hi all...
I have been wondering what the max size is that you could expose and get a good print out of a 20x24 aluminum screen? I know that it would ultimately be determined by the size of the film that you can print or get, but lets say that you could print any size... what size might you get from a 23x31, a 25x36, a 42x48 screen?
I use 20x24s and the biggest I can get without being a real PITA is about 12x15. You need to leave room for ink on the ends, otherwise it gets all over the frame. Also, I use 14" squeegees, and I have printed 13+" wide graphics, but the squeegee deflects at the ends and it's tough to get an even print.
Occasionally when desperate I've done as little as 1/2" clearance, but that's not a recipe for a good print (I'm sure many printers would rightly criticise me for even trying that).
It will depend on mesh tension, etc. but you want at least 1" clearance around the whole image, preferably more.
1/2" clearance is incredible - I'm assuming the prints were turning out satisfactorily if you're posting about it.
I'm printing a 16"x12" design right now, and my frames are 1.5" square, so I've got an inner diameter of 21"X19". The prints turned out fine, but that's as big as I'd go. Even pushing that, it was annoying having ink sneaking into the corners and edges of the screen.
I've printed 23"x15.5" designs on 23"x31" screens before.
1/2" clearance is incredible - I'm assuming the prints were turning out satisfactorily if you're posting about it.
Satisfactorily for the job at hand - but definitely not perfect. It was a grungy all-over sort of a print with very little contrast (black on grey), so it didn't need to be perfect. Which is fortunate, because most of them weren't
The biggest problem was a tiny inkwell, and a tiny clearance at the end to finish my squeegee stroke. I had to roll the squeegee to get a full stroke across the actual print area.
Definitely not something I'd actually recommend doing. Just throwing it out there as an "amazing what you can do if you're desperate".
print area for a screen size. 
