General tips for dual extrusion printers

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I'm using an FDM printer with dual nozzles, not an Ultimaker made one, to print with a main material and a support strut material.

 

The printer has its own slicer, which isn't very good, hence I've been using cura, with great success, for single material jobs.

 

But now I want to slice in cura for dual material jobs too.

 

It seems whatever I try there are always new complications.

 

And this is made even trickier because the dual nozzle printer has two nozzles on a single gantry without any kind of rocker lever such as that which an Ultimaker S5 has to raise and lower the nozzles according to which is in use.

 

With this printer both nozzles are at the same height and the unused one always gets dragged over the print while the other is operating.

 

Any general tips on the correct setup to use here?

 

I've tried purge/prime towers, but this causes some very weird issues where the printer homes to 0,0 after raft laying, then returns to print on the model but finds itself misplaced by the nozzle offset and therefore printing in mid-air.

 

I've also had issues where there seems to be some sort of vertical height difference between the two materials being printed with, so that when one is printed above another there is a big gap between them and the layer being applied won;t stick to the printed one below.

 

Any suggestions, or good guides on setting up dual extrusion with "custom FFF" type machines.

 

Thanks