Speed improvements: feed or DOC?

New Home Forum Mostly Printed CNC – MPCNC Advice – MPCNC Speed improvements: feed or DOC?

This topic contains 9 replies, has 4 voices, and was last updated by  tampe125 1 week, 2 days ago.

Viewing 10 posts - 1 through 10 (of 10 total)
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  • #83266

    tampe125
    Participant

    Hello again,

    finally I have a “proper” spindle: a 500W chinese spindle (full details here). Before I was using a Dremel that I had lying around and my settings were VERY conservative, since that little tools could do very little.

    I applied the suggested settings from the Milling Basics page, now I wanted to speed up things a little. I will cut plywood only, I made some tests with a Depth Of Cut of 2mm and things seems to went fine. What should I do now? Keep increasing the depth until I can find the limit? There is more margin?
    Should I try instead to go faster and increase the feed speed?

    Any suggestions? What’s an usual depth of cut?

    #83268

    Jeff
    Participant

    Generally (from what I’ve seen here) DOC is better then Feed Speed.  A higher DOC disperses the heat on the router bit better so you aren’t always just using the tip.  Fewer passes is also faster then more but faster passes (if that makes sense).  Everyone’s build is different so you just need to keep doing tests with yours.  I would increase the DOC by 1mm at a time and see how it performs.  As you are doing it, just make sure you are still making good chips and that they are being cleared.  Look at the Milling Basics page under the MPCNC or LowRider pages to give you some more info.

    I’ve been looking to find the “correct” settings as well, but since these machines are all custom, there is no one right answer.

    2 users thanked author for this post.
    #83273

    Guffy
    Participant

    use this calculator (it also available as android application)
    https://fswizard.com/www/
    set Wood as material and parameters of your tool/spindle

    #83278

    tampe125
    Participant

    Thank you for the link to the calculator, but that answer actually raises more questions.

    All my tools are something like this  , so how many flutes do they have? I can see that the RPM are an important factor, how can I get it (there’s no indicator on the spindle)?

    #83292

    Bill
    Participant

    Those look like four flute combo bits (both down cut and up cut) and are close to the worst choice you could have made (though they’re nice and cheap). When you spin a bit like that fast there’s not a lot of time to get the chip out of the way and the chips are going to be really small. You are much, much better off with a single flute bit which gives plenty of room for the chip to start and clear even with the high RPMs. The ones you have will work, but you’ll have a much harder time keeping things from scorching and you won’t be able to push the depth or speed much without packing the grooves full of dust. If your spindle has speed control, drop it as far as you can (maybe 2000-4000 RPM?) and then start increasing DoC. Once you see how deep you can go without packing the grooves up you can start increasing the speed of movement.

    2 users thanked author for this post.
    #83298

    Guffy
    Participant

    try to use “HP/roughing end mill” and flutes… looks like them are 6 or more.
    your spindle can rotate 3000-12000rpm. i guess it should be +- proportionally to angle of potentiometer or input control voltage 0-10V (do you control speed from firmware?)

    #83320

    tampe125
    Participant

    Regarding the tools: yeah, I know they’re pretty cheap/bad, I had troubles with chips getting out. I chose to start out cheap and then move to better tools. Speaking of it, what’s a good number of flutes? I found some 4 flutes tools, but 2 are better?

    Regarding RPM, I’m using the potentiometer and I’m trying to “hear” the best speed .I’m try to use the firmware.

    #83321

    Guffy
    Participant

    Those look like four flute combo bits (both down cut and up cut) and are close to the worst choice you could have made (though they’re nice and cheap). When you spin a bit like that fast there’s not a lot of time to get the chip out of the way and the chips are going to be really small.

    Such bits in our country and in Russia named “corn” bit. Usually it used to cut pcb, plastic and plywood

    #83323

    Guffy
    Participant

    Most of bits i bought are carbide single flute. 1/8, 3mm or less. And i have a few 2 flutes bits. I bought them in two local internet shops instead of aliexpress just because i can buy one required item here and have one day shipping – for bits this matters.

     

    #83568

    tampe125
    Participant

    Thank you all for your replies.

    Just bought some 2 and 1 flutes tools, they should arrive tomorrow so I’ll start playing around.

    Thanks again for your patience!

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