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Newbie printing the treefrog, but it loses it's leg!  

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graz
 graz
(@graz)
Active Member
Newbie printing the treefrog, but it loses it's leg!

Can anyone identify the problem with this print?

My first layer tests all went well.  My Live Z is set at -1.000

Best Answer by bobstro:

There are likely 2 things going on with your print.

  1. Your Live-Z adjustment is a bit high. The lines in the brim should form a solid structure with few if any gaps. Try adjusting your Live-Z a bit lower (make it more negative). I'd go about 0.06mm lower to start.
  2. Your bed may need some cleaning. If there's the least amount of grease on the PEI, your part can partially dislodge.

Either of these can contribute to adhesion which will allow the print to wobble as the nozzle passes over it, often resulting in missing limbs and other problems. If that leg came loose, it wobbled and a good bond wasn't formed between it and the body.

Here's a big info dump on these issues...

The printer doesn't really "print a blob" or "print spaghetti". The mechanism is rigid and doesn't start wildly swinging around for unknown reasons. The printer moves as it's being told to according to the gcode. What is happening is that your part is either coming partially loose, causing it to wobble around as the printer continues to extrude (creating the blob), or completely loose, leaving the printer extruding in free air (creating the spaghetti). Your underlying issue is bed adhesion. This is a common problem that can be caused or aggravated by two factors that need to work together well for successful prints. Here's mama's tried and true copypasta recipe to get you going...
 
You are having bed adhesion issues. Filament should lay down cleanly on the PEI print surface and hold throughout the print. There are 2 main causes of bed adhesion issues. Even if you're dubious that these are the cause of your problems, they're 2 fundamental troubleshooting steps that you need to complete to rule out the basics:
 
  • A dirty PEI print surface. Even if you don't think this is the cause, it's always a good idea to make sure your PEI surface is clean before trying any other fixes. If it's a smooth PEI sheet, take it to the kitchen sink and give it a good dunk with Dawn (original formula, no vinegar or hand softener variants) dishwashing soap or your local equivalent (e.g. Fairy in UK). Use a clean paper towel to clean it off, and another to dry it. Avoid using any sponge or cloth that has been in contact with grease. Above all else, avoid touching the PEI print surface. Once it's good and clean, you should be able to use 91%+ isopropyl alcohol between prints, 100% acetone when that fails , and another dunk when acetone fails. Worst-case, use a 3M 7445 ScotchBrite pad or equivalent on smooth PEI to give it a very light buff, but only infrequently. If you've got a textured powder-coated PEI print surface, the official instructions are to use 91%+ isopropyl alcohol on it only. Rumors persist that some tribes deep in the jungle have had good luck getting started with these sheets by giving them a wipe with 100% acetone and a dunk with Dawn. Either way, there's no real warranty on these sheets. YMMV.
  • If you have not already done so, try using Jeff Jordan's "Life Adjust" procedure for calibrating your Live-Z setting. It is much easier to use and understand than the on-board routine and much easier to make mid-print adjustments accurately with. In general, start high (less negative) and work lower (more negative) in large increments (e.g. 0.1mm) until the filament starts to stick on its own. When you've got your Live-Z setting adjusted properly, you should be able to gently rub the extruded lines on the PEI surface without dislodging them.  Then start lowering (more negative) the level until there are no gaps between layers. You should not be able to peel the lines apart after printing, but the top should be regular. 
 
Remember that the effectiveness of a solvent such as isopropyl alcohol is going to depend on concentration and volume relative to the amount of grease you're trying to remove. 71% pads work... on very tiny amounts of grease. A squirt of 91% works better, but if there's a lot of grease, you need a lot more alcohol. This is why the wash under the sink with Dawn is so effective: There's a much larger volume of Dawn-and-water rinsing stuff away instead of just moving the broken-down grease molecules around.
  
And above all else, avoid touching the PEI print surface.
 
Glue stick is NOT necessary for PLA on the PEI print surface. You paid the big bucks for a Prusa with a removable spring still sheet with PEI, so clean it up and take advantage of it. Save the glue stick for printing sticky stuff like PETG that might adhere too well. Even then, I only find I need glue stick when printing high-temp PETG at 260C+ temps.
 
Try those 2 steps. If you're uncertain of the Live-Z results, post pics here of the 75x75 print bottom and you'll get quick help. If you want more detail, I've consolidated my notes on Prusa PEI adhesion, bed cleaning, and Live-Z calibration
 
A bit of trivia - The reason higher concentrations of alcohol seem to be harder to find is that isopropyl alcohol is most effective against bacteria at roughly a 71% concentration. A bit of distilled water helps slow evaporation, making the alcohol more effective. If you're looking in pharmacies, that's why 91% and higher seem to be hard to find.
 
Publié : 07/12/2020 8:06 pm
egar
 egar
(@egar)
Estimable Member
RE: Newbie printing the treefrog, but it loses it's leg!

Hi @gina'

Like you, I'm a newbie too, but have been getting a lot of printing hours under my belt over the last two weeks. 😉 

I had exactly the same problem with the treefrog on my first couple of prints.  It appear the foot came loose from the PEI sheet during the print.  I wasn't exactly sure why, but guessed the print surface, as shipped from Prusa, wasn't as clean as it should have been.  So I cleaned it thoroughly with soap and water, followed by several strong scrubs with alcohol wipes.  Since then, I've had no issues.

For what it's worth, since the first few days, I've been printing primarily in PETG and using Windex as a cleaning/separation agent and everything has been great.  Switching back to PLA has been fine, just cleaning with alcohol before every PLA print.

For the most part, I've been printing in PETG after my first few PLA projects. 

Publié : 07/12/2020 9:04 pm
graz a aimé
egar
 egar
(@egar)
Estimable Member
RE: Newbie printing the treefrog, but it loses it's leg!

Wow, I had a lot of typos and left over fragments in that post.  I tried to go back an clean it up a bit, but apparently I can no longer edit my own post.  I've done that successfully in the past -- does anyone know the restrictions that prevent re-edits sometimes?

Publié : 07/12/2020 9:31 pm
Ferly
(@ferly)
Eminent Member
RE: Newbie printing the treefrog, but it loses it's leg!

There is time limit, about 5 minutes I believe. It's really dumb.

Publié : 07/12/2020 9:42 pm
bobstro
(@bobstro)
Illustrious Member
RE: Newbie printing the treefrog, but it loses it's leg!

There are likely 2 things going on with your print.

  1. Your Live-Z adjustment is a bit high. The lines in the brim should form a solid structure with few if any gaps. Try adjusting your Live-Z a bit lower (make it more negative). I'd go about 0.06mm lower to start.
  2. Your bed may need some cleaning. If there's the least amount of grease on the PEI, your part can partially dislodge.

Either of these can contribute to adhesion which will allow the print to wobble as the nozzle passes over it, often resulting in missing limbs and other problems. If that leg came loose, it wobbled and a good bond wasn't formed between it and the body.

Here's a big info dump on these issues...

The printer doesn't really "print a blob" or "print spaghetti". The mechanism is rigid and doesn't start wildly swinging around for unknown reasons. The printer moves as it's being told to according to the gcode. What is happening is that your part is either coming partially loose, causing it to wobble around as the printer continues to extrude (creating the blob), or completely loose, leaving the printer extruding in free air (creating the spaghetti). Your underlying issue is bed adhesion. This is a common problem that can be caused or aggravated by two factors that need to work together well for successful prints. Here's mama's tried and true copypasta recipe to get you going...
 
You are having bed adhesion issues. Filament should lay down cleanly on the PEI print surface and hold throughout the print. There are 2 main causes of bed adhesion issues. Even if you're dubious that these are the cause of your problems, they're 2 fundamental troubleshooting steps that you need to complete to rule out the basics:
 
  • A dirty PEI print surface. Even if you don't think this is the cause, it's always a good idea to make sure your PEI surface is clean before trying any other fixes. If it's a smooth PEI sheet, take it to the kitchen sink and give it a good dunk with Dawn (original formula, no vinegar or hand softener variants) dishwashing soap or your local equivalent (e.g. Fairy in UK). Use a clean paper towel to clean it off, and another to dry it. Avoid using any sponge or cloth that has been in contact with grease. Above all else, avoid touching the PEI print surface. Once it's good and clean, you should be able to use 91%+ isopropyl alcohol between prints, 100% acetone when that fails , and another dunk when acetone fails. Worst-case, use a 3M 7445 ScotchBrite pad or equivalent on smooth PEI to give it a very light buff, but only infrequently. If you've got a textured powder-coated PEI print surface, the official instructions are to use 91%+ isopropyl alcohol on it only. Rumors persist that some tribes deep in the jungle have had good luck getting started with these sheets by giving them a wipe with 100% acetone and a dunk with Dawn. Either way, there's no real warranty on these sheets. YMMV.
  • If you have not already done so, try using Jeff Jordan's "Life Adjust" procedure for calibrating your Live-Z setting. It is much easier to use and understand than the on-board routine and much easier to make mid-print adjustments accurately with. In general, start high (less negative) and work lower (more negative) in large increments (e.g. 0.1mm) until the filament starts to stick on its own. When you've got your Live-Z setting adjusted properly, you should be able to gently rub the extruded lines on the PEI surface without dislodging them.  Then start lowering (more negative) the level until there are no gaps between layers. You should not be able to peel the lines apart after printing, but the top should be regular. 
 
Remember that the effectiveness of a solvent such as isopropyl alcohol is going to depend on concentration and volume relative to the amount of grease you're trying to remove. 71% pads work... on very tiny amounts of grease. A squirt of 91% works better, but if there's a lot of grease, you need a lot more alcohol. This is why the wash under the sink with Dawn is so effective: There's a much larger volume of Dawn-and-water rinsing stuff away instead of just moving the broken-down grease molecules around.
  
And above all else, avoid touching the PEI print surface.
 
Glue stick is NOT necessary for PLA on the PEI print surface. You paid the big bucks for a Prusa with a removable spring still sheet with PEI, so clean it up and take advantage of it. Save the glue stick for printing sticky stuff like PETG that might adhere too well. Even then, I only find I need glue stick when printing high-temp PETG at 260C+ temps.
 
Try those 2 steps. If you're uncertain of the Live-Z results, post pics here of the 75x75 print bottom and you'll get quick help. If you want more detail, I've consolidated my notes on Prusa PEI adhesion, bed cleaning, and Live-Z calibration
 
A bit of trivia - The reason higher concentrations of alcohol seem to be harder to find is that isopropyl alcohol is most effective against bacteria at roughly a 71% concentration. A bit of distilled water helps slow evaporation, making the alcohol more effective. If you're looking in pharmacies, that's why 91% and higher seem to be hard to find.
 
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

Publié : 07/12/2020 10:30 pm
bobstro
(@bobstro)
Illustrious Member
RE: Newbie printing the treefrog, but it loses it's leg!
Posted by: @ferly

There is time limit, about 5 minutes I believe. It's really dumb.

It's unfortunately required to avoid spam. Spammers would post legitimate-seeming posts, then come back weeks or months later and fill them with spam links. I do wish they'd open it up to hours at least.

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

Publié : 07/12/2020 10:32 pm
graz
 graz
(@graz)
Active Member
Topic starter answered:
RE: Newbie printing the treefrog, but it loses it's leg!

@bobstro

That was an incredible answer.  I will follow your advice.

Thank you.

Publié : 07/12/2020 10:39 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Newbie printing the treefrog, but it loses it's leg!

Hi Graz, 
Did you slice the print yourself? 
It looks like the Brim has printed with a tiny gap  separating it from the Frog Model, 

this is often caused by the Elephant's foot compensation settinf which is set at 0.2mm by default

Note, it is an intermediate mode setting
regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Publié : 08/12/2020 5:28 pm
graz
 graz
(@graz)
Active Member
Topic starter answered:
RE: Newbie printing the treefrog, but it loses it's leg!

@joantabb

No I didn't slice this myself.

Publié : 08/12/2020 5:45 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Newbie printing the treefrog, but it loses it's leg!

Oooohhhh ! wonder if I am seeing things or whoever did the slice, missed the issue.... 

In your picture, there appears to be a tiny gap between the frog model and the brim

in this picture I sliced the treefrog with default settings and the gap is difficult to picture so I have looked from below the build plate in this picture

and then  I changed the elephants foot setting from 0.2mm to 0.00 mm and as you can see below, the gap seems to have gone

as you can see, changing the elephants foot setting seemed to close up the gap.

so the chances are, once you sort your first layer adhesion, you could probably have printed the frog without the brim... 🙂

 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Publié : 08/12/2020 7:55 pm
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