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How do you make round holes in thin fiberglass

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  • How do you make round holes in thin fiberglass

    I want to make a series of approx. 1/4" round holes in some thin sheets (about 5 plies of 5oz fabric)of fiberglass. I'm getting tri-lobular holes. I'm considering trying some carbide fiberglass routers and finishing with a some sanding cones on a Foredom (Dremel like flex shaft tool)...I wanted to get opinions before I go out and lay down my cash. These perforations do not have to be exact size but do have to look uniform with appealling craftmanship when finished and painted.

  • #2
    Get a unibit stepped drill bit. They cut nice holes but you have to be careful about not pushing too hard or you'll get to big of a hole if it goes in too far.

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    • #3
      Might try a gasket punch (sharp one) on some scrap. I have no experience here\
      Steve

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      • #4
        Fiberglass is quite abrasive so using regular HSS drill will dull it quite quickly. Definitely go with carbide and for a clean hole keep the RPM high. For 1/4" hole, try the carbide drill bits used for PCB drilling, which has a cutting end profiled like 2 flute endmill.

        Albert

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        • #5
          Try sandwiching both sides with a thicker material. I use lexan or Plexiglass on the top side so I can see my marks. Use MDF board or some other inexpensive material on the back side. Clamp all three very tightly, this will minimize tearout. Use HSS drill bits, cheap ones, you can resharpen them as needed or just through them out. Unibits give better holes in sheet metal but are to expensive to waste on such abrasive material.

          I hope this is helpful

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          • #6
            Try using a centerdrill and drill all the way through with it. You didn't tell us the thickness of the material. Fiberglass will dull almost anything quickless.

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            • #7
              Try using a centerdrill and drill all the way through with it. You didn't tell us the thickness of the material. Fiberglass will dull almost anything quickly.

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              • #8
                That's ok WJ. We knew what you meant the first time. We all have occasional disconnects between brain and fingers.

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                • #9
                  lynnl,

                  At 3:00 am I'm not sure brain was even in gear to disconnsct.

                  WJ

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                  • #10
                    In the manufacture of printed circuit boards for electronics industry they use a lot of fiberglass/epoxy laminated material called FR4. They drill it with solid carbide drills at a very high speed (30K rpm). The drills are a special helical cut drill. For large holes they use a pin router or NC router which they also use to route out the outside profile of the PCBoard. If you have a local PCBoard shop you may be able to get one of these special bits from them and use a wood router or die grinder to get the speed up. If you just have a few holes to drill try HSS bits and resharpen them often.

                    ------------------
                    Dick
                    Dick

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                    • #11
                      abn:
                      Either use a structured tooth diamond tool to drill/route or a cheap diamond point will do a beauty job - use water to keep that nasty dust down as the particles of glass can damage your lungs. Used of any edged tool will just damage it - even carbide.

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                      • #12
                        For thin materials I use a variation on the hand held cutters that we used in chemistry class to cut holes in rubber corks. I use the thin wall telescoping brass tubes sold by Small Parts or hobby stores. Cut a 45 degree angle at the end of a brass tube. The tip of the cutter is at the inside wall of the tube. You don't even need a lathe. Out in the field I just rotate the tube against the file as I draw it across a file. You get a sharp edge that cuts surprising clean holes in rubber, paper, and many plastics. Rotate the "cutter" at fairly low speeds. Kock out the disks that accumulate in the cutters barrel every so often when you remove the cutter to touch up the edge with a file.
                        I have notched small teeth in some tubes to drill around broken screws in soft materials.
                        457863656C73696F7220212000

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                        • #13
                          abn,

                          I use a forstner <sp?> bit to drill 1/16" G10 fiberglass from time to time. It works pretty well. Like the others have said, carbide would be best, but good luck trying to find a carbide forstner bit. You really need something that cuts the outside edge first and then removes the middle. A brad point bit might work just as well.


                          Chris Attebery

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                          • #14
                            The center drill idea sounds good to me. I bet it would work okay. A carbide center drill sounds even better. Maybe playing with the tip angle of a twist drill would help some too. Stoning the cutting edges to reduce rake stops a twist drill from "pulling" in brass; don't know what it would do in fiberglas.

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                            • #15
                              By chance, I found a webpage on how to drill through fibreglass. Unfortunately, it's not in English.

                              http://elm-chan.org/docs/drill.html

                              Albert

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