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First print was great, next day not so great  

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mtingey
(@mtingey)
New Member
First print was great, next day not so great

Hi guys,

Assembled a new mk3s kit over the last week and finally got it running last night. Printed a prusa logo and it looks pretty good, particularly the bottom. I turned the printer off afterwards and this morning attempted a benchy which has some issues. Retried printing the prusa logo again and I have gaps in the first layer. Ive checked belt tensions (belt test says they are both at 260 give or take) and the pulleys are tight. Ive tried adjusting the extruder tension without any change. Ive recalibrated and also redone Z height a few times which made it better but still not perfect.Any ideas on what im doing wrong? Using the included prusa grey PLA if it makes a difference.

The bottom prusa logo in the photo below was last night's and seems perfect. the top one is the first layer of an aborted print today. Benchy attached also.

Thanks!

 

Best Answer by jsw:

It looks to me like you have a combination of a bed adhesion issue, possibly a Z calibration issue, and shifted layers.

Please be sure that your bed is Really Most Sincerely Clean.  Whether to use a water-based agent or an organic solvent is the subject of endless-loop debate.  😉

I would recommend using one of those Z calibration test prints, similar to the 3X3 one below.  This will help you dial in or confirm your Z calibration much better than the internal procedure.  All squares should be even and uniform.  It's a good sanity check to run periodically.

Also be sure that everything is tight, particularly the grub screws on the pulleys.  Random shifted layers can be caused by loose grub screws or loose belts.  A good sanity check is to hold the stepper motor shafts tightly with pliers and try to move the print bed or extruder.  They should not exhibit any 'play' or 'slop' and should be solid in place while you hold the shaft tightly.

As for belts, I have never trusted the numbers.  I think that a better test is to press them together, and they should indeed move but resist the pressure, or pluck them and watch/listen for them to sound like a bass guitar string.  (LOL, if you have perfect pitch, you can tune your belt for a low 'E'.)  😉

 

Posted : 23/09/2020 1:51 pm
jsw
 jsw
(@jsw)
Famed Member
RE: First print was great, next day not so great

It looks to me like you have a combination of a bed adhesion issue, possibly a Z calibration issue, and shifted layers.

Please be sure that your bed is Really Most Sincerely Clean.  Whether to use a water-based agent or an organic solvent is the subject of endless-loop debate.  😉

I would recommend using one of those Z calibration test prints, similar to the 3X3 one below.  This will help you dial in or confirm your Z calibration much better than the internal procedure.  All squares should be even and uniform.  It's a good sanity check to run periodically.

Also be sure that everything is tight, particularly the grub screws on the pulleys.  Random shifted layers can be caused by loose grub screws or loose belts.  A good sanity check is to hold the stepper motor shafts tightly with pliers and try to move the print bed or extruder.  They should not exhibit any 'play' or 'slop' and should be solid in place while you hold the shaft tightly.

As for belts, I have never trusted the numbers.  I think that a better test is to press them together, and they should indeed move but resist the pressure, or pluck them and watch/listen for them to sound like a bass guitar string.  (LOL, if you have perfect pitch, you can tune your belt for a low 'E'.)  😉

 

Posted : 23/09/2020 3:55 pm
mtingey liked
mtingey
(@mtingey)
New Member
Topic starter answered:
RE: First print was great, next day not so great

Thanks for the comprehensive reply jsw, much appreciated!

Before you replied I loosened off the X and Y axis belts by one tooth as I couldnt loosen any more in the adjustments and readjusted. The numbers only changed by a handful of units but the tension is definitely looser. While I was there I double checked all pulley grubscrews. I also purged the extruder at 260 degrees C and reloaded.

I just finished printing a XYZ test cube and it came out much much better. Not sure which of the above (or a combination of all) did the trick but it seems better. Im going to do another benchy now and see how it turns out! If im not happy after that I will do the 3x3 Z calibration (and will do so periodically regardless).

One question; You mentioned bed adhesion. I am cleaning the bed between each print with isopropyl alcohol and the part overall is sticking really well to the bed. Does it look like individual strands are not sticking even though overall it is?

Thanks again for your help! I will report back on the benchy tonight 🙂

 

Posted : 23/09/2020 4:59 pm
mtingey
(@mtingey)
New Member
Topic starter answered:
RE: First print was great, next day not so great

Second Benchy was far better!

Posted : 23/09/2020 7:46 pm
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