Flying extruder with 4th axis



  • Hi there! i´ve got a homemade 1m tall delta with a bowden double geared extruder+gearbox in it...it pulls the filament well, but having a teflon tube so long it´s making the tunning a little nightmare, and i was thinking on puting a flying extruder, but with a 4th axis that holds the motor. I read on this forum that i´m not the first one thinking on this idea, but i couldn´t reply on that chat because is locked. i know exactly how to do the mecanics, with an endstop on top etc... the only thing i need to know is if someone has already the firmware that makes this system work, or someone that can help me on developing the firmware. The holding platform needs to move with the Z heigth, and move a little down when the effector goes to the corner. i´m planning to implement a kind of a bowncy platform that allows the motor to turn in X-Y similar to camera stabilizers. Thanks


  • administrators

    I don't think anyone has implemented kinematics for that arrangement yet, but I don't think it would be hard to do. Essentially, the 4th motor is another tower, with X Y coordinates and a Z offset that you would specify in M665 and/or M666 and/or M669. A small complication is that the "arm length" for that virtual tower will probably be different from the other arm lengths, so this will have to be taken into account.

    I presume that the new axis motor would be homed in the same way as the three towers, and at the same time.



  • Hi there! i don´t actually understand well how you want to implement the X-Y movements in the 4th axis, i was just thinking on making a platform that hangs on top of the effector and moves in Z axis, and turns a little left-right and backward-forwards. Anyway...can i count on your programing skills then? i´m pretty determinated to create this "arm"


  • administrators

    I was thinking that the 4th axis will be controlled just like the others, except that the "arm" will be shorter because it is really the Bowden tube. So the firmware will maintain a fixed distance between the platform and the centre of the effector.

    You may wish to consider mounting the extruder on gimbals, like the Zatsit extruder. That would allow the Bowden tube to find its own optimum angle.



  • Hi there! yes, the extruder motor will be hanging from a magnetic ball so it can turn a little in any direction, all the system is almost finished, it has an endstop on top, 2 rails for guiding the arm and a 8metric thread to move the 4th axis. i will post a picture or a video when finished ....hopefully today. the printing volume will be 400mm in diameter ....i was planing to use a 300mm long teflon tube to start with, the shorter the better, but for now i will do tests with 300mm long tube. the extruder motor´s height needs to follow Z height and when it goes to the corners it needs to go down a little.....hopefully wont be so difficult for you to program that in the firmware. i´m only using 1 extruder so we can use the second extruders driver to drive the 4th axis motor.



  • Hi there!!! the setup is complete!! hopefully everything goes fine with this configuration, i just moved the 4th axis putting the conector in the extruder´s driver and works fine so far. i put the pictures here to see the mechanical configuration, and if you have any questions for the development of the firmware just let me know.!6_1542051232800_índice.jpg 5_1542051232800_índic1e.jpg 4_1542051232800_índi1ce.jpg 3_1542051232800_í1ndice.jpg 2_1542051232800_índi11ce.jpg 1_1542051232800_ín11dice.jpg 0_1542051232799_índ111ice.jpg



  • Hi there!
    I made some calculations, and having a 300mm teflon tube and 400mm diameter printing area, when the effector goes to the corner the effector needs to go down 75 mm aproximately, maybe a little bit less taking in mind that the motor also turns. i think that once having the firmware i will need to do many tests and play with those numbers


  • administrators

    Are you sure that screw drive will be able to move the extruder fast enough? The screw pitch looks very fine in the photo.



  • I´m not sure at all....we need to test for that, but i didnt wanted to put a belt because it will move down when switching off the printer bending the teflon tube. i think test is needed to see how works and then modify if is needed



  • @dc42 said in Flying extruder with 4th axis:

    Are you sure that screw drive will be able to move the extruder fast enough? The screw pitch looks very fine in the photo.

    I agree, it looks really fine pitched. I would be using a 4 lead screw that turns 8mm per revolution. I use them on my big printer and can move my heavy table really fast.

    I like the design though. Great job on it.



  • Thanks mate!! I also thought on puting this 4 lead screw but keep in mind that there is 1m long...i had hard time looking for the ones that make 8mm per revolution being 1m long. i did some tests with this configuration and moves really well but you have to push hard in order to gain some speed. another fast option would be to put belts with some counterweight in the other end so there would be no problem when switching off AND it would be more quiet.



  • Here goes another picture of the whole system0_1542123739940_WhatsApp Image 2018-11-13 at 16.40.18.jpeg



  • By the way the pitch i´m using is 1.25mm. It is a regular M8 thread



  • Details of the firmware settings for this? Sorry if I didn't understand. I would like to do something similar on my delta but for a camera that follows the Z height of the print but offset by a set amount.



  • @alexander-mundy said in Flying extruder with 4th axis:

    Details of the firmware settings for this? Sorry if I didn't understand. I would like to do something similar on my delta but for a camera that follows the Z height of the print but offset by a set amount.

    Would you be interested in an $10 for the parts (not including stepper or servo) external box that "polls" the printer and does this? It could drive a stepper or a servo (angle, not movement). I've been thinking about creating one, and am curious if others would find it interesting.



  • @alexander-mundy This system was also built thinking on putting a camera to the moveable arm...i designed some holes to attach a camera in a future



  • @ander said in Flying extruder with 4th axis:

    By the way the pitch i´m using is 1.25mm. It is a regular M8 thread

    You can always use a lower microstep setting (1/4 or 1/2) or just use full steps but you will have much more stepper motor noise that way. It will move faster though.



  • I just found and ordered 4 lead screw of 1m long, is going to move so much faster, and this way i don´t have to change anything to the original setup for now....after uploading the firmware we will see if aditional features are needed when testing like some system to help the motor not to be super bowncy



  • Hi there!!
    I just received the lead screw, tomorrow i will change it so the 4th axis can move so much faster.

    @dc42 , did you have any chance of working on the firmware?
    i had to cut the 1.2m teflon tube that was going from the motor to the hotend to make the modification and now the printer is not working ever since.


  • administrators

    @ander said in Flying extruder with 4th axis:

    Hi there!!
    I just received the lead screw, tomorrow i will change it so the 4th axis can move so much faster.

    @dc42 , did you have any chance of working on the firmware?
    i had to cut the 1.2m teflon tube that was going from the motor to the hotend to make the modification and now the printer is not working ever since.

    I'm sorry, I won't have time to look at this until the 2.02 release is finished.


 

Looks like your connection to Duet3D was lost, please wait while we try to reconnect.