

    Thread Starter Active Member

    May 31, 2008
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    Oh, by the way, what does the "HF" stand for?
     
  6. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    HF = Harbor Freight (http://www.harborfreight.com/)

    It's a national chain selling imported, mostly Chinese, tools. Quality control is highly variable, but getting a little better with time. I would still be reluctant to buy something without being able to examine it first.

    Bandsaw blades broken into short segments fit my scroll saw were what I used. They dull very quickly from the glass fiber.

    John
     
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