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One of the challenges of technical writing is maintaining a logical continuity, where one action is followed by its logical successor, a straight-line progression of action, when in fact technical progress is typically anything but straightforward so there may be some skipping around. A number of things influence the selection of this locomotive project. I chose 7.5" gauge because the nearest available tracks to me are 7.5" gauge. I chose a British 0-4-0 because firstly I love British locos, and then as I mentioned previously I wanted something I could build quickly.
Tools can also play a large role in project choice so I'll list mine to give you an idea of what I have to work with: Lathe: Harrison 10"x24", Mill: Jet 8" x 30" combination horiz/vert, drill press, die filer, cutoff bandsaw, 1x42" belt grinder, oxy/acetyl torch, and the other miscellaneous gear and accessories as would typically go along with these machines. One item which has been particularly useful is a heavy 9" rotary table (Troyke). I acquired my tools piece-meal over a span of 30 years and they give me the capacity to easily build a 7.5" gauge locomotive. I don't use CNC or insert tooling (yet) and my one "modern" indulgence is a DRO on my mill. My most often used workshop tool is a file.
Occasionally I will do some job the hard way, that is, I'll use a material or technique that I could easily have done differently and saved time. My answer to that is that I often do things to challenge myself, to see if my skills are up to snuff or to develop new skills. Most times I'm glad I tried it out or acquired a new skill, but sometimes not, and I'll try to tell you which times are which. It was also important for me to be able to say, in the end, that I built it all myself, within my own workshop, and so far with the exception of the casting I haven't put anything out to be done by others. There are a couple of things that will need to be MIG or TIG welded and that will have to be put out.
Some years ago I had the opportunity to buy a few odd castings for the BRIDGET loco (mentioned above) and these included a set of drive wheel castings and cylinders which were very close to the size needed for the TICH, although the BRIDGET driver castings were 5" diameter and the TICH called for a 4" driver. So the decision was made to re-scale the original TICH to accommodate oversize drivers and in the end the loco is very little over the overall size of the original. The cylinders however did not work out well so I decided to make a pattern for the cylinders and have those poured in cast iron. I would have made many more patterns for iron castings over the course of the project but in my area walk-in, loose pattern iron foundries are a thing of the past. More on the cylinders much later on.
A full set of original drawings for the 7.5" gauge version was acquired from GLR in the UK and start was made. I began redrawing in Cad (Autocad Ver.LT97) and a plank 1/4" HRS (hot rolled mild steel) plate was bought to make the plate frames. The original drawings call for 5/32" plate but 1/4" actually cost me less and it would add weight on the drivers which any 0-4-0 can always use more of. Many things on this model are heavier than necessary and in almost very case it was a matter of being able to add weight for little or no more cost or trouble.
I began by rough-sawing the frame plates to size on the cutoff bandsaw (in upright position) and the two rough plates were dressed (filed) and matched up. I then drilled through in several paces which I knew would later be cut away (or enlarged) for bolting holes. Two holes located in opposite ends of the pates were reamed for dowel pins so that if the frames needed to be separated, as they would be many times, the dowel pins would make certain the plates lined up exactly when machining continued. First the frames were clamped in the mill and all edges, slots, offsets, etc, were finish milled.
With the frames mounted squared in the mill, critical holes for shafts, screws, pins, etc, were indicated in and drilled or bored. The axlebox slots were chain-drilled and bandsawed out (Photo-1) and the finished axlebox slots were indicated in and milled out (Photo 2). In Photo 2 you can see a set of axlebox horns being try-fitted in a slot, but that is getting ahead of the story. Drilling and countersinking (when necessary) for most bolt and rivet holes was done and the frame plates were essentially complete. Some holes were not drilled at this time because the exact locations various things remain to be decided and much of this will be decided by try & fit. Some already drilled holes will not be used and will be filled. Photo 3 - a finished frame held by Your Humble Servant, although as you can see horns, axleboxes, and pedestal caps had been added by the time this picture was taken.
If anyone wants more detail or information on, or to discuss anything I have or will describe in this thread I'll be more than happy to do that, but to keep this thread easier to follow I'll do that on the How To board.
