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Decreasing quality of print sheen and layer adhesion [PETG].  

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jason halter
(@jason-halter)
Active Member
Decreasing quality of print sheen and layer adhesion [PETG].

       using i3 MK3s with PETG.  I print 90% of my stuff in PETG.   Over the last few months I have noticed the printer producing increasingly poor sheen and layer adhesion.  Go back a few months, my configuration was perfect. The sheen was a glossy finish and layers were as good as it gets.  Now the sheen is no longer glossy what-so-ever [matte only]?  The results are the same with brand new PETG as with old PETG, and I have confirmed on a second printer it IS NOT the filament.

     I have noticed that the display has become slow as well, as if everything is just a 1/2 second behind than usual [electric lag]?  Machine has ~ 1000 hrs of service now.

So:  Q 1:  do you suppose there is a voltage / electrical draw that is causing the extrusion [and its quality] to be poor and poorer? Possible power supply issue or possible control board problems...

       Q 2:  Do you suppose the original extruder motor has issues?

Things I have done already:  Motor bearings [yes you read that correctly] swapped out on E-motor and X-axis motor.  resulted in no change.

Thoughts on what to do next:  Thinking of going with a Bondtech extruder assembly and a mosquito hot end, but concerned with the possibility that the issues lies in the electrical domain?

 

Hopeful for help and constructive thoughts and remedies.

Posted : 30/06/2021 3:50 pm
bobstro
(@bobstro)
Illustrious Member
RE: Decreasing quality of print sheen and layer adhesion [PETG].

PETG is very (very very) prone to absorbing moisture. Have you dried your filament or tried other spools? If your filament has absorbed too much moisture, you'll get inconsistent extrusion which contributes to stringing, and uneven quality which contributes to the matte appearance.

After ensuring the filament is dry, look for what's different. Are you using a different brand of filament? Here are some test prints I did when I was determined to figure out what settings I needed to adjust to eliminate fine stringing. Retraction increases in increments of 0.02mm from front-left t0 rear-right:

Notice that after the first part with no retraction, there is almost no string with any amount of retraction. Once I calibrated the extrusion multiplier and made sure my filament was dry, I've been getting good results with PETG using 0.02-0.04mm retraction, 0.4mm z lift, and no wiping. If stringing starts, before making any setting or hardware changes, I toss the filament in my dryer. "When in doubt, dry it out."

If you were getting great results, I wouldn't go doing wholesale hardware replacements without first nailing down why your quality dropped in the first place. I'd hate to spend the time and money on upgrades only to find the old problem persists.

I've got some notes on troubleshooting and eliminating stringingthat you might find useful.

Edit: No ideas on a lagging display, sorry.

Edit2: Be sure to eliminate any other software issues from the equation. Try a print off SD card.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 30/06/2021 6:35 pm
Swiss_Cheese
(@swiss_cheese)
Noble Member
RE: Decreasing quality of print sheen and layer adhesion [PETG].

isn't it funny that when PETG first reared it's head that the manufactures called it hydrophobic ?

The Filament Whisperer...
Posted : 01/07/2021 1:35 am
Diem
 Diem
(@diem)
Noble Member
RE: Decreasing quality of print sheen and layer adhesion [PETG].

Machine has ~ 1000 hrs of service now.

So time for a full maintenance session and re running all the calibrations; but I guess you've done a lot of that.

concerned with the possibility that the issues lies in the electrical domain?

Incredibly unlikely.

Have you fitted a new nozzle?  The old one may have worn.

But I'm with @bobstro, dry your filament before trying anything else.

Cheerio,

Posted : 01/07/2021 11:33 am
jason halter
(@jason-halter)
Active Member
Topic starter answered:
RE: Decreasing quality of print sheen and layer adhesion [PETG].

Like I said in the original post.  It is not the *Filament* . I know that PETG is hygroscopic. I know what wet and dry PETG is. I know, I know, I know... Not a newbie here.    IT is not the filament.

     My thoughts are focused on such that it has to do with the amount of heat applied in the hot-end along with the speed that it is applied to create whatever is programmed into the g-code [combo of elec and mech].   I always use the same conditions. I have an excellent CONFIG. SETTING. INI that has created perfect prints on this i3 MK3s machine for weeks and months. I always, always use the SD card. 

     I have done complete maint on this machine, lubed bearings, swapped motor bearing [again, yes motor bearings, *625ZZ*], increased extrusion rates from 95 --> 98 --> 102 all resulting in having a matte sheen and poor layer adhesion.  Well layer adhesion gets better with a higher flow rate, marginally. 

   I suppose I could try a new ceramic heater cartridge, as it is a cheap option?

My main concern is such that the LCD screen is significantly slower than previous months.  Its like everything on the digital controls side is lagging 1/2 sec?  As soon as I put the SD card in, it takes over 2-3 secs to populate the list,  and this is why I am asking here, on this forum, has anyone encounter this type of situation?   I think, pretty sure,  it is not a mechanical issue, as all bearings & belts & motors are ok, pretty sure... 

And this ^ is why I am leaning towards a possible elec supply problem?   what are the chances that someone has a schematic with appropriate voltages at specific test points that can be verified why a voltmeter?  Or had the same issue and found a solution.  

   The photos [not so great] below display the good sheen on the LEFT and the matte sheen with poor layer adhesion [i3 MK3s] on the RIGHT. I know it is subtle in pics, but in person it is quite significant, IMO. 

    

   

Posted : 01/07/2021 2:40 pm
bobstro
(@bobstro)
Illustrious Member
RE: Decreasing quality of print sheen and layer adhesion [PETG].
Posted by: @jason-halter

Like I said in the original post.  It is not the *Filament* . I know that PETG is hygroscopic. I know what wet and dry PETG is. I know, I know, I know... Not a newbie here.    IT is not the filament.

You seem to enjoy making wholesale hardware replacements, and I'm not about to try to talk you out of it. Go for what you enjoy. Nobody's trying to insult you or throw shade on your quals. Again though, if you were getting great results with the hardware and something changed, I wouldn't go doing wholesale hardware replacements without first nailing down why your quality dropped in the first place. Then maybe make targeted upgrades if a repair is insufficient.

Issues with poor inter-layer adhesion and finish quality even when using settings and filament that worked previously do indicate "something changed". I wish people asking for suggestions would not be offended when we try to eliminate the basics. It's basic troubleshooting. We don't review your resume before responding, and even pros can overlook the basics. Take the suggestion to verify the filament for what it is, and if it's a non-issue, carry on.

If filament is eliminated, what you're describing (poor inter-layer adhesion, change in finish) points towards temperature issues. Some thoughts in no particular order:

  • Please verify you are using the same slicer settings that worked previously. (Again, don't be offended. Basic question. Prusa presets change and might not always be obvious. We realize you're a pro etc.) Do you have any old gcode that you can verify now prints with diminished quality?
  • Another basic troubleshooting suggestion, and please for the love of God don't be offended, have you tried slowing the print down? Using the same heat settings but slowing down feed rates might indicate something is affecting the maximum volumetric rate your hotend can handle and possible feed or friction issues. Same temps but slower gives filament more time to melt fully. Spin the knob back to 50% speed mid-print. That can identify a different set of problems than pure temp-related problems.
  • Any firmware or other changes that might have been done to the printer? Thermistor replacement, new heater block, nozzle material, anything like that? We've had several instances where a "direct drop-in replacement" wasn't.)
  • Have you done any temperature readings or other verification that temperatures are off? Does bumping temps 5-10C restore the previous finish? (This also eliminates considerations like partial clogs and nozzle problems.)
  • Have you done direct temp readings or voltage measurements? A thermistor is cheap to replace and can certainly impact temperature readings.
  • Have you done a PID tune? This mostly stabilizes temperatures, but your issues do sound temperature-related.
  • Any possible environmental issues? Increased AC usage due to the blasted heatwave? Addition or modification of an enclosure?
  • I have had worn nozzles affect finish quality. @Diem's suggestion to try another nozzle both confirms the nozzle is good and might identify a partial clog. Have you done cold pulls? Again, I realize this is a very rudimentary troubleshooting step and this is not meant as a slight.
  • Have you verified the power supply voltages? Thermistors? Heater cartridges?

The yellow section on the right looks very dirty. Is that just an artifact from the picture or is that actually showing in the print?

As for the slow menu response, Marlin on an 8-bit controller is known for response issues. A large number of files can also impact performance. And of course, a failing card may cause retries. Have you tried a new card or reformatting the old one? If you remove the card, are the menu responses still slow? If you use OctoPrint or similar software, is the menu sluggish when printing via USB? 

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 01/07/2021 3:36 pm
Diem
 Diem
(@diem)
Noble Member
RE: Decreasing quality of print sheen and layer adhesion [PETG].

Like I said in the original post. It is not the *Filament* . I know that PETG is hygroscopic. I know what wet and dry PETG is. I know, I know, I know... Not a newbie here. IT is not the filament.

OK, so dry it anyway.

increased extrusion rates from 95 --> 98 --> 102 all resulting in having a matte sheen and poor layer adhesion.

Go back to the values that worked the first time - now, what has changed in the environment?  Season/weather?  Air con?  Ambient temperature? - have you tried an enclosure?

Try a small change (rise?) in the extruder temperature.

My main concern is such that the LCD screen is significantly slower than previous months. Its like everything on the digital controls side is lagging 1/2 sec? As soon as I put the SD card in, it takes over 2-3 secs to populate the list

Try reformatting the SD card.  Don't let it get too full.

The apparent lag is probably user(you) familiarity, a known cause of baseless UI dissatisfaction ... did you time it when new, and again now?

And this ^ is why I am leaning towards a possible elec supply problem? what are the chances that someone has a schematic with appropriate voltages at specific test points that can be verified why a voltmeter? Or had the same issue and found a solution.

It's all on github but don't bother.  Electricity supply problems don't manifest that way.

Cheerio,

 

 

Posted : 02/07/2021 12:20 am
ssill2
(@ssill2)
Noble Member
RE: Decreasing quality of print sheen and layer adhesion [PETG].

@diem

The list being populated slowly is improved in 3.10 of the firmware.  It had to do with indexing and the number of files.   To get around this I started making folders/directories on the sd card so there were as many files in a single dir.

It got WAY better with 3.10 firmware though.

Posted : 07/07/2021 7:31 pm
jason halter
(@jason-halter)
Active Member
Topic starter answered:
RE: Decreasing quality of print sheen and layer adhesion [PETG].

update:

       I believe I have found the issue, refer to the pic for specific measurements.    

I cut out the thermistor, measured it many times. Everytime the #'s were close to actual values, but seemed to fluctuate w/o stability???

Confirmed with other thermistors, so as to be sure, and confirmed that the thermistor is working/ not-working properly.   Getting readings from 95K ohms to 117+K ohms.  all within the same specific area.  So what is up with that....

     You can see where X marks the spot on the pic. There is a break in the wire's shielding @ that very point.  My preliminary findings is such that when the sheilding is exposed the resistance increases [a little is from the heat in my fingers]. The increased resistance is being interpreted by the control board as a higher temp than what is actual.  Since the break in shielding is ~2 cm from the sensor, I believe it to be messing with the device. Secondly the thermistor is reading all over the place from 103 [~7.5°C] at present time to 116+[~40°C]. All @ the same room temp.  Which is definitely not good enough for required intended application(s) [unstable]. 

     Going to order parts.  will update later.  Probably good to employ silicon sheathing on the new wires when they get here. 

Posted : 07/07/2021 8:28 pm
ssill2
(@ssill2)
Noble Member
RE: Decreasing quality of print sheen and layer adhesion [PETG].

@jason-halter

wow good catch.   Those wires are super thin so I'm always careful when brushing the nozzle to clean it.  Excellent sleuthing.

Posted : 07/07/2021 8:29 pm
Peter in Katy
(@peter-in-katy)
Estimable Member
RE: Decreasing quality of print sheen and layer adhesion [PETG].

@jason-halter

I got here late to the party, but immediately thought of the thermistor.
Matte appearance and poor adhesion with petg are almost always printing with too low temperature.

First, I'd bump up the temp 10°C.  When/if that worked, I'd replace the thermistor.  If that didn't fix it, only then would i worry about something more exotic.
Glad you figured it out.

Posted : 10/07/2021 12:06 pm
jason halter
(@jason-halter)
Active Member
Topic starter answered:
RE: Decreasing quality of print sheen and layer adhesion [PETG].

Update #2;

     Thermistor replaced, quality of sheen and layer adhesion are now back to normal.  

      I did change out the power supply as well prior to the thermistor swap. Why? just because I had one on the shelf that was a higher wattage of 500W and it did not cost me anything.  The original PS is rated at 240W.  The Prusa/original PS had an output voltage of 23.81V with a voltage drop of 0.01V.  The 500W Chinese PS had a voltage output of 24.32V with a voltage drop of 0.02V. 

Reference the Photo A-B-CNot studio quality photo, but gets the point across...

A:  Original equipment, no alterations what-so-ever.   Contains no sheen and also poor layer adhesion.

B:  New power supply [500W].  Resulted in improved layer adhesion and an improved homogeneous appearance, no sheen at all.

C:  New power supply [500W] and new thermistor. Resulted in the return of glossy sheen and same layer adhesion as B.  [PETG is now wet and in need of drying, but good enough for determining my issue(s)]. 

 

Notes:   Beware of your thermistor wire shielding. I believe this was all caused by a wire that was nicked and later started to get worse over time.  It was hard to determine the exact fault as every time I measured the resistance of the thermistor I was getting a fairly good measurement [ in the zone]. The more I measured the resistance the more I could see that the thermistor was becoming unstable.  The measurements were out by 15-40°C or dead on.  So it was not easy to find the exact issue.  

     I have added a chart for proper thermistor values, in my first update update, the values I posted were not correct. 

     Lastly, I would recommend a silicon sock [sheathing] over the thermistor wiring. I think if there was that level of protection in the first place I may have not had this issue. 

Posted : 13/07/2021 3:17 pm
bobstro
(@bobstro)
Illustrious Member
RE: Decreasing quality of print sheen and layer adhesion [PETG].
Posted by: @jason-halter

[...]

A:  Original equipment, no alterations what-so-ever.   Contains no sheen and also poor layer adhesion.

B:  New power supply [500W].  Resulted in improved layer adhesion and an improved homogeneous appearance, no sheen at all.

C:  New power supply [500W] and new thermistor. Resulted in the return of glossy sheen and same layer adhesion as B.  [PETG is now wet and in need of drying, but good enough for determining my issue(s)]. 

I think you have your labels reversed in the image. C is definitely not the best quality in the picture.

Any pics of the original power supply with the thermistor replaced? Or is that A in the image?

Socks are good for many things. Keeping gunk off the wiring definitely reduces wear & tear.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 13/07/2021 3:30 pm
jason halter
(@jason-halter)
Active Member
Topic starter answered:
RE: Decreasing quality of print sheen and layer adhesion [PETG].

Ref: A-B-C.jpg    

     A: [first print] original equipment, all around.    It was at this point where I noticed poor layer adhesion and a matte finish.   --> into remedies.

     B:  [second print]. Different power supply swapped in [500W Chinese].  Resulted in improved layer adhesion and a more homogeneous    product, but still contained a matte finish.

     C:  [third print] the 500W PS plus new thermistor.  Layer adhesion really good, glossy sheen restored. 

G-code: all same

Temps & cond's: all same.

Filament: Same same; however, you can see that the filament has become wet as there are blobs, zits and stringing [it was left out too long].  But, I do not care about that ATT as the intent was to solve the layer adhesion and lack of glossy finish.  From this point I can go to using a dried out PETG filament where the end results are a more polished product. 

 

Cheers. 

 

Posted : 13/07/2021 3:50 pm
bobstro
(@bobstro)
Illustrious Member
RE: Decreasing quality of print sheen and layer adhesion [PETG].

Maybe it's just me, but A looks to be the best of the bunch. 

I would have been curious to see how simply replacing the thermistor with the original power supply affected results. Interesting that the underside fillets (always a problem) look pretty good on C.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 13/07/2021 4:06 pm
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