Prusa i3 PLA fails to stick to first layer on curves
I have been searching around on google and not found any answers to this dilemma. I am using a Prusa I3 printer with PLA, trying to print horseshoes for the company I work for. They are for model horses, so quality is fairly important. I seem to have gotten all the settings dialed in just the way I want them and for the most part, the prints come out fine. There is however one annoying thing that keeps happening. When the filament is going around the curve of the top of the horseshoe on layers beyond the first, the filament does not follow the curves of the first layer. But its not every time. It seems like it is just the 2nd or 3rd Layers that are doing it. I have adjusted the flow rate, the speed, the layer height, temperature, and nothing seems to get rid of this irksome issues. I can of course provide more in depth details, and am including a pic of what i am getting. Any Ideas?
I'm voting first layer too high off the bed. Also try blue tape not masking.
1st layer height is .3, the rest are .1. i run the first layer at 210 and the rest at 205, bed at 70 throughout. Filament diameter is set to 1.75. the first layer seems to stick perfectly and further up the layers go just fine.the thing is, the nozzle follows the curve, but the PLA just stretches out until it sticks in the center. Also, blue tape is on the way, that's the stuff that came with the printer.
@jeremiahharless the first layer height should be at least 50% of nozzle diameter to allows good adhesion and speed between 50 and 75%, your masking tape must be free of dust after sanding.
UPDATE: I found perimeter settings in Slic3r and slowed down the external perimeter and small perimeter print speeds to 25% on the gcode and set the printer itself to 15 percent. the result was a complete cure, but double the print time. I am going to keep upping the print speed on the external perimeters a little at a time to find the sweet spot between speed and adhesion. I will post my results once I have it dialed in.
It could very well be that your print speed is too high (starting from the 2nd layer) for the motors to keep up comfortably. Try reducing the print speed to perhaps 75-80% of what you are using to see if it addresses the issue. You should also check you model to make sure there are errors in the STL. Sometimes such mesh errors can cause funny things to happen. Do you see the irregularities in the print preview at all?
I have set the overall print speed down to 15% because this printer prints way too fast to begin with. I can try reducing it further, but the slicer software I am using (Slic3r) only allows me to adjust the first layer print speed. It's also frustrating that it is just the 2nd through maybe 4th layers that do this, and the rest look fine. I checked the preview in Slic3r and nothing looks out of sorts on the model, but any horseshoe model i print suffers this on the curve. Could it be the slicer soft itself?
I got the same problem on a Ultimaker 3 with Cura. The problem was, that there is a hidden option for the initial layer. By default the first layer is set to something around 130-150 % of the normal layer height.
So if you set up 0.2 mm the initial layer will be printed with 0.27 mm and this can cause problems. After setting this initial layer height to also 0.2 mm the print stuck really good at the bed.
I also made similar observations on my own Anet A8.
Is that printed on to tape? It looks very uneven. I'm guessing this is general bad adhesion and its just showing up best when going around curves.
If you print onto tape, try putting it down with a squeegee, so it's absolutely flat and level with no creases or bubbles.
I've personally had very little luck printing onto masking tape.
I t looks bad because thats the 15th or so print on that tape. It's the stuff that came with the printer. First layer adhesion is almost too good, its PLA on PLA in the 2nd and 3rd layers that seems to be the issue. I have a Davinci AIO that prints ABS and doesnt seem to have this issue on curves.
Interesting. Cooling coming on after the first layer? Maybe too cold to bond. Might be worth doing a few small tests with a range of temperatures, at very low speeds (say around 40mm/s). Then try bending them until they break. If they come apart at the layers easily: too cold. Keep going up until it snaps as one piece.
Using a combination of external and small perimeter speed settings (Slic3r), as well as slowing down the overall print speed on the printer itself, I was able to get reliable curves on the horseshoes. I have also downloaded Cura and am playing with the advanced print options that it comes with.
1) try and increase the extruder temp by 5 degrees for the first layer and see if that helps
2) disable coolign for the first few layers.
3) try adding some PVA glue (washable school glue or elmers washable gluestick) to the masking tape
if the above failed set a z offset (in slic3r the z offset is in the printer tab)
3a) if you manually level with paper and have access to a caliper. change the z offset in your slicer, to a negative of whatever you used to level.
3b) if you manually level and you don't have a caliper set the z offset to -.1, if you used something thicker like a business card try -.15 or -.2