The small aluminium spring clamps arrived in the mail today so I put a little time into an initial setup of the chassis jig prior to soldering the hornguides into position. The inside bearing surface of the ball-races are machined to a highly precise diameter, unfortunately the steel axles and rods used in the wheel-sets and jig rods of the HH Master Chassis are no quite so precise. I’d polished the axles and fiddled about with the ball-races and managed to get a good slip fit of each wheel-set with two of the horn-guide assemblies. The manufacturing tolerances vary on the steel rod I’m using in the jig, this has something to do with it being drawn bar rather than ground bar (I’m assuming this means the rods would be polished and machined down to an exact size in ground bar). Anyhow, when I tried to push a horn-guide onto the rods last night they wouldn’t fit. By checking the axles (that did fit) I was able to determine I needed to remove something like .05mm from each of the rods. I pondered on this for a while: removing such a small amount from the surface of the three rods cleanly in my lathe would not be a terribly convenient or simple matter. To start with I’d have to set the lathe up and this would take far more time that the actual machining job. In the end I chucked each of the rods in my drill press and applied a flat file to them till they were the required dia. About 20 minutes work. A bit of water and some wet and dry and all three were a lovely slip fit into the ball races.
I decided to do a preliminary setup and take a photo to add to the blog but everything you can see in the photo will have to be disassembled and redone as there is still a lot to do before I can solder the hornguides permanently into position. As you may notice I’ve added an intermediate spacer (between the left hand and middle axles) in the chassis. I have two more of these to solder into position but before I do this I need the motor/gearbox and this may not arrive for another couple of weeks. I also need to determine the exact, final position of the hornguides. They need to be square to each other, and the chassis, and they also need to be set at the same height, with the chassis parallel to this position. If they aren’t exactly the same height in relation to the chassis it will sit either high or low at one end. I’ve yet to determine these settings exactly and mark them on the chassis, but this will happen next.
The operation of soldering the hornguides into position is very simple once the position of everything is set and the components held in place with the spring clamps. I’ll shorten the little bolts you can see in the top of each horn-guide and set these into position permanently. I’ll disassemble all the hornguides and take the suspension springs out so that they all sit at their top ride height. I’ll then set all six guides into position and put a small dab of solder on the top edge. Quick as a flash with a very big iron. After the guides are in position temporarily I’ll remove the whole assembly (chassis, clamps, ball- races etc) and solder the brass hornguides into position permanently by running solder down the side of all six. Again, far easier to do than describe 🙂