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    Default machine losing its position every time I do an undercut with a keyseat cutter

    I am pretty new to machining and have been tasked with using this machine for creating one-offs and prototypes:
    https://www.ebay.com/itm/20280771500....c100010.m2109

    The problem I am having is that every time I try to use a keyseat cutter to do an undercut or cut a simple O-ring groove, the stepper motors start to skip steps or something and then the machine starts drifting further and further away from where it is supposed to be cutting.
    For example:
    I tried cutting a (2.63mm deep x 4.775mm high) circular oring groove in 6061-T6 aluminum using this cutter: Solid Carbide Key Cutter W/ Corner Radius - Series 101
    with a 0.2mm stepover and 2.4mm stepdown, and by the end of the first stepdown the shaft of the cutter was rubbing against the part, which meant the machine had drifted by about 0.5mm, rendering the oring groove useless.
    I had definitely aligned the WCS correctly this time since I knew I would have trouble cutting this O-ring groove and I wanted to eliminate the possibility of the WCS being misaligned.
    For speeds and feeds I used 257 smm (843 sfm), and a feedrate of 100 mm/min (3.937 in/min).

    The manufacturer recommends 300 sfm, which equates to 2400 RPM for this cutter. I am not certain my machine can handle such a slow rpm without having even more trouble.

    How do I go about cutting these O-ring grooves without having such issues?
    I work at a subsea R&D company, so I definitely need to be able to cut functional O-ring grooves.

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    Default Re: machine losing its position every time I do an undercut with a keyseat cutter

    Have you read the jargon at all?
    It's described as a sheet metal engraver.
    Basically for engraving coins and such.

    If you want to stepdown at 2.4mm you need a mill for that.
    You need to step at most 0.3mm, doing the job in several passes.
    That's where your problem is. The weight/force of the head pushing down on it is litterally stopping the little motors from moving it.

    Put it this way. You see the cat statue that was cut?
    It says the roughing process was done with a 6mm end mill, rpm 12000, Feed at 1200mm/min, at 0.3mm depth / stepdown.
    Finish was R2 ball mill, rpm 12000, Feed at 2000mm/min depth / stepdown of 0.05mm!
    THAT is the depth of cut it's designed for



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    Default Re: machine losing its position every time I do an undercut with a keyseat cutter

    Quote Originally Posted by OhFudge94 View Post
    I am pretty new to machining and have been tasked with using this machine for creating one-offs and prototypes:
    https://www.ebay.com/itm/20280771500....c100010.m2109

    The problem I am having is that every time I try to use a keyseat cutter to do an undercut or cut a simple O-ring groove, the stepper motors start to skip steps or something and then the machine starts drifting further and further away from where it is supposed to be cutting.
    For example:
    I tried cutting a (2.63mm deep x 4.775mm high) circular oring groove in 6061-T6 aluminum using this cutter: Solid Carbide Key Cutter W/ Corner Radius - Series 101
    with a 0.2mm stepover and 2.4mm stepdown, and by the end of the first stepdown the shaft of the cutter was rubbing against the part, which meant the machine had drifted by about 0.5mm, rendering the oring groove useless.
    I had definitely aligned the WCS correctly this time since I knew I would have trouble cutting this O-ring groove and I wanted to eliminate the possibility of the WCS being misaligned.
    For speeds and feeds I used 257 smm (843 sfm), and a feedrate of 100 mm/min (3.937 in/min).

    The manufacturer recommends 300 sfm, which equates to 2400 RPM for this cutter. I am not certain my machine can handle such a slow rpm without having even more trouble.

    How do I go about cutting these O-ring grooves without having such issues?
    I work at a subsea R&D company, so I definitely need to be able to cut functional O-ring grooves.
    The minimum speed for these spindles is 6000 RPM any less and you will stall the spindle if the steppers are loosing steps you may be over loading them or they may need some settings changed

    Mactec54


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    Default Re: machine losing its position every time I do an undercut with a keyseat cutter

    Quote Originally Posted by mactec54 View Post
    The minimum speed for these spindles is 6000 RPM any less and you will stall the spindle if the steppers are loosing steps you may be over loading them or they may need some settings changed
    I doubt it's the settings.
    Trying to go 2.4mm DOC on a machine classed as an engraver. Say no more.



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    Default Re: machine losing its position every time I do an undercut with a keyseat cutter

    Quote Originally Posted by dazp1976 View Post
    I doubt it's the settings.
    Trying to go 2.4mm DOC on a machine classed as an engraver. Say no more.
    It has a 2.2Kw spindle it will do that in aluminum with ease , he just has to get his speeds and feed correct

    There are no spec's on the stepper motor size, to make any assessment of what is going on with the lost steps, but most likely over load from running the cutter too slow

    Mactec54


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    Default Re: machine losing its position every time I do an undercut with a keyseat cutter

    Quote Originally Posted by mactec54 View Post
    It has a 2.2Kw spindle it will do that in aluminum with ease , he just has to get his speeds and feed correct

    There are no spec's on the stepper motor size, to make any assessment of what is going on with the lost steps, but most likely over load from running the cutter too slow
    I found 1 that states they're: 57 two-phase 3A 150N.cm.
    If that can help you guide him with his F, S, RPM & DOC values.

    It is way less than what I had on a mini mill though and that was c**p.
    Stalled & lost steps at anything above 1mm deep.



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machine losing its position every time I do an undercut with a keyseat cutter

machine losing its position every time I do an undercut with a keyseat cutter