Thursday, June 28, 2018

A Blast From The Past

Having finished the Clayton commission I decided I'd try and finish some of my stalled projects before starting anything new. First up on the workbench is my build of Backwoods Miniatures Canopus. Last time this appeared on the blog was November of 2015, when I was in the middle of trying to fix all the issues with the parts supplied with the kit; on that occasion the slidebars being two narrow. While problems still remain the model is really quite close to being finished, and so I'm going to make a determined effort to see it through to completion.

After altering the slidebars and riveting the connecting rods to the crossheads, the next step in the instructions is to fit the cylinders. Not entirely surprising but it turned out not to be as simple a task as it sounds. In theory all I needed to do was drill a 0.8mm hole through each of the two whitemetal castings for the piston rods to slide through. I drilled the first cylinder with no problems at all, but drilling the second one seemed impossible. Not only did I break a drill bit but even when I'd found a second drill I just couldn't get it to drill through. I'm guessing an impurity of some form in the casting. Either way this left me with only one usable cylinder, so I decided to turn up a replacement. Fortunately I checked the one good casting against the loco before starting as in the end I had to turn up a pair of cylinders.

The instructions suggest that the cylinder should have two notches on one end into which the slidebars fit into. My castings didn't and worse still when the cylinder is held in place against it's bracket the slidebars are almost a millimetre too short to meet the face of the cylinder. So my turned replacements are the same diameter as the cast parts but about 1mm longer so that they fit in the bracket and against the slidebars.



While the cylinders are now a bit longer than they should be I don't think they look too out of place on the loco. Even having moved the slidebars outwards (back in 2015) the clearances are still really tight but turning the motor by hand seems to suggest there is enough space for everything to move past each other.... just. The test will be when I find where I've put the rolling road so I can give it a powered test where I can watch everything closely.

5 comments:

  1. Looks good. when painted you won't be able to tell. If you can get carbide drills they should chomp through anything. They do snap as all small drills do unless cleared constantly. A small drill press would help in this regard. Use WD40 as a cutting fluid on aluminium.

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    1. PS. My maternal granddad used to make his own drill bits out of spring wire. He was a carving fork maker so drilled tiny holes in steel. He made me a few the wire was hammered flat into a lozenge shape and the cutting edges ground on. Then they were hardened and tempered as normal.

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  2. Nice having a lathe isn't it!

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    1. It is indeed. Unfortunately I seem to have done some damage to the tailstock when I used it last. I was using it to drill a hole in the centre of a turning and thought it was just being stubborn, what I hadn't realised was that it was already at it's maximum extent and I tried to wind it further. I've stripped it down and can't see any obvious damage (some slight wear on the grub screw) but it is now much tighter to turn than before, and seems to catch part way around each turn. Will have to strip it down for a second look. Fortunately it still works, even if it's not as smooth as before.

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  3. As someone who's never made anything for a hobby since the Meccano days I still can't quite understand why I find your posts so fascinating.

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