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Problem - Benchy overhang curl hitting nozzle  

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Your Fave Mullet
(@your-fave-mullet)
Active Member
Problem - Benchy overhang curl hitting nozzle

Hi everyone!

I'm new here and I need assistance!

I Finished building my MK3S+ yesterday and all seemed well when I printed the first layer and the Prusa logo... But now I try the 3D Benchy and I have thrice failed. I watched the nozzle hit the the overhang curl and it snapped off the sheet. 

I am using the PLA that came with the kit, the smooth pei sheet, which I have cleaned, and the gcode from the provided SD card. I have read other posts relating to the same issue and I have seen many suggestions but none seem to have solved the issue. 

The cleanest print I achieved was when I slowed the print speed to 90 and then 80 as I observed the curl forming. 
On the pics that's the one closest as well as the first layer shown. There is some stringing present here too. 

The printer is not placed in a room with draught.

Please let me know if there is anything I have missed that can help anyone help me.

Thank you!
Liam 

This topic was modified 1 month ago by Your Fave Mullet
Posted : 21/06/2021 9:38 pm
John
 John
(@john-6)
Reputable Member
RE: Problem - Benchy overhang curl hitting nozzle

Lifting of the print in PLA is usually sign of either unclean plate or too high live z but the prints don’t look bad. 

This post was modified 1 month ago by John
i3 Mk3 [aug 2018]...
Posted : 21/06/2021 10:28 pm
Your Fave Mullet
(@your-fave-mullet)
Active Member
Topic starter answered:
RE: Problem - Benchy overhang curl hitting nozzle

@john-6

Hi John

Thanks for your reply 🙂

I agree they ain't bad at all! Or at least not to my untrained eye haha.

I'll try wiping the surface tomorrow with some IPA. I have acetone too bI believe that can be a bit too abrasive? Maybe I can dilate it and try that? 

Posted : 21/06/2021 10:37 pm
Brad
 Brad
(@brad-2)
Eminent Member
RE: Problem - Benchy overhang curl hitting nozzle

I also think that this is just bed adhesion. Looking at the bottom of your Benchy I would say that you are slightly too high. I am sure that properly cleaning your bed and lowering your Z will solve this problem. I would not use acetone on a new sheet though.

Posted : 21/06/2021 11:06 pm
John
 John
(@john-6)
Reputable Member
RE: Problem - Benchy overhang curl hitting nozzle

I dont have any links but clean plate with dishwashing liquid (dawn seems to be the favourite so look for something without added scents) and lots of hot water rinsing and dry with non lint paper towel. Dont handle surface with fingers.

Acetone should only be used infrequency as it deteriorates the surface.

 

Washing is a proven method to get a good adhesive surface.

If you feel the need to use the chemicals - start with Acetone >>IPA>>dishWashing liquid last

 

Then make sure your live z is good - search "Life-z Jeff Jordan" (sic) - its a long thread but you probably only need to read the first couple of pages. Maybe someone has the link

This post was modified 1 month ago 2 times by John
i3 Mk3 [aug 2018]...
Posted : 21/06/2021 11:15 pm
bobstro liked
John
 John
(@john-6)
Reputable Member
RE: Problem - Benchy overhang curl hitting nozzle

here is the link

https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/#post-22992

i3 Mk3 [aug 2018]...
Posted : 21/06/2021 11:21 pm
Diem
 Diem
(@diem)
Prominent Member
RE: Problem - Benchy overhang curl hitting nozzle

The logo is a print designed to be particularly easy for a first try.

Benchys are test parts that stress every variable and setting.

Even if you have everything perfect right now your chance of a perfect benchy next week is low.

During the first few weeks of use the printer will run-in and settle its parts together; then you will have to go over the basic maintenance checks, lubricate and recalibrate. Even if you got everything dialled in perfectly today, it would all need re-doing.

Better to settle, temporarily, for a basic working printer and get some useful printing done, make your early mistakes, establish a routine and generally get used to the process. Then when you do your one month service you can take extra care knowing the new settings on your now stable printer are likely to last for several months.

That said: your first layer calibration needs attention, you can go lower, more squish.

At the end of the calibration you are aiming to print a single layer *sheet*. It should be possible to peel it off in one and fold it without the threads seperating. If it breaks into lines it is too high, not squished enough. If it is a single sheet but with wavy lines or drag marks on it you are too low.

For most people it pays to use 7x7 mesh bed levelling.

I'll try wiping the surface tomorrow with some IPA. I have acetone too bI believe that can be a bit too abrasive? Maybe I can dilate it and try that?

IPA is a useful maintenance cleaner but if the bed is dirty nothing beats dishwashing detergent (Dawn/Fairy) and plenty of HOT water, rinse well and dry with a fresh paper towel. Handle by the edges only.

Acetone should be reserved for situtions when nothing else works and you are considering discarding the sheet.

Cheerio,

Posted : 22/06/2021 9:50 am
Your Fave Mullet
(@your-fave-mullet)
Active Member
Topic starter answered:
RE: Problem - Benchy overhang curl hitting nozzle

@brad-3

Ah thank you so much! I'll lower it a little. At the minute it's at negative 0.715.

When I finish work I'll experiment a bit more. 

Posted : 22/06/2021 1:17 pm
Your Fave Mullet
(@your-fave-mullet)
Active Member
Topic starter answered:
RE: Problem - Benchy overhang curl hitting nozzle

@john-6

This is great stuff thank you!! 

Posted : 22/06/2021 1:18 pm
Your Fave Mullet
(@your-fave-mullet)
Active Member
Topic starter answered:
RE: Problem - Benchy overhang curl hitting nozzle

@diem

Ahhh I see!

So the device is to be "worn" in so to speak? And when I come to my first monthly service and then recalibrate then those calibration settings should last several months?

Understood. This is all great advice thank you so much.

It seems that in this case the culprit is most likely the z level and/or the adhesion.

 

Posted : 22/06/2021 1:25 pm
Diem
 Diem
(@diem)
Prominent Member
RE: Problem - Benchy overhang curl hitting nozzle

@your-fave-mullet

'Run in' is the usual term.  Every owner builds their MK3 very slightly differently.  At first they are different beasts but with use they converge on a common standard.

It seems that in this case the culprit is most likely the z level and/or the adhesion.

There are hundreds of threads on here addressing the issue; the first layer is the foundation of a successful print, most newcomers have problems with both aspects.

Cheerio,

Posted : 22/06/2021 2:18 pm
Your Fave Mullet
(@your-fave-mullet)
Active Member
Topic starter answered:
RE: Problem - Benchy overhang curl hitting nozzle

Hi all!

Great news! Benchy was a success!!

So there are a couple issues I see.. Stringing and there's a blob under 2 of the arches of the cabin. This may have been due to when I turned the fan speed down as I witnessed the curl forming.

See pics of the base. I'm still experimenting with the Z level.

This was at - 0.760mm

Honestly, thank you all so much for the advice! I cleaned the sheet with IPA wipes then fairy liquid and hot water. Then lowered the Z level to the value mentioned above.

I brought the z level down further just now to - 0.880m and I believe this is what it looks like when it is too squashed??

I guess now is the time for fine tweaks. 

I've also noticed that parts of the belt sides have had the black colour rubbed off. Is that normal? And is the belt test a good enough test to see if overtightened or too loose?

Again thank you all so much so far. I want to out everyone's answer as best answer, haha. 

Posted : 22/06/2021 7:12 pm
John
 John
(@john-6)
Reputable Member
RE: Problem - Benchy overhang curl hitting nozzle

Fine Tweeks - review the link I posted earlier to get an optimal z value - the thread recommends using larger test square say 50 or 75mm sq  which you adjust live across a range of values as you print.

https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/#post-22992

i3 Mk3 [aug 2018]...
Posted : 22/06/2021 11:59 pm
Diem
 Diem
(@diem)
Prominent Member
RE: Problem - Benchy overhang curl hitting nozzle

For belt checks:

https://www.prusaprinters.org/prints/46639-tension-meter-for-the-gt2-belts-of-i3-mk3s-or-prus

It MUST be printed in Prusament PETG or the spring tension will be wrong.

Cheerio,

Posted : 23/06/2021 10:03 am
Your Fave Mullet
(@your-fave-mullet)
Active Member
Topic starter answered:
RE: Problem - Benchy overhang curl hitting nozzle

Fantastic stuff from both there.

Wow this is all amazing advice. Thank you again!

I got the triceratops skull printed overnight too! No problems! 

Posted : 23/06/2021 11:32 am
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