First Time DIY Build - Need Some Advice & Criti


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    Question First Time DIY Build - Need Some Advice & Criti

    Hi All,

    Just signed up this forum, i am currently designing a small (Large Desktop?) sized CNC Router for our business, it will primarily be used to machine 1mm Intumescent Fire Sheet, but also for producing one off parts for some of our older machines (Aluminium, Steel etc?). We have two much larger CMS Routers already that we use for production of which i create C Based programs for. I have a pretty sophisticated knowledge of building 3D Printers but this will be my first router, i had found this design online and really like how robust it looked:

    https://jeremyyoungdesign.com/2016/0...inal-assembly/

    So the design is heavily based on that machine.

    So far it is looking to be built from the following:

    Frame - Genuine Rexroth Extrusions & Connectors.
    Gantry - 18mm Aluminium - Bespoke Plates, Would need to have these made (Pricey?!).

    15mm Linear Rails & Carriages from Automotion Components - On all Axis

    4NM Nema 23's on All Axis

    I was recommended to get the AM882 Drivers from China, they seem to be very good, any personal experience of them on here?

    Dual RM2010 Ballscrews on X Axis

    Single RM2010 Ballscrew on Y Axis

    Single RM1605 Ballscrew on Z Axis

    Appropriate Fixed & Floating Blocks on each Axis.

    Ebay / Chinese 2.2kw Water Cooled Spindle.

    DDCSV1.1 Stand Alone / Offline Controller to be used in conjunction with aspire.

    Proximity sensors for endstops / homing.

    I have designed the Gantry to try and maximise the workable area / axis travel within the frame, however after running an analysis in Solidworks i can see that the weight distribution of the gantry is biased towards the back edge, as in this picture - it is quite difficult to see but there is a point inserted by the text "Point 1":



    Here is a general overview of the machine and how far i am with it so far:



    Any advice, comments, criticism is very welcome and appreciated.

    Thanks

    Alex

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    Default Re: First Time DIY Build - Need Some Advice & Criti

    So i know i keep banging on about the weight distribution of the Gantry, but i really am being stupid today. It seems at some point i had lost all of the material properties for my assembly parts, ive just spent a little while going through and properly setting the weights of each component, i have based the Aluminium Plates on being a 6061 Alloy, whether or not this will be the material the plates are cut from i dont know, but it was the most common material so i though i would go with that, i re rain the analysis and it has given me a hopefully accurate Centre of Mass for the gantry, indicated by the Red Dot, im hoping this is a pretty acceptable balance and wont cause any undue wear or stress to the linear bearings:



    Thanks

    Alex

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    Default Re: First Time DIY Build - Need Some Advice & Criti

    Remember your expectations really define what will be suitable.

    Quote Originally Posted by AlexDoran View Post
    Hi All,

    Just signed up this forum, i am currently designing a small (Large Desktop?) sized CNC Router for our business, it will primarily be used to machine 1mm Intumescent Fire Sheet, but also for producing one off parts for some of our older machines (Aluminium, Steel etc?). We have two much larger CMS Routers already that we use for production of which i create C Based programs for.

    Interesting; most machines talked about in these forums, run some variant of a G-Code interpreter.
    I have a pretty sophisticated knowledge of building 3D Printers but this will be my first router, i had found this design online and really like how robust it looked:
    The biggest factor to come to terms with is the need for robustness of the build. The stiffer the machine the better, the harder the materials the stiffer the machine has to be.
    I wouldn't recommend such a machine if you want to seriously machine aluminum and especially steel.

    By the way steel often requires a different spindle depending upon what you are trying to accomplish. Beyond that it is next to impossible to get milling machine performance out of a very low end router build.
    So the design is heavily based on that machine.
    I'd consider something different especially if you want to do serious aluminum milling.
    So far it is looking to be built from the following:

    Frame - Genuine Rexroth Extrusions & Connectors.
    I'm not a big fan of building structural parts of a router out of extruded aluminum T-Slots. This becomes an even bigger issue as you move up the scale of machining difficulty.
    Gantry - 18mm Aluminium - Bespoke Plates, Would need to have these made (Pricey?!).
    The gantry really needs to be a beam of substantial size and rigidity.
    15mm Linear Rails & Carriages from Automotion Components - On all Axis

    4NM Nema 23's on All Axis

    I was recommended to get the AM882 Drivers from China, they seem to be very good, any personal experience of them on here?

    Dual RM2010 Ballscrews on X Axis

    Single RM2010 Ballscrew on Y Axis

    Single RM1605 Ballscrew on Z Axis

    Appropriate Fixed & Floating Blocks on each Axis.

    Ebay / Chinese 2.2kw Water Cooled Spindle.

    DDCSV1.1 Stand Alone / Offline Controller to be used in conjunction with aspire.

    Proximity sensors for endstops / homing.
    These may become a problem if you machine a lot of metallic materials. It depends upon how well you can protect them from false trips. This is actually an issue with most switches but some inductive pros switches can be easily switched on by chips hanging in front of the switch.

    I have designed the Gantry to try and maximise the workable area / axis travel within the frame, however after running an analysis in Solidworks i can see that the weight distribution of the gantry is biased towards the back edge, as in this picture - it is quite difficult to see but there is a point inserted by the text "Point 1":
    I'm very concerned by how you space out the linear bearing blocks. The gantry supports look like an upside down pyramid, this is a bad thing. You really want your pyramid right side up. Yes this uses up some of your linear travel but it enhances stiffness. How far you spread the bearings out is a function of how high your gantry is and how much cutting force you need to resist. The same thing applies for Y and Z axis saddles.


    Here is a general overview of the machine and how far i am with it so far:



    Any advice, comments, criticism is very welcome and appreciated.

    Thanks

    Alex
    As for what you got so far, it really depends upon what you want to accomplish the machine, which would likely be fine for wood and some plastics but could certainly benefit from beefing up to handle aluminum. As for steel I don't see this as a practical machine for that. Steel in general is not where one would normally apply a router type machine but if you where to build such a machine you really need to have a well equipped shop with the large tools to pull off a far more robust machine.

    As for the use of extruded aluminum it has its place. In your case Im a bit concerned about the physical size of the extrusions you are using. However I really prefer steel in many places on a machine. For one thing it is cheaper. There is an issue of flatness of the steel but realize this aluminum extrusions are not flat either and rail mounting can be very tricky, in the end if you are looking for precision you will end up paying for milling services or use an alternative approach to flattening the beams. You also want to avoid flat panels preferring instead box sections



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First Time DIY Build - Need Some Advice & Criti

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