If you keep the head hot during the pause, and over the print, you will melt the material already deposited.

If you move to X0 Y0 (like on a layer change) and pause there, you can cool off the head (or not), but will want to prime (advance) some material before resuming your print - or risk an initial void, as the heated material will expand and drip to some extent.

If you move to X0 Y0, retract, and cool off for your pause, you should be able to heat up, advance, and resume with few issues. You will probably still need to some manual cleaning where the resume was, as there is likely to be some buildup.

Also, if you let the bed cool during your pause, your print may become unstuck from the bed.

Pausing a print: A vital aspect to anyone who tries to do something advanced with 3d printing.

There are three (3) things:

• Never pause over the print. Your pause "script" should lift the head up from the model and rapidly move it over to a parking region, which is clear of the bed (ideally).


• Keep the bed warm, but retract the filament. Ensure that the filament gets retracted prior to the pause. Also the bed must stay hot/warm to ensure the part doesn't loose adhesion, and doesn't begin to warp out of shape (in the case of ABS).


• Do not shut off the motors. If you are pausing so that you can insert objects into the print (screws, washers, electronics etc) then touching the print can cause the bed to shift. Keeping the motors running will help resist any movement of the build plate during said operation. If you are pausing to do a filament change then keeping the motors energized will help resist the back driving of the lead screw (or belts or whatever is moving the z axis) so that you don't accidentally push the z axis out of position.

Of course the most important thing is the resume command. It should "undo" the movements of the pause command and return the machine to a printing state.

It is not recommended to pause prints a considerable amount of time as the printed model will shrink and might warp during the pause. Also, layer bonding between the old and the new art after resuming will be weak, but this can be used to induce planned breaking layers.

On the other hand, if you have set up your printer properly, it is quite safe to leave the room even during the print:

• Maxtemp and Thermal Runaway Protection need to be set


• a smoke detector over the printer should be installed


• the printer should be placed in a way that no flammable objects can get in contact with it