Your first print & fit experiment

A useful first print is easy to understand

The practice tile is 30 × 20 × 3 mm. Its broad flat face makes it a straightforward starting exercise. Our downloadable file has not been physically tested on your printer. You will create the first evidence for your own material, plate and settings by printing, observing and recording the result.

A print can look clean yet have an undersized hole. It can have correct outside dimensions yet contain weak layer bonds. Appearance, dimensions, fit and load capacity are separate questions. This lab checks basic process behavior and fit; it does not establish fatigue life, impact resistance or suitability for a walking robot.

Clearance gives two parts room to meet

The second practice file is a 60 × 20 × 4 mm coupon. Its five through-holes have nominal diameters of 3.0, 3.2, 3.4, 3.6 and 4.0 mm, arranged left to right in the supplied design view. Read the download's dimension guide before rotating the part so that you can preserve the hole order in your notes.

A nominal 3 mm rod does not necessarily measure exactly 3.000 mm. Neither does a hole drawn as 3.2 mm necessarily print at that diameter. Choose a known smooth test pin where available and measure it. A screw can provide a practical go/no-go check, but its threads make it a poor precision diameter gauge.

A fit check should observe the existing hole, not change it. Forcing a threaded screw into a tight plastic hole can cut or deform the material. Afterward, an easier fit may reflect the damage rather than the original printed size. Stop at resistance and record that result instead of forcing the test.

Measure the process you actually used

Diametral clearance is hole diameter minus shaft diameter. A 3.2 mm hole around a 3.0 mm shaft has 0.2 mm total diametral clearance, or 0.1 mm on each side when centered. Real fit also depends on roundness, length, texture and alignment. Record whether the pin slips freely, drags, requires force or does not enter.

Do not scale the whole robot to correct one tight hole: that changes every length and hole spacing. First establish whether the issue is local geometry, unit interpretation, first-layer expansion or the printing process. Only then make a controlled correction and test it again.