This isn't a complete install yet, but one I've been working on far a while. Funny enough it's in a locomotive that's been talked about a bit in a different thread (Kato re-releasing the Banetsu Monogatari event train in the new colour scheme, and MicroAce also releasing a C57-180 in the new colour scheme)
I've attempted to install a decoder in this loco before, with limited success. I had to superglue and other questionable ways to attach wires to the frame. It worked fine at first. After being in it's box for a few months (I hate not having any space to even put up an oval :/), I wanted to run it a little on my roller stand. I put it on the stand, but had forgotten which decoder address it had. So, I went into programming mode, read the decoder, and noticed that the CV that says whether there's a short circuit said that there was a short circuit on the motor. So, time to take it apart and see what's going on. Of course, the wires let go of the frame the moment I took the shell off, and I figured it was time for some research.
Anyway, as I mentioned in other threads, the metal frame of these loco's is made of a material that dissipates heat really fast. That makes it near impossible to solder anything onto the frame directly. You would need either a VERY powerful soldering iron or a small torch. Disadvantage of either of those methods is that you need to take the locomotive apart completely. Any plastic bit still left on the frame will melt. Not too mention the entire frame will be far too hot to touch, and the metal cools down real slow.
Another way to solve it, would be to use superglue or epoxy to glue some copper or brass plates onto the frame. This works to some extent, as long as you make sure you solder a wire on to the plates first, and you need to make sure the plates make a connection with the frame. Superglue and epoxies don't conduct electricity. Also, superglue doesn't hold too well on the frame. I've used this method twice, once with success (I think at least, the loco ran fine after conversion to digital, but it has been in the box since I tested it way back) and once with no success at all.
So, then I read about American prototype modelers having the same problem with their Kato trains. Their suggestion was to drill a hole into each frame half, tap some thread in it, and then insert a screw. You can then solder the wire on the screw. This, to me, sounded like a good and very stable way of doing this. Tiny screws like that require very little power to heat up, so they're easy enough to solder on. Add a bit of threadlock on them, and they won't be going anywhere either. So, after a quick hunt for a suitable tap and die set, I was ready to try this.
The drill I used is a Tamiya 1.0mm one, which I use together with the Tamiya pin-vise. You can use an electric drill or a Dremel or some such, but I needed accuracy more than speed, so a hand drill or pin-vise was the way to go. The tap and die set I use is from Conrad in Germany. They have an international store and have a LOT of interesting stuff. I couldn't find a set that was small enough in the local hardware stores, but Conrad had one specifically for modeling. It includes taps and dies for 1.0, 1.1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2 and 2.5.
This image shows a 1.0mm hole on the left frame half, and a 1.2mm screw in the hole on the right frame half (and a lof of drilling/tapping residue, need to clean that up ;))
Next image shows both screws in place.
This is a sideview of the screws. The screws were actually 2cm long, so I had to cut them to length. I left them a bit longer than the parts of the frame I put them in. This allows me to solder on either end, depending on how much space I have to work with.
And the last one for now, a test fit of the motor. You could say it barely fits, but since it's N-scale, I'd call this plenty of space ;) The orange and grey wires are the ones for the motor, I already connected those during the first install. The thin copper wires are coated wires of around 0.02mm thick, and they are for the headlight.
More to follow when time permits.
