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Thread: Cutting grp sheet

  1. #1
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    Cutting grp sheet

    Just a quick one guys what's the best way of cutting grp sheet ? I need to cut the a3 piece I bought and don't want to bodge it !!
    Thanks

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    For FRP g-10 material I've had good luck with a tablesaw
    Just make sure to wear a mask

  3. #3
    Better Tone thru Mathematics bob p's Avatar
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    use a carbide-tipped blade for cutting, and carbide-tipped drill bit. G10/FR4 will ruin the edges on a regular blade & bit.
    "Stand back, I'm holding a calculator." - chinrest

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    Supporting Member Chuck H's Avatar
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    for FR4 I use a Dremel metal cut abrasive disk and then fine up the lines with a stationary belt sander I have. The trouble "I" have is all the 1/8" drill bits I go through when I drill for eyelets! They dull pretty fast with the effort and I never get great results resharpening. NBD. They're not expensive.
    "The man is an incompetent waste of human flesh. He should donate his organs now to someone who might actually make good use of them." The Dude re: maybe I shouldn't say, but his name rhymes with Trump

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    Quote Originally Posted by bob p View Post
    use a carbide-tipped blade for cutting, and carbide-tipped drill bit. G10/FR4 will ruin the edges on a regular blade & bit.
    cuting into a sandwich together with eg. some scrap wood is a way for neat edges. Can try even with adesive tape for some materials. Basicaly the problem is where the tool dents goes out from material and can broke, dents the edge. It is necessary to ensure a sturdy support under. A piece of scrap wood is just enough to reinforce, sandwiched better. I cut with non-ferrous carbide disc with good results
    Last edited by catalin gramada; 10-27-2017 at 05:29 AM.
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  6. #6
    Better Tone thru Mathematics bob p's Avatar
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    In the past I'd always used a table saw with a carbine blade for cutting G10/FR4. Now that I have a cold-cut $aw for cutting steel I'll be using that for cutting my G10/FR4 boards. That's probably the best solution, but I wouldn't recommend it to anyone who isn't already interested in buying a cold cut saw for other reasons. They're just ridiculously expensive. Most people would be better off with a dry-cut ferrous metal saw because they're so much cheaper.
    "Stand back, I'm holding a calculator." - chinrest

  7. #7
    Better Tone thru Mathematics bob p's Avatar
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    Chuck, do yourself a favor and get some of the carbide tipped bits from McMaster for drilling your holes. They'll hold up a lot longer than your regular drill bits, and even though they're more expensive they should be cheaper in the long run because you don't have to replace them so often.

    I prefer the heavier 1/8" boards over the 1/16" boards when I'm building turret boards because I counterbore the holes rather than drilling them through. The idea behind the counterbore is that I can build a turret board that has swage that is recessed into the counterbore such that the bottom of the board is non-conductive. Then I don't have to mess with stand-offs. I can just bolt the boards right to the chassis.

    When it comes to purchasing counterbore bits, even the non-carbide ones are significantly more expensive than conventional drill bits. Even worse, the carbide tipped ones cost multiples of what the regular counterbore bits cost. But carbide tips, either on a drill bit or a counterbore bit, are so much more durable with G10 that it's actually cheaper to use the carbide ones.

    McMaster is a good supplier.
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  8. #8
    Supporting Member Chuck H's Avatar
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    Quote Originally Posted by bob p View Post
    Chuck, do yourself a favor and get some of the carbide tipped bits from McMaster for drilling your holes. They'll hold up a lot longer than your regular drill bits, and even though they're more expensive they should be cheaper in the long run because you don't have to replace them so often.

    I prefer the heavier 1/8" boards over the 1/16" boards when I'm building turret boards because I counterbore the holes rather than drilling them through. The idea behind the counterbore is that I can build a turret board that has swage that is recessed into the counterbore such that the bottom of the board is non-conductive. Then I don't have to mess with stand-offs. I can just bolt the boards right to the chassis.

    When it comes to purchasing counterbore bits, even the non-carbide ones are significantly more expensive than conventional drill bits. Even worse, the carbide tipped ones cost multiples of what the regular counterbore bits cost. But carbide tips, either on a drill bit or a counterbore bit, are so much more durable with G10 that it's actually cheaper to use the carbide ones.

    McMaster is a good supplier.
    Will look into the carbide bits. But you know how it is. When you find spontaneous time and inspiration for the project and you need a bit, the hardware store IS RIGHT THERE. And I'm not inclined to small orders because the shipping always rubs me wrong. I'll have to look into the McMaster cat when I'm flush and see what else I might like to purchase to bulk up the order

    EDIT: Hmmm... I could sure use a new, better quality caliper
    Last edited by Chuck H; 10-27-2017 at 04:33 PM.
    "The man is an incompetent waste of human flesh. He should donate his organs now to someone who might actually make good use of them." The Dude re: maybe I shouldn't say, but his name rhymes with Trump

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  9. #9
    Supporting Member Chuck H's Avatar
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    I just looked into GRP product. Glass Reinforced Plastic (duh, I didn't know). I've never worked with it myself. G10 and FR4 are glass reinforced epoxy I believe. So, much more like other fiberglass products. I have to wonder then if the same methods used for fiberglass board materials wouldn't cause heat problems cutting GRP. Slower speeds and occasional pauses when cutting or drilling would probably mitigate this.?. Otherwise wet methods would be in order and that means expensive specialized tools. Something I do when grinding knives from flat stock is dip the heating steel into a bucket of water to cool it between every few passes on the belt. For cutting chores soapy water tends to stick around better than plain water (because soap breaks the surface tension of the water). So there's some experimenting in your future I think.
    "The man is an incompetent waste of human flesh. He should donate his organs now to someone who might actually make good use of them." The Dude re: maybe I shouldn't say, but his name rhymes with Trump

    "...less ear-friendly but handy for jazz." Leo_Gnardo

  10. #10
    Better Tone thru Mathematics bob p's Avatar
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    I buy my G10/FR4 boards from McMaster, as either 2" or 3" wide "bars" that are 3-feet long. When I need to cut off a strip for a project I just take the 3-foot "bar" make a crosscut on a table saw with a carbide tipped bit and a mask. (Mask is important.) I've never had any problems making a quick crosscut on a table saw with a plain old carbide blade.

    They also sell the boards in huge sheets, like 2x2-ft and all the way up to 4x8-ft, where you'd have to do much more cutting to fashion an amp board. Shipping something that big is also a problem, so I stick to the 2" and 3" wide "bars" that are either 2-ft or 3-ft long. They are easy to ship in a tube, and since they're already cut to width, all I have to do is a quick crosscut to make them the length I want. I prefer the "bars" over the "sheets" because making only a 2" or 3" long cut is that's easier on the tools than it would be to rip and crosscut the big sheets.

    As far as speed goes, I've never had burn problems with a table saw or with a drill press.

    If you want to consolidate an order to make shipping costs reasonable, look around for other tools and hardware. McMaster's catalog is 1000 pages or so. They have everything you could want, all under one roof. Small nuts and bolts, standoffs, bushings, bits, etc.
    "Stand back, I'm holding a calculator." - chinrest

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    McMasters catalog is 3600 pages and the new one will be 4000 pages. Or so I was told by my friends wife who works on the catalog layout. she does not understand how more could be added

    I love that place. I am fortunate to be able to get a family discount which amounts to 30-70% off listed price.

    my new favorite item is this, aluminum washer with neoprene isolating gasket. good for transformer mounting - https://www.mcmaster.com/#standard-washers/=19zwmxd

    Bob is this what you buy ? https://www.mcmaster.com/#grade-g-10...olite/=19zwlt3

  12. #12
    Better Tone thru Mathematics bob p's Avatar
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    I haven't seen an actual print catalog in longer than I can remember. I don't order enough to deserve one.

    Yes, I buy the G-10/FR-4 in the "bar" format. They've been yellow for as long as I can remember but they have different colors now.

    I see that the "bars" come in 2-ft and 4-ft lengths, not 3-ft like I said earlier. I'm not sure about the actual model, but these look like what I've been buying since the 90s:

    1/8" x 2" x either 2-ft or 4-ft: http://www.mcmaster.com/#8557K13

    1/8" x 3" x either 2-ft or 4-ft: http://www.mcmaster.com/#8557K15

    I think most people doing eyelets and turrets would prefer 1/16" and just drilling all the way through them.
    "Stand back, I'm holding a calculator." - chinrest

  13. #13
    Better Tone thru Mathematics bob p's Avatar
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    be aware that the bars only come in 1/8" and thicker, and 1/8" is too thick for a lot of work, like mounting snap-in caps. snap-ins work best with 1/16" board, but those boards are bigger in length and width and need to be cut down to size. so there is a trade off.

    I like the bars, because I can order them cut to width and just cut off a chunk with a chop saw if need be. But because they're thicker I have to counterbore them. on a recent project where I needed to mount snap-in caps, I wished I had 1/16". because I only had 1/8" I had to counterbore the bars to make them 1/16":

    caps-3.jpgcaps-4.jpgcaps-5.jpgcaps-6.jpgcaps-7.jpgcaps-8.jpgcaps-9.jpg

    you might be happier getting the 1/16" sheets and cutting them down.

    Chuck, it looks like I have a burn mark in my second pic. Oops.
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  14. #14
    Supporting Member Chuck H's Avatar
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    My point was that GRP is plastic. I don't know which plastic, but it's not going to be the same as other fiberglass products (like G10/FR4) which are bound with a catalyzed resin. Ordinary plastics are softer and more heat sensitive.
    "The man is an incompetent waste of human flesh. He should donate his organs now to someone who might actually make good use of them." The Dude re: maybe I shouldn't say, but his name rhymes with Trump

    "...less ear-friendly but handy for jazz." Leo_Gnardo

  15. #15
    Better Tone thru Mathematics bob p's Avatar
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    my bad -- I saw GRP and assumed that it was a glass reinforced polymer like G-10. I guess my brain did some auto-translating that it should not have been doing. my apologies to you and the OP for the confusion.

    yes, you're right. there are differences that are easy to overlook with the confusing alphabet soup. I'm not used to working with GRP since I've been using G10 for ages. I hadn't realized the same details about GRP as it's been off of my radar, so to speak.

    I'm a big fan of G10 (aka "garolyte") but even with G10 it's possible to leave some heat related tooling burns. At least the stuff doesn't melt though. i find that I don't have to worry all that much about tool speeds with G10. normal tool speeds for hardwoods seem to be OK, which means that as a practical matter you can get by alright with normal woodworking tools at their normal speeds, nothing all that special being required except carbide tipped bits for longevity. common woodworking tools may not be optimal but they work just fine. G10 definitely eats through non-carbide tooling, though.
    Last edited by bob p; 10-28-2017 at 08:58 AM.
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    I'm pretty sure GRP (aka FRP) is just a generic term referring to glass-fibre and plastic resin composites, usually polyester or epoxy resin. I've never seen the term applied to thermoplastics, i.e. glass-filled nylon. The material in question is most likely just G10, FR4, or equivalent. Just a difference in terminology I think.

    Andy
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    Better Tone thru Mathematics bob p's Avatar
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    One nice thing about trade names like "garolite" and specific formulations like "G-10" is that they remove all of that ambiguity. Knowing that a specific product conforms to MIL-I-24768/27, UL 94V0 removes all ambiguity about it's worthiness for our application.

    To further remove ambiguity: G-10 is a material type specification, and it's technically correct to use the term G-10 to identify a product. FR4 is a fire retardance rating, it's not a material type specification. When shopping we're looking for a G-10 product with a FR4 rating, not an FR4 product.
    "Stand back, I'm holding a calculator." - chinrest

  18. #18
    Supporting Member Chuck H's Avatar
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    Quote Originally Posted by Bloomfield View Post
    I'm pretty sure GRP (aka FRP) is just a generic term referring to glass-fibre and plastic resin composites, usually polyester or epoxy resin. I've never seen the term applied to thermoplastics, i.e. glass-filled nylon. The material in question is most likely just G10, FR4, or equivalent. Just a difference in terminology I think.

    Andy
    I suppose your right. I read "plastic" and I assumed thermoplastics. Usually if something is somehow better that is indicated in it's moniker. ie: Polyester Resin, Space Age Polymer or Catalyzed Epoxy. All plastics for sure, but where's the slick marketing in just calling them plastic Thinking about it now it makes sense because I don't know of any thermo plastics that would have the necessary bonding strength to take advantage of glass fiber reinforcement.

    Ok, so, all of the above good advice from Bob applies
    "The man is an incompetent waste of human flesh. He should donate his organs now to someone who might actually make good use of them." The Dude re: maybe I shouldn't say, but his name rhymes with Trump

    "...less ear-friendly but handy for jazz." Leo_Gnardo

  19. #19
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    I use a 10" abrasive disc in my ancient table saw. It works perfectly, doesn't seem to dull and makes clean cuts.

    Dave
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  20. #20
    Better Tone thru Mathematics bob p's Avatar
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    wouldn't the abrasive disc make the substrate get hot? IME cutting metals abrasive disks end up heating the workpiece a lot. so i'd be concerned about heating the G10 board. otherwise the abrasive disc sounds like it could be a good option ... but boy oh boy, that type of cutter would put a lot more small particulate stuff into the air that I don't want to breathe. mask required. i recently went to a specialized saw for cutting ferrous metals so I wouldn't have to mess with abrasive discs any more. but for someone who doesn't want to commit to expensive tools, i think an abrasive disc would probably be a good way to go if it doesn't heat the board enough to give it burn marks.
    "Stand back, I'm holding a calculator." - chinrest

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    No, it doesn't heat it up. I never noticed the material melting at all and no marks on the edges. It does make a fine dust, so a mask is a must. I also like that it doesn't chip the material at all.

    Dave
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