Tall Prints - a community guide

I am by no means an expert but I am hoping to start a discussion and collation of advice on printing tall (and narrow) objects. It seems to be a frequent problem Bambu Lab owners have and there is not much collated advice I have seen.
The Bambu Lab line of printers are fast. Tall and Narrow prints are prone to significant torque, acting as a lever arm according to the formula:

Torque = Force x Distance

Thus the combination of the speed and the nature of the print means it is easy to break supports or dislodge the print. Here are some of the principles I have learned but do please share your thoughts on this. Ideally, this could become a new Wiki article.

  1. Strong Bed Adhesion
    a) Plate type +/- use of glue
    b) Use of brims where first layer contact is small
    c) Increasing Bed Temperature - more adhesion but makes print more prone to elephant footing. I go with 60-65 sometimes.
  2. Stable printer
    a) A fast printer vibrates which may cause layer shifts, poor adhesion, poor quality overhangs
    b) Placing the printer in a stable location will ensure quality and success
  3. Supports
    a) Organic Tree support base is wide in proportion to length = higher chance of success as the base spreads out the force over a larger surface area.
    b) Normal supports are good for a large planar area especially when being supported directly from the bed. Normal supports together strong; weak in patches.
    c) Support brims: These help but may still detach or tear as they do not spread out force much.
    d) Support infill (interface pattern): Consider using this as the support gets taller to prevent breakage and spread out force. The trade off is ease of removal and more filament used.
    e) Enforced supports for stability: Consider enforcing supports on a stable part of the model to stabilise your support. This will spread any torque to the entire model. Trade off is any support residue on removal.
  4. Speed
    a) A key issue
    b) Torque: Fast printing speeds create torque. This also might cause partially melted filament (see Bambu Wiki) which then drags the print. Once you achieve height, the torque becomes larger, making breakage or detachment more likely
    c) Modifiers: Consider slowing speeds with a modifier over delicate parts of the print or globally slowing speed, especially sparse infill (often the fastest)
    d) Layer Height: This is exacerbated with lower layer heights as the slicer increases the speeds and there is often less layer adhesion
    i) Print speed is proportional to layer height so theoretically you should be able to go faster with lower layer heights but it doesn’t always pan out.
    e) Melt Filament Index: Not all 3rd party filaments flow as fast as Bambu filament. BambuSlicer sets fairly high speeds (consider doing Max Volumetric Flow calibration in OrcaSlicer)
  5. Temperature
    a) Flow rate is also dependent on Temperature
    b) Consider increasing temperature (consider temp tower via OrcaSlicer)
    i) Trade is off is stringing, different finish etc.
  6. Cooling
    a) I am still learning about this
    b) Strength: Less cooling means stronger parts. First layers are often not cooled. Most default BambuSlicer profiles involve significant cooling, particularly with the Aux Fan on.
    i) I have used third party profiles successfully with the aux fan completely off
    c) However, more cooling means better quality (geometric accuracy).
    d) So for high-detail prints, you may want to err on the side of more cooling.
  7. Infill
    a) This is directly out of the Bambu Wiki
    b) Avoid Grid and Triangle which involve crossing within the single layer and may cause the nozzle to scratch the infill.
    c) Rather try rectilinear, gyroid or concentric infill

Update: The new print profiles seem to deal with the speed issue. The ‘high quality’ profiles are much slower and use less acceleration than the ‘extra fine’ profile. I have yet to test it out but I imagine it will reduce the nozzle’s tendency to hit the print.

Thank you for reminding me to have a look at the high quality profiles. Here are the differences. No rocket science, but good to have.

Here are some tips I saw on reddit for tall thin objects. They all boil down to cooling:

  1. Minimum layer time: 10+ seconds
  2. Turn on lift head as well so it moves away from the print and lets the print cool
  3. Max fan as well

My comments to them:

  1. Sounds plausible. I didn’t try it yet.
  2. I think this doesn’t apply to BS/Orca, AFAIK the minimum layer time doesn’t add a pause but decreases line speed for the whole layer.
  3. This may be needed for accuracy, but is also bad for strength. Just like you wrote.

I’ve had very thin objects end up melted/deformed (due to insufficient cooling) AND extremely weak bonding (could be too much cooling, but also just an inherent property of vertical thin objects with FDM), at the same time. It’s not easy to balance this perfectly.

For our specific slicer/printer combo, the key might be just HOW we cool: We have plenty of variables: The part fan, the aux fan, the chamber fan and last but not least - opening of door or top lid. Oh and BTW there’s also the Cold Plate! If you need less heat but (like me) hate noise, that plate is a gem! I use it without glue - works for me.

I ran with the aux fan at standard profile settings for too long. Nowadays I run it much slower, but usually at least 10% so to help overall chamber temperature by circulating colder air from under the hotbed. For massive pieces, too much aux fan introduces warping even to PLA. For tall prints, we might want it, but perhaps not at Bambu’s default speeds?

Also, I’ve been opening the lid for PLA/PETG lately, I usually didn’t until recently.

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Thank you for this. It seems I can’t edit the original post making this venture slightly difficult but having the advice here in the thread will be helpful nonetheless. I guess it makes sense for Bambu to slow down speeds and acceleration in the ‘high quality’ profile as this will reduce force.

I didn’t actually consider the effects of the plate temperature on the chamber temperature - that’s an important variable. Have you found printing with the top glass off makes a difference? I have this option but haven’t done it for convenience. I have also only used the textured plate so far.

I wonder if there should be a calibration model that tests aux. fan speeds and other important variables. Perhaps an overhang test but slightly modified.

When using the Cold Plate, you usually get away without any opening or chamber fan. For PEI plates and printing PLA, TPU or PETG, I may crack it open an inch or so in the front (using this sensible model). Given I tend to use very low speeds (if any) for the chamber fan, I usually watch the chamber temperature more than anything else. If it hits 35°C and is still climbing, I’ll usually crack the lid open rather than increase the fan - doing both should be mostly pointless. When opening at the top, warm air will vent out by itself so no fan is needed. I never leave the door open, it’s too risky for several reasons (including but not limited to cats).

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