I’ve gotten a lot of problems solved but I have one that is rather persistent. When I print, the first layer or two are wider than the rest of the print. A very small amount, but enough to be noticeable. Gut reaction is “the bed is too hot”. But I run it at 55C for natural PLA and when I tried 50C, I lost adhesion. Also, 55C is also lower than the low end of what’s recommended in the lulzbot filament guide (60-70C).
I’ve tried tweaking the bed temp and the nozzle tem, all to no avail. I’ve also tried lowering the bed temp after printing a few layers. No dice. Any suggestions?
If you are using Slic3r there is an over-extrusion factor for the first layer. This extra plastic could be what you are referring to. The purpose is to help with the adhesion of the plastic to the bed.
Okay, fiddled with that but found if I don’t keep it at that, I don’t get adhesion. BTW, I’m using the lulzbot provided slic3r profile for 0.22mm (meant to mention that earlier).
I get what you’re saying about how that’s how the first layer is done to help ensure adhesion. But are people just always sanding off their first layer when they have something with straight walls where it matters if the bottom flares out? Or are you figuring out a way around this? If it’s just a “this is how 3d printing is” then hey, it sucks but I can move on without thinking there’s some tweaking I could do to fix it.
I just wish I could tell it “increase the first layer extrusion width, but decrease the first layer perimeter to compensate”. As far as I can tell all the perimeter settings are for all layers, though.
What temperature is your bed set at? Try using Cura with the same model to see if that changes the first 5-10 layer stacking. That will help to see if it’s a gcode issue or not.
Same issue with Cura. I had to create a 0.22mm Cura profile based off the slic3r one, so I hope I got that right. But it looks the same.
Here is the model in case anyone is suspicious of it. It’s just a 20mm cube made in Cubify Design. Couldn’t get much simpler. 20mm_cube.stl (684 Bytes)
BTW, still no luck with this. I’ve tried setting the first layer extrusion width to .42mm (as as the default extrusion width set in the lulzbot .22m profile). Simultaneously, I have the first layer height same as the subsequent ones. Print adheres fine, but the first layer is still wider. I now have calipers and the top layer measures 20.06x20.14mm while the bottom layer is 20.52x20.66mm.
Try reducing the first layer width at Print Settings > Advanced > Extrusion Width > first layer: to something smaller, to see if that compensates for it.
if printing with pla on tape like the above suggestions solves it, then the problem was bed temperature related, like suggested earlier. If you find that you don’t have good part adhesion with the bed set at a lower temperature, you can use normal school gluesticks to treat the bed. Many users have had success with it.
Not going to lie, I’ve noticed it a lot more since I read this thread. What your pictures describe, reminds me of one of the “before/after” pictures I saw for installing the auto levelling probe.
see this thread (see second post from top) https://forum.lulzbot.com/t/temperature-error/58/1
