FPT / IPT formulas?
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    Default FPT / IPT formulas?

    So there are a million calculators out there and I have tons of formulas in an excel spread sheet for reference. The one thing I can't find much info on is inches per tooth on tools. The only formula I have come across is Diameter/200. But that seems like a hyper conservative cut. For example, leaves a .000625 FPT on a .125 endmill.

    There's obviously a lot of factors with cutter, coating, material to cut, etc. All the formulas are super straight forward but I can't seem to find a good table of values for what chip loads to use.

    Mainly using simple HSS, some carbide, on Aluminum. Does anyone have good reference material or formulas for determining feed per tooth?

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    I usually use the upper end of the mfg.'s recommendations for feedrate and bump up the SFM.

    Obviously it depends on what you are doing (workholding, desired tool life vs. production rate, machine HP).

    But if the manufacturer puts the data out there for all to see, you better believe it, they did their homework.

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    Harvey Tool - Speeds and Feeds for every tool

    This one is good for small tools. Keep in mind I think it is all for solid carbide. Honestly, I wouldn't waste the time using HSS, except drilling and keycutting/jewelers type slitting saws.

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    Thanks.

    What I am currently working with is a lot of left over tooling that was used with a Tormach PCNC 1100. Things have been upgradded, got a new Haas SMM2, gotten a lot of Maritool tool holders and all that. But kind of an assortment of bits to use until we replace them all. We do small batch prototyping so dont have the production or budget of large shops. So just trying to find some decent guidelines to help program in speeds and feeds.

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    OP, one thing you want to get started on (if you haven't) is get into trochadil(?)/high speed type machining. The mini will like you better for it. Light radial cuts, full depth (if possible). And upgrade to carbide endmills as soon as possible to take advantage of the 10k rpm spindle...

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    I'd recommend using FS Wizard. Start at 50-60% of his recommended feed rates until you get used to your machine. Once you use the machine for a while you'll see how hard you can really push it.

    FSWizard Machinist Calculator

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    I cannot recommend this one enough. It has everything I need and more.
    I've been using it since for about 5 years maybe more I can't remember.
    Advanced CNC Speed And Feed Machinist Calculator - HSMAdvisor
    It's not just for HSM toolpaths, you can use it for drills, slotting, etc... and you can define your own machine specs too so it knows the limits of what it can push.

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    42 is the answer!!

    The formulas are all worked out obviously. If you want formulas, ask.

    Every Tool is different, not just the material used to make it, but the designation of Tool meets different needs (Drill, Endmill, Tap, and all their variants)

    But determining chipload per tooth has a lot of variables. Unfortunately the real knowledge comes from time, experience, failure, trial, error, good advice, bad advice, etc. I rarely use manufacturer's recommendations. I think they are part of the marketing strategy. Ideal set-ups don't happen to me very often. I would look for an older book like; Shop Theory or Audels Machinists and Toolmakers handy book.

    You might get better wisdom in the General sub-forum.

    BTW what is diameter/200? What is the 200 value?

    R

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    Quote Originally Posted by litlerob1 View Post
    BTW what is diameter/200? What is the 200 value?
    Probably tool diameter / 200 = fpt

    E.g., 1/2" endmill: .500 / 200 = .0025, which seems to be a reasonable starting point or rule-of-thumb. My gut tells me it'll get overly large with larger tools though. YMMV....

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    In addition to the already-mentioned fine FSWizard and HSMAdvisor calculators
    You can also check out the live machining formulas here:
    General Speeds and Feeds Formulas | HSM Machining

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    Quote Originally Posted by zero_divide View Post
    In addition to the already-mentioned fine FSWizard and HSMAdvisor calculators
    You can also check out the live machining formulas here:
    General Speeds and Feeds Formulas | HSM Machining
    FWIW, I love your website.

    Lot more professional and accurate than CNCCookbook.......

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    Quote Originally Posted by mountie View Post
    Probably tool diameter / 200 = fpt

    E.g., 1/2" endmill: .500 / 200 = .0025, which seems to be a reasonable starting point or rule-of-thumb. My gut tells me it'll get overly large with larger tools though. YMMV....
    That seems pretty conservative overall, but maybe for tool steels, exotics? Not sure as I have not cut much of any type of steels in years.

    We usually run .005fpt / 1000sfm on a 1/2" endmill in aluminum, and that is still pretty conservative. The only reason I (we) don't push harder is alot of times we are holding onto .05-.100", and with different skill level of operators it can get dicey.

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    Quote Originally Posted by Mike1974 View Post
    That seems pretty conservative overall, but maybe for tool steels, exotics? Not sure as I have not cut much of any type of steels in years.

    We usually run .005fpt / 1000sfm on a 1/2" endmill in aluminum, and that is still pretty conservative. The only reason I (we) don't push harder is alot of times we are holding onto .05-.100", and with different skill level of operators it can get dicey.
    That's a fair point. I need to remember that many of you are running more capable machines than I (Haas TM-1P)....

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    Quote Originally Posted by litlerob1 View Post


    BTW what is diameter/200? What is the 200 value?

    R
    Think of it as 1/2 of 1% of the cutter diameter.


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