Tolerances will vary from part to part, depending on the materials, size, shape, number of cutouts and other configuration possibilities.
However, as a general rule of thumb, the following tolerances should apply.
±.020" for the 1st 12"
±.002" for each additional inch
Hand Trimmed Dimensions:
CNC and hole to hole tolerances sometimes must be increased due to the coefficient of thermal expansion. Our CNC and other computerized trimming machinery are capable of cutting to within ±.0005, however, plastic does move due to temperature changes. The formula is as follows:
Length (inches) x temperature difference (F°) x .00005"
Example" 20" at 90°F will move to 19.98" @ 70°F
20" x 20°F x .00005 - .020"
Please keep this in mind when designing any plastic part. Slots and over-sized holes work well.
Further discussions are welcome to help you overcome any possible design problems.