Chama Shop Update

Aside from the usual annual work, the bulk of our efforts this winter have gone into repairing the 484. It is the last of the K-36s to have the valve gear rebuilt and valves set. We are also turning the tires, converting the main journals to oil lubrication, and replacing rod bushings.

We made some modifications to 488s front end. The main change is to split the cyclone in two parts to facilitate removal and installation during annual inspections. This is an idea borrowed from the D&S and will save considerable time compared to disassembling the front half piece by piece as had been done previously. We eventually intend to modify all the cyclones this way. We are boring the draw bar pin holes in the tender frame. These have worn badly over the years causing the pin to ride at an angle. We will install hardened bushings to bring the hole back to original diameter and alignment.

489 is spending the winter in Antonito and the crew over there is doing the annual inspections and the 5 year flexible staybolt inspection.

The left link of the 484 was worn to the point that it needed re-grinding. The D&S allowed me to use their home built link grinder for the job. This machine was built by Mark Yeamans and, as I understand it, is the only machine to have survived the fire in usable condition. It is a slow process which took me two days of work but it does a very good job, refinishing the link to within about .002" parallel over its length.


The normal wear pattern for these is a worn area in the lower part of the link where the link block spends most of its time in operation. That can be seen as a lighter area on the inside face of the link in this picture.


Cleaning up the wear required removing about .100" from the link. A new link block was needed. The D&S grinder is designed to make these as well but I did not have time to get it done. We have a special jig for making link blocks in our shop. It is a bit like something Rube Goldberg would design but it does the job very nicely.

The left side is anchored to the table through a bushing that turns freely and forms the axis. The right side is attached to the mill table loosely. The block to be machined is bolted to the plate and the center held at the precise radius needed. The Y axis on the right mill feeds the block past the cutter and the X axis on the left mill moves the jig to the proper side of the block and determines the amount of material that will be milled on each pass. The depth of cut is adjusted by the manual quill feed.


The front side of the block is being cut in this view.


The finished link block fit into the re-ground link. The block works with a clearance of only a few thousands of an inch.


More to follow....