To begin with I carefully pulled the existing Jump Packs off using a sturdy blade, then proceeded to drill out the sections of both parts to be magnetised. You can file these sections off easily with a hobby file during the assembly process while the models are unpainted, but I found it easier to use a rotary tool to remove sections of the torso without risking damage to shoulder pad or legs.
|Best tool for quick converting, a high rpm air drill. A Dremel will work just as well.|
Magnetising the Model
Once you have made a hole roughly the same size as your magnet I find it best to 'glue' them in with green stuff or equivalent modelling putty. This will set hard enough to hold your magnet while allowing correct positioning without having to file precisely or get your hands covered in glue. The pictures are not exactly step-by-step but give you a good idea of how I applied the green stuff, used an un-magnetised jump pack to ensure a flush fit, then filed down the area once it was cured overnight.
The following pictures are a little more helpful, showing the size of hole drilled, the extra step of pushing the green stuff up to the edges of the magnet for better grip. I allowed this first stage of green stuff to cure, then applied a second dab to make a flush fit between the magnet at the rest of the jump pack. Before this stage you want to make sure you have the correct polarity! Here I simply attached the line of magnets to the already cured body, then stuck the jump pack on the end. This can be tricky to remove the magnets leaving only one behind, but if you have long enough fingernails you can slide the whole lot off, leaving just one attached. Metal tools make things interesting too.
This is pretty much the same as the step above. Check polarity, slide to remove and either add more green stuff to fill gaps, or cut away the excess as pictured. Backpacks have an easy squared of face to make sure the magnet is level, but you can always use the edge of a table or stiff card to square it off.
|All ready for some paint. You may need to touch up any unpainted areas exposed by removing the jump packs.|
When I first magnetised my jump packs I tried painting them. I tried double varnish, let them dry for weeks, used automotive touch up paint, all without preventing what you see below: chipped paint. I have since scraped back to bare magnets, as they are designed to be knocked against each other anyway. If you are using them for removable weapons on vehicles you may want to cover the exposed magnet with a decorative attachment?
When it comes to painting the rest of the model, it is very easy to just paint over the magnet as well with your base coat and just scrape the paint off with a sculpting tool. Always avoid filing the magnet during assembly as the metal flakes are difficult to remove and can get into your paints/brushes.
|Avoid chips by leaving the magnets unpainted.|
One subject I haven't touched on is what size of magnet to use. My local FLGS (friendly local gaming store) only had one size in stock the first time, so the choice was easy. I have since tried smaller magnets for my Imperial Guard and found them to be far too weak. My goal is always to have the joint strong enough to pick the model up by the part to be magnetised, and these actually fell off when move the model by the base, let alone picking them up by the arm! The choice is a little trial and error, but bigger is usually better.
|"Too small and it will fall off"|
An indication of the strength of the magnets used.