Saturday, March 28, 2009

Diamond rail cutting

Ever since I completed the upper tier bridge structure I've had a "to-do" item of cutting the rails on both sides of the bridge in order to make it removable.

The challenge is that the rail gap must be wide enough to prevent electricity from passing across it, but narrow enough to allow the trains to pass smoothly across the gap. It is especially challenging in N scale to get a small enough gap because our wheels are so tiny. We can't use insulation to pad the bridge gaps, as we do the other rail gaps on the layout, because the bridge rails need to come up easily when the bridge is removed.

I tested a couple of thin-blade manual saws on some left over track and found them wanting: in part because it was hard to keep the saw from wandering off course and damaging the track surface; and in part because the back-and-forth saw motion created a lot of strain on the rest of the track.

Then I tested a rotary tool, commonly called by the name brand "Dremel", and it worked great. The only problem was that the resulting gap was too wide due to the width of the blade.

Today, while I was in Denver for other reasons, I dropped by Caboose Hobbies and found a thin Dremel diamond blade that looked to be perfect. It was $19 (yikes) but as no other solution is apparent, I bought it. After testing on a piece of scrap track I tried it on the track on the right side of the bridge:


The rail gap is so small in this picture that it is almost impossible to see. Look at the upper track, immediately to the right of the wooden bridge side. Below that track you can see the tools used -- the rotary tool with diamond blade, safety glasses (the blade really kicks up a lot of fine dust), and a simple box cutter I used to cut the plastic ties after the rail was cut.

The only problem was that after cutting it turned out that the track itself wasn't sufficently glued down on the right side of the cut. So, I added some glue (the white stuff at the bottom of the track in the photo) and used a pin to hold the track in place until dry.

Once dry I'll gently file the rail edges and test with a locomotive. If this works I will add the diamond blade to the track laying arsenal for special situations like this.

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