Raft/Support Material sticking too well to print.

Hi everyone, 

After replacing the hot end on my M200 every print I’ve made has stuck to the raft and cannot be removed easily (had to resort to using the exacto knife that came with it to remove some, and ended up stabbing my thumb badly) and likewise the support material is sticking too well to the model compared to before. Does anyone have any suggestions to remedy this? 

- Dave 

What does your first layer look like? Is it partly smooshed into the perfboard as it should be, or is it super-smooshed? Is the nozzle bumping over previous layers while building the raft? This would indicate poor height sensing, resulting in a too-small initial height setting, resulting in the Z axis not being exactly where the slicer thought it would be, which can screw up the precise distances required for easy raft & support removal. This can be caused by poor electrical contact between the nozze and plate. You can insert a thin (0.2mm?) shim between the nozzle and plate when height sensing is performed in order to increase this distance, at the possible expense of some adhesion.

Also try cleaning the nozzle and silver pads to improve contact when sensing height. I lightly scuff the pads with some sand paper, and use a rag or wire brush on the nozzle when hot.

A tell tail sign things aren't right is if the bed moves the extruder up a little when touching. It should just lightly kiss the nozzle.

Check/reseat the hotend thermocouple connection/mounting and the fan connections/mounting.  Poor thermocouple setup can make the controller think the hotend is cooler than it actually is, excessively heating the filament. Poor fan operation can cause make the filament not cool quickly enough. Both can cause adjacent layers to fuse more than desired including rafts and supports.

Additionally, if the problem is only occurring on the bed raft, also check the bed thermocouple.