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Z-Height. Smooth vs. textured vs. filament


7milesup

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Hi guys.

I have had my Voron 2.4 up and running for a little while now although there are a number of loose ends to tie up (SB LEDs not displaying correct colors or shutting off at the end of print for example). 

I am having a rather rough go of getting my prints to consistently stick to the print surface.  I have the TAP head installed and operating correctly (I think!).  I spent some time this morning attempting to dial in my z-height but there are some anomalies occurring during during the beginning of the prints.  Initially I printed on the textured side of the flex plate and was able to get some items printed, although I had a six layer width skirt on them for adhesion.  Then I switched filaments (from Zyltech to Overture) and had numerous print failures.  I decided to go back and do some re-calibrating, such as my extruder rotation distance setting (it was off). 

Once I felt I got the Z-height dialed in (it was a large number IMHO...something like -0.480) for the smooth build plate I then attempted a print on the textured side, which failed.  The print came loose and after analyzing the first layer, there was not enough 'squish.'   I do have the first layer extrusion width set to140%.

So these are the questions I have....

1.)  Why is there a difference between smooth and textured z-height distance on the same spring steel bed sheet?  Overall, the spring sheet is "x" thick, there once it is dialed in I would think that the z-height setting should be the same.

2.)  Should the smooth and textured sides require different z-height calibration, is there way to save each config and call that parameter up when starting the print?

3.)  Is it considered best practice to stay with the same mfg of filament to prevent/reduce print issues?  When I printed with my Prusa, it didn't really seem to matter much.

I am using SuperSlicer BTW.

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6 hours ago, 7milesup said:

Hi guys.

I have had my Voron 2.4 up and running for a little while now although there are a number of loose ends to tie up (SB LEDs not displaying correct colors or shutting off at the end of print for example). 

I am having a rather rough go of getting my prints to consistently stick to the print surface.  I have the TAP head installed and operating correctly (I think!).  I spent some time this morning attempting to dial in my z-height but there are some anomalies occurring during during the beginning of the prints.  Initially I printed on the textured side of the flex plate and was able to get some items printed, although I had a six layer width skirt on them for adhesion.  Then I switched filaments (from Zyltech to Overture) and had numerous print failures.  I decided to go back and do some re-calibrating, such as my extruder rotation distance setting (it was off). 

Once I felt I got the Z-height dialed in (it was a large number IMHO...something like -0.480) for the smooth build plate I then attempted a print on the textured side, which failed.  The print came loose and after analyzing the first layer, there was not enough 'squish.'   I do have the first layer extrusion width set to140%.

So these are the questions I have....

1.)  Why is there a difference between smooth and textured z-height distance on the same spring steel bed sheet?  Overall, the spring sheet is "x" thick, there once it is dialed in I would think that the z-height setting should be the same.

2.)  Should the smooth and textured sides require different z-height calibration, is there way to save each config and call that parameter up when starting the print?

3.)  Is it considered best practice to stay with the same mfg of filament to prevent/reduce print issues?  When I printed with my Prusa, it didn't really seem to matter much.

I am using SuperSlicer BTW.

 

My setup is different than yours, so take my info with a grain of salt.  I'm using the default  Omron proximity sensor and endstop switch.

My Z height is the exact same on either side.  No measurable difference.  My PLA doesn't stick as well to the textured side though, so it would definitely seem different.  But, it's the same.

 

 

I've found that the Z height difference between constant failed prints and perfect print adhesion is about .03mm.    my first layer width is .55mm, or about 137%.  I run a .25mm thick first layer, then .2mm for all the rest.

 

My procedure for setting the Z height is to use a sheet of printer paper as a feeler gauge.  The paper is about .1mm thick. 

 I run the "z_endstop_calibrate" command, then, manually lower the head into the paper untill I have a mildly firm drag,  then remove the paper and lower it .03mm more.  That's the sweet spot on my rig.  The paper +  .03mm more 🙂

 

So, I'm assuming that the paper being .1mm thick means "mildly firm drag", hasy nozzle 0.1 mm above the plate.     Dropping it .03mm more,  has me zeroed at .07mm height.

 

since my first layer thickness in PrusaSlicer is set to .25mm,  that should mean I'm running my first layer with the nozzle 0.32mm above the bed.   

 

It works great at that setting, pretty much 100% of the time.

 

if during my z_endstop_calibrate procedure I skip the part where I lower it .03mm more,  I get failures on EVERY single print. 😞

 

I've experimented with running even closer but ABS starts to stick way too tight.   PLA seems to tolerate being too close, but not ABS.   

Definitely don't print PETG super close. It'll never come off.  Use hairspray as a release agent for PETG.

 

Edited by ken226
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Hello, have you checked the pressure of the Tap on the bed?  Too much force or not consistent force exercised during the Z-zero could cause inconsistency, i tested mine with a small scale (an accurate kitchen one will give you an idea of what's going on under the nozzle, assuming it can measure less than 500 grams. The Tap doesn't know what's under, so is just fine.

I say that because the Tap once you determined your Z-offset (machine heat soaked obviously) is not affected by the spring steel thickness, as the reference is always between the tip of the nozzle and the sensor inside the Tap which are all part of the Extruder, so your Z-offset start when you touch the bed and end when you hit the sensor, which practically is on the gantry(fixed part of the X carriage).

You may want to squeeze the material a little bit more with a textured sheet, to allow the filament to penetrate deeper into the texture, but that is in order of .02/ .03 mm, not more in my experience.

Hope that make sense...

  

Edited by Manny
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Another thing i highly recommend if you don't have it already, is the nozzle brush and clean routine before the zero, anything under the nozzle during the zero offset and Z-zero is lethal for the first layer consistency, i would't print anymore without it after i installed it.

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36 minutes ago, Manny said:

Hello, have you checked the pressure of the Tap on the bed?  Too much force or not consistent force exercised during the Z-zero could cause inconsistency, i tested mine with a small scale (an accurate kitchen one will give you an idea of what's going on under the nozzle, assuming it can measure less than 500 grams

I have a scale to do that but what is the number that I should be looking for on that test?  And, if it is incorrect, what do I do about it? 

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I have mine at 250 grams, but is entirely up to the magnet force i think, if is more than 300/350, i would seriously consider to review the linear guide and check the mechanical alignment. The total extruder weight do not matter, as the moment the nozzle hit the bed, the weight is zero, is just the force that the gantry need to detach the magnets and frictions from the MGN9 carriage that count.

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8 minutes ago, Manny said:

I have mine at 250 grams, but is entirely up to the magnet force i think, if is more than 300/350, i would seriously consider to review the linear guide and check the mechanical alignment. The total extruder weight do not matter, as the moment the nozzle hit the bed, the weight is zero, is just the force that the gantry need to detach the magnets and frictions from the MGN9 carriage that count.

Awesome.  I will look into that tomorrow evening.

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To be completely honest(but is just my opinion), I'm planning to get back to my original Z-end stop, Tap is a cool gadget, but it add a lot of weight to the extruder mass and consequently vibrations and other sorts of problems that comes with it.

The Tap would be much better if we could integrate a load cell (like the Creality CR6) has, it will remove the need of carriage, linear guide, magnets, etc... and cost less.

I'm working on a sort of basic Macro to select various spring steel sheet thickness and set up the offset difference(like the Prusa have), if I succeed, I'll share the results and Macro. I would love to have this integrated in my Klipper screen, but I'm not that good in coding.

 

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11 minutes ago, Manny said:

To be completely honest(but is just my opinion), I'm planning to get back to my original Z-end stop, Tap is a cool gadget, but it add a lot of weight to the extruder mass and consequently vibrations and other sorts of problems that comes with it.

I am looking into the Biqu Microprobe. Stacking Layers did a couple great videos on it and it looks like a smaller, refined and more accurate take on the BL-Touch style probe.

20230315_234046.thumb.jpg.c1bb3cac68230091af01550f39f98db9.jpg

 

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I had problems at first with the PEI surface. One thing you must do is clean it thoroughly with detergent and water. Do not touch the surface afterwards - any oil from your hands will prevent the part from sticking. I used a Scotch Brite pad to scratch the surface when i clean it - this gives a little more stick. You can wipe the surface with some rubbing alcohol and a clean cloth or paper towel between prints. I've never had a problem after that with prints sticking. Also, PETG will release once the plate cools. I've tried hairspray on PEI and never had much luck with it (I swear by hair spray for glass - it works great for any filament and prevents PETG from fusing itself to the glass).

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Thanks for your reply @SuperBoppy.  I was wondering about scuffing the surface of the plate slightly.  What about the textured side?  Do you scuff that slightly too? 

Yesterday I printed a few small items and it took a bit of futzing to get them to stick.  To some extent, it seemed to depend on how clean the surface was and what I cleaned it with.

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