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Thread: 2 flute vs 4 flute Question

  1. #16
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    Nov 2022
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    Northern Colorado
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    David, youíre not terribly far off at 0.005Ē moving at 175, so you donít really fall into the dust category. Those are at least chips. I donít know a lot about your machine or your depth of cut used on hardwoods but itís possible youíre still spinning a tad fast or you could increase IPM a little.

  2. #17
    Quote Originally Posted by Michael Burnside View Post
    David, youíre not terribly far off at 0.005Ē moving at 175, so you donít really fall into the dust category. Those are at least chips. I donít know a lot about your machine or your depth of cut used on hardwoods but itís possible youíre still spinning a tad fast or you could increase IPM a little.
    Depth of cut on hardwoods is sufficient to cover the bottom of the compression bit which is 0.25" on the bit I use, so my DOC is usually around 0.300" on 3/4" thick stock. If it's a piece that I've planed or resawn down to around 1/2" then I cut it in one pass, same spindle speed and feed rate. I've cut the same pieces at 250 ipm but unless it's a production run 175 ipm works out fine for me, especially for one-off pieces.


    I'm not understanding where the 0.005" came from, though (chip load, maybe?). Can you enlighten me, please sir?
    David
    CurlyWoodShop on Etsy, David Falkner on YouTube, difalkner on Instagram

  3. #18
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    Quote Originally Posted by David Falkner View Post
    Depth of cut on hardwoods is sufficient to cover the bottom of the compression bit which is 0.25" on the bit I use, so my DOC is usually around 0.300" on 3/4" thick stock. If it's a piece that I've planed or resawn down to around 1/2" then I cut it in one pass, same spindle speed and feed rate. I've cut the same pieces at 250 ipm but unless it's a production run 175 ipm works out fine for me, especially for one-off pieces.


    I'm not understanding where the 0.005" came from, though (chip load, maybe?). Can you enlighten me, please sir?
    Yes the 0.005" is the rough estimate of chip-load given you are running at 18K RPM, moving at 175 IPM with a 1/4" 2-flute endmill. Ironically given the 18K RPM as a fixed target, I'd have started with 225-250 if my machine could handle it, but again, I don't think you are too far off. I'd say you're in the -20% to -30% category, unlike many that are >100% off The only thing that saves poor chip-loads is taking shallow bites, but it won't stop dulling bits or burning wood and honestly their jobs are just taking longer than necessary.

  4. #19
    Got it, thank you! I have cut at 600 ipm but it was due to a typo in my setup. However, the bit, machine, and piece of wood handled it without any issues. I was a mess watching it cut that fast but the machine just grinned and rode it out. But that also tells me I could be cutting much faster than 175 ipm.
    David
    CurlyWoodShop on Etsy, David Falkner on YouTube, difalkner on Instagram

  5. #20
    Join Date
    Dec 2010
    Location
    WNY
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    9,848
    Quote Originally Posted by Wes Grass View Post
    Forgot, slotting with a 4 flute puts a flute on centerline, which is trying to deflect ... 'things' ... while the trailing flute is generating one of the walls.

    A climb cut might need a finish pass to get the dimension and finish you want, depending on material, thickness ... and the rigidity of the machine.

    A 2 flute ramps its way in and out of the cut, with less deflection... usually.

    Tools last longer as well, on finish passes ... the flute gets a good bite into the material, instead of 'rubbing itself to death' from the progressive entrance with a conventional cut.

    Disclaimer: I'm mainly a 'metal dude'.


    I mostly use 2 flute end mills. On my machine a climb cut always results in a tapered sidewall, so I use a conventional cut when I need a true 90 deg angle. I haven't tried a finishing pass with a climb cut, however, so that may solve the problem. I'll have to give it try sometime.

    Overall, I'm not worried about bit life. I'm more concerned about part quality. 80 ipm with a 0.25" 2-flute bit and 0.175" doc gives me parts with a nice smooth finish. The chipload is only 0.004 but bits still last a long time.

    John

  6. #21
    Join Date
    Feb 2009
    Location
    Cedar Park, TX - Boulder Creek, CA
    Posts
    865
    More 'memb'ring ... when I started there they were using bits for cutting drywall to clear electrical boxes. Blunt tip for a pilot, and they were grinding that off. So a blunt end with no relief.

    I scrounged some 'worn out' 1/4" carbide endmills from my scrap box and brought them in for a demo.

    'Wow ... where do you get these?'

    LOL

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