Brim - great for adhesion but hard to cleanly remove - perforation.

[sr1329 3]

So I like my models to be really clean but sometimes I can’t get good adhesion without a brim. So I was wondering why the brim could not be perforated. We could then just peel it off cleanly and do some minor sanding if needed. 

[burtoogle 516]

Try setting the brim gap to 0.1 or thereabouts.

[sr1329 3]

Thanks I’ll try that. Would it still adhere the model to the bed if there is a full gap? 

[burtoogle 516]

If you use a small gap (i.e. 0.1mm) you will find that the brim does still mostly touch the model but is easier to remove.

 

Surprisingly, it does still help reduce the model's corners curling even when there is a visible gap between the inside of the prim and the model perimeter. This is the model that inspired the brim gap feature.

 

 

Printed using PLA, I noticed that the corners on the side tended to lift from the build plate unless I used a brim but the brim was hard to remove without looking ugly so I tried using a wide skirt with a very small gap and it still helped reduce the curling of the corners. I am guessing that a brim helps reduce curling by reducing the temperature change between the layers at the edge of the model.

 

I have also noticed when printing PETG that corner warping is greatly reduced when the bed temp is increased so for that material using a high bed temp (at least 75 deg) and a brim with gap gives me little warping at the corners.

 

 

[DivingDuck 105]

Sometimes it is also a good idea taking attention on setup values for part cooling. My fan for example is quite powerful so that I need to reduce the normal speed to about  50...70% for PETG.

[sr1329 3]

Yes sounds like a great idea. The setting itself says the thermal benefits are preserved. I have a print running with a 0.1mm gap. Let’s see how it works. If it’s smooth I’ll reprint a screen face i’m printing. I want it to look good. 
 

I also have an upgraded fan and keep it off for 2 layers and 40% after for PETG works well. I still get some curled edges very minor though. 

[Enigma_M4 120]

23 hours ago, burtoogle said:

Try setting the brim gap to 0.1 or thereabouts.

Hi,

 

the brim gap was the most useful enhancement of the last cura versions.

My first test after availability was printing a comb (PLA), using a 0.2mm gap. It printed perfect and the brim just separated while removing the print from the build plate, resulting in the cleanest first layer I ever got (no elefant foot).

Printing with CPE (PETG), a 0.3mm gap results in a very well adhering brim, which can be removed nearly perfect, just bending up and down.

Many thanks to all who were involved in the implementation of this great feature.

 

Regards

[sr1329 3]

Thanks for that information. I did 0.1 on PETG can’t wait to get home and see how it peels. Next time I’ll try 0.3mm. 

 

The other thing i’m a huge fan of in Cura are the tree supports. They are a game changer (not that I have much experience in the game). 

[Enigma_M4 120]

Playing the game WILL result in experience 😉.

I forgot to mention that my experience is made with an UM3, 0.4mm nozzle, so the gap value may vary for other printers / nozzle sizes / materials.

A higher gap value for PETG may result in what I experienced with PLA, but I wasnt brave enough going above 0.3 at all (It's just trial and error and achieving a big learning curve while playing the game 😉).

[burtoogle 516]

30 minutes ago, Enigma_M4 said:

Many thanks to all who were involved in the implementation of this great feature.

 

It was me, you're very welcome!

 

32 minutes ago, Enigma_M4 said:

Printing with CPE (PETG), a 0.3mm gap results in a very well adhering brim, which can be removed nearly perfect, just bending up and down.

 

I use 0.1mm for PETG and don't normally have any problem removing the brim. As I mentioned above, one thing that really helps with avoiding corners lifting is to use a high build plate temp. For me, going from 55 to 75 degrees reduced the corner warping considerably.

[Enigma_M4 120]

4 minutes ago, burtoogle said:

It was me, you're very welcome!

 

Then my praise was in just the right place 🙂.

[DivingDuck 105]

1 hour ago, burtoogle said:

For me, going from 55 to 75 degrees reduced the corner warping considerably.

This is true. I use for my PETG a higher value about 81°C in combination with a glass bed and 0.1mm too.

[sr1329 3]

So I got home and debrimmed my model. 
 

I keep my bed at 80c. 
 

My normal flow for the PETG I use is 93%. 
 

First layer flow is 100%. Brim width is 8mm. 
 

What I found was the brim was fully adhered to the model but was easier to peel off. Not perfectly but cleanup was easier. 
 

I think I would try 0.3 next time. 
 

Zero warping BTW and it was a flat model pretty thin and flexible even. I suppose the smaller surface models are more prone to warping?

 

Also i’m wondering what’s the difference between flow and layer width. In my mind they would be the same thing but i’m new to 3D printing. 

Edited August 14, 2020 by sr1329

[sr1329 3]

Tried 0.3. It is still attached to the model. However I just can snap off the brim cleanly. This is a game changer. Models are clean and taking off the brim is like the popping bubble wrap of our times - so much fun. I could print stuff just to pop the brim off now. 

[burtoogle 516]

Sounds good, and are you still getting decent adhesion and minimal corner warping?

[sr1329 3]

8 minutes ago, burtoogle said:

Sounds good, and are you still getting decent adhesion and minimal corner warping?

 

On the one print I did adhesion was fine and warping was non existent. In any case it is still attached but just comes off really easily. 
 

I had a few failures this morning and left to work but I suspect it is some other issue. I’ll diagnose when I get back.

[sr1329 3]

I printed a few more parts. I’m finding 0.4 to be ideal especially with larger parts with a lot of first layer geometry. Otherwise 0.3 is better for smaller parts. 
 

No warping or bed adhesion issues. But also yesterday I did maintenance on my hot end and mount. It was a bit loose before. Now my first layer adhesion is so good that I may not even need a brim. However it seems like no harm and lets the extruder work a little before the main print. 
 

With 0.4 gap it has no disadvantages at all so I’ll keep using a brim. 

[sr1329 3]

So it may be obvious now but needing to go as wide as 0.4 to have easy removal of the brim on a 0.4 nozzle is a sign of the nozzle being too close to the bed. Now that I have figured out my proper Z-offset 0.4 appears as thin line between the print and brim.

 

Parts have no warping whereas I had incidents of warping when my nozzle was too close to the bed.

 

I suppose it's a better calibration aid than the usual "look at lines at top of your first layer".

 

 

[xtrude64 0]

This sounds like it will fix my problem with impossible brim removal on small parts. Where are the settings for Brim gap? I searched in the settings and it did not return anything for Brim Gap.

[obewan 37]

Under build plate adhesion called 'brim distance'

[stevecu 0]

So, I'm very new to 3d printing (day 2), just set up a new Ender 3 V2. 

 

I'm using Cura 4.91 and do not have the option for brim gap. I only get the option to create a brim vs. skirt, but no options to customize it. 

 

The brim prints, and solves the adhesion problem I was having. But I want to try this gap option to make removal cleaner. 

[GregValiant 1,342]

It's "Brim Distance" and it's with the other brim settings in "Build Plate Adhesion".  You will need to play with it a bit.  I set it at 0.1 and it works OK.

Next to the settings search box is a drop down for setting visibility.  Set it to "All".  Brim Distance is supposed to unhide itself when you choose "Brim" so maybe there is something going on there.