DuetWifi on a wood/alu router?

  • Hello,

    I'm thinking about using DuetWifi for (my first CNC build) wood/aluminum router.

    I can't find anything about that except this: https://forum.duet3d.com/topic/17/milling-cnc-with-duetwifi
    It's an 2 year old thread and there is no clear answer besides: "...sort of..., ...you may...,...it depends...".

    My situation is:

    • I'm a designer/illustrator/artist therefore seriously math/physics/programming challenged
    • all that electronics stuff: Ohms, Watts, Amperes, Volts... you might as well tell me to perform brain surgery
    • I'm good with: power tools, Windows, PC assembly, soldering, screws, nuts and bolts
    • I'm not afraid to use multimeter if you tell me what to do and what to expect
    • just got my first 3d printer a week ago - Anycubic I3 Mega - simple to assemble, cheap and well working
    • pressed a few buttons in Ultimaker Cura and started printing MPCNC parts
    • ordered these stepper motors: https://ebay.to/2PfCUV8
    • I'm undecided which board to buy: RAMBo, Smoothieboard or DuetWifi
    • I really like the wifi option in Duet and all good things I heard about it
    • I really don't care about spending 50-100 $/€ more or less for electronics
    • I just need it to work and be as simple as possible, the support in case of any problems would be nice

    I decided to build MPCNC because it's simple and cheap and seems easy to assemble.
    I'm also thinking about using the same MPCNC machine as a 3D printer, paper cutter or laser engraver by changing tool mounts.
    I'm aware that complicates things so it's not that important.
    Yes, I know MPCNC is a weak frame for any serious wood/alu work and I know that 3D printing requires different mechanics compared to routing.
    I don't care about speed or power, I just want it to work for some light prototyping, toys for my kids and similar.
    This is my first build and I'd like it to be as painless as possible.
    I' rather spend a bit more than waste time and money and not succeed.

    My question is:

    Is there a clear tutorial/documentation that I could follow and make a working router with DuetWifi?
    Something like: "you take wire A and connect it to point B and than you enter value X in software and you get result Y".

    Thanks for any help in advance and excuse my english - it is my second language.

  • administrators

    @ivan There are a few users here on the forums that are using the Duet to control various CNC machines including routing, or are generally knowledgeable on CNC, @Catalin_RO and @Danal come to mind.

    I am not aware of a tutorial that is as specific as connect wire A to point B for CNC machines, there will be a bit more research and learning required however if you break it down into various steps it should be manageable.

  • The Duet boards are a good choice for a machine like a 3D printer, CNC and Laser as all 3 of these modes are supported natively - specifically for light CNC work.

    Building your first CNC machine yourself will take time and patience, but many people have done it and theirs work. Having a good support channel (like this forum for Duet related issues and questions) will make it easier.

    The way I see it (have not built a CNC before):

    Step 1:
    Planning. You have done quite a lot of this already (what motors will be needed, what controller, the materials you want to work with, a good CNC design), but there are a little bit more that also goes into the planning:

    • What speeds are you looking to achieve?
    • Which spindle are you going to attach as the tool head?
    • Will you need dynamic speed and rotation direction control on your spindle?
    • Hardness of the materials you will be working with? It is nice to set the goal of machining aluminium and even hard woods, but they are very hard materials, that needs strong motors to allow the tool to move through. Also a weak frame might have bending issues in hard materials.

    Not trying to put you off, but personally I would not use a Nema17 stepper motor for a CNC machine - they can work for 3D printing and even lasers, but CNC have a lot of resistance. The ones you linked to simply does not have a lot of push/pull power (torque; these have 59Ncm, which basically means at a radius of 1cm from the center of the motor's shaft, it can push or pull with a force of 59 Newtons; 10 Newtons are 1kg). For comparison the 3D printers I work with have between 40 and 48Ncm stepper motors that simply skip steps when there is something in their way. That extra torque you have, will only make a small difference and I believe when machining, you will need to use an excruciatingly slow speed.

    On stepper motors, unless you have a length restriction (due to the frame), I would go for as long motor as I can afford - longer motors require less current (Amps) to get the same amount of torque. If going with a Duet, it is important that your motor's current rating is below 2.5A (for now, that is what you need to know). The Nema 23 motors can usually be powered from a Duet without requiring external drivers (unless they need more than 2.5A).

    Moving on to the spindle. There are many options available, but the most important things are: the higher the Watts rating, the easier it will work through your material (a 900W is a better option than a 400W spindle - the 900W will use more power/electricity while running, so energy costs should also be taken into account). Some people by the (usually) Chinese spindles and they can work very well for many people's needs. Others buy a router from a make like DeWalt (in USA the model 611 is very popular; it also have a 240V mains version for the rest of the world).

    Here it is important to note what voltage is needed by your spindle: the generic Chinese ones are mostly about 12V (which requires as 12V speed controller and 12V power supply; good news is that you can run your Duet from the same power supply). The Dewalt option uses Mains directly (it comes with a plug for mains so usually no need to even wire a plug for it), and have built-in speed control (though the Duet can't control its speed and direction).

    Now on to the power supply: For a Duet and 5x 2.5A stepper motors, I would suggest using a value of 100W. If your spindle will draw from the same power supply (like the 12V ones do), you should add their rating to the power supply (for example if it is rated at 500W, you add 500). Finally add a 20% safety margin (power supplies like running at about 80% of their maximum rating) so that adds another 120W, giving us 720W minimum power rating for the power supply, though usually they work in 50W increments, so we look for a 750W power supply at 12V.
    If your spindle runs directly on mains, like the DeWalt, you don't have to add its power requirements to your calculation and can simply use something like a 150W at 12V power supply (making it a lot cheaper and easier).

    A next big consideration is how to you will move your axis. Using an Ball Screw configuration gives very powerful and smooth motion, but costs a lot of money. Similar options are Lead Screws, Threaded rods, belts etc. Each have their advantages and disadvantages and their own set of extra parts required to make them work.

    Since you mentioned the laser, it is highly recommended to ensure you have an enclosure for your machine, when using the laser. This enclosure should filter the wavelength used by the laser module you use. In addition also use the standard laser safety guidelines (goggles etc).

    What type of endstops will you use (mechanical, optical etc)? What method will you use to probe/home the Z above your material?

    Step 2:
    When you have gone through all the planning, only then start buying and acquiring what you determined will be required by your build.

    Step 3:
    Assemble the frame. Without a frame, there is nothing to mount your electronics to. With the frame assembled and axis tested to work well, and run smooth, you can start to add the electronics.

    In this step you might also need a lot of help, since electronics are sensitive and if connected the wrong way, they will blow.

    Step 4 configure the firmware and start testing.

    Step 5: enjoy.

    I am actually also looking to get a CNC machine. For many years now I have thought of and done research thinking I will build my own. Very recently I developed the need for one and there is simply not enough time to build my own, so I will be getting a kit where everything is pre-made: I will just need to assemble it and can start working. Maybe later I will replace the controller with a Duet (this kit can't run autonomously), but that will not be as difficult as building your own from scratch.

    Building your own will force you to learn new skills in the fields where you say you are challenged; to me that is the fun part - I started 3D printing with little electrical, engineering, firmware programming etc knowledge (so little it was dangerous), and now I build and mod 3D printers (and their firmware), build my own IOT and embedded devices etc.

  • @t3p3tony Thank you for your suggestions. I'll check posts by the users you mentioned. Perhaps I'll contact them.

    I'm not afraid of researching and learning. I'm afraid of researching, learning, troubleshooting, wasting days and money and not succeeding in the end.
    I'd rather spend $100 more on some other product.
    All this CNC electronics stuff is new to me and I'll never understand it as some engineer could - and I shouln't actually have to.
    My $300 printer came half-assembled with a short manual and I assembled it, learned slicing in Cura and was printing in an hour or so. It was a nice experience.
    I wish I could be sure DuetWifi could be assembled, checked and working under a day.
    There might be a single checkbox I didn't know I should have checked and I could waste huge amount of time troubleshooting.
    That's why Im asking for some kind of tutorial/walk-trough.

    I wish I could find something like this for DuetWifi: http://smoothieware.org/cnc-mill-guide
    That seems like a detailed walk-trough that could be accomplished in under a day.

    I'll try analogy with web technologies: I don't mind a bit of "CNC-HTML/CSS" but if I have to understand and tweak jQuery or phpMyAdmin I'm screwed.

  • administrators

    It's fair to say that Smoothieware has a longer history of supporting CNC machines than Duet has; however we have been working hard to add CNC features that were missing from the firmware.

    One aspect in which the Duet may be better than the Smoothieboard for a CNC application is that the maximum stepper motor current is higher. Depending on how much motor power you need, this could save you from needing to use external stepper drivers. The standard advantages of the Duet will also apply, e.g. much better web interface, fast file upload to the SD card through the web interface, quieter stepper motors, and resume-after-power-fail capability.

    I have taken a quick look at that Smoothieware guide. It is one very long page containing a lot of information. The vast majority of that information is about connecting things to the board and is exactly the same as it would be for a 3D printer instead of a CNC machine.

    The Duet documentation has separate pages for different topics. You will find those pages in the wiki at https://duet3d.dozuki.com/. Specifically:

    Forum members already using Duets in CNC machines can tell you more.

    Regarding your analogy, if you use Duet you will need to become familiar with the some of the GCodes used to configure the firmware, although the online configuration tool will generate most of them for you. With Smoothieware you will need to become familiar with the commands in the config.txt file instead. Either way you will have a learning curve.

    HTH David

  • @jacotheron Thank you for a detailed reply. I really hope you didn't write all that just for me. 🙂

    I basically agree with you about all you wrote.
    I did my research and read a lot of forums, different opinions and articles.

    I wish you would've seen MPCNC I mentioned before your reply - it could've saved you a bit of writing.
    I agree with you about using NEMA17 motors for a router being weak but MPCNC uses 5 NEMA17 - 2 on X and 2 on Y axis.
    Also if you check the gallery or forums it seems it works well for wood routing, even aluminum.
    The guy that developed all that recommends NEMA17 53Ncm or 59Ncm, Dewalt 660 (600W) router and RAMBo board but I really would like to use DuetWifi because it is more powerful, can be extended in the future and has wifi.

    I really don't care about speed, the machine could work all day and night for all I care.
    It will be used a few times a month.
    Later on I could improve performance, buy a spindle, new motors, build another frame, whatever.
    This is my first CNC experience and I just wish I could make a working machine for as little money as possible so I can play around.
    The only thing that worries me now is electronics and software.

  • I would suggest a 1/4" palm router like a DeWalt DWP 611 or Bosch Colt. That is about the bare minimum. They are basically turbo charged laminate trimmers.

    Speed does matter. You want to cut fast enough to maintain sufficient chip load, for the depth, and RPM. This cools the bit, and keeps it from burning up. You will also create more chips, less dust. The bit should be cool enough to touch (with the router unplugged) when your done cutting. Typical handheld wood routers have universal brushed motors so our minimum spindle RPM is limited due to poor speed control/torque at the low end of the speed range. So chip load is going to be controlled by feed rate.

    So with a 1/4" end mill in wood you would probably want to be able to cut at at least 1.5 IPS or 40mm/s. More ideal would be 3-5 IPS, or 80-120MM/S, while climb cutting at 1/4"-3/8" depth. I own a machine that does that but it also cost $15,000 and has a 3.5" hp router motor, so obviously thats out of the question here.
    Just an example of how CNC routers quickly get exponentially heavier and more expensive.

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