hi,
what am i doing wrong here :
i’m modelling a seat and i want to straighten up the plane of the back. as this isn’t along a regular axis i selected one of the faces and assigned it as the transform orientation. i’ve tried allsorts from that point to try and bring the other faces into alignment so the plane of that back is smooth but i can’t get it - can anyone point me in the right direction?
many thanks.
select those faces, then hit s, then Z,Z (yes, twice) then 0(zero)
you should, with that orientation selected, be able to just press s z 0 to flatten it . if that doesnt work you may have to rotate it so its flat on a viable axis then flatten it.
Just hitting Z once will flatten in the global axis, hitting it twice will go into local axis which is what he wants.
outstanding. 
many thanks bud.
oh yes, sorry i was thinking that it went according to what orientation mode you were in
