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Thread: It's finished

  1. #1
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    Default It's finished

    Well it's finished and it works. Well 99% finished anyway....

    It'll do 275mm on each axis. Mainly cutting perspex.
    Just starting to work out cutter speeds and feed rates. At the moment it's running with the Dremel flat out and a feed of 7mm/sec which is about 1.4 ft/min. I think the rpm's are too high as the chip is very small. If i increase the feed rate the Dremel starts to run out of grunt (3mm cutter). So I should either reduce the cut depth so I can increase the feed or drop the rpm.Correct??? Would welcome any thoughts on suitable feeds and speeds.

    Thanks


    CNC :: IMG_1354.jpg picture by 4Lowie - Photobucket

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  2. #2
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    The ideal thing is to cut at the correct feedrate. It will avoid the tip edge rubbing on the material and becoming blunt. But if you're taking really shallow cut passes, you'll only be using the lowest bit of the cutter to do cutting work... so it will wear out quicker.

    I usually cut around 9000 to 1200mm/min with a 2-flute 3mm endmill 8000rpm, up to 2mm depth of cut. That's also using compressed air to blow the chips out and provide some needed cooling. I'm unsure what a dremel can accommodate though. You might need to increase the RPM and also the feedrate to match.

    Best thing to do is to run some tests. Cut some slots and vary FR, DOC, RPM. You might break a couple of bits in the process, but you'll learn heaps.



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    Default Heat

    Run without air once and see how hot the perspex and the cutter get. Too hot is not good!
    Yeah, you need to keep some material in the teeth.

    Cheers



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    Quote Originally Posted by Eclipze View Post
    I usually cut around 9000 to 1200mm/min with a 2-flute 3mm endmill 8000rpm, up to 2mm depth of cut.
    Is one of those numbers a typo? 9000? 1200?



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    Yep... meant 900 to 1200mm/min.
    You'd need a pretty fast machine to even rapid traverse 9000mm/min.

    Usually I slot cut at slower speeds when cutting thin acrylic, i.e 3mm thick. Otherwise there is too much flex/stretch in the material from the cutting force and accuracy drops.



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    That little thing is awesome, I'd love to build one for my little dremel. Any chance of getting a copy of the plans/part list? What sort of stuff have to cut on it?



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    I'd drop the rpm.



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