>such that the height of the spring can be animated by going into the Parameters
I don't think the person who wrote those instructions used the best technique.
Start a new part.
Create sketch line for axis from origin and dimension as desired initial Spring_Length =
Exit Sketch.
(You alread have one of the origin planes at the beginning of the line.)
Create the second plane by clicking on the line and the second enpoint of the line.
You should be able to figure out the rest. Post back if you get stuck.
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