Abstract: The present invention provides a 3D printer comprising a base, a build platform, an adjustable support assembly (e.g., including a resilient support point having a spring and a post) coupling the build platform to the base, and a locking mechanism that secures a position of the build platform relative to the base. The locking mechanism can include a releasable clamp positioned between the base and the post. The present invention also provides a method of tramming a build platform on a 3D printer. The method comprises resiliently supporting the platform on a base at a first support point, pushing on a build surface of the platform at the first support point to move the platform relative to the base, and locking a position of the platform relative to the base at the first support point after the pushing step. Preferably, pushing includes contacting a print head with the build surface.