Adjustable Support — Parametric Two-Piece Screw Jack (1× and 2×)

Adjustable Support — parametric screw jack

A two-piece printable screw jack: spin the inner post inside the outer sleeve to set the height. Buttress-style helical thread, single start, 5 mm pitch (so one full turn = 5 mm of travel on the 1× size). Use it under wobbly furniture, to prop up a plant pot, brace a GPU, level a camera, or anywhere you need a few cm of adjustable height.

Bundle

• post.stl + sleeve.stl — original 1× size:

• Sleeve Ø36 mm at the base disc, Ø30 mm at the threaded shell

• Post Ø16.5 mm at the thread crest, Ø24 mm at the top contact disc

• ~20 mm of travel range

• ~35 mm total height of the post

• post_2x.stl + sleeve_2x.stl — 2× scaled-up size:

• Sleeve Ø72 mm at the base

• Post Ø48 mm at the contact disc

• ~40 mm travel range

• ~70 mm total post height

• adjustable_support.scad — the source. Top of the file has a scale_factor parameter; set it to anything you like (0.5, 1.5, 3 …) and re-render part="post" and part="sleeve".

Fit

The thread is intentionally slightly loose — about 0.5 mm of radial slip per side between the post crest and the sleeve groove, and 0.4 mm axial gap between mating teeth. That gives a free-spinning feel rather than a tight, frictiony one; the trade-off is that the post can rattle a hair when unloaded. Under any actual load (the whole point of a support) the play disappears and the thread sits firmly on its load-bearing flank.

If you want a tighter fit, reduce axial_slop and shrink sleeve_thread_root_d / sleeve_thread_crest_d by ~0.1 mm in the source.

Mechanism

The thread profile is a buttress shape — flat horizontal load face (the pressure flank) plus a 45° back flank that's printable as a self-supporting overhang. The post prints top-disc DOWN on the bed (this is what the part="post" STL exports already) so the pressure flanks end up face-up and the trailing flanks end up face-down at 45°, within FDM tolerance. The sleeve prints base-on-bed; its internal teeth print with the same buttress orientation.

Print

• Orientation: sleeve base on bed; post top-disc on bed (pre-rotated in the STL).

• Layer height: 0.16 - 0.2 mm. Finer layers = smoother thread engagement.

• Walls: 3 minimum.

• Material: PLA or PETG. PETG flexes a hair more — slightly looser feel; PLA stays crisp.

• Supports: none — the buttress profile and the top-disc-down print orientation between them mean no overhangs > 45°.

Assembly + use

1. Print the four parts.

2. Drop the post into the sleeve from the top. Work the seam with a knife if there's any first-layer flash on either thread.

3. Spin the post to find the engagement; once it catches, it'll spin freely up and down through ~20 mm (or ~40 mm on the 2× size).

4. Place under whatever needs propping; spin to taste; done.

Tweaking the SCAD

The file is dense with comments. The key knobs at the top:

• scale_factor — uniform XYZ scale.

• thread_pitch — axial advance per turn (default 5 mm × scale).

• post_thread_h — extension range (default 30 mm × scale).

• axial_slop — fit tightness (default 0.4 mm × scale; lower = tighter).