Smaller NEMA17 for the Extruder



  • I bought this smaller motor for my direct drive extruder.
    https://www.filastruder.com/collections/electronics/products/nema17-stepper-motor

    It keeps skipping, and isn't powerful enough to push the BondTech Extruder I paired it with. Or so it seems...
    There are times when it works just fine... But then at the very end it will start to fail.
    Other times, with the same print, it will just give me a foamy print.

    Any thoughts would be great, but my first question is...
    What should I set the milliamps to?
    I believe this motor is rated for 1400, and I have never set any of my other motors that high. Just never needed to.
    They all run cool and I generally keep them at or less than 1200.

    Thanks for your help!



  • I have the same motor with a titan extruder, which has the same reduction, 3:1, as the bondtech.
    I used it at 1400ma with no problems, even with long prints.



  • @3doeste Good Stuff!
    Thanks for the feedback!



  • What bondtech extruder?



  • @cata
    I am using the BMG on a CoreXY (V-Core).



  • I am still having issues. Had to turn the temp up to 240c so far to get it to stop. 220c to 230c still had issues.... still playing with it.
    What are does your config look like for microstepping?

    Thanks!



  • @bluedust Look to your hot end rather than the extruder motor. If the motor coupled with a BMG can't push the filament through, then it's because there is too much restriction at the hot end. The usual reason is that you are trying to push filament through faster than it can be melted, but it can also be a partial blockage of the nozzle or, if it gets worse as the print progresses, then you have heat creep issues making the filament expand in the heat break area. Too high a retraction amount can also cause this issue.

    For info, I use similar spec motors in terms of torque on my 5 BMGs (Diamond 5 colour hot end). These ones https://www.omc-stepperonline.com/nema-17-bipolar-18deg-18ncm-255ozin-07a-29v-42x42x25mm-4-wires-17hs10-0704s.html?search=17hs10-0704s. They are 1.8 degree rather than your 0.9 degree and the rated current is 700mA which I run at 600mA, but the rated torque is the same.



  • From what I understand different microstepping settings can affect torque...
    Your motor will have better torque as it has to run at lower steps then the one I have.
    Thats why I was asking for the config used for the motor...

    Thanks!



  • @bluedust said in Smaller NEMA17 for the Extruder:

    From what I understand different microstepping settings can affect torque...
    Your motor will have better torque as it has to run at lower steps then the one I have.
    Thats why I was asking for the config used for the motor...

    Thanks!

    Not significantly. But in any case, I use 128x and have used 256x but then I hit the maximum step pulse frequency of 200KHz when retracting at 3600 mm/min. So I either run 128x and set the maximum speed to 3600 or 256x and set the maximum speed to 1800.

    Note that unless you are using a mixing hot end, and you have mixing ratios that are low single digit percentages, then 16X micro-stepping is fine - especially with your 0.9 degree motors.



  • @bluedust Hi, I have 801,81 at 16x interpolated to 256x.



  • You did not state if this is 12v or 24v. I use the same E3D motor with a Titan on 24v at 1000ma with no issues. Not an expert on this but I seem to recall that the 0.9 degree motors do not do as well on 12v.



  • @tj
    24v Printer.



  • What volumetric rate were you attempting to reach (calculate from layer thickness, extrusion thickness, and print speed)? Hot end? Nozzle diameter? Printed material? Filament diameter?

    I had issues with the 1.8 degree motor skipping steps when I tried to print faster than 60mm/s with PLA though a standard v6 with 0.4 nozzle Titan extruder. I'll have a look through my notes to try and find out what the volumetric rate was. For a while my layer thicknesses were too thick. Any over extrusion will also increase the likelyhood of extruder motor skipping steps.

    What is the spec sheet line 'max starting PPS'? If that's max steps per second to be translated to Instantaneous speed then thats low. Having said that I can't see it specified on other spec sheets so it is difficult to compare!

    Currently I tend to get skipped steps in constant extrusion when my volumetric rate exceeds 10mm3/sec with a standard V6 and standard Ormerod 2 extruder at between 180 and 200C hot end temp. I have a larger stepper but run at 12V. I'll look up holding torque.



  • @bluedust said in Smaller NEMA17 for the Extruder:

    I am still having issues. Had to turn the temp up to 240c so far to get it to stop. 220c to 230c still had issues.... still playing with it.

    do double check your thermistor values. using the wrong ones can lead to temperature differences of 40C easily



  • Following on from my last post the stepper motors I can print up to 10mm3/sec with are the standard Ormerod motors which have a rated current of 1.33A, 2.1Ohm resistance, 2.5mH inductance and a holding torque of 2.6 kg.cm.

    Interestingly the shorter motor on the E3D is almost identical spec but with more torque. Rated current of 1.33A, 2.1Ohm resistance, 2.5mH inductance and a holding torque of 3.2 kg.cm.

    This indicates that my previous issues were Titan or volumetric rate related.

    Sources:
    http://f01.s.alicdn.com/kf/HTB1KrKMHVXXXXaEXXXX.PRXFXXXy.pdf
    http://motechmotor.com/productDetail-0104-40.html


 

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