Changed from 0.5mm to 0.3mm nozzle.

Changed from 0.5mm to 0.3mm nozzle do I need to re set extruder steps or something?

I've change my extruder steps M92 430 to M92 E477 after some calculation following the old ormerod 1 instruction, seems better. more testing later.

dont forget to set 0.3 nozzle in slic3r or whatever slicing software you're using

There is no need to change the extruder steps per mm. The extruder feeds exactly the same amount of filament per step whatever nozzle size you have, and in addition the nozzle will push out exactly the same volume of plastic - it will just be harder to push and it will come out thinner. As it is more difficult to push out, your extruder will start skipping at a slower speed than was the case with the larger nozzle, so you may have to adjust your print speeds.

Dave

Thanks Printing ok now. Just the infill and solid are very thin. maybe its the extrusion width?

Changing extrusion width might be an option - although using a .3 nozzle to print with .5 extrusion width is not what you want...
What is your layer hight? I found .15 to be good, .2 to be max for a .3 nozzle.
Infill is quite weak, nevertheless. Using honeycomb as infill method in slic3r is a good idea if you need a more rigid part.

Most important for printing with a .3 nozzle is to get your be leveled - the .3 is not very forgiving and even small deviations will have effects on upper layers.

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antlvk
Thanks Printing ok now. Just the infill and solid are very thin. maybe its the extrusion width?

Well, changing to a .3mm nozzle means that it cannot extrude as wide as it did with a .5mm nozzle. Getting a 0.5mm width might be pushing it a bit - I'm not sure what maximum width is possible, but try setting that width & see if it works. You will probably have to print slowly because the extruder motor will need to push hard to get that volume of plastic through such a small orifice. Note that Slic3r will adjust the spacing of the infill so that although the lines are thinner there will be more of them closer together so the percentage of infill is still the same and so it should be about the same strength.

Dave

Printing ok now, with width of 0.4-0.45mm settings