Trimming S2-glass

Discussion in 'Materials' started by catahoula, Mar 24, 2020.

  1. catahoula
    Joined: Mar 2020
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    catahoula New Member

    Hi,

    Does anyone have recommendations for cutting cured unidirectional S-glass laminates? I am moving my laminates this direction for the strength and flexibility, but it is much harder to cut, especially across the fibers, without fraying or burning than carbon or woven e-glass.

    Currently I'm using a rotary wheel, though am considering moving toward routing, whether flush trim with pattern or CNC. Still, any advice about cutting geometry (abrasive, burr, or compression) is applicable and appreciated.

    I'm new here, but I've lurked for a long time and have learned a lot about materials and modeling from this forum. This isn't a boat-specific question but I grew up in boats, used to build model sailboats, and aim to get back to actual boats soon. Still I think the topic could be useful for other boat builders.

    Thank you!
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    You can get diamond cutting wheels that are quite thin, I have a couple hidden somewhere, about 4 inch diameter. They would cut it OK, and less dust. This is the type of thing, for some reason there is a specified direction of rotation.
    Diamond.jpg
     
  3. catahoula
    Joined: Mar 2020
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    catahoula New Member

    Thanks, yeah I've been using abrasive diamond cutoff wheels so far, which breeze through carbon and woven glass. The new laminate is 4 layers of uni s-glass, with carbon on the outsides, and it burned up my diamond wheel in seconds. Pretty wild how tough this stuff is! It may require full flood coolant to keep from overheating. I'm looking now at adjusting the laminate so each layer of uni is between other layers of woven fabric. One other aspect is that glass laminates in infusion or autoclave processes have a higher fiber content than carbon, and this is going to be exaggerated with the stacked unidirectional plies. Maybe it's something to do with the lower amount of resin burning up quicker under the heat of cutting, which would also be a reason to alternate with weave.

    Edit to add: fiberglass thermal conductivity is way lower than carbon, at 0.04 W/mK vs 1.7 W/mK. That explains why I've had similar success cutting carbon wet or dry but have always struggled with fiberglass to a greater or lesser extent when dry cutting. Flood coolant makes either pattern-based routing or cnc cutting necessary as flood coolant makes hand trimming very difficult. I'm going to experiment with a mist cooling setup first and see if that is enough.
     
    Last edited: Mar 25, 2020
  4. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    were you using the type of wheel pictured ?
     
  5. catahoula
    Joined: Mar 2020
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    catahoula New Member

    Was using a 1.5" dremel diamond cutting wheel. Very thin but similar surface to what you posted
     
  6. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    I use two methods to cut cured glass. Depends on the cuts. Also, I am just using e glass I believe.

    I use a 4" circular saw with a carbide blade. It works pretty well for many cuts, but your thicknesses might drive heating as you mention and I get some infrequent frays out of the matrix. For my work, those areas are almost always getting taped, so I don't really worry about stand of flying glass here or there.

    I also use a carbide oscillating tool/blade, again on lighter cuts than you are trying. I don't know if you could get a diamond edged oscillating tool, but the oscillating tool gives great control; despite being slower. It also almost never frays glass out of the matrix.

    I tried cutting with diamond wheels and I felt like they did a nicer job, but were really spinning too fast and removing too little material for the exchange and the cost of wheels and speed of cut were not worth it. Let me know if this is of any help at all. I am just an amateur builder.
     
  7. catahoula
    Joined: Mar 2020
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    catahoula New Member

    Actually I've been meaning to try an oscillating tool but haven't got around to it yet. Thanks for the reminder, I'm going to try that tomorrow.
     

  8. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Don't bother if you don't get at least carbide blades. Regular ones won't last. Another idea would be to attach an airline to the tool. You could direct an air stream toward the cutting edge to reduce heating. It would be pretty clean that way, too. Keep in mind that moving air can actually cool below ambient temperatures as well.
     
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