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bertho

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Posts posted by bertho

  1. Hi everybody!

    My name is Bas and I am new at Ultimaker. One of the things that I am working on is improving the filament feeder.

    The three most important changes:

    • metal ring at entrance
    • bowden tube runs deeper into housing
    • removed part of the housing under the feeder wheel where the filament was touching the housing

    Please let me know if you'd like to test this redesign on your UM2!

    Cheers!

    Bas

    Welcome Bas,

    The improvements are simple and practical. Good work.

    It can be simplified a little bit further:

    Remove the stop for the Bowden so it can be pushed all the way down to the bearing.

    The Bowden will pull up slightly so there will be clearance when there is force on it. Regardless, it is stainless steel against Teflon so even if it would touch during retraction it is insignificant. See

    (I tried to insert a picture, clicked on the Image icon and it asked for an URL, no option for a filemanger to select a picture. I copied and pasted a screen capture, which displayed properly, but I got a message saying "format not allowed". What am I missing?)

    Bertho

     

  2. One source of a clicking belt noise is misaligned pulleys. The belt gradually runs up on the edge of the pulley and then snaps down again.

    The second one that I have been trying to trace down is a pitch error between the belt and the pulleys. Gradually the belt and pulley gets out of alignment and then it snaps back into the grooves. For example if the belt pitch is 2.5mm and the pulley is 2.5mm. It would happen if the pulley is a little bit too large or too small.

    Bertho

     

  3. I have UM1 so I cannot comment on its performance. I did many measurements on the original extruder after my upgrade.

    See:

    http://vinland.com/UM_Extruder_Bearing.html

    http://vinland.com/Extruder_Drive_Force.html

    Instead of using a platform scale, try using a luggage scale. They work great since they are designed for "pulling".

    They are very low-cost. I have bought several brands both in China and in the USA and when checking the calibration I have always found them to be accurate.

    Bertho

     

  4. [...] If I'm not around, I use shutdown G-code to at least purge the head, reduce the temperature in stages (feed at ~10C steps) and retract the filament before it cools. [...]

    I'm interested in the way you set this up - could you please share/explain how you do this??

     

    calinb lists many good points above.

    I too like to avoid the heat creeping up the extruder after shut down. To avoid it I slowly feed some extra filament while the head normally cools off. That way cold filament is pushed in so the heat never creeps up and later creates a possible jam at start-up. The actual code is extremely simple:

    G1 F40 E75 (tweak it to fit your machine)

    Here is my complete end code:

    ;End GCode

    M104 S0 ;extruder heater off

    M140 S0 ;heated bed heater off (if you have it)

    G91 ;relative positioning

    G1 F300 E-5 ;retract the filament a bit

    G1 Z2.0 F?max_z_speed? ;move straight up

    G1 X-20.0 Y-20.0 F9000 ;move quickly off the print area

    G28 X0 Y0 ;home X/Y, so the head is out of the way

    G1 Z40.0 E5 ;lower the table to leave space for extrusion

    G1 F40 E75 ;extrude to cool off the head quickly

    M84 ;steppers off

    G90 ;absolute positioning

     

     

  5. Robert Wrote:

    The extrusion length will change with the rubber compression since the drive wheel radius will change. I do not know how significant it is and it could be compensated for.

    Ian wrote :

    I am thinking for in the direction of rubber from atleast two sides like you said. this way the system grabs the filament in the hand and gently pushes it up.. zero damage to the filament.... better ??

    Ian :smile:

    Gently?? it better grab it really tight :-)

     

  6. Interesting subject!! I have been looking at how to further improve the UM1 extruder drive but as usual I am running out of time. I did not realize that UM-2 has changed to direct drive. If I am going to play with this, I might as well go in that direction to be up-to-date.

    Any suggestions for finding the stepper in the USA and knurled wheel? I am not too enthused with the knurled wheel but it could be a starting point.

    Bertho

     

  7. I have seen many questions & comments about temperature errors so I very carefully measured the head temperature of my UM using two different K type thermocouples of good quality and two different meters. All readings were taken at the set temperature of 210C with a stable settled down temperature. Both TCs were properly bolted on to the heater aluminum block and wrapped around the block to reduce conduction errors.

    Meter #1: Fluke 52 TC #1 209.4C TC #2 209.1C

    Meter #2: Extech 42525 TC #1 210 C TC #2 209 C

    The Fluke max error @ 210C is +/-0.4C and the TC max error is +/- 1.1C so the measurement accuracy is typically +/-1C.

    So it appears that I am lucky with my UM and all four measurements are within 1 degree C of the set value. I have no idea how other UM performs since this is a single sample measurement. As I have mentioned before, a properly designed TC measurement setup should be very good.

    I suspect that many of the reported temperature errors often are measurement errors. It is difficult to accurately measure the temperature since IR is not accurate and temperature probes often do not make proper contact and there is conduction of heat through the measurement leads that will affect the reading.

    Bertho

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