Assembling the MDC 2-8-0
by Stephen Hatch


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This is the old style with a caveman motor and all. I went through the assembly of the frame and drive train and found all the areas that need attention. The mechanism did build up into a smooth running unit in about 2 hours but it has some things that must be done.
First off, the frame itself has quite a few rough edges all the way around. These will foul the drivers and cause friction, so I filed all the flashing to make all of the edges (especially around the driver slots)smooth with no catches. Also remove the flashing from all the edges on the bottom plate.
Second......not all of the drivers rotated smooth in their journals so I use a fine jewelers file to make sure that each driver sat and turned smoothly in it's journal. Be carefull here because you can't put the metal back.....so easy..little strokes are best. Keep test fitting the axle in it's slot as you go.
I noticed that three of the axles were .092 (92 thousandths) and one of them was .094 (94 thousandths). That axle would have caused trouble later on so I was extra carefull in filing it's axle slot. This caused a major "hitch" in the smoothness of the mechanism and would have made a poor running loco if I hadn't corrected the fit. Remember to go easy with the file here. It doesn't take much to get a perfect fit but sloppy (too big a slot) is hard to fix.
The gears are also marginal....but fixable. I noticed that each of the three gears had very rough edges so you want to VERY CAREFULLY using a jewlers file....take the edge off of both sides of each gear. Just the tinyest bit of the corner edge of each gear will let them slip by each other as they turn and not "stick" against each other. The instructions show this in the trouble shooting section. Don't wait for trouble. fix the problem before it starts.
This edge is probably the main culprit in making a "not smooth" unit. Also the double step gear I got, has a flaw in it's teeth on the small gear. A couple of the teeth aren't fully formed. A bad casting from the injection machine. I installed it anyway for now but I will replace it with a new one. File the shaft flat on the small gear end It sticks out a bit and will interfere with the bracket that holds this gear in place. Taper the edge of this big gear and the small idle gear.
Once I did those things, the unit with the caveman motor draws about a tenth of an amp and turns with out a hitch. It is VERY smooth. I used the files and tools in the picture so you can see that no exotic tools are necessary.
I will wait till everyone can do these first steps before I proceed. So please let me know and I'll do the next steps in the assembly.
Once again:
1. File the eges smooth on the frame. File the bottom flat. (big file)
2. Fix the axle slots so that each axle rotates smoothly without binds
3. Fix the edges of the gears so they ride past each other. (3)(file edge angle)
4. Fix the step gear journals so gear turns easily. (very carefully)
Also (almost forgot) file the shaft on the double gear small end flat. It sticks out and is too long to fit in the slots. This is covered in the trouble shooting page as well. Also these slots were too tight for the gear. I had to relieve them just a bit with my file so that the gear would turn in it's mounting freely.
So there were actually four places that would have caused hitches or poor running characteristics that had to be modified. Once done, the unit is fine.
Good luck.....have fun......and let me know when to proceed.
-Stephen Hatch WTA

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