Can anyone think of a reason why my prints would start with a Brim that does not print, but when part is started, flow seems to occur 1/4 to 1/2 way through the first layer. From that point on, the printer seems to print well. The print head slows noticeably, before it actually begins to lay down material. I am able to produce satisfactory prints, other than that first few seconds where the part is started but no material flows.
I’ve been playing with Z offset and have manually leveled my print bed numerous times…to no affect.
I went back to Snapmaker’s way of doing things - extrude 30 mm before printing to get it primed. I actually bumped it up to 40 and also let it knock off on the corner like they did.
Skirt is typically for the purpose of priming anyhow.
Once the nozzle cools it takes a little momentum/pressure to get things going again.
If you aren’t really into tinkering with start/finish gcode, you can add more skirt.
Some slicers let you have a minimum skirt length as well. Just compensate for it by adding more priming.
Thanks for the input MooseJuice, I’m using that particular starting Code technique, along with the skirt, so I know it is primed when it tracks over to start the skirt. It almost looks like the nozzle is too close to allow filament out, that I should see it flowing out somewhere else? I may have to break down and learn something deeper about Gcode, so I can look at this print file.
I am using S3D for the slicer set up with Fast/Medium Quality/High Quality options. The Fast option uses a 0.2mm layer height and seems to work OK, once the filament begins to flow as described in my original note. However, the Medium (0.16 layer height) and High (0.08mm layer height) do not work at all and the flilament just ends up gumming up around the nozzle???
Yeah… theres a good chance your nozzle is too close, or your bed is warping on you when heating up.
It takes a long time to get acquainted with how to combat this.
First step would be to set your bed to the temperature you want to print at for about 15 minutes, then calibrate and re-set your z offset. Then watch the lines that are printed once priming is done… adjust further up or down as needed to get a nice flat line that touches the line next to it, without the sides of the line looking wobbly or junk sticking out the top of it.
Doing a higher calibration grid should help you, but learning the “squish” is really the key to printing. You’ll find that the bed will be better in some areas than others, so a higher grid can help with this, but ultimately there’s limitations to what success you’ll get out of the bed without becoming accustomed to dealing with them.
As above, it definitely sounds like bed is too close. You can sometimes mitigate this by ramping up the nozzle temp, so that the flament flows more readily - that introduces its own problems (heat creep, buildup), so I won’t recommend it as a solution, but I did find with a stubborn PLA filament that pre-heating the nozzle to 240 and then dropping the temp to 200 for first layer got things to stick.
The one thing I did that helped the most with intial adhesion was to use a dial indicator mounted on the print head to map out the heigh differecences of the bed. I found that excluding the outer rim of squares, there is a difference of roughly 0.23 mm between the lowest and highest points. I have set my initial layer height to a minimum of 0.24mm to account for this (0.32 if I ever need to use the full build plate).
The recommended minimum layer height is 1/4 of the nozzle diameter, so 0.1 mm for an 0.4mm nozzle. I have successfully printed 0.8mm layers without a problem on the snapmaker. Could probably go down to nozzle size, though really at that point you should be considering smaller nozzles (e.g. 0.1mm nozzle).
That said, initial layer is another beast entirely. This is what sticks the print to the bed, and the bigger that layer, the better. I mentioned 0.24mm because that compensated for the variance in height on the bed of my machine. The bed of your machine will have a better or worse difference in heights. You can always use a glass bed if you want no difference in height (i.e. if the 0.08mm is really important to you).