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  1. #181
    Hi Dave,

    That used to happen to me a lot. Slot milling over 8mm risks poor chip evacuation and clogging of the tool. I've seen people machine the outside material completely away (i.e. an outer pocket to leave the central island, not a perimeter slot). But then you need to be able to hold the part in the middle which isn't always possible.

    Another option is to use something like adaptive machining to mill a larger width slot than the tool.

    I tend to reduce the DOC when over 8mm into a slot and that works OK. I vacuum out the slot on every pass and give a quick spray of WD40.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  2. #182
    Adaptive does look good but none of the CAM software i have can do it.

    I tend to pocket the part out, leaving tabs etc to hold it, on the 8mm tool i used a 12mm pocket so two passes, but when the tip is deep in the pocket the air/coolant cant reach it and i was not paying enough attention i guess.

    I'll see if i can rescue the part with the modified paths and some extra air blast.

  3. #183
    Beginning to think i may never get this part cut :(

    I increased the speed to 9000rpm, and dropped the feed-rate a little as well as reducing the DOC a little.

    Good news was that it picked up the position ok.

    It made it about three passes then bogged down again, this time i hit the stop button pretty quick.

    Restarted and after a couple of passes cutting air, the motor turns off!
    No message on the VFD or screen.

    I gave up at this point and went in for dinner.

    So, why would the motor turn off if Mach did not know and there was no fault on the VFD?

  4. #184
    No idea why the motor turned off, it run ok tonight. Even managed to get the part finished.

    Reduced DOC to 1mm, feed rate to 800mm/min and rpm up to 9000.

    I think the issues may the cutter itself, not being designed for aluminium, just a standard two-flute slot drill.

    Now i need to flip it over, align to the axes and find an accurate way of picking up the x&Y datums.

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