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  1. #1
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    Default Countersink feed and speed

    I am having trouble finding the right feed and speed for a 60 degree 1-1/2” single flute countersink for my haas mini mill.
    Material is 1018. There is a 13/32 hole that is pre drilled. I am having to go about 1” deep with the countersink, bringing the largest diameter to 1.2”.
    To be safe I am currently running 300rpm and .5” IPM. It’s putting a high load on the spindle and surface finish isn’t good. Any help would be appreciated. Thanks

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    That's a lot of metal to be removing with a countersink.
    That said, you may want to change to a multi flute carbide countersink and up the RPM's into the spindle's "sweet spot".

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    Spiral out with the cutter so it isn’t taking it all with one pass.
    Don


    Sent from my iPhone using Tapatalk Pro

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    You probably need a different tool. I would probably get a smaller tool and interpolate it.

    If you were going to do what you're doing, with your tool, The first problem you have is that you're cutting 1018. You'll fight to get a good finish with that.

    Secondly, your rpm is probably fine, but your feedrate is probably too low. A faster feed will usually get you less chatter on your finish.

    You didn't say how the finish is bad. Is it chatter? Or is it torn up?

    I am guessing it looks like shit because it is torn up. If that is the case, your tool probably doesn't have enough relief behind it and is rubbing. I am guessing that because you're going .5ipm and you mention high spindle load. I know its just a minimill but that's damn slow for that rpm.

    I'd be trying a different tool.

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    I agree with a different tool and milling/interpolating it method. That machine is light weight and you should use technique over the one shot method. An insert chamfer mill cutter or an endmill with rads to rough. Finish with a c-sink via interpolating and depth cuts to bring it to size and give the finish a nice look.

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    Oooh. That’s a huge countersink to do with a Haas. Like the others I would highly recommend interpolating it. Probably be surprisingly faster, and better for your machine. A drill-mill would be a starting point, a helical flute chamfer mill would be better.

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    Just ramp down the cutter you have
    Don


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    Quote Originally Posted by RMW864 View Post
    I am having trouble finding the right feed and speed for a 60 degree 1-1/2” single flute countersink for my haas mini mill.
    Material is 1018. There is a 13/32 hole that is pre drilled. I am having to go about 1” deep with the countersink, bringing the largest diameter to 1.2”.
    To be safe I am currently running 300rpm and .5” IPM. It’s putting a high load on the spindle and surface finish isn’t good. Any help would be appreciated. Thanks
    I’ve had to do big ol 90 deg c’sinks in a mini mill in 304. I had to do low quantity’s. I spiraled out with an endmill bottom to top then spiraled out with a bull mill bottom to top. All this was done in CAM and I wasn’t worried about run time as much as rattling the machine to many pieces.

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  13. #9
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    Someone's playing a joke on you or you're putting us on...no one is that stupid to use a single flute chamfer cutter to do that.

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