Chassis MkII

The past week has seen me make some progress on my locomotive scratch-building project but in three separate areas. As outlined in the previous post I got some work done on the hornblocks and guides and spent a couple of hours assembling these during the week. All six of these are now assembled and are currently sitting on the wheel-sets they will eventually hold in position on the chassis I’m working on. I’m waiting on some small aluminium clamps from the US which I’m going to use in soldering up the chassis and hornguides. I’ve been waiting for an excuse to buy some of these mini clamps from Micro Mark and this project has finally led me to making a purchase. Up to this point I’ve been using ladies hair clips (evidently used to hold the hair to rollers) to do my horn-guide setups but I’ve never had enough of these and they don’t seem to be available anymore. I snatched mine from a local hairdresser who was going to throw them out as there’s not much call for them since rollers stopped being an de rigueur for women of a certain age. Just to explain: when you set up the hornguides on the chassis ready to solder them into position you need small spring clamps to hold them in place as you solder. Because of the heat from the soldering operation they need to be metal and because this operation involves solder, aluminium is ideal as this metal won’t solder to anything if something goes astray. I need at least two clamps for each horn-guide so this means I need 12; six on each side of the chassis. I placed an order for 4 packs of 5 which will allow me to solder up a loco with four or five axles if I need to at some point down the track.

The second job I worked on this week was to enlarge the holes in my recently assembled side rods and set the wheel spacings on my Hobby Holidays Master Chassis jig. I’ll write in more detail about this jig later when I come to actually use it to set the horn-guides in place. At this stage I will confine myself to saying that this is one of the best investments I have made in terms of hobby tools. It is a fantastic bit of kit and I can’t recommend it highly enough. If you want your locos to run well, either kit built or scratch, then nothing else comes close in my estimation to this bit of kit. This past week I had to refine and enlarge the holes in the rods and ensure that these were a nice slip fit onto the steel jig rods used to hold the wheels in the correct position. A lot of filing and boring (boring out holes but it was boring to do as well) took place and these are ready to use to set up the horn-guides when I’m ready to carry out the operation.

After my earlier, failed attempt to get the chassis right I decided to take a bit more care using the lessons I'd learned from MkI. This is the result.

After my earlier, failed attempt to get the chassis built in MkI, I decided to take a bit more care using the lessons I’d learned from MkI. This is the result. The front of the loco is on the right hand side.

This afternoon I was ready to have a go at assembling chassis MkII. I’d left the two halves tack soldered together for a couple of weeks and lucky I did because I’d managed to forget to file in a very slight slant onto the front end of the frames on the top edge. You can just see this in the photo above on the far right hand side. Doing this after they had been separated would have required quite a bit more effort to get them to match. After this small job was done I was ready to separate the two halves. With a small amount of heat applied from a soldering iron (I had learned not to use the big iron to attach them to each other this time) and some pressure from a Stanley knife the two halves popped apart sweet as a nut. I cleaned these up with Jif and some 600 git wet and dry paper. Aside from having to shorten the long leg of the rear spacer by 1.5mm I was able to re-solder the spacers from Chassis MkII into position without any further modification. I will solder in two intermediate spacers and various other bars and parts to hold things like pony trucks in place when I have the motor and gearbox in hand. There’s little point in soldering the rear intermediate spacer into position as I’m bound to place it in a position that will interfere with the gearbox so this will have to wait.

I've included this photo to demonstarte the highly sophisticated tools and techiniques I use in my workshop. This jig consists of a piece of 12mm ply, some 1'X1

I’ve included this photo to demonstrate the highly sophisticated tools and techniques I use in my workshop. This jig consists of a piece of 12mm ply, some 1’X1″ pine screwed at a right angle to each other and some balsa. High tech hey? 🙂

Because the frames on chassis MkII didn’t have straight top edges I needed to hold the two halves in alignment in two planes as I soldered the spacers into position. I’d made up the jig of 12mm ply and 1″x1″ pine for chassis Mk I but this time I used some balsa to hold the parts in the correct relationship to each other while I applied the soldering iron. The critical elements of making such a jig are:

  1. The two lengths of 1″x1″ pine must be in 90 degrees to each other. If they aren’t and you rely on the corner thus formed to produce a right angle your chassis will not be square.
  2. You must ensure the base is flat. It’s important that you check that the ply or mdf you’re using is truly flat. I happened to have an off-cut of ply that was about the width I wanted and all I needed to do was cut it to length. See how there is no gap under the front edge of the ply in the photo? It’s flat!
  3. It’s worth checking that the edging material you use (the pine) is square and straight. Don’t assume, use a steel straight edge to ensure that the top of the ply and the edge of the pine form a right angle. You need your chassis frames to be parallel and square in all planes. It’s not rocket science but you do need to ensure that things are as they’re supposed to be. Compromise and your loco won’t run properly.

Getting the chassis to this stage was a lot easier to do than it is to write a description of how I did it. I don’t expect anyone reading this to follow along and build a 20 with me but I do hope that some of you are thinking “I could do that”. Yes you can! 🙂

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