Raspberry Pi is a series of small single-board computers developed in the United Kingdom by the Raspberry Pi Foundation in association with Broadcom. Early on, the Raspberry Pi project leaned towards the promotion of teaching basic computer science in schools and in developing countries. Later, the original model became far more popular than anticipated, selling outside its target market for uses such as robotics. It is now widely used in many areas, such as for weather monitoring, because of its low cost, modularity, and open design.
The Raspberry Pi’s popularity and ongoing success are due to its accessible price and incredible community. At $35, it has attracted a range of users from school children to professional programmers. It could be why over 30 million boards have been sold.
The Raspberry Pi is a micro-computer initially designed for education. It has all the components you would see on a normal desktop PC – a processor, RAM, HDMI port, audio output, and USB ports for adding peripherals like a keyboard and mouse.
TDM Solutions have come up with a solution to the ‘over-heating’ problem that the Raspberry Pi 4 computer processor experiences by designing and manufacturing the Kool Case. The ‘over-heating’ is referred to thermal throttling under load. In other words, the processor stops working when it gets too hot. The CPU protects itself when it reaches a temperature of 82 degrees. This happens purely because of the design and construction of the casing that the board sits in. The Kool Case maintains a temperature of less than 60 degrees C under maximum load. The Raspberry Pi 4 has been built so you have a complete desktop experience
Alongside these recognisable components is one of the key parts of the Pi – the GPIO (General Purpose Input Output) header. This is a block of pins that let you connect your Raspberry Pi to the real world, connecting things like switches, LEDs, and sensors (and more), which you control with some simple code.
It also runs a full desktop operating system based on Debian Linux, called Raspbian. If that doesn’t mean much to you, consider that Windows, Linux, and Apple OS X are all operating systems.
The comparison to a normal desktop PC pretty much ends there. Although greater performance is being offered especially with the latest Raspberry Pi 4. The Raspberry Pi is a low power (5V) micro-computer. It’s powered by a micro-USB power supply similar to a smartphone charger and offers computing power akin to a mobile device. The speed and performance of the new Raspberry Pi 4 is a step up from earlier models. For the first time, they have built a complete desktop experience.
However, the Raspberry Pi computer processor has had a key failure. It is referred to thermal throttling under load. In other words, the processor stops working when it gets too hot. The CPU protects itself when it reaches a temperature of 82 degrees; this happens purely because of the design and construction of the casing that the board sits in.
Enter the Kool Case
With a background in the automotive industry designing and manufacturing jigs and fixtures, product R&D and production machining with 5-axis CNC machines at his disposal, Jim Plester was approached by his son-in-law to see if he could come up with a solution to the ‘over-heating’ problem that he was experiencing with his Raspberry Pi 4.
“I am always up to the challenge. My company Tool Die and Mould (TDM) Solutions is a design company and we have completed some interesting and demanding projects for high-end automotive OEMs in the past,” said Plester.
Plester’s experience includes working on projects for Rover, Ford, Vauxhall, Lotus, Audi, Rolls Royce, Bentley Motors and Jaguar Land Rover, as well as Boeing, Airbus and Denel Aerostructures in the aerospace industry, using modern CNC machining technologies.
Plester’s passion and hobby is restoring Lambretta scooters, the Italian automotive icon. Lambretta-inspired Plester has even combined with manufacturers Iconic Design to create a collection of chairs made from old Lambretta scooter spare parts and upholstered leather. Using traditional Lambretta colours (white, red and black), the chairs are built and designed using 20 different models of Lambrettas produced from 1957 to 1971.
“Like any electrical component, a CPU generates heat when it is being used. When heat can’t be dissipated from a system, the microprocessor defends itself by thermal throttling. The CPU chip slows itself until heat no longer threatens its existence. To keep CPUs cool heat sinks are used. They have a high thermal capacity and a large surface area so they can both absorb and radiate away as much heat as possible. It is possible to overwhelm a cooler though. If your cooler isn’t strong enough you may find that your CPU gets hotter and hotter, until your computer suddenly loses performance. This loss of performance is your CPU reducing its clock speed, so it produces less heat, in a process called thermal throttling,” explained Plester.
The weight of the Kool Case is only 251 grams and has dimensions of 100mm by 85mm by 33mm. It is available in a plain case format or can be customised with logos and an anodised coating to suit your colour preference
“In the case of the Raspberry Pi 4 computer processor unit it has been designed and launched with a wealth of new features to tempt users into upgrading: A more powerful CPU and GPU, more memory, Gigabit Ethernet, and USB 3.0 support. More processing power means more electrical power, and the Raspberry Pi 4 is the most power-hungry member of the family.”
“Development is continuous, with new software and firmware improving each board long after it has rolled off the factory floor. Raspberry Pi 4 is no exception. Since launch, there have been a series of updates which have reduced its power needs and, in doing so, enabled it to run considerably cooler.”
“However, with thermal throttling still being inevitable something needed to be done.”
Passively ‘kooled’ case
“We have now designed what we call a passively ‘kooled’ case to house the Raspberry Pi 4 computer processor unit.”
“The core function of the case is to prevent the Raspberry Pi 4 computer processor from thermal throttling under load, which happens at 82 degrees C, with our case we maintain a temperature of less than 60 degrees C under maximum load.”
“It is a CNC precision machined aluminium case manufactured in aircraft grade 6082 T651 aluminium with machining tolerances of +/-0.05mm and material thermal conductivity 180W/m.K.”
“CNC techniques used include surfacing, facing, pocketing, profiling, roughing, drill, tapping, reaming and chamfering and waterline machining was used on all thin wall sections (1mm or less) with rigid tapped holes and a split line.”
“Fully optimised CNC code using Vericut CNC verification, simulation and optimisation software has been used for the designing and machining process, reducing CNC cycles times by over 50%.”
“The weight of the Kool Case, as we have named it, is only 251 grams and has dimensions of 100mm by 85mm by 33mm. It is available in a plain case format or can be customised with logos and an anodised coating to suit your colour preference.”
“Obviously, the big benefit is the prevention of thermal throttling under load. Added features are that the motherboard LED indicators are visible, the SD card is accessible as is the GPIO ribbon cable access, 2-way locators are used for improved fitment, and the case is strong and rugged making it suitable for harsh environments and by its very nature is silent running.”
“We have done all our tests and have now started the process of manufacturing in numbers. At the same time, we have sent product to our agent in the UK and will hopefully get some positive order numbers in soon.”
“Whether you’re editing documents, browsing the web with a bunch of tabs open, juggling spreadsheets or drafting a presentation, you’ll find the experience smooth and very recognisable – but on a smaller, more energy-efficient and much more cost-effective machine. The Raspberry Pi 4 has been built so you have a complete desktop experience. Now with our Kool Case you will not have to worry about thermal throttling.”