The following article, written and illustrated by Stewart McSporran, describes his experience of building a MODRATEC Lever Frame for his 'Loch Awe' model railway. The article is reproduced here by kind permission of the The 2mm Scale Association who published it in 'The 2mm Magazine'.

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Building the MODRATEC Lever Frame - Stewart McSporran

At this point you are instructed to fit the framework to its baseboard. Do not be tempted to skip this step thinking you can fit it after it is built. The instructions warn you that the slightest change in the dimensions of the frame could seize the works. After building one I can believe this.

I recommend painting the levers prior to assembling them in the frame. The instructions say to paint them after fitting, but this is just not really feasible. Figure 9 shows the levers in place. The masking tape is there to stop the paint being chipped when the loose lever falls and strikes the tappet guide in front of it. This will happen!

Figure 9: Levers Fitted. Note Protective Masking Tape

As mentioned earlier, the levers are fitted with a sprung ball bearing. The purpose of this is to push against the lever guide and hold the lever in place. Fitting these ball bearings is the trickiest part of the exercise; it involves using one of the drilling guides to hold in the ball while the lever guide is fitted. The ball has to be pushed home, against the spring, into the hole prior to sliding the drilling guide over it. I found that using the blunt end of a drill was most successful in depressing the ball into the blind hole. Figure 10 shows a lever, ball and template just prior to pushing the ball home. The lever guides are the horizontal tubes in the lower part of the picture. Warning: only one spare ball is provided for each set of six levers and when you make a mistake they shoot off like bullets. Do not attempt this part of the assembly unless you are in a very relaxed frame of mind, and I don't mean relaxed as in two bottles of Old Peculiar either!

Figure 10: Fitting the Securing Ball and Spring to a Lever [Click for full size image]

Assembly of the tappets follows next. At this stage you are simply making sure that they run smoothly in their guides. There will be a fair bit of twisting and bending here before it all hangs together. Figure 11 shows the lower tappets in place.

Figure 11: Testing the Fit of the Lower Tappets

Once the tappets are moving smoothly the locking bars are prepared. This involves drilling holes in them for the pins and marking the position of each vee cut out in the tappets. The lower tappets are marked by pushing a pen through the holes in the bars and drawing onto the tappets. For the upper tappets you carefully mark the tappet adjacent to the appropriate hole. Each vee is filed out and a gentle curve put in to push the locking pins out of the way.

Some of the full length locking bars are then cut up into smaller sub bars. The pins are prepared from brass bar and then fitted into the bars using an interference fit. I found this fit a little loose and used Locktite^® to ensure the pins stayed put. Figure 12 shows part of one bar after the pins have been filed to size.

Figure 12: Locking Pins in a Locking Bar

Now comes the time to fully assemble the locking bars and tappets and to check everything works smoothly. Figure 13 shows the locking bars and one of the upper tappets fitted. Figure 14 shows the fully assembled bars and tappets.

Figure 13: Locking Bars in Place and One Upper Tappet [Click for full size image]

It is best to fit the locking cover plate before testing the frame, otherwise the upper tappets may jump out of their guide slots.

Figure 14: All Upper Tappets In Place

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