Replacing Coupling Rods.

Replacing Coupling Rods : Here's a couple of methods you can use for making replacement coupling rods. Its not unusual when scratchbuilding a new loco chassis to make the rods first and use them  as a jig to drill axle bearings holes or holes for axle bushes, but there are times when there's a need to make replacement rods. Here are a couple of methods that may be of use.

The  first method is the simplest, but requires the use of either a milling machine or compound slide mounted on a bench drill. For those that don't know what a compound slide is, a simple  miniature version can be found on the GW rivet press, one slide moves the workpiece in the left /right axis, and the second slide moves in the forward / back axis, the workpiece is  moved by turning calibrated dial knobs on each slide. Compound slide tables can be added to any bench drill, you could even use a single axis slide from a lathe and bolt it to the  drill table. This enables you to move the workpiece a precise distance, so that one crankpin  hole can be drilled, workpiece is moved a determined distance, second hole is drilled.

Second method requires the use of a lathe to modify a couple of axles that are turned  down at each end to the same diameter as the crankpin bushes.

A third method not illustrated below is to use the loco's chassis as a drill jig.  Clamping the chassis to some rod material and spot drill through the bearings to leave a tiny indent as a drilling guide. Problem with this method is that some bearing material will probably be removed unless an 1/8" dia shaft was used with a smaller drill force fit in the end of the shaft.

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