Rack base kit, 3U, 7.5-inch
ParamTweaks
In the box: 14 printed parts and 44 bolts.
7.5-inch, 195 mm depth. The packing list follows the selected variant. The heat-set inserts arrive pressed into the posts.
| 4 | Post | Number 1 on the drawing |
|---|---|---|
| 2 | Bottom bar | Number 2 on the drawing |
| 2 | Top bar | Number 3 on the drawing |
| 2 | Side rail, 195 mm depth | Number 4 on the drawing |
| 1 | Base tile, front, 195 mm depth | Number 5 on the drawing |
| 1 | Base tile, back, 195 mm depth | Number 6 on the drawing |
| 2 | Top rail, handle, 195 mm depth | Number 7 on the drawing |
| 36 | M6 heat-set insert, 8 mm | |
| 40 | M6 nyloc nut (DIN 985) | |
| 40 | M6 x 16 socket screw | |
| 4 | M5 x 20 socket screw | |
| 4 | M5 nyloc nut (DIN 985) | |
Description
One 3U section of our printed 7.5-inch rack: the start of every rack in the narrow line. Stack extensions on it for 6U, 9U and up.
Printed parts (PETG): 4 x post, 2 x bottom bar, 2 x top bar, 2 x side rail, 2 x base tile (front, back), and 2 x top rail with a carrying handle. Fourteen pieces against the 10-inch kit’s sixteen — the base plate is 189.7 mm wide, which goes on a 250 mm bed without being cut across, so it is two tiles rather than four.
Hardware included: 36 M6 heat-set inserts (pressed before shipping), 40 M6 nyloc nuts and 40 M6 x 16 socket screws for the bars and rails, 4 M5 x 20 socket screws and 4 M5 nyloc nuts for the base. Exactly the same count as the 10-inch kit, and not a coincidence: every bolt here lands in a hole pattern the posts already carry, and the posts are the same printed part in both lines.
The handles come as standard. A built 3U section is most of a kilo and people move these, so the two top rails are in the box and in the price. Build it without them, or with a plain groove instead of the grip, and the price is the same.
Mounting pattern: three M6 inserts per U at 15.875 mm — the same hole ladder as our 10-inch rack, twelve pitches across the panel instead of sixteen — on the front posts and the rear ones. Panels are 190.5 mm wide; the frame is 224.5 mm across, and 195 or 260 mm deep — chosen when you build it, and priced for each. At 195 its side and top panels each print in one piece; at 260 it takes the very same side panel as a 260 mm 10-inch rack. Ten-inch panels do NOT fit it, and 7.5-inch panels do not fit a ten-inch rack: the two lines share a hole pitch, not a width.
A post runs the full height of its section, so a 3U section is 3U and nothing more. Everything else in the rack — the bars at each end, the next section up — bolts to the two rows of holes each post end already carries, which is why the front stays clear for its whole height. The base is a vented plate in two tiles, each carrying a prong at both ends that bolts up into a post.
Why 7.5 and not 7. A panel has to be a whole number of hole pitches or its slots do not land on the frame’s grid: 7 inches is 11.2 pitches and cannot be built. 7.5 is exactly twelve, and it still takes a 3.5-inch drive across the tray floor with 11.75 mm to spare — which 6.875 inches, one pitch narrower, does not.
