How to save that bad 1st layer with a soldering iron
The problem of a little glob of filament on the 1st layer seems to crop up too often. If the print is allowed to proceed anyway the problem is sometimes not important, it gets covered by following layers, but often it leads to a bigger problem on the next layer.
I have not yet diagnosed the cause of these burps but I have found a good work around. I have a temperature controlled soldering iron that I keep at 275 Celsius and if a glob or high streak appears I do a Pause and use the iron to melt down the bump. There may be a slight visual after-effect but that is usually not an issue. Print saved. You do have to pay attention throughout the 1st layer.
The reason for the undesired globs is not clear. I often print with Paramount PETG filament, I like their choice of colors. I usually print using the PrusaSlicer .20 Quality setting at 250-90 Celsius.
I have suspected that my 1st layer z setting is too high or too low but most of the 1st layer usually looks great, except for the occasional glob and the unexplained streaking.
In the photo below you can see long darker lines that are not as high as the other lines and you can see lighter colored lines that are higher than the other lines. These variations are a mystery to me. You can also see repeated dark/light lines at right angles to the others that seem to be on the bottom of the layer. I cannot feel a variation in height of these lines.
Any ideas as to the source of these anomalies may lead to my having fewer globs to melt with the iron. Thanks for any help with this issue.
PS. I have also found that a good flat fingernail file is a great tool to file off little high spots on the 1st layer and to do final cleanup of the completed print.
RE: How to save that bad 1st layer with a soldering iron
I'm sure those blobs are what some call 'boogers', which are little bits of scorched filament that get stuck on and around the nozzle and drop off onto the prints at the most inopportune times.
I've gotten into the habit of using a soft brass wire brush and cleaning off the nozzle are before most of the prints.
RE: How to save that bad 1st layer with a soldering iron
@jsw
I will get a brush and try that. I know of these blackened bits of filament. I have had to deal with them as well. The blobs are different. Clean filament oozed out in the normal pass.
RE: How to save that bad 1st layer with a soldering iron
With petg , clean nozzle before printing, often filament gets stuck on nozzle.
Do a Test with a temp tower, with petg, if you are printing to hot, you have more blobs.
Look if you have a leak higher up in the nozzle?
Measure the thicknis of filament.
Use a 7x7 calibration, this is a setting in the printer, your first layer gets then better.
Clean bed with dish soap, then model sticks better.
With petg use window cleaner, so petg does not stick to hard.
RE: How to save that bad 1st layer with a soldering iron
I think your nozzle is a little big too down. It squeezes the filament too much on the bed and some part starts to accumulate on the nozzle. This filament on the nozzle burns because of long heating and when it is more of it, it is dropped back on the bed. So I would try to re-adjust Z a bit. If this happen in higher layers, it can be because of overextruding, to high temperature or even partially blocked nozzle (filament does not go straight down but turns up and again stays on the nozzle during movements)
RE: How to save that bad 1st layer with a soldering iron
Thank you peter-m26 and milos-v. Very nice z level tuning video. I do not have problems with sticking or not sticking. I use the powder coated bed and the PETG sticks beautifully and releases with no problem. I clean with iso-propyl alcohol before every print and wipe the hot nozzle clean. I have been thinking that milos-v description describes my problem. Once I am into the 2nd layer and beyond I get great prints.
I have done a z level calibration again being very careful and find that with an adustment upward of .02 I get a much better 1st layer and less of the streaking and globs. I need now to get a brush to clean the nozzle better.
RE: How to save that bad 1st layer with a soldering iron
Good to hear, that it is moving the right direction. Just a comment, you do not need to make the whole Z calibration. You can just adjust Z during the print or before the print. Usually I am able to adjust while the skirt around is being printed in the beginning of the print. We are talking here about very small adjusment, like +-0.010 or 0.020 at max. I change by the steps of 0.010 and take a look. If needs more, than again. Finally you will have it in your eye, how should the line look like, what is too much squeezed and what is not enough. Live adjust Z is the on of the first commands in menu when print is started.
In general, it depends on what filament you print and what type steel sheet you have. PETG usually holds very well on the bed, so squeezing to much is contra productive and cause this issues whith blobs. On the opposite side, for PLA or ABS it is better to squeeze a little bit more. PLA does not create such a blobs, unless you go really too much down. Unfortunatelly calibration needs small adjustments based on used material. If you setup an average, it can work, but will be never perfect 🙂
RE: How to save that bad 1st layer with a soldering iron
Thank you again milos-v. I used the very nice "First Layer Calibration by iClint". I enclose his package below. It is five 25mm squares placed across the bed. As each square is printed I do a live z adjust, changing the amount by .01. I chose the value for the best square and repeated the process changing the amount by +- .005, again choosing the best square as my final setting.
Good to learn that this adjustment is filament type sensitive.