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  1. #1
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    Default Engraving Polycarbonate Coolant/Lubricant

    We are engraving polycarbonate with a "D-bit" style tapered cutter at 12,000 RPM to typically 0.4 mm on our Men's Shed router.
    There are problems with the swarf sticking to the cutter, and one of members is trialling a "turps/baby oil" mixture with some limited success.

    What do others use for this application ?

    Is a brush adequate, or do we need a spray ?

    Thanks for any assistance,
    John

  2. #2
    BobL is offline Member: Blue and white apron brigade
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    Default

    I have used meths when milling PC.
    Meths evaporates quickly and helps keeps the bits cool but BEWARE not to gas yourself and don't forget it is volatile and a fire hazard so cannot be used near a brushed motor.

    This website is pretty strong on not using any sort of oil and suggests using water.
    Polycarbonate FAQs | Emco Industrial Plastics

  3. #3
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    Thanks Bob,
    I would be reluctant to use water on our chipboard and MDF constructed router, but straight metho sounds good.
    I don't think we would have any issue with our brushed spindle motor because the router is used in a well ventilated area, frequently too ventilated.

    Would it help to increase the speed ?

    John.

  4. #4
    BobL is offline Member: Blue and white apron brigade
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    Default

    I'd try increasing and decreasing the speed.

    Also try a compressed air jet.

  5. #5
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    Hi John, when cutting polycarbonates, with a scroll saw, a trick is to put masking tape over the cut. You could try that over the cutting areas, decreasing speeds would help, as the cutter speed going to fast melts the poly. As Bob said try using compressed air to cool the tip.
    Kryn
    To grow old is mandatory, growing up is optional.

  6. #6
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    Australind , WA
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    I use my Fogbuster on everything I cut.
    It can be used water and air, or just air on its own. You can add something to the water as well, if you see fit. Only a very small amount of water is used.
    It is very effective in keeping the tool and the job cool to stop swarf sticking to the tool.

  7. #7
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    A couple of issues when cutting and lubricating plastics

    1/ be sure that your lubricant is compatable with the plastics ....... I cant remember the details with polycarbonate, but Acrilic does not like hydrocarbons .... get most oils or hydrocarbon solvents on acrilic ..and sooner or later the acrilic will craze. check the details with Polycarb.

    2/ with any material ..... tool and feed speed are pretty much everything .... you need to be cutting in a way that the tool is cutting cleanly ...... non optimal tool speed or feed rate and you will start to melt the plastic.
    Some of the problem you will be having is the round nose bit ...... because the cutting edge speed will be different from the outside of the blade to the inner tip of the ball ...... changing to a flat bottom cutter may help ...... a lot of the plastic signs I see are cut with a flat bottom cutter.

    3/ do you have direct dust extraction at the cutting tool ....... removing waste quickly and directly so it does not re-enter the cut helps all cutting operations ....... the waste is not recut and ground back into the job, this is very important because the waste is already hot ........ direct dust extraction will remove the waste and the heat carried by that waste AND the job will not have a blanket of waste keeping the heat in ....... also the airflow of the direct dust extraction will cool both the job and the cutting bit.

    4/ make sure your bits are sharp and clean ....... if the bits are dirty that will make stuff stick to them much worse ..... start with bright clean shinny and sharp bits ...... AND YES plastics are harder on cutting edges than many people want to believe ...... and the require absolutely sharp edges.

    5/ If you are looking for a lubricant I'd be looking for something detergent based ....... Lennox used to market a detergent based cutting lube that had no solvents, you may find dishwashing liquid works just as well. ... if you use detergent you won't need much ..... you are lubricating not cooling ......

    6/ as far as using volatile solvents like metho around brush motors .... DON'T ...... unless you fume extraction is perfect there is a very real chance of fire.

    cheers
    Any thing with sharp teeth eats meat.
    Most powertools have sharp teeth.
    People are made of meat.
    Abrasives can be just as dangerous as a blade.....and 10 times more painfull.

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