Tray Length and the 50 Year Old Problem
A common issue that arises when putting a new greenhouse together is the issue of variation in tray length.
There are variations in most tray lengths (not just our own) which can cause problems on many ‘t’ rail benching systems if not checked.
The problem started with the introduction of the Styrofoam flat in the 1960’s which shrinks after a few weeks and months by up to just under half an inch (1cm). Therefore, when people copied the original trays they made shorter trays as they copied the shorter shrunk tray. After a few months these new trays also shrunk so that they were now far shorter than the original trays.
The original tray length on Speedling sized trays in Florida was 26 7/16th’s or 672 mm’s and nurseries needed to allow for the shrunk size as well. In Mexico and many other areas the standard tray length is 26 3/16th’s or 665 mm’s and in Brazil both of these sizes can be found.
The problem is that the trays have to fit on a narrow ‘t’ rails on most nursery benching systems and if the tray is to long it will not fit and if it is to short it will fall off the benching.
The solution is to check any new trays before you order them. Firstly check they will fit properly on your benching and secondly if you are building a nursery it is worth using wider ‘t’ rails and make them to fit all of the tray lengths you intend to use. We have a handy guide on how to set up/adjust T-rails to best fit trays here.
On the 10x20 inch bedding sized trays these also alter a lot in outer dimensions but this is not usuallu as big a problem, as the trays generally do not go on ‘t’ rail benching systems.
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