Brim or no brim
How 'regular' is it to use a brim? I've found that sometimes the brim layer doesn't stick while the raft adheres very nicely and evenly (like the pictures). When I adjust for getting the squish perfect for the brim, the raft is not satisfactory (plowing in my case). I can't seem to fine the happy medium where they are both correct at the same z-setting and/or bed level correction.
The brim filament that doesn't adhere gets moved around, and dragged into the raft and makes a mess. I noticed the 'no brim' option.
Other things I've tried for getting good, even adhesion is a thicker first layer, slowing the first layer to 10mm/s, various bed temps, and of course making the nozzle 5 degrees hotter for the first layer.
My 1st layer is quite even throughout the bed. I just can't get a good brim AND a good raft.
I welcome any thoughts.
If your brim doesn't stick you have a serious adhesion problem ... please run a first layer Z calibration and post a picture of it *on the print sheet*
Brim is used when a part has a small footprint for its area, eg is tall and thin; the brim increases the footprint and aids adhesion.
Cheerio,
RE: Brim or no brim
I have run that and the 3x3 test many, many times. I get nice rafts, but the brim and sometime the perimeter lines have issues. I'm using PLA on the smooth PEI plate that came with my kit and no additional adhesion.
The 3x3 test produce nice rafts that are consistent across the plate.
I'll post a pic of the 1st layer test.
RE:
For the smooth sheet and PLA, dishsoap will clean much better than IPA. I am guessing it has something to do with the residue you see when you remove PLA parts. PETG does not have this issue. When my bed adhesion on my smooth sheet seems suspect I clean well with soap. If I don't want to use a brim, I'll sometimes use gluestick which works well.. but a good soap clean should work well on Prusa's smooth sheet. I've never used a raft, but I don't print really small parts.
RE: Brim or no brim
I did some experimentation using the glue stick and that is working very well. It seems to greatly improve the adhesion of the brim and first layer perimeter. Maybe that was the missing link. I've had two perfect prints with merely the addition of the glue.
OK, Glue stick is used to *reduce* adhesion. If a thin glue layer actually improved the hold you definitely need to post your first layer and make certain the print sheet is clean.
Cheerio,
RE: Brim or no brim
Not the optimal color for a photo of this, but this run was mostly good with a slight miss on the upper left side. The raft looks good. This is a freshly, soap and water washed plate.
RE:
Get a really good close up of the square.. at first glance your stuff looks okay.. The glue is really a different surface to print on that allows filament, such as PETG to bond to it, rather than the PEI print bed. On the smooth surface the PETG can bond too well and damage the PEI. Hence glue which makes a good bond on its top surface, and then the glue bottom surface releases from the PEI with the model. I've used glue stick on my smooth surface for some particular small models and it provided a better adhesion than just the smooth sheet, and my smooth sheet was clean.. and my Z is good. But, generally I don't use glue stick on the smooth sheet for PLA for most models. You could have some bad areas on your PEI sheet.. have you turned it over and tried again? (is the other side "new"?).. but your square certainly adhered fine, so maybe you no longer have an issue. Did you print your models that didn't adhere?
RE: Brim or no brim
You may be slightly high still. All corners should be square.
Read this post, download the files, and print the one for the material you’re using (PLA I think?).
This will give you a much better way to fine tune your Z height. The built in calibration routine is fine to get you in the general neighborhood of a correct Z level; this routine will help you really dial it in. The annoying beep tones midway through the print are to alert you to make a change to your Z level. Once you are familiar with the print you should be able to make 4-5 adjustments during one print. When you think you’ve nailed it, print one complete square with your final setting. When it cools and you take it off the print sheet, bend it in half along the layer lines; it should hold together, not break anywhere. If it breaks, you’re still too high.
Cheers
RE: Brim or no brim
Thank you and I agree. I've continued to adjust this. I've abused this PEI sheet in the course of learning. The other side is a little worse, and I can see on this 'good' side that I drug the nozzle too low on a portion. The center front area. I will be replacing this soon.
RE: Brim or no brim
RE: Brim or no brim
Maybe I'm getting closer. Below is the first layer of this lid. The arrow indicated the direction of the nozzle travel. The very slight ripples running perpendicular...I'm thinking these are contraction? But other than the red circled area, I'm getting a fairly uniform lay down of filament over this large area.
I've adjusted the z-level a lower -1.275 to hopefully get that circled area to go away in the next go. This pic is of the several I've run.
The circle area in the image is roughly over the center screw on the hot bed. It's fairly tight at this point, but do you suppose tightening that down a bit more would help?
Great suggestions! And I feel like I'm finally making progress. Now to check out the 'life adjust z' post.
Thank you!
RE: Brim or no brim
If that’s a first layer print you are actually too low (negative value) now.
Print another single layer object and dial back up, more positive. You’ll find the proper value somewhere between where you are and ‘too high.’
Cheers
That first layer should stick, it's too low but good enough for now.
So the PEI surface is the next suspect.
It may be time for an acetone refresh. First get it thoroughly clean with dishwashing soap and plenty of HOT water then clean again with acetone and fresh paper towels, handle by the edges only.
Do not use acetone for general cleaning as it will damage the sheet, use a routine like this:
Clean with IPA between prints.
At the first hint of a problem, use dishwashing detergent and HOT water.
If that's not enough use acetone: once or twice a year at most.
Cheerio,
RE: Brim or no brim
The beauty of a Brim is that even if if unnecessary in a particular case, cost nothing in either time or material.