Welcome.
First, proper alignment can produce an order-of-magnitude increase in the number of boards that can be printed without wiping. The initial alignment can be made either by: * Peering through the stencil apertures at the board underneath and adjusting the board position to align with the stencil apertures. OR * Printing onto a clear, fixed film and aligning the board under the film. OR * Printing either onto the board itself or onto the board covered with clear adhesive tape, until the alignment is correct. Here, the print must be wiped off after each adjustment.
Once acceptable alignment has been achieved on one board, several boards should be printed with no further adjustment. These boards should be inspected for misalignment, and any correction made for the average error.
Second, some semi-automatic printers are dogs that can�t hunt 16 pitch. Adding vision, while techically possible, may be like putting bifocals on a blind man.
Third, if you print 16 pitch too fast, the paste will never "see" the apertures that go east / west and only recognize the north / south apertures.
Forth, HASL is tough to print on for devices with 16 pitch.
Now, let's talk. Tell us about your machine, set-up method[s], board[s], wait time between print and reflow, specific problem in terms issues and breadth, and all the other stuff that you didn't tell us in your original post.
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