Couple questions before I make the purchase



  • Hi,

    I've used a duet 2 wifi for a few years now on my printer and couldn't be happier. I'm now towards the end of a CNC router build and I'm looking for a control board to use.

    Sorry to ask what are probably newbie questions here but I'm struggling to find answers for some of these. So much so that I've completely finished my cnc build (mechanically speaking) but still have no idea when it comes to the electronics yet.

    My current setup for the CNC is 4x nema 23 3A steppers, supplied through 4 Tb6600 (chinese clones) (36v input) , controlled by an UNO/Grbl breakout board

    I've found a HC board on here that looks ideal for my setup, but I've got a couple questions I can't seem to find answered anywhere.

    • What voltage can I supply for the stepper motors? (I've used these and it makes no mention of voltage : https://www.aliexpress.com/item/32823072753.html) I cant see where on the board page on here any specs for input voltages etc

    • Is it possible to setup a homing script for skew compensation. I.e where you home 2 points in the x and y axis, and the machine applies the skew correction automatically from that.

    • Does the web interface change when set to cnc mode to show controls for setting the work offset etc, or can it only be done by the saved macros on the right?

    • Since it runs reprap and not something cnc orientated like grbl, am I going to run into issues trying to export compatible gcode files from cad packages?

    • What other limitations should I be aware of when using this compared to something designed for CNC from the ground up?

    Many thanks in advance



  • I can answer a couple of questions

    • I use the ooznest version on my dads CNC router. Its included in the firmware download https://learn.ooznest.co.uk/Wiki/WorkBee_Firmware_Releases. It allows setting of the work offsets through the web interface.

    • They also have a post processor for fusion360 available at the bottom of that page to allow duet compatible gcode to be produced.

    Are you looking at the duet 3 rather than the duet 2?



  • Thanks for that, The fusion 360 post processor sounds great since I use that for the majority of my 3d printing modeling.

    I'm looking at the Duet 3 HC : https://www.duet3d.com/Duet3Mainboard6HC which I'm not sure is supported on the ooznest firmware releases?



  • @Asdasd1234

    It'll be supported on DWC as long as its ran in standalone mode rather than connected to a raspberry pi.

    The duet 3 can support an input voltage up to 32V. It doesn't allow control of external drivers although an expansion board is planned for this.

    I'm not aware of any limitations when it comes to CNC control for a router. The duet 3 also has a connection for controlling a VFD.

    The only question I can't answer for you is about skew compensation.


  • administrators

    @Asdasd1234 said in Couple questions before I make the purchase:

    Hi,

    I've used a duet 2 wifi for a few years now on my printer and couldn't be happier. I'm now towards the end of a CNC router build and I'm looking for a control board to use.

    Sorry to ask what are probably newbie questions here but I'm struggling to find answers for some of these. So much so that I've completely finished my cnc build (mechanically speaking) but still have no idea when it comes to the electronics yet.

    My current setup for the CNC is 4x nema 23 3A steppers, supplied through 4 Tb6600 (chinese clones) (36v input) , controlled by an UNO/Grbl breakout board

    I've found a HC board on here that looks ideal for my setup, but I've got a couple questions I can't seem to find answered anywhere.

    Maximum input voltage for the MB6HC is 32V.

    • Is it possible to setup a homing script for skew compensation. I.e where you home 2 points in the x and y axis, and the machine applies the skew correction automatically from that.

    You mean for compensating for the X and Y axes not being exactly 90 degrees from each other? Yes you can compensate for that, but you need to take measurements manually and then put the required compensation in the startup configuration file. If your frame is stable, you should only need to do this once.

    • Does the web interface change when set to cnc mode to show controls for setting the work offset etc, or can it only be done by the saved macros on the right?

    Currently the web interface is not optimised for CNC use. So you would have to use macros for workplace offsets etc. or else send the commands manually through the console.

    • Since it runs reprap and not something cnc orientated like grbl, am I going to run into issues trying to export compatible gcode files from cad packages?

    Unlikely, because RRF understand most flavours of CNC G-Code. It doesn't handle G18 or G19, so the only circular moves you can do are in the XY plane.

    • What other limitations should I be aware of when using this compared to something designed for CNC from the ground up?

    I'll leave that for others with more CNC experience than me to answer.



  • Thanks for all the responses

    @jay_s_uk said in Couple questions before I make the purchase:

    @Asdasd1234

    The duet 3 can support an input voltage up to 32V. It doesn't allow control of external drivers although an expansion board is planned for this.

    I was planning to ditch the TB6600 drivers and drive direct from the board. Would the steppers I link in the original post be ok for this if I supply 32V?

    @dc42 said in Couple questions before I make the purchase:

    You mean for compensating for the X and Y axes not being exactly 90 degrees from each other? Yes you can compensate for that, but you need to take measurements manually and then put the required compensation in the startup configuration file. If your frame is stable, you should only need to do this once.

    I don't think I explained that well. I've seen something similar to this poorly drawn example: https://i.imgur.com/1xGqyCS.png
    In that, I've seen machines home at the red points and work out the work-offset and apply it on a part-by-part basis rather than need to manually work it all out etc. It doesn't seem like it would be too difficult to add as a feature if it's not already.

    Currently the web interface is not optimised for CNC use. So you would have to use macros for workplace offsets etc. or else send the commands manually through the console.

    No problem at all. Is the firmware open source? If so, adding those buttons in "should" be within what i can actually do lol



  • @Asdasd1234 said in Couple questions before I make the purchase:

    I've seen machines home at the red points and work out the work-offset and

    You can probe in any axis and set the work offset for that axis, all available now. NIST G-Code standard G54, 55, etc, etc. Automated "touch" conductive, or switch, or manual with a "wiggler" (edge finder) or ...

    I don't believe there is a way to probe the same edge multiple times and set an "angle". But then again, I may not be understanding the diagram, because I haven't seen this feature in any other "hobbiest" level CNC systems.

    Duet is shipping conditional g-code right now. Variables will be added soon. Once that is available, a macro that can calculate the angle seems VERY straightforward. What to do with the results of that calc... that I'm less sure.



  • @Danal said in Couple questions before I make the purchase:

    I don't believe there is a way to probe the same edge multiple times and set an "angle". But then again, I may not be understanding the diagram, because I haven't seen this feature in any other "hobbiest" level CNC systems.

    That's fine, It's not something deal breaking, I just saw it in some DIY builds on youtube a while back and assumed it was a common feature.

    EDITL Just seen your edit. Having the variables would indeed make that easy by the sounds of it!



  • @Asdasd1234 said in Couple questions before I make the purchase:

    it was a common feature

    It may be something that I just haven't run across. I do a fair amount of home CNC, including some limited production runs. And, I was taught by a pro, and still talk to him a lot. Of course, that doesn't guarantee that I do or don't have a gap around a specific topic, like rotated work coordinate systems.



  • @Asdasd1234

    The motors look ok, apart from the inductance being slightly on the high side. See https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors#Section_Inductance
    You could use the EMF calculator at https://www.reprapfirmware.org/ for an overview on max speed etc.

    And if you go with the Ooznest DWC version there will be nothing to edit to get the work offset buttons. DWC is open source though and can be found at https://github.com/chrishamm/DuetWebControl



  • @jay_s_uk said in Couple questions before I make the purchase:

    The motors look ok, apart from the inductance being slightly on the high side. See https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors#Section_Inductance
    You could use the EMF calculator at https://www.reprapfirmware.org/ for an overview on max speed etc.

    That calculator and article are great, I know an electrical engineer so I'll get them to go over it with me rather than pester everyone on here even more.

    And if you go with the Ooznest DWC version there will be nothing to edit to get the work offset buttons. DWC is open source though and can be found at https://github.com/chrishamm/DuetWebControl

    Sorry I misread above as it not working on duet 3, my bad. I'll still have a play around with the code though, software is more my thing than the electrical side.

    Many thanks to everyone for their help, I'll grab a board and have a play about with it.



  • @Asdasd1234 said in Couple questions before I make the purchase:

    Sorry I misread above as it not working on duet 3, my bad. I'll still have a play around with the code though, software is more my thing than the electrical side.

    It won't work currently if connecting a raspberry pi or other SBC to the duet.
    I've messaged them to see if the source for their changes are available as we can then port the changes across to the latest build and produce an SBC build of DWC


  • Moderator

    @Asdasd1234 said in Couple questions before I make the purchase:

    adding those buttons in "should" be within what i can actually do lol

    You just have to write a gcode file, with gcodes in it to do whatever you want, and save it to the 'macro' folder on the Duet SD card. Then the macros are available, as clickable entities (almost buttons) in the DWC and on the PanelDue. See https://duet3d.dozuki.com/Wiki/Macros

    Edit: yes, the firmware and Duet Web Control (DWC) are open source. See https://github.com/dc42/RepRapFirmware and https://github.com/chrishamm/DuetWebControl

    Ian



  • Is workbee "firmware" really a release of Duet/RepRap firmware that they've certified, PLUS their web interface? Or is the actual firmware (that runs on the board) different?



  • @Danal

    The firmware has not been changed I believe. They've just supplied different versions of the config.g file for each machine. They probably also test each version to "certify" it

    The main changes to DWC can be seen here https://learn.ooznest.co.uk/Guide/How+To+Use+WorkBee+Control/22?lang=en
    They've mainly updated the dashboard to allow for multiple work co-ordinate systems and quick setting of X, Y and Z offsets.
    At the moment, its based on 2.0.4 I think.



  • Perfect, thanks.

    That's more or less what I thought, just wasn't sure.



  • @droftarts said in Couple questions before I make the purchase:

    @Asdasd1234 said in Couple questions before I make the purchase:

    adding those buttons in "should" be within what i can actually do lol

    You just have to write a gcode file, with gcodes in it to do whatever you want, and save it to the 'macro' folder on the Duet SD card. Then the macros are available, as clickable entities (almost buttons) in the DWC and on the PanelDue. See https://duet3d.dozuki.com/Wiki/Macros

    Edit: yes, the firmware and Duet Web Control (DWC) are open source. See https://github.com/dc42/RepRapFirmware and https://github.com/chrishamm/DuetWebControl

    Ian

    I was thinking more along adding current display of work-offset co-ords or something that might fall outside of that range. But the other version I was linked seems to already do most of what I wanted to add. I make use of the macros list on the side already for purges/filament changes on my printer which are a great feature.





  • Sorry I've got one last bit to question
    I saw above someone mention connecting to it with a RPI, and a bit on the product page saying
    "Dedicated High speed bus to a single board computer (e.g. Raspberry Pi) for the user interface and plugins"

    Does this mean that the Duet 3 doesn't have the interface available from just the board like the duet 2? Do I need an RPI to run the web server? My only experience is the duet 2 wifi which was just plug and play on that front.


  • administrators

    @Asdasd1234 said in Couple questions before I make the purchase:

    Sorry I've got one last bit to question
    I saw above someone mention connecting to it with a RPI, and a bit on the product page saying
    "Dedicated High speed bus to a single board computer (e.g. Raspberry Pi) for the user interface and plugins"

    Does this mean that the Duet 3 doesn't have the interface available from just the board like the duet 2? Do I need an RPI to run the web server? My only experience is the duet 2 wifi which was just plug and play on that front.

    You can run Duet 3 either in standalone mode (like Duet 2) with its web server using the Ethernet port and local SD card, or with an attached RPi.



  • Ah ok, that makes more sense, thanks


  • administrators

    ..and in standalone mode, you can connect a PanelDue to it.



  • It is possible to tell RRF a transformation matrix (M669), so transforming the machine coordinate system to match the workpiece could be done with some conditional G code. I think you would need variables though, and those are not supported yet.


Log in to reply