Forcing seam position to a wipe tower

In order to get a steady flow in all layers I want to make a small part (tower) which must be printed prior to the main part. Something like the skirt but with preextrusion in all layers. I don´t know well how to force this part to be printed first. Forcing the hotend to travel near this part and away the main part doesn´t work always.

I can manage with just an extrusor placing the tower near the table origin but to do the same with dual extrusion in order to get a preextrusion in both extrusors is a no way for me. In Cura you can do this with the wipe tower but both extrusors build the same tower and this falls if both materials don´t adhere.

There´s a way to do preextrusion for both filaments on each layer with sli3r?

Have you tried setting the "Extra length on restart" in the extruder retraction settings? IIRC that's designed to get the filament flowing.

Dave

If you force priming of both nozzles prior to printing a layer, the nozzle used second on any layer is bound to ooze. The purpose of the tower is to prime the nozzle about to be used, before it starts printing on any given layer.

However, in answer to your question, you could write some custom gcode to be executed on layer change to print two towers - one for each extruder. There's some ooze busting g code here - [forum.bukobot.com] which you could adapt.

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Thanks for your answers. Now I got it!

I´m building a prime tower with some Gcode in layer change Gcode for support preextrusion. The main part preextrusion is given by an ooze shield placed around the main part. I have no oozing because the hot end is 0.3 mm (bowden) but preextrusion is needed to get extruded plastic at the start of the layer.

Thanks a lot!