Dell Latitude rack cluster

Why

Imagine a company that is periodicaly upgrading and replacing laptops. The old ones are still fully functional and with decent performance (i5 4th gen, 8 Gb RAM, SSD), but there is no legal process to give them away or sell to employees. So you can either scrap them or figure out what can you do with all that computational power laying around.

Thus, the idea was born. Lets dedicate an empty networking rack and build a computational cluster out of them.

Design

The general idea had to comply with following constraints:

• thermal design - hot air must be flowing correctly within the cabinet
• fit on a standard 19'' rack shelf - no additional construction, mounts, support, assembly
• hot swap - blade design allowing to take a laptop out without disassembling the whole unit
• half-depth rack - only one block per shelf. Two blocks on one shelf in full depth rack would have thermal/hot air distribution issues

The models

The overall shelf is split into three parts: Front, Back, Top.

Back and Front components are responsible for holding the laptops upright. Back has a slight bump to make sure laptops are not pushed too far. Front has a slot for ID tags.

Top component ensures the laptops stay parallel to each other and also has a slot for UTP cable routing. It is designed to fit just right between power connector and laptop with extended battery (if present).

Each component was divided into 3 sections (left, center, right) due to printer bed constraints and later connected together via dovetail joints.

One model is provided. Import it into Slic3r and "Split into objects". Then pick the parts you want to print and delete the rest.

Original plan included stand also for power supplies (see photos) but the idea was scrapped due to multitude of their form factors.

More photos from the process: https://imgur.com/a/bqFW5K9

Models for the labels/tags

The text is based on OCR-A font. rackCluster_insertable_tag - single tag rack_labels_text - the text on the tags rack_labels_tabs - tabs with embossed holes for the text

You can print them on MMU printer, print two colors within one layer using this approach or just use the ColorChanger 2 layers (front facing) black, 2 layers in color, two in black.

When printing MMU, make sure to print the front side of the label facing the print bed. The colors will nicely blend into one solid layer.

Slicing / Print setting

top layers: 4

infill: cubic, 10%

8mm high slab infill modifier: 15%

The slab modifier improves rigidity in the bottom 8mm of the model.

Result

Print times

Commonly printed in groups of three - 1 top, 1 front, 1 back.

Printers were set to print around 120% speed and average time to print one set was around 12-13 hours.

Material consumption

Approximately 1 kg PETG per shelf (incl. some trials and failed models)

Category: Engineering