Rack fit test 1U for 10″ and 19″ racks – ear, M3 joint and tolerance comb (free)

A real 1U rack ear, a piece of device carrier with the M3 joint and a tolerance comb: check rack and printer before printing the full insert. Fits: 10″ racks (slot for 234.0–239.5 mm hole spacing) and 19″ racks (465.1 ± 1 mm); the same hole width and height for both. Our rack inserts consist of a device carrier and two rack ears. This free part contains exactly that joint in a small format, so you can check before the big print: - 1U ear with slot (6.5 mm high): screw it to a rail. Does your screw fit (#10-32, M5 or M6), does the plate sit within one unit without touching the next one? - Carrier piece with the M3 joint: bolt the ear on with 2 × M3×10 countersunk screws and nuts. Do the nuts go into their pockets, are the fronts flush? - Tolerance comb: snap off the 10 mm tongue and try it in the three slots (+0.3 / +0.5 / +0.7 mm, 1–3 notches). Our joint uses +0.5 mm.

Hole spacing: there is no standard for 10-inch racks. We found 235 to 238 mm centre to centre; our 10″ ears have slots for 234.0 to 239.5 mm. Measure the hole centres on your rack if in doubt. 19″ ears: 465.1 ± 1 mm per EIA-310. Hole width and height are the same for 10″ and 19″, so one test part covers both. The dimensions come from standard tables, manufacturer data and community measurements; our part has not been tested on a rack yet. That is exactly what this test part is for. Load of the inserts: without rear support (2-post rack) 1 kg at most, with the rear support brackets (4-post rack) 2 kg at most, both guide values, not a tested load rating. The test part itself carries no device. Print settings - Material: PETG (or ASA), ideally the material of your later insert. - Layer height 0.2 mm, 3 walls, 15 % infill, no supports. - Orientation: As the file is laid out: ear upright, carrier piece front face down (like the real carrier), comb and tongue flat. - Print time approx. 1 h 09 min, about 18 g.

Hardware (not included) - 2 × M3×10 countersunk screw (ISO 10642) - 2 × M3 nut (ISO 4032) - 1 × your rack's screw with a washer

Assembly - Snap the parts off the bars and deburr. - Screw the ear to one rail with a rack screw and washer; check the height against the next unit. - Press the M3 nuts into the pockets of the carrier piece from inside, fit the ear (tongue into groove) and fasten with 2 × M3×10 countersunk screws. - Try the tongue in the three comb slots: the one that fits without force and without play shows your printer's clearance.

Safety For checking the fit only; do not hang anything from it. Fit 10″ slot covers 234.0–239.5 mm centre to centre, 19″ 464.1–466.1 mm. FAQ Which screws do I need? For the rack, your rack's screws (#10-32, M5 or M6) with a washer, because the head is only slightly larger than the slot. For the joint, 2 × M3×10 countersunk (ISO 10642) and 2 M3 nuts. How it's made Parametric CAD (build123d, Python), exact solids. The CAD code was written with an AI assistant and checked by us; no AI-generated meshes or images. Renders are made from the CAD in Blender; they are not photos. License CC BY 4.0: free to use, also commercially; credit Magmacode when you share it or derivatives. Matching rack inserts for Mac mini, mini PCs, Raspberry Pi, UniFi gear and switches are in the Magmacode profile.