I am now into the finishing off stages.
Just a few holes to drill in the main block and make the points system. The holes are coordinate drilled from the dimensions shown on the plans and the points system is built up from the precise instructions as well, so I won't go into super detail unless someone asks about it.
Three holes are drilled in the top face, but I am showing this one especially.
The hole requires two operations, I went down first with a 2.5mm drill to give a recess in the bottom, it can be a fair amount deeper as it is only to give clearance, and then followed it down with a 6mm end mill to the specified depth. This forms the flat bottom hole that is required for correct fixing. See C-o-C below.
I hope this explains what I am on about. A very similar operation to fitting a bursting disc, or core plug as some people call them.
The fourth hole is drilled thru the side to allow access to the cam grub screw, to allow it to be adjusted.
Be very careful to drill the correct side. I nearly did the wrong one, but luckily caught it before making the mistake. It makes adjusting rather difficult if drilled in the other side.
At this stage, the screw for the main shaft was fitted and the rotor Loctited onto the shaft as far as it could go down.
A piece of supplied exact to size ferrule is cut to length and fitted into the centre hole. This hole is in fact reamed, and the ferrule should have been an interferance fit, but it wasn't, just a tight push. So uncle Loctite came to the rescue and fixed it.
At this stage three things had been completed. The first was to fit the ferrule in the centre hole flush with the top. The second was to tap the far hole out to 3mm. In fact, again belt and braces, I fitted a helicoil in there, to me it makes the tightening of the screw a lot more rigid. For the third bit, I had fitted the fixed point as shown in the above sketch.
You will also notice a brown stick thing poking up out of the ferrule. That is in fact a piece of Tufnol type rod, that when cut to the correct length will follow the cam and push up on the contact spring to make the points break, and so fire the stored energy in the coil.
The points system was then made up to instructions from a bit of spring steel strip with two holes drilled thru it (no problems with that, just good tapping lube and a slow speed), and a couple of insulators, plus of course a screw and solder tag.
I will just mention, in my supplied kit, if you are careful with the cutting, there was enough materials supplied to make up a replacement points part, just in case you buggered something up. But no spare tungsten points, so be careful with those.
The operating pin isn't finished just yet, as I still have a couple of jobs to do that requires the minimag to be stripped down. The first is the optional back cover, but the other is one of my own.
If you notice the upstands, I have carried on with the coil mounting screw holes and brought them out to the back.
I have a fetish about cables vibrating and swinging about, maybe fracturing. So I am going to use those two holes to hold some home made cable clamps, in keeping with the overall look.
So other than those, the Minimag is finished. It just needs to be timed to get the maximum spark out of it. That will be done later.
The back view, minus the cover plate.
So in the next few days, I will be making these extra bits, plus an operating stand to put it thru it's paces.
Overall I have really enjoyed making this little out of the ordinary piece of equipment. The materials supplied to me were excellent, the build instructions and plans have been modded in places, and that info has been passed onto Julian in the hope that he will take notice of them and modify accordingly.
So would I recommend this to a total beginner, no. But on the other hand, if you have made an engine for this to fit onto, then I see no problems at all. Just keep things as tight as you can.
Now open to questions and comments.
John