MAX MPCNC FEEDRATE?

New Home Forum Mostly Printed CNC – MPCNC Advice – MPCNC MAX MPCNC FEEDRATE?

This topic contains 11 replies, has 6 voices, and was last updated by  Sven 1 week, 4 days ago.

Viewing 12 posts - 1 through 12 (of 12 total)
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  • #88326

    Jutoto
    Participant

    Hello

    what is the max feedrate of the MPCNC in the firmware setting?

    is it the same for all supported board?

    thank you

    #88328

    Kyle
    Participant

    #define DEFAULT_MAX_FEEDRATE

    Search for that in your Configuration.h file. The values there are listed in mm/sec.

    Ryan has his firmware with the following as downloaded from the Github page:

    /**
    * Default Max Feed Rate (mm/s)
    * Override with M203
    * X, Y, Z, E0 [, E1[, E2[, E3[, E4[, E5]]]]]
    */
    #define DEFAULT_MAX_FEEDRATE { 120, 120, 30, 25 }

    #88330

    Jutoto
    Participant

    Ok thank you.
    so the max feed rate for X & Y is 120 mm/s

    And what is the max X & Y feedrate that we can consider in the most optimistic case for this machine? if you consider having the easiest material, the most efficient milling cutter and the most efficient spindle…

    It is just to define the very optimistic up limit for a excel calculator tool

    #88339

    Barry
    Participant

    That’s not really how it works.  Every machine’s feeds will be different since every machine is build slightly different.  You could probably run full speed in something like foam insulation though.

    #88450

    Jutoto
    Participant

    That’s not really how it works. Every machine’s feeds will be different since every machine is build slightly different. You could probably run full speed in something like foam insulation though.

    Yes I know, but it was just to use the software max speed rate into some formula using Vc, Vf, n, Z, fz… in excel, to have a reference point for the speed that the formula will give me.

    as you speak about it, can you give me the max speed rate that you could use for MDF cuting with a 1/4 ” 2 flutes, because in this case the formulas gives me a speedrate which can be beyond of 40mm/s and I think it’s a lot for this machine.
    it seems to me that between 20 and 30 mm/s it can force too much for the rigidity of the machine when I cut MDF 15mm. Of course by adjusting the rpm of the spindle …

    #88454

    Barry
    Participant

    Not really.  I generally don’t cut with quarter inch end mills.  1/8 or 1/16″ is what I use.  I have a 2mm depth of cut at 10mm/s set in estlcam right now, but I can’t remember what it was for.  I’m pretty sure it was my mystery barn wood.  Which is either 200 year old oak(when it was used), or 200 year old pine(again when it was used).  I very rarely cut MDF.  When I do, it will usually be half thickness depth of cut at 10 to 15 mm/s.  I can slow it down if I need to with repietier.

    #88469

    Ryan
    Keymaster

    Yes I know, but it was just to use the software max speed rate into some formula using Vc, Vf, n, Z, fz… in excel, to have a reference point for the speed that the formula will give me.

    https://fswizard.com/www/

    There is a number that says cutting force. find what you machine can handle well, then you know how to set up every cut. You choose the right values and make sure it does not exceed the cutting force your machine can handle. As you can see there are many many variable s but that one numbers tells you what they all add up to at the end of the bit.

    Then, you need to take in account your depth of cut, as that effects what you machine can handle the most. If you can handle 1kg at full extension you should be able to handle double that number at about half extension of the Z. (it is reverse of that for the LowRider)

    #88477

    John
    Participant

    I can slow it down if I need to with repietier.

    Speaking of this, I have wondered and meaning to ask a while back, if it’s possible to have the “feedrate” on the LCD work, just like we do in 3D printing, so we could adjust the speed simply with the knob if we need to during a job.  I have tried mine and it does nothing.  I reckon that would be very useful.  How do we turn it on?

    #88501

    Barry
    Participant

    No idea on the lcd, I do it in repetier.  I do know not to speed it up too far, it will overspeed the z axis…  That’s the real problem.

    #88529

    Ryan
    Keymaster

    I have wondered and meaning to ask a while back, if it’s possible to have the “feedrate” on the LCD work

    It does, or at least should. Are moves are much longer so you will not get a response until the buffer catches up. A printer can do ten moves and clear the buffer in a fraction of a second, it can take ours mills minutes (or longer) to do the same. I think the buffer has something like a 12 line capacity-ish.

    #88542

    John
    Participant

    Ah that must be it then. Thanks Ryan

    #99627

    Sven
    Participant

    Yes I know, but it was just to use the software max speed rate into some formula using Vc, Vf, n, Z, fz… in excel, to have a reference point for the speed that the formula will give me.

    https://fswizard.com/www/

    There is a number that says cutting force. find what you machine can handle well, then you know how to set up every cut. You choose the right values and make sure it does not exceed the cutting force your machine can handle. As you can see there are many many variable s but that one numbers tells you what they all add up to at the end of the bit.

    Then, you need to take in account your depth of cut, as that effects what you machine can handle the most. If you can handle 1kg at full extension you should be able to handle double that number at about half extension of the Z. (it is reverse of that for the LowRider)

    where can i see the cutting force there? that would be really interesting, since thats the consistent value, no matter what material you use, if your cutting force is within the limits, there you go.

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