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  1. #1
    Hi All,

    I want to cut a 50mm diameter cylinder out of a block of 6061 aluminium that is 40mm thick. I have downloaded GWizard to determine the correct feed and speed. My CNC machine is a 6040.

    The figures entered into GWizard are:

    Material - 6061 aluminium
    Tool - Carbide Endmill
    Tool Dia - 6mm, 3 flutes and a 'stickout' of 40mm
    Cut depth - 4mm
    Cut width - 4.6608mm (I don't understand this bit)
    KW limit - 0.8kW
    RPM Limit - 24000
    Min RPM - 1200
    Feed Limit - 10160 (2%) (I don't understand this bit either)

    The RPM comes out at 14031 RPM and Feedrate 205.3 mm/min

    All the reading are now in black but a warning re "Chipload is low, may cause rubbing!" is displayed.

    Please can someone check my figutes and what will be the best way to mill this cylinder from the block?

    Regards

    Gary

  2. #2
    Gary,
    I'd try a ramped profile cut, experiment with shallower DOC to see what the calculator says.
    Any calculator will assume a rigid milling machine though, which few of us have.
    See what the calculator says about a single flute cutter, they're great for chip clearance,

    - Nick

  3. #3
    Hi Gary,

    I take it you have filled in the setup page for your machine i.e. use generic gantry router and specify the weight of the gantry etc?

    The two settings you don't understand are:

    Cutting Width = Step over - what CAM strategy are you using to mill the cylinder? (I assume from a square block) If you are going for a slot cut then you should use 6mm and if using side milling of some sort then use 2.4mm on a 6mm cutter (although a 6040 machine may struggle with this much depending on depth of cut).

    Feed Limit = the feed rate of your machine before stalling occurs or the feed rate limit you have setup in the machine control software (MACH3?) (The 2% is the % of the limit the suggested feed rate is running at e.g. GWizard may suggest 1000mm/min for a machine with a limit of 10,000mm/min, which would be 10%).

    As Nick suggests I would try a single flute cutter for aluminium, unless you are going to side mill the block inwards to the cylinder using something like adaptive clearing or a similar strategy and then I would say your feeds for a 3 flute cutter are too low.

  4. #4
    Hi Nick and Washout,

    Thanks for the explanations and ideas. I entered various values into GWizard and selected 'Fine Finish'. Here are the final figures calculated:

    1 flute 6mm carbide endmill
    50mm stickout (Bottom of collet to tip of endmill). The block of Aluminium is 40mm thick.
    1mm depth of cut
    15671 rpms
    2.76 mm/sec (165.5 mm/min)
    Fine Finish

    Any higher and the deflection is too much, so now to buy a good endmill :)

    To use a 3 flute, I would need a spindle speed of 36,000rpm. My 6040's max is 24000rpm. I don't know the weight of my gantry. I didn't think to check that before assembly. I have purchased a 'clock micrometer' to check the alignment of the gantry to the bed.

    "using something like adaptive clearing". OK, I need to read some tutorials.

    Cheers

    Gary

  5. #5
    Gary,
    Have you tried a shallower cut with faster feed with the 3 flute? You ought to be able to get enough advance per flute that way, you'll need air to clear chips and cutting lubricant (WD-40 or a 30/70-20/80 engine oil/paraffin mix) to reduce chip adhesion to the cutter, a quick squirt into the cut once every pass or two is usually adequate,

    - Nick

  6. #6
    Hi Nick,

    OK, back to GWizard to try new numbers. I have an aerosol of cutting oil and a small air compressor and gun. As this will get messy (I was hoping to make dry cuts) I need to find/make a large perspex cabinet/cover. Yet another project, O Joy!

    Cheers

    Gary

  7. #7
    Hi Gary, my 6040 are not too fond of deep (long stickout) cuts with any 2 flute cutters. 1 flute seem to be much more in harmony with the rigidity, on my machine at least. The cutters I prefer, are from sorotec.de, 1 flute alu end mills. They stay sharp forever, and dont break easy.

    Just my thought on what have worked best for me.

  8. #8
    Quote Originally Posted by sinnsvak View Post
    Hi Gary, my 6040 are not too fond of deep (long stickout) cuts with any 2 flute cutters. 1 flute seem to be much more in harmony with the rigidity, on my machine at least. The cutters I prefer, are from sorotec.de, 1 flute alu end mills. They stay sharp forever, and dont break easy.

    Just my thought on what have worked best for me.

    Hi sinnsvak,

    Many thanks for that information. I was having problems finding 1 flute endmills. I'll purchase one from Sorotec.

    Regards

    Gary

  9. #9
    Hsmadvisor....

    much better than gwizard imo.

  10. #10
    HSMAdvisor here too.

    Input your data and then set the cutter engagement slider to minimum performance for this machine.

    Oh, and will definitely need lubricant on that - WD40 is good, paraffin too, maybe air-blast to clear the chips, chip recutting is a major tool-killer.
    Last edited by Davek0974; 11-09-2016 at 01:53 PM.

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