2mm pitch z screw

Discussion in 'Guides, Mods, and Upgrades' started by Taede, Nov 3, 2016.

  1. Taede

    Taede Member

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    I wondered if more people use the z lead screw to manually trim the bed when printing the raft.

    Although the bed height sensor is precise, i am still not able to get the perfect first layer consistently. Often this results in stopping the print after printing the raft, adjusting the Z offset (and store in memory) and retry.

    I just simple turn both leadscrews a few clicks while printing the raft to adjust the bed height. This might not be as advertised, but the sensor is not precise enough to me and requires multiple iterations to adjust using the z offset.

    However the 8mm pitch on the leadscrew is to course to perform this manual operation, and i am planning to swap these for 2mm pitch lead screws.

    I understood that in the past the bigbox is upgraded from 2 to 8mm leadscrews because of z banding, which seems strange to me as the bed is not supported or effected by the leadscrews when correctly installed.

    Are more people using the manual bed level routine and does changing the leadscrew to 2mm pitch have an effect on print quality?
     
  2. moshen

    moshen Well-Known Member

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    I'm not sure the 2 to 8mm switch was for z-banding, where did you read that? I assume it was just for supply reasons. As fr manually adjusting the height you can look at flashing a Marlin firmware with babystepping enabled. This lets you adjust the z in realtime using the control panel.
     
  3. Spoon Unit

    Spoon Unit Well-Known Member

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    Here's my process, every time I change or clean the bed. So the assumption here is that everything is assembled well and trammed.

    1. Run through the mesh bed leveling processes. At each point, I lower the nozzle to the bed (or raise the bed to the nozzle if you like) until it's just touching. I do this by eye, finding an angle where I can see light or a reflection from the bed in order to get the nozzle just touching.
    2. Set Z-Bed to +0.95 as a starting point. I print mostly in 0.3 layers, and 0.95 seems to be the perfect offset for 0.3, though you can fiddle with this either pre-print (Control > Motion), or during print (Tune)
    3. Print a test object one layer thin and large enough to give me enough time to tune. Consider printing this test object at every corner and in the center to ensure a perfect first layer across the bed.

    If I'm going to print in thinner layers, I need to adjust the Z-Bed as +0.95 won't be right otherwise for a pefect first layer. I'm printing with 0.15 at present, and I think I have it on +0.55. Ultimately, this is a tuning operation and I watch first layer like a hawk.
    The thinner the layer, the bigger the impact of not getting the mesh bed leveling spot on.

    The only time I ever actually fiddled with the screws themselves was when trying to level dual nozzles. It's too tedious for me, and I didn't ever feel I could trust bowden of that length plus Titan to deliver consistent results. I await the dual X carriages with baited breath.
     
  4. Taede

    Taede Member

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    You are right indeed, I mistaken the initial Z wobble issue was resolved by changing to another lead screw

    I will look into babystepping, this sounds like the best solution to me. I do want a means to tweak the initial layer height without restarting the print and hoping for the correct adjustment

    Also noticed that I pushed down the bed when changing the glass or removing a print, which offsets the R and L motor. That is another reason to switch to 2mm pitch leadscrews, but I will start with the babystepping enabled and being more careful on the printbed :)
     
  5. Taede

    Taede Member

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    Thanks for sharing, I often swap my build plates as the standard glass plates chip easily and I also use a glass plate with PEI. The IR sensor still detects the top but with a small different offset for each build plate. I like to tweak the bed height when printing the raft and first layer, in order not to restart the print.
     
  6. Spoon Unit

    Spoon Unit Well-Known Member

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    I've never used one yet on the BB.
     

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