I keep getting this fused together what setting do I use to get this right?  

RE: I keep getting this fused together what setting do I use to get this right?

The gap between the two parts is probably smaller as the tolerance of your printer. Find out what the tolerance of your printer is which the 0.8 mm nozzle and alter the printed part according to it, or use a 0.6 or even a 0.4 mm nozzle to print this parts.

The basic working tolerance is half an extrusion width.  With a 0.8mm nozzle the default extrusion will be about 0.9mm so the expected tolerance is 0.45mm.

So: either adjust the size of the mating parts, increase the gap. Or: change to a smaller nozzle with an extrusion width less than the pre-defined gap.

Cheerio,

RE:

It looks to me like your CAD method needs to be re-thought as your X axis clearance is much smaller than your Y axis clearance.  Also, if you need them to be friction fit, they need to be printed separate and then assembled.  This can be done on the same sheet, just not in their 'assembled' position.  You'll not get friction fit without fusion if you insist on printing them like shown.

-J