Plan of Construction
So we have a cutting plan and now I would suggest it may be a good idea to also have a plan of construction at this stage. All models can be broken down into sub assemblies and individual tasks.
It is not a case of having to do things in the order written down. I have already suggested that certain more difficult tasks, or more time consuming, may require specific time set aside. These key tasks are highlighted in green
on the list. Other items could be done in these odd half hours here and there, but there are one or two tasks that are best done in a set order and I will point this out when the time comes. So here is the plan which is to design and construct a chassis, which can be dis-assembled for painting and repair and which uses jigs for accurate assembly of components.
1. Separate the frames and the spacers from the other parts and make up compensator
2. Fold chassis sides together keeping them folded along the top edge
3. Drill all holes and clean up all edges except the folded one
4. Use the 1.5mm axle holes to set up the coupling jig5. Make up the coupling rods on the jigThis must be done before 6 onwards
6. Separate frame sides. Cut rectangular cut outs for the horn blocks, check then allocate horn blocks
7. Mark out, drill, cut and fold spacers8. Make up frames using jigs9. Match horn block components and assemble horn blocks as per instructions
Using assembly and spacing jig 10. Fit horn block assemblies and compensator using jigs
11. Make up motor and gearbox unit, check how it will fit against drawing
12. Test unit with power, if OK run in motor/gearbox on bench
13. Fit crank pins to wheels and check for correct fitting using jig
14. Fit one wheel to each axle and check they are square. Do not fit other wheels yet!
15. Using a slow motor and gearbox true wheels in turn
16. Allocate horn blocks to each axle, and motor /gearbox as appropriate17. Partially fit other wheels and quarter using jig17 must come before 18 using this method18. Press fit other wheels on to the axles and check for being square
19. Re-fit axles in the correct order and use temporary retaining wires
20. Check all moving parts for freedom, do rolling check, keeping gears disengaged
21. Trial fit of coupling rods, open up holes if necessary, treat as two 0-4-0’s
22. Fit crank pin nuts and tighten. Check for binding. (Chassis must be free before 23)
23. After tweaking to get all running as an o-6-o tighten gearwheel grub screw and try motor under power and Test run
24. Fit more permanent retaining nuts on crank pins make up pick ups, fix motor, fit and test
25. Fit other details including brakes, sand boxes, etc.
26. Check running on bench then test run and watch for shorts, clear same
27. Drop wheel sets and pick ups
28. Paint chassis
29. Refit wheels etc. and test run with body when assembled.
Next we will look at the jigs and tools needed to do the work, the making of jigs for the beginner will give practice in metal working technique and will equip him with a workable system, which will allow him to build consistently well right from the start. We shall also cover materials at this stage.