About this project
One clearance, five orientations.
A printed thread needs a gap cut into it before it will turn, and how big that gap has to be depends on which way the thread axis pointed while it printed. This coupon holds that comparison still: every hole is the same thread at the same clearance, and the only thing that changes along the bar is tilt — 0 degrees at the first station to 90 degrees at the last, in even steps.
Each hole sits on its own domed post with a flat collar face square to the hole axis, so the bolt always enters perpendicular to a flat face and the thread never has to start on a curve. The thread's lead-in taper chamfers that face, so there is no thin crescent of first turn to catch on. Every hole leans the same way, which keeps the engraved band on the front of the bar clear.
How to use it: print it once, flat on the plate, in the material and profile you actually use. Then run one bolt down the row. The angle at which it starts to bind is where your printer stops reproducing a thread at that orientation — and that is the angle to avoid when you place a threaded boss in a real part.
Engraved into the bar: the thread size, the clearance it was cut at, and the tilt at every station, so the printed part documents itself.
Parameters: thread size and pitch, diametral clearance, how many stations and how far the last one leans, the lead-in taper angle, collar height, and the post height.
Set the clearance to the figure you calibrated upright — the tester in the article below finds it — so that tilt is the only variable left in the experiment.
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