Re-Building a Simplex Loco

Hi John

I'd checked the squareness if I was you, the laser beam tends to fan out so you don't get a square edge, the better lasers tilt the head to correct this, if in doubt get some more stretchers made a couple of mill over size so you can machine them square. Getting the frame square is a real critical feature as it will impact on the running of the locomotive and the smooth operation of the coupling rods and valve gear. Its easy enough to check the frame for squareness you just have to measure across the diagonals over common points, with a long steel rule what you want is for the two reading to be the same, this will tell you if the frame has been assembled square or not.

Cheers

Stew

G'day Stew I am taking your advice and I will remake the stretchers giving me plenty of space to mill them square. As you said the stretchers have to be square to the frame or else it will muck everything else up and I am not very happy to take a gamble on these. Thanks mate John

You could machine them square, and if under size, a packing strip could be put in place, if this is done carefully it's going to take someone with a microscope to see what you'v done.

Ian S C

Yes, the frame stretchers must be straight, square and parallel. Also, the frames themselves should be straight. If not, they need to be adjusted until they are relatively straight, The stretchers will pull them straight to some extent, but they need to be quite straight to begin with. Straight and square frames are the foundation for everything on the locomotive. This needs to be constructed as well as possible.

David