Not sticking to bed on 1st layer?

Hi,
I've been 3D printing with a PLA filament and the 1st layer is very unreliable and rarely sticks to the bed.

When the extruder extrudes the filament, the filament tends to curl back and stick to the extruder. The following filament that is extruded then sticks to the bed, but because of the first bit of filament curling back and sticking to the extruder, as the extruder moves along the bed it pulls off the laid filament?
I have tried various temperatures from 190 degrees celsius up to 230 degrees celsius.

The bed is a wooden bed with a blue waxy masking tape over the top.
Some other PLA filaments used seem to stick ok.
Any tips please?

Check nozzle gap when homed is 0.1mm Max - slightly less if you can get it.
Start with 190C temp for first layer then maybe 185C
Try setting the first layer height to 150% (Slic3r)

You mentioned the bed tape being waxy? Can't think that would be much help but I don't use tape so can't really comment.

also first layer should go down slowly if nozzle is less than 0.6mm, i have 0.35mm, and 0.5 nozzles in use currently. i set first layer speed in slic3r to 15mm second , and make sure to skirt the part at least with 10 loops to ensure the nozzle has pressure built up.

The thing that makes the biggest difference for me is to run the first layer at 15mm/sec as stated above but also force the first layer wisth to be printed at around 150% to 200% of nozzle diameter. That sticks it down like glue. Go to the advanced section in Slic3r and set the first layer width manualy. I print PLA on blue painters tape on one machine with a glass bed and the other with a wooden bed, the extra width made a big difference on both machines.

I hope your post doesn't mean you are running with tape on the glass, if you have a hot bed you don't need tape.
The usual arrangement seems to be the y-carriage with the pcb heater mounted above it on stand-offs or springs then a glass sheet above that.

If your print is lifting off then the glass isn't hot enough which might be caused by a). glass too thick, b). thermistor not in contact with the glass, or c). insufficient heat caused by too small power supply or heating resistors if it is a DIY hotbed.

I normally use 3mm picture glass as it is nice and thin and flat but I recently cut a piece of glass off a photocopier top plate and made a really nice 200x200 cover sheet. The only problem was it is 5mm thick so it is very hard to heat up. I added insulation to the bottom of the heater but I still had to run it at 75 degrees C to stop the print lifting off or the whole object sliding off the bed mid-print.

Addendum: I run the hot end at 199 for the first layer then 185 after that, and I run the bed at 65 for the first layer then 60 after that. Also, if you are jamming your hotend with PLA (common problem) you should consider adding a fan to cool the barrel down.

Edited 2 time(s). Last edit at 05/09/2013 05:44AM by Wired1.

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