First layer not adhering to raft - can anyone help? - 3D Printing

I’ve been happily printing for a while now with my Wanhao Duplicator i3 using PLA but a recent problem has occurred wherein, during the initial stages of a print with a large base surface area, the first layer has not stuck to the raft. This produces a surface effect similar to the gills of a fish, where, in one direction, the surface bows and parts of the filament stick up proud of the raft about 3mm high, forming raised ridges open on one side, at regular intervals. This obviously greatly int

5 Ways to Fix PLA Not Sticking to Bed

ultimaker cura - Part not adhering to the raft - 3D Printing Stack

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Built the machine, but when I do the first layer calibration it

Raft silhouetting

First layer not adhering to raft - can anyone help? - 3D Printing

First layer not adhering to raft - can anyone help? - 3D Printing

How can I print without a raft or brim? My filament always messes

3D Printing Troubleshooting Guide