Primary thoughts

As the secondary coil is pretty much finished I have already been thinking about construction of the primary coil. Both coils will sit on a perspex 50cm 12mm thick disc which is supported above the second layer of the main module on 8 30mm diameter 20cm long perspex pillars.

The second level contains the MMC module, the spark gap module and a step down transformer module for the spark gap motor. All modules are mounted on ceramic standoffs.

I have yet to finish off wiring and the support disc is not yet fitted. As you can see I have coated it in masking tape ready for marking up the holes for drilling.

The pillars are drilled out to 5mm and then threaded to take M6 bolts. If you want some advice for drilling and tapping perspex takes a look at my Drilling and Tapping Perspex page.

The primary and secondary coil will sit on the top perspex disc (covered in masking tape above). At this point I have decided to upgrade the design from the original plans (yet again). I thought it would be a good idea to mount the primary coil underneath a perspex disc which should help prevent strikes to the primary coil. Also I heard if you do this any strikes that hit the perspex create an interesting effect as they spread out over the perspex. I will install a more traditional strike rail around the edge of this protection disc. The disc diameter was decided at 90cm and it would need a 170mm diameter central cut-out to allow the 150mm diameter secondary coil to pass through.

And here it is. Ordered from Trent Plastics, it turned up at work this morning. Took me about 10 minutes to remove the 3 layers of cardboard packaging.

The thickness is 5mm and I paid extra to have the inside and outside edges polished. It's a big piece of plastic and does flex a little, but there will be 8 radial combs from the centre outwards to support the primary coil and these will add extra stiffness.