Caravans are fitted with a variety of external doors and lockers (garage, gas, toilet cassette and so on). Invariably, they have some form of catch to keep them open while you are rummaging about inside.
In most cases, these catches use friction as the retaining medium. Some are assisted by springs (nylon or metal), but still have a friction action as their mainstay of operation.
I have a wide assortment of door catches spread around the outside of my (older) caravan, but they all have one thing in common. They're not particularly great to start with and their operation deteriorates over time, owing to frequent use and exposure to the elements.
This project shows you how to assemble a magnetic door or locker catch, thus removing the reliance on friction.
Magnetic external catches are readily available on the market, but they can cost £25 to £30 for each pair, whereas the catches in this project cost in the region of £6.50 per pair.
Not only is my catch cheaper (by a long stretch): the magnets used in this project are the rare-earth neodymium type, which are often referred to as 'super magnets' and are very powerful, ensuring a firm hold whenever the door or locker is open.
These are the magnets that have made the likes of drones and electric bicycles possible!
Neodymium magnets are extremely powerful and will attach to each other with great force if they are placed in close proximity to each other.
As such, they will need to be treated with considerable respect, because it is all too easy to get your skin, fingers or clothing trapped between them. And for this reason, they should never be given to children as a toy.
When working with these magnets, keep metal tools at a distance, otherwise they will forcefully attach themselves to the magnets, possibly causing injury and damage.
Another concern with the magnets is that they are brittle and will shatter if allowed to drop onto a hard surface or to slam into each other.
They will also rust if exposed to water - in this project, they are sealed in epoxy, so these problems won't arise.
For the catch assembly, mainly non-ferrous materials (copper and aluminium) have been used.
This means that the various parts will not be trying to grab hold of the magnets during assembly, which could make for a very difficult situation.
- Neodymium magnets, 20mm diameter x 10mm deep. These should be readily available, for example on eBay. For my project, I bought some at a cost of £8.50 for five with free p&p.
- Copper 22mm end-caps. These can be bought in any DIY store.
- Epoxy resin. A dual pack 25ml dispenser will be ample for making several catches.
- Aluminium plate, 3mm thick. Once again, eBay has many suppliers of this material.
- M4 x 6mm stainless steel countersunk screws.
- Nitrile rubber sheet. Many suppliers can be found on eBay.
- Conventional toolbox
- 22mm washer punch (although scissors will suffice)