Magically changing feed amounts



  • hi just sharing something that has happened to me while doing small prints my machine works fine (have done larger prints in the past just fine (not sure if i did them before are after last firmware update) but on large prints i.e over 3 hours
    so lager prints have been failing stats off fine then first 10mm of layers over a 250mm x 170mm print and my printer start to leave gaps like its partly jammed bottom of print perfect top of print crap gaps like its clogged ..so i have unclogged it change filament retry same thing again
    scratch head print smaller prints there fine go for a big one 17 hour print leave printer after 30 mins come back again bottom layer fine upper layers are crap total crap air holes everywhere
    and again i change filament change printer nozzle cheek for clogs nothing
    any and this over a two week period
    this time new filament new nozzle all oiled and primed smaller print 1 hour and it dose it again after about 40 mins anyway this time i pause print
    extruder is extruding so i pull the feed line apart make sure thats ok moves great decide to cheak feed amount as im running out of thing to look at and i push feed 100mm and i get 50mm (now this was set up and checked and double checked not delving my eyes i retried anther 4 times asked for 100mm but only got 50mm
    so i thought hmm OK ill reset the feed rate up turned off the machine had tea (yummy salmon and pasta bake)came back to a cold machine switch on switch me pc on getting read to reset up feed rate got my steal ruler out again remeasured my feed amount and nearly fell off my chair as i asked for 100mm and it feed me 100mm 5x in a row

    so now i thought maybe its matter hacker messing with it i use matter hacker to make my g codes which i use on my machine but i walked away and left the it on with filament in the printer so now i do have clog and i managed to kill my thermistor clearing the clog so no more testing tonight
    anyone had any thing similar to this happen

    things im going to try in order
    similar print using cura
    then update firmware ..then.. (complet wipe and install )



  • summary

    printer is changing feed rate as print start tested by using puase print
    and doing feed length checks
    start of print ask for 100mm and was given 100mm
    about an hour in ask for 100mm and was given 50mm ?

    now ive update firmware i was on 1.15c so about 6 mouth old
    and now using cura and not matter hacker encase it is gcode and there g code creator doing it ill get back to you and let you know if i get any change


  • administrators

    My guess is that it's a mechanical issue caused by the back pressure from the nozzle and the extruder stepper motor heating up, which will cause the filament to soften especially if you are using PLA. How hot does the extruder motor get after an hour of printing? What extruder design and what motor is it?



  • yes i am now thinking you may be on to something did the update and tried slic3r cura is pants its just my oppinun dont shoot me
    im using all metal Bowden Extruder out side of case i got a 1.7amp stepper motor running at 1.2amps
    and it seems i can now not feed 100mm thought my extruder (e3d v6) with out the motor jumping

    in case you want to see config file below

    ; Configuration file for Duet WiFi
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool on Sat Nov 19 2016 12:24:27 GMT+0000 (GMT Standard Time)

    ; General preferences
    M111 S0 ; Debugging off
    G21 ; Work in millimetres
    G90 ; Send absolute coordinates…
    M83 ; ...but relative extruder moves
    M555 P5 ; Set firmware compatibility to look like Repetier

    M667 S1 ; Select CoreXY mode
    M208 X0 Y0 Z0 S1 ; Set axis minima
    M208 X270 Y270 Z250 S0 ; Set axis maxima

    ; Endstops
    M574 X1 Y1 Z1 S0 ; Define active high microswitches
    M558 P1 X0 Y0 Z0 H5 F120 T6000 ; Set Z probe type to unmodulated, the axes for which it is used and the probe + travel speeds
    G31 P600 X0 Y0 Z2.5 ; Set Z probe trigger value, offset and trigger height

    ; Drives
    M569 P0 S0 ; Drive 0 goes forwards
    M569 P1 S1 ; Drive 1 goes forwards
    M569 P2 S0 ; Drive 2 goes forwards
    M569 P3 S1 ; Drive 3 goes forwards
    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
    M92 X79.5 Y79.5 Z400 E87.68 ; Set steps per mm
    M566 X900 Y900 Z12 E120 ; Set maximum instantaneous speed changes (mm/min)
    M203 X6000 Y6000 Z180 E1200 ; Set maximum speeds (mm/min)
    M201 X500 Y20 Z250 E250 ; Set accelerations (mm/s^2)
    M584 X0 Y1 Z2:4 E3
    M906 X800 Y800 Z800 E1200
    I30 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout

    ; Heaters
    M143 S260 ; Set maximum heater temperature to 300C
    M305 P0 T100000 B4008 C0 R4700 L0 H0 ; Set thermistor + ADC parameters for heater 0
    M305 P1 T100000 B4008 C0 R4700 L0 H0 ; Set thermistor + ADC parameters for heater 1

    ; Tools
    M563 P0 D0 H1 ; Define tool 0
    G10 P0 X0 Y0 ; Set tool 0 axis offsets
    G10 P0 R0 S0 ; Set initial tool 0 active and standby temperatures to 0C

    ; Network
    M550 Pduetwifi ; Set machine name
    M551 Ptony ; Set password
    M552 P0.0.0.0 S1 ; Enable network and acquire dynamic address via DHCP

    ; Fans
    M106 P0 S0 I0 F500 H-1 ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
    M106 P1 S1 I0 F500 H1 T45 ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    M106 P2 S1 I0 F500 H1 T45 ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on

    ; Custom settings are not configured





  • administrators

    It looks to me from the photo that you are using an un-geared extruder. Those typically need a long, high-torque Nema 17 motor run close to its maximum current to deliver enough force, especially when printing PLA. So try increasing the current to 1.5A or 1.6A.



  • thanks for the tip ill look into geared bowden are better motor if you have found any you think are cool are work great please share
    thanks for your help



  • @aparkin:

    thanks for the tip ill look into geared bowden are better motor if you have found any you think are cool are work great please share
    thanks for your help

    If you have the cash http://shop.bondtech.se/ec/extruders/bondtech-qr-175-universal.html



  • Ouch thanks for the link but it will cost me and extra in import tax I'll stuck with UK stuff
    Are print something out


  • administrators

    @aparkin:

    Ouch thanks for the link but it will cost me and extra in import tax I'll stuck with UK stuff
    Are print something out

    I recommend either the E3D Titan or the spring-loaded variation of the RapRap Ormerod extruder which is mostly printable. Both have a gear ratio of around 3:1.



  • I can't really tell from the pics but another possibility is that whatever drives the filament is slipping on the motor shaft. It's a quick check to make sure that the grub screws are all tight.

    A little tip - with a bit more aluminium extrusion you could mount the extruder above the bed, roughly in the centre which will reduce the length of your Bowden tube to less than half what you have now which will help in all sorts of ways.



  • Thanks for the tip



  • yep you was right it was maniacal i retro fitted an old wades extruder its running upside down and back to front but now it works like a charm so now to find that ormerod extruder

    thanks for all the help

    of course i can not shut the door but ill fix that soon



  • OK the problem is still persisting on long prints my printer fails a couple of hours in but small prints.look much beter
    Is it worth putting a fan over the duet board


  • administrators

    If it's a Duet WiFi, then with the motor currents set as low as you have them it is most unlikely that you need to cool it with a fan.



  • Untested yet! just sermizsing.
    But I'll add a fan on board change the motor for one of the z motors
    I also get strange things happen when I have motor wire crossed over and I thought I got good ones for Germany….
    Never mind anyway I'll try all the above and make sure nothings come lose see if I can shorten my bowden tube
    And I'll get back to you let youknow how I get on
    p.s may take a few days
    Thanks for all the help



  • ok slight update not sure if this is related guess time will tell after a bit of head scratching wondering why nothing is working i found out i have a corrupt memory card pc is scanning and fixing is it worth retrying same card are just replacing it
    p.s so happy i copied my setting to an earlier post



  • hi all thanks for the help (dc42)
    ok problems

    memory card stopped working ( replaced card sorted )
    extruder getting hot and over extruding and under extruding and completely failing after 3 hours

    turned out i had my blue wire ad snapped inside the sheaf …....while cheeking and rerunning all the wire it fell in half in my hand strange

    its now 4 hours into a 6 hour print and back to normal
    p.s i got an extra motor in the post now


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