Thursday, December 24, 2015

Rail Cutting Jigs

So having given you a few days to think about the mystery 3D printed objects I'll put you all out of your misery. They are jigs to help cut rail at the correct angle for making Hudson Type 1 and Type 2 points in O14. While I have the KBscale jigs for actually soldering the rails together they rely on you cutting or filing the rail ends to either 15 or 9 degrees and I found doing this accurately was a bit of a nightmare and so a jig or two sounded like a good option.

The printed jigs are actually the third iteration of the basic idea which was to trap the rail in such a way that a razor saw could cut it at the given angle. The first attempt, which I've unfortunately thrown away so can't show you, used four pieces of 4mm square section styrene stuck to flat sheet, two on each side of the rail. The pieces on each side were offset so that you ran the saw across the rail resting it against the ends of the blocks. It worked well enough to produce the first crossing I made but it wasn't easy to hold the rail still while pushing the saw against the blocks.

The second jig used 12BA nuts and bolts to both clamp the rail and to help position the saw. The screw holes being carefully positioned so that they both allowed the nuts to grip the web of the rail, but also to act as the guide for the saw. While this was much better at keeping the rail in place it was still difficult to keep the saw in place against the upright screws, there was a danger of sawing into the nuts, and the cheesehead screws meant that the jig wasn't very stable on the worktop. It did, however, allow me to build two Type 2 point without requiring any extra filing of the rail ends.

The printed versions continue the idea but without relying on the screws to guide the saw. The two printed parts are used to clamp the rail in combination with grooves in both halves. The slightly bendy nature of the strong and flexible plastic is actually really useful here as it allows you to really tighten the jig so that the rail doesn't move at all. The saw then fits within in the guide formed between the top part and the block on the bottom half making it much easier to cut the rail.

I haven't had a chance to build a point using the new jigs but I have cut a couple of rails to check that they work and they appear to work very nicely which should make it easy to churn out more crossings in the future.


  1. I was only half a street behind you.
    Have a good feast.

  2. Well at least I understand that which is a start.