Please help with choosing hardware and machine size

New Home Forum Getting Started Please help with choosing hardware and machine size

This topic contains 6 replies, has 2 voices, and was last updated by Profile photo of Juraj Juraj 3 weeks, 1 day ago.

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  • #20908
    Profile photo of Juraj
    Juraj
    Participant

    Hi guys, my name is Juraj, i come from Croatia and this is my first post.
    I have decided to build mpcnc and now i need some equipment and size advices.
    I have sourced most of expensive hardware and electronics from china for around 150$ but i still have no idea what spindle to use.
    I would like to have enough power to make complex parts in aluminium blocks, but i also plan to use machine to cut wood, acrylic etc…
    https://www.aliexpress.com/item/1-5KW-milling-spindle-1-5KW-ER11-CNC-air-cooled-spindle-motor-4-Bearings-A027A/32427916566.html?spm=2114.10010108.1000023.3.x3z8uo
    I found this spindle and it is within acceptable price range (with shipping 150$) but i don’t know if it’s too big or too heavy for mpcnc.
    How much power is enough for good aluminium cutting ? I dont want to overkill it..

    From there comes my another problem… what size ?
    I know there is more flex with bigger machine and that may not be problem when cutting wood but precise cutting in 5×5″ aluminium block on 1.5 x 1m (5x3ft) machine seems like a joke to me.
    Any advice regarding max work area of machine so it can remain very precise. I would like to build 5×3 ft machine but i will sacrifice work area if it’s needed for precision. Stainless steel conduit is being considered, i think it is alot cheaper in Croatia than US but i still have to check that. By the way, what wall thickness should i look for ?

    One more thing. What is considered to be standard cutting Z-hight ? I would like to have Z-axis as high as possible but i don’t know what tehnical problems come with that .

    Thanks in advance for all your help !

    #20913
    Profile photo of vicious1
    vicious1
    Keymaster
    #20914
    Profile photo of Juraj
    Juraj
    Participant

    Thank you, this helps but it does not give me specific answers, like power needed for aluminium cutting and best precision to scale ratio. I’m sure someone know that information so i don’t have to waste money on trial and error 🙂

    #20915
    Profile photo of vicious1
    vicious1
    Keymaster

    I have answered this questions a few times in the last few days. I will have to re word the FAQ I guess I thought this was all in there.

    Power-If you watch some of my videos, the first aluminum ones are using a flex shaft rotary tool probably a 1/4th the power of the dewalt or less. You can cut aluminum with a dremel. Power isn’t actually a big factor in precision, it is needed for speed. I know the physical tool size is covered in there.

    Machine size- This is also covered in there. If you don’t think it was covered well enough tell me the tolerances you are expecting. All you say is complex parts. If you want specific answers you need to ask specific questions.

    #20918
    Profile photo of Juraj
    Juraj
    Participant

    Ok, fair enough. For example, i need to be able to mill rc car parts, like suspension arms, chassis, engine mounts and stuff like that. Tolerance i would expect when making these parts is 0.1mm or 0.005in.
    I know z-axis depth is important as well as spindle precision when it comes to tight tolerance.
    But, on the other hand, i’m into sign making business so bigger machine that would be able to cut acrylic would come in handy.
    So, i’m trying to find sweet spot between these two or in other words, max machine size that would be capable of 0.1mm precision on ALL axis.

    #20919
    Profile photo of vicious1
    vicious1
    Keymaster

    I just added an few lines in the FAQ’s about tolerances.

    Sorry that just is not a good idea. Small aluminum High precision parts and large signs do not mix on any machine really.

    The tolerance you are asking for is what is expected from a large machining company using $100k+++ machines with a maximum machining size of 10x7x3″, link -https://www.firstcut.com/firstquote.aspx, and https://www.protolabs.com/resources/faqs.

    They promise no higher than .13mm, so expecting a sub $500 machine to beat there performance just isn’t really feasible.

    So if you make a nice small machine for your high tolerance parts, and get something with low run out and a good tool you can get very high precision/accuracy. I doubt any sign you make would need .1mm tolerances, so Best is a second machine. Just to give you an idea of .1 outside the world of 3d printing. Milled wood changes size by about 4% depending on humidity, metal does depending on temp 500mm of aluminum changes roughly +/-.1mm for ever 5 degrees Celsius.

    #20927
    Profile photo of Juraj
    Juraj
    Participant

    I’ll go with 600w spindle and smaller machine then. Thank you !

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