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G1 Z 0.400 F7800.000

IsraelIsrael
in Slic3r
Hi, and thanks in advance for you suggestions.
On or about line 22 on the G-Code for any print, I get this entry after slicing. Obviously this value is too high for the filament to adhere to the print bed. it does not matter what size nozzle I use. I can see an air gap between the nozzle and the bed. So changing the g-code to
"G1 Z 0.040 F7800.000" this places a nice brim and skirt on my printing object. Where in the world and what numbers do I use to get it to the value I choose, as opposed to manually changing every g-code? How do I make the default change to this number? I bet it is as simple as someone identifying where the value is changed and explaining the math involved.

Sincerely,

Israel


Comments

  • RepetierRepetier
    Original value is first layer height. Reducing it will also reduce filament amount so that is not the right solution. Your main problem is that z=0 is simply too high. Make it trigger deeper and it will work as expected.
  • IsraelIsrael
    Great info! But I am a NOOB. How do I "make it trigger deeper"? and Z=0 being to high? please explain.

    I do have a good level on the bed to the nozzle, using a single sheet of paper, on all four corners. I do verify this before I print.

    The procedure I use is that I home all Axis's then move the x-axis position so that the extruder is over the bed on the nearest corner, check the gap with paper, move to next corner and repeat this for all corners. I am a novice at this 3d printing world.

    Am I doing this correctly??

    The only thing I can think of moving around to lower the z-position, is to change the z end stop so the extruder is .04 below the bed. So when I send a print, it will be at z=0, but would that be too close?  Maybe lower it 0.36 to put me at 0.040 above the bed as it starts to print...

    I don't know...
    Please advise.

    Israel
  • RepetierRepetier
    Depends on what you do. Do you home z and never move z and only change bed height until paper fits below? Is the extruder/bed hot when you do so? That may change height and if you have some ooze below nozzle it will give you the wrong height meaning too high, which is your problem.

    Paper method is ok, but metal block method is better. Nearly the same, difference is if you have e.g. a aluminium block knowing it is 6mm heigh you home z, then G1 Z6 so distance is 6mm. Heat up extruder to prevent ooze change height. Now moving will not scratch over bed and the block is less forgiving. Adjust bed so it just fits smoothly below extruder. Do this for all 4 bed screw position and repeat until satisfied.

    Then check slicer setting. If you have 0.4-0.5mm nozzle you want first level height 0.2-0.3mm and extrusion width 150-200% so it pushes some filament on bed. The more uneven the bed is the more extrusion you want, but do not go higher then 0,8 * nozzle diameter for first layer.
  • IsraelIsrael
    Depends on what you do. Do you home z and never move z and only change bed height until paper fits below?

    I home z and never move z and change the bed height as you stated.

    Is the extruder/bed hot when you do so?

    I have only done this to a cold bed.

    if you have some ooze below nozzle

    I clean off any ooze before I check the bed height, the nozzle opening is definitely clear so that any build up does not affect the bed height.

    Paper method is ok, but metal block method is better

    Please explain this in other terms, where do I get a block???  I think you are talking about having a preset distance on top of the bed, set the G1 Z6 to 6mm, adjust the bed to fit snuggly to the top of the "Block", I think this might "zero" in the distance to the bed better.

    Then check slicer setting. If you have 0.4-0.5mm nozzle you want first level height 0.2-0.3mm and extrusion width 150-200% so it pushes some filament on bed. The more uneven the bed is the more extrusion you want, but do not go higher then 0,8 * nozzle diameter for first layer

    This makes sense, for a .04 or .05 mm nozzle distance from bed and extruder should be 0.2 to 0.3 mm. what do you mean extrusion width 150-200%, where to I change this?

    THANKS AGAIN IN ADVANCE

    ISRAEL

    FYI, The printer is a Geeetech Perusa I3 X, If this helps any.
  • RokoRoko
    I think the "block" would be a metal block of known height. Home Z  or under Manual Control tab in the g-code window type in G1 Z0 hit enter. Then type in G1 "known height of block" hit enter, Adjust.

    I use Slic3r usually. Under Slicer tab with Slic3r as slicer hit configuration. Under PrintSettings select your layer height. Go to Layers and Perimeters and set first layer height
    Go to Advanced and set first layer width.
    Save

    Cheers.


  • RepetierRepetier
    Exactly, any block will do. Measure with digital caliper and you know wat to set. I use a block from alu extrusion for this. Paper is compressable and it is a bit subjective when it moves. If a block fits below extruder without lifting it and without pressing bed springs down you feel it much better.
  • IsraelIsrael
    OK, I am using a feeler gauge and it helps a lot.  Hear is a thought... I found another printing/slicer program that sets 3 spots on the bed with 3 adjustments per spot. First the 1mm, then .1mm then .01mm... Then it saves that info in the eeprom and the printer then does auto-leveling for you.  Does Repetier, Slic3r, or Cura do any of this type of adjusting for the bed???  The biggest difference I have noticed with this is that the z-axis motors do a lot of movement because the bed does not have to be level. They even have a video with the bed at about 25 degree skewed angle and the printer is printing an object perfectly.
  • RepetierRepetier
    Firmware can do autoleveling if you have a z probe, but hosts have no manual mode to set autolevel.
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