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Looking for smaller quality CNC mill - advice appreciated.

Discussion in 'CNC Mills/Routers' started by evalon, Jul 8, 2018.

  1. evalon

    evalon Well-Known
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    Hi all,

    I am about to buy a diy CNC mill kit and in my search for a suitable kit have come across this site which indeed is very inspiring ;) ... Many interesting builds and ideas ...

    By posting here I hope one of you may help direct me to a diy kit which fulfills the wishes I have for a CNC mill - I would appreciate such advice :)

    Key requirements for the CNC I am interested in buying is that it should have an appr. 40*40*7 cm milling cubic, and be able to mill aluminum, copper, brass and the like in "close to" manufacturing quality. Also, I admittedly don't have a very high budget so the price also needs be reasonable - preferably no more than EUR 750 altogether (from within the EU). It will be fine if it can be a good second hand machine.

    For a start I aim at getting a solid & stable construction and possibly save a bit on the spindle motor & electronics - which may later be upgraded. I will be using estlcam & an arduino uno to control things.

    Among the openbuilds CNCs I have been inspired by e.g. the RawCNC 1.5 (should be smaller though):,

    Rawcnc 1.5 Desktop Edition

    and the C-beam designs, possibly the Ox build if strengthened with e.g. these changes:



    I am, however, a bit unsure of whether or not the C-Beam or Ox builds themselves are sufficiently stable - so I hope someone knowledgeable here may possibly guide me to a design which fulfills the criteria I have listed above.

    Thanks for help in this ;)

    Jesper
     
  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    About as close as you're going to get on the budget specified would probably be something along the lines of a Sphinx which should be at a similar level of stiffness to the Workbee or any other C-beam framed system. To meet budget though you will need to hand cut the plates which is not a big deal if you have reasonable layout skills. Access to a drill press would also be helpful. As for the motors don't assume you need the most massive size available. Something in the 1.25Nm range should be sufficient. Instead focus on the drivers that will get the most power out of the motors you have.
     
  3. evalon

    evalon Well-Known
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    Hi Rick ... Thanks for your feedback & suggestion. I will take a look at the Sphinx ...

    I do have access to a drill press and possibly also a small CNC which could be used to make some plates if needed.

    Thanks for this tip! I will then go for something like the smallest nema 23 motors and good driver electronics. Would something like the DM542 microstep driver be fine?

    Cheers & thanks again for your suggestions,

    Jesper
     
  4. evalon

    evalon Well-Known
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    A P.S.: Would you have a suggestion for a "good/reasonable" beginner's spindle motor?

    Jesper
     
  5. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    DM542s are great drivers and are ideal if you can fit them into the budget. You can easily take them up to 36V which will give more power to the motors and you are not likely to outgrow them. But they don't come cheap and will eat up a fair amount of your budget. This is where you need to choose a path economically. Buy cheap and buy twice or find the money to stretch the budget to do things right the first time. The latter is obviously more economically sound but not always possible. Another option I've come across is the DM332T which based on specs should pair nicely with a midsize NEMA 23. Don't know anything about them though as I don't recall anyone here ever having used them.

    As for the spindle, that truly comes down to budget. Many default to the Dewalt or Makita trim routers simply based on price. 1.5kw spindles are nice and probably something you should aspire to at some point but they don't come cheap. This is one area though that upgrading at a later date doesn't really have a negative financial impact. While most upgrades create additional filler for the junk drawer, a trim router sent to the shelf just becomes just another tool in the reserve arsenal.
     
    GrayUK and MaryD like this.
  6. evalon

    evalon Well-Known
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    Hi Rick ... Just a brief posting to say that what you are suggesting looks very much in the direction of what I am looking for. Kudos to you ;-) ... I have, however, decided to draw up a CNC router myself (I have access to some 15 mm thick aluminum at a reasonable cost) and hope to finish a first/second drawing this evening.

    About the spindle, the makita or dewalt may be interesting for a first version. You write "trim router" - I tried searching for this on ebay but what comes up are specific wood routing tools. Is it one of those - or do you or another builder here have a key word that I would search for?

    Cheers & thanks,

    Jesper
     
  7. Giarc

    Giarc Master
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  8. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Yes, they are designed for wood use but work fine with soft metals. Typically in the US we use the Dewalt DWP611 and the Makita RT0701C. (I'm not sure what their 220V equivalents are called.) The only real issue is rotational speed as they run a bit fast for metal but that is easily resolved using appropriate bits and feed rates.
     
  9. evalon

    evalon Well-Known
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    @Rick 2.0 & Giarc.

    Thank you both for your feedbacks. Yesterday I looked into Dewalt & Makita routers available within the EU and for some reason they are scarce and seem to be more costly than in the US for similar (not the same, though) models. Maybe there will be a good find one of these days ...

    Have a good day,

    Jesper
     
  10. evalon

    evalon Well-Known
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    @ Rick 2.0 or one of the other openbuilders: I wonder if you may be able to help with a suitable supplier for this ... ? As it is I have decided to go with a double ball-screw design - similar to this one:

    YACLR CNC

    with the two differences that I will instead be using:

    - 15mm xyz linear rails, and
    - 1204 ballscrews

    However, I don't know of a good, yet price reasonable supplier for either of these parts (preferably within the EU or - if good and price-reasonable - also in China/Asia). Any chance you would know of such a supplier? I am aiming for good/reasonable parts as I can't afford e.g. Hiwin parts.

    Thanks for any insights ;-)

    Jesper
     
  11. evalon

    evalon Well-Known
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    Hi again,

    So, I have been drawing and now have more or less completed a CNC which will allow for an appr. 38 * 40 * 11 cm work cubic (model picture & .stl file attached). I have not yet made the holes in the plates - will wait with that until I am sure the design is as I would like. Please be welcome to comment if you find that a part of the design could be better/stronger.

    I have chosen to make the gantry side plates quite high so as to allow for a wide z-axis workspace. These plates are projected to be 10mm aluminum - which seems to be a lot - but given the length and my wish to make close-to-professionally finished millings I wonder if they should actually be thicker? Or maybe it would be feasible to attach a strenghtening shape on the outside of the side plates ...

    The Z-axis base material also is 10mm aluminum - assuming this is a reasonable balance between stability, rigidity and weight ... (?)

    The base of the CNC is made of V-slots - 20x80 & 20x60 - which will be glued together to give additional stability. The top two plates on the base are 15mm 5754 aluminum plates.

    The main issue with this design is that it will be somewhat more expensive than I had projected. Thus the raw cost of everything excl. the spindle will be about 800 EUR. And then I probably will have to drill just about 2000 holes ... :confused:

    Regarding the spindle I have found this one of ebay UK:

    Palm Router / Laminate Trimmer c/w Guide 240V D26200 ZEN (Not Dewalt D26200) | eBay

    It is a little less powerful than the Makita RT0701C - and could be lower quality - but I am hoping that it may be used for a start until I can afford a more powerful & higher quality spindle motor ... (?).

    Also, in this context: if someone here has a schematic of the RT0701C or the Dewalt DWP611 I reckon it would be relatively easy to modify these routers to operate at a lower rpm - thus allowing for the bits and speeds that are actually desired ...

    Regarding the linear rails (MGN15C blocks & rails of 550 mm, 505 mm & 250mm) and ball screws etc. (SFU1204 & BF/BK10; 550mm, 600mm & 300mm) I would still appreciate a suggestion on where to buy such components in reasonable quality & price ... Any ideas, anyone (within the EU or China/Asia preferred unless shipping from the US can be reasonable)?

    If one of you know of a metal working shop that may cut the aluminum plates etc. then that might also be interesting. And, lastly, realizing that this is some work, I may still be interested in buying a second-hand good-quality CNC, if available ...

    Have a good day,

    Jesper


    cnc-mill-v8.jpg
     

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  12. evalon

    evalon Well-Known
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    Hi once more ... This is just to say that I have chosen to buy a WorkBee instead of building the CNC mill myself. I concluded that it would take too long and since I mainly want to use the CNC it was too much of a digression.

    Cheers,

    Jesper
     
    GrayUK likes this.

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