It's kind of strange how Fisher Pierce went from manufacturing their twist lock photocontrols with windows that slide and lock in place in the 70's, to this type where the windows are sonic-welded in place in the 80's, then from the 90's on back to the slide and lock type. These were a bad idea from the beginning. After some exposure to the sun the windows fall out.
Yeah I assume back in 1980 this was a cheaper alternative to the snap-in windows but this proved to be a poor design so that's probably why they went back.
I would think the slide-in windows would be cheaper to install. With this type they need the equipment to do the sonic-welding of the windows to the cover.
Unless they used glue or something. I see what looks like glue residue around the edge of the two units (the other is a dayburner; I haven't posted pics of the dayburners yet).
It very well could be. Yeah ultra-sonic welding uses high frequency vibration to essentially weld the two parts together AFAIK. How did you find out that's how FP did it? From what I understand that process is supposed to bond better than glue, but perhaps they uses dissimilar plastics that didn't make a reliable bond, similar to dissimilar metals?
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