Building a machine specifically for large hardwood 3d milling.. looking 4 suggestions


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    Question Building a machine specifically for large hardwood 3d milling.. looking 4 suggestions

    Hello, I'm looking to build a CNC machine specifically for larger sized 3D hardwood milling, with long bits.

    And cut it FAST.

    I was using a CRP4848 before, with a Hitachi router, but with the deep 4" cuts, and according to my newbie calculations I was running things fairly slow, not wanting to ruin the $200 wood slab or the bits.

    I ended up having to sell that machine, and am wanting to build another one with this in mind.

    I'm considering using a 2x4' CNC Router Parts PRO model this time around, as I liked my first one, but will likely get the smaller model to save space.

    I'm also looking at getting a spindle, to have flexibility for slower RPM's and more power. But how much power?

    My 2-sided large cuts were ending up at 10-20+ hours per side, and I'm hoping to shave that down considerably.

    I'd really like to hear suggestions on what things are most important. Do I really need NEMA 32 stepper motors, or will NEMA 23 be ok? I was getting 500+ rapids with my 4 axis NEMA23 setup, but was limited in cutting feed rate by power/bit depth I believe (according tho the feed speeds I calculated with Gwizard.)

    Do I need a more powerful spindle? I had 2 1/4 hp last time.

    I'd also welcome suggestions on how to align and secure 2-sided 3d cuts. My last version was pretty shoddy and had to be adjusted once the cut was underway. Assume I'm cutting out of a bit 4" slab of wood.

    Thanks!

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    Community Moderator ger21's Avatar
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    Default Re: Building a machine specifically for large hardwood 3d milling.. looking 4 suggest

    Need more info.
    What exactly are you doing?
    What type of bits, how deep per pass, and how fast?
    What kind of wood?

    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
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    Default Re: Building a machine specifically for large hardwood 3d milling.. looking 4 suggest

    Quote Originally Posted by ger21 View Post
    Need more info.
    What exactly are you doing?
    What type of bits, how deep per pass, and how fast?
    What kind of wood?
    Hi Gerry,

    Long 6-8" ballnose bits 1/2" to 1/4" in diameter, as deep and fast as possible, Alder, maple or other hardwood.

    I'm looking for characteristics of a machine that can cut this stuff as fast as possible, taking 30 or so hours per project is making stuff I want to do unprofitable so if getting more power or better stepper motors will help I'd be interested in knowing.



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    Default Re: Building a machine specifically for large hardwood 3d milling.. looking 4 suggest

    I think the length of the tool is going to be the limiting factor. Even a 4" long tool is going to chatter like crazy at higher feedrates, especially a 1/4" diameter tool. Not sure where you're even finding 6"-8" ballnose bits?

    If you need to cut that deep, and do it fast, imo you need to use at least 5/8"-3/4" tools, and an extremely rigid machine.


    Anything that requires that much 3D carving is not going to be profitable, unless you can charge a lot of money for it, or build a multiple spindle machine that can cut several at the same time.

    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Default Re: Building a machine specifically for large hardwood 3d milling.. looking 4 suggest

    Quote Originally Posted by ger21 View Post
    I think the length of the tool is going to be the limiting factor. Even a 4" long tool is going to chatter like crazy at higher feedrates, especially a 1/4" diameter tool. Not sure where you're even finding 6"-8" ballnose bits?

    If you need to cut that deep, and do it fast, imo you need to use at least 5/8"-3/4" tools, and an extremely rigid machine.


    Anything that requires that much 3D carving is not going to be profitable, unless you can charge a lot of money for it, or build a multiple spindle machine that can cut several at the same time.

    Not sure why I mentioned 8", but here is where I got the 6" ballnose - End Mill, End Mills, EndMill

    Thanks for your input, I'll look into bigger roughing bits and yes, I've even thought about a second machine so I have more work being done.

    Any thoughts on how many HP I'd need to do big cuts with a 3/4" bit?



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    Default Re: Building a machine specifically for large hardwood 3d milling.. looking 4 suggest

    I suspect your limitations were
    1. rigidity and
    2. multiple details.
    Most-all, or maybe 98% of diy machines are weak on rigidity.
    Rigidity is everything.

    A hitachi router is extremely limited vs a real machine.
    You need a real spindle, ie a VFD+spindle, or a servo (3-phase motor) driven industrial spindle.
    The chinese ones are actually decent, by most reports.

    I also suspect your toolbits were far from ideal.

    Even using small toolbits,...
    an industrial machine, modern, could probably do your 30 hour job in 1 hour or less.
    With same size tools, probably.
    Explanation.
    Higher rpm, air-blast to cool the tool, very much higher speed, very,very, very much higher acceleration.
    Power at spindle as such is unlikely to contribute much (wood, 3/8).

    Suggestions, to do 5-10x better.

    Use a CSMIO-IP-S controller (the cheaper 250 kHz should be, I think, fine). Or similar.
    AC brushless servos, of 5000 counts. The cheap nema 23 size ones at around 290€ landed, from any favourite supplier.
    5000 counts servos / 3000 rpm (=50 rps) need 250 kHz.

    A chinese-sourced spindle, probably 3 kW for You.
    Air blast.
    Solid carbide toolbits.
    5x heavier frame and mounting and gantry.

    O.
    Gluing (yes glue is enough) with *industrial* goop cast iron (steel) slats to frame members should make everything vastly more rigid and heavy (sand surfaces, glue immediately after).

    Servos and the better motion-control engine will get you about 10-20x better results in small-move motion control, making all detail-work that much faster.
    Typically, about 2/3 - 4/5 of 3d stuff and total time depends on this.
    Acceleration is mostly very much more important than top speed.
    Servos are 5-10x faster, concept, than steppers, real world, in acceleration.


    Servos will increase top speeds 3-4-5x.
    This will have big effect on some stuff, and some effect on all stuff.

    A real high-frequency spindle is vastly more rigid, and accurate, than a hitachi router.
    You can push 3-5x more work, at least, through one.

    For example, in alu that is perhaps 3x harder than wood to mill;

    a modern high speed Brother speedio has often run 5-7 kW of alu in output power through a 3/8 end mill in alu.
    Typically running 10-16.000 rpm, or max rpm.
    This is likely 3-10x your material removal rate at max if accounting for wood vs alu.

    If you don´t have a high speed spindle, you cannot run carbide (shatters).
    If not a rigid machine/mount, cannot run carbide well (shatters).
    Air-blast coolant often helped others to increase performance.

    Any of the suggestions will help, quite a lot. Imo. Ime.
    All together will increase results immensely. Ime.

    When I went to a hw pulse controller, results doubled.
    When I went to brushless ac servos, results tripled, again.

    I personally never did woodwork, but better results on metal should translate to better results on wood.
    Anecdotes from clients on plastics and online, indicate the same.

    The HSM trick/system is to run really high rpm, really high feedrates.
    This keeps the tool cooler,
    reduces pressure/deflection at tooltip,
    needs a less rigid machine,
    removes huge amount of material.
    HSM can be or is often 2-4x more effective, and commonly/sometimes with better accuracies/finishes in roughing.

    And the same hsm system works industrially in steel, even in heavy production like auto stuff.
    Some of it even uses mql lubrication today in steel, mostly air with tiny micro-dots of oil.
    So no more wash-pump coolant like a pressure washer, but an invisible air-blast (cold).



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    Default Re: Building a machine specifically for large hardwood 3d milling.. looking 4 suggest

    I don't think HSM (High Speed Machining) is really intended for wood - the speeds it operates at are fast for steel, but wood is supposed to cut a lot faster already. A beefier spindle and thicker tools will help, but there's a limit to how fast you can expect to remove these hardwoods. The CNCRP machines are pretty good for the price, but if you're really pushing the envelope I doubt they'd be rigid enough to let you go much faster than you did before. For high-speed production you'd want to use a big industrial router, like a Komo or Thermwood, fitted with a 3-phase spindle rated at 7hp or more. Even the manufacturers of spindles like that discourage the use of long tools in them.

    Holding onto two-sided parts on a 3-axis machine usually involves setting up the part so it ends up in a frame of wood that it's connected to by a series of "bridges" - little tabs you remove later by hand. If the block the part comes out of stays intact, then it's not too hard to keep it in registration when it's flipped over, and to hold it down in a new position.

    Frankly, this doesn't sound like something you're really going to be able to do a lot faster than before, at least without throwing a lot more money at the problem. So either figure out something else to make that you can actually do faster, or charge enough additional money for what you're making that it becomes profitable.

    Andrew Werby
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    Default Re: Building a machine specifically for large hardwood 3d milling.. looking 4 suggest

    Why are you replying to a 3 year old thread???

    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Default Re: Building a machine specifically for large hardwood 3d milling.. looking 4 suggest

    I guess if you want speed on the motion you need to get the NEMA 34 kit matched with a 2.5KW watercooled brushless spindle motor
    Building a machine specifically for large hardwood 3d milling.. looking 4 suggestions-494378330_o-jpg
    Building a machine specifically for large hardwood 3d milling.. looking 4 suggestions-4-5kw-er25-380v-water-cooled-spindle
    6mm one side cut carbide bit, you can push the set-up up to 6000 FRO without stalling the stepper motor hardwood can be like a styrofoam on a 22K rpm spindle, just make sure to test cut first using the cursors on how deep it can cut before stalling the set-up, in my experience 10-15mm deep on my current set-up, on a NEMA 32 set-up I can only go up to 3-5 mm hardwood deep cut depending on the tool sharpness



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Building a machine specifically for large hardwood 3d milling.. looking 4 suggestions
Building a machine specifically for large hardwood 3d milling.. looking 4 suggestions