Module Progress--ICRR Bridge at Kankakee--NSF56K

[Zox]

...you can scribe and snap the styrene from inside the arches.  (line cut with scroll saw is not critical then, just allows you to snap out each side individually.)

I picked up some 1/8" styrene sheet this afternoon, so I've got the material to work with. However, is it really possible to use the "score and snap" technique on styrene that thick? In the past, I've found 0.040" to be about the greatest thickness at which this technique will work; at 0.060", it starts turning into "score and bend and mangle and twist and eventually the wreckage may part" for me.

Is there some secret to successfully scoring-and-snapping thick styrene that I'm missing?

By the way, I'd like to give a nod here to Lad's Hobby Center in Ellicott City, MD. They don't have much in the way of N-scale in particular, but they have an excellent assortment of scratchbuilding supplies and tools. That's where I grabbed the 1/8" sheet today--they stock a wider variety of styrene than any other hobby shop I've seen.

[wm3798]

Sounds like a job for Dremel Man!

Lee

[Sokramiketes]

Hmm... last time I scored and snapped 1/8" thick styrene it seemed to work OK.  I was using 1/2" strips of 1/8" thick to match with 1/8" cork on some module ends.  It may not break completely square, but should be relatively clean and easily trued up with some sanding or a sharp mill file.  If you have a problem, use a pair of needle nose pliers or something along the score line so that all the pressure is at the line. 

[Zox]

Thanks to all of your suggestions, I'm making progress once again.





Please note that this isn't as done as it looks; I only have the three panels made so far, and they're just sitting roughly in place, not fastened. Even so, to my eyes it's finally starting to resemble the prototype bridge, so I'm pretty stoked right now.

Score-and-snap does indeed work at these thicknesses, as long as you take care to hold both sides solidly. The secret seems to be to bend it 'til it cracks, then snap it back the other direction to finish the break. For me, this produces a cleaner shape than breaking it all the way through from the same direction.

It turns out that I was getting hung up on two problems. First, the scroll saw really isn't very accurate, at least when trying to follow any sort of curved line. Second, even when I got the cut precisely on the line, it still didn't fit right. Apparently my jigsaw-fu on the arches was weaker than I thought.  : So I'm having to scribe each panel individually to fit the arch it's going in. Fortunately, this is easy enough to do with score-and-snap techniques. (It's obvious from the pictures above that I'll still have some gap-filling work to do once the sides are mounted.)

As Skibbe suggested, I'm now using the scroll saw to do relief cuts between the sub-piers, to help the score-and-snap. I'm also doing three or four cuts within the area of arch, cutting from the edge up to the scored line. That way, I'm only trying to break out small pieces at a time, instead of the entire curve of the arch at once.

I'll be taking a bit of a break now, then probably spending a few minutes making a positioning jig for the scribing step. Then it's mass production from there. I'm hoping to have all the panels made by this evening.

[wm3798]

I'm still trying to figure out where you'll work in another flying saucer, but other than that, it's looking unbelievably good!

Lee

[Zox]

I spent a lot of time yesterday making a whole bunch of these:



I'd hoped to finish up all the side panels last night, but it took longer than expected. Theoretically, each of the panels would be identical--even the short panels at the north end would be the same shape as the others, just with one sub-arch cut off at each end.

In reality, each arch varied just enough that I had to fit each panel individually. I managed to wreck a couple of panels before I finally finally settled on a procedure that worked:

• With the bridge on its side, trace the top side of the arch onto the pre-drilled panel.
• Score the panel along the traced line.
  
• Use a scroll saw to make "relief" cuts into the panel. The cuts make it easier to snap along the curved line of the arch, and reduce the chances of deforming the panel from stress.
• Snap off the pieces below the arch.
• Mark the vertical cuts down from the circles, to outline the sub-piers.
• Make those cuts with a rotary tool, since scoring-and-snapping didn't work reliably on the small, odd bits I was trying to remove.
• With rotary tool, file, sandpaper, and knife, "massage" the panel until it fits properly into place.

Finally, though, the deed is done:



Again, the panels are just sitting in place, not attached--but the fact that they will sit neatly in place makes me happy.

Hopefully, this will be the low point of the project--I think I have a pretty good handle on how to proceed from here. But this nearly sunk me, and I thank all of you for the suggestions that helped me get through it.

The next step is to shovel some of the debris off my work surface, so I have someplace to continue working! After that, it'll be some detail work on the panels, followed by making foamcore cores for the sub-piers (to fill side-to-side between the side panels).

[Frank Amato]

Looks fantastic!  Thanks for taking the time to document and post!!!

[Zox]

I haven't gotten any real work done since Sunday--I've been a bit under the weather. But I've been doing some planning.

Here's an outline of the intended module, superimposed over a (roughly) to-scale overhead view of the actual bridge:



No, there's not really a giant ruler spanning the river.

It looks as if, with just a little bit of selective compression, I can fit the dam onto the module after all. I'm almost tempted to make the edge of the module follow the contour of the dam, and have the river spilling over the edge, but I think I've already set myself enough engineering challenges for one module.

[wm3798]

You said it, now you have to do it. ;D
Lee

[Zox]

Tonight's progress doesn't look like much, but it's a couple of hours' work--keeping in mind, of course, that there are actually twelve of these.



I used a Squadron scribing tool to make the joints between the concrete blocks. I don't know whether they'll even be visible when I'm done, but at least I'll know I made the effort.

Next, I made the cornice at the top of the panel, laminating together three 0.30" strips of graduated width to get the stepped effect on the bottom of the cornice. Then, I glued the cornice to the top of the panel and trimmed it to length with a razor saw. Finally, I used a triangular file to make the joint lines in the cornice.

Why didn't I use the scriber for the joint lines on the cornice? Because I found that the scriber really only works if you can run it against a straightedge or other guide--I was entirely unable to use it freehand. Unlike, say, a #11 blade, the scriber won't even follow its own previously-made lines. It will skitter right off like it has a mind of its own. For the long, flat pieces, the scriber worked beautifully. But for the short, raised surface of the cornice, the file was much more controllable.

And even after that explanation, it still doesn't look like much, does it?  :-\ Oh well, any progress is good progress. 

[Zox]

Since this module needs to be able to run trains by the evening of April 13 (setup night for the next GSMTS in Timonium), I'm going to have to let the bridge detailing slide for a bit, while I build the module it's going to sit on. This weekend, I was able to get the frame-and-leg assembly largely completed.



My previous modules have consisted of separate frame and leg assemblies. This time, I decided to see if I could make a folding, single-piece design. The final design seems to be pretty solid without being ridiculously heavy. I don't have a lot of good in-progress pictures, though, because I kept having to redesign things on the fly--parts of it actually fold in exactly the opposite direction of my original concept!

I still need to add "foot" bars and levelers to the bottom of the legs, and replace the clamps with some sort of dowel-and-latch alignment/fastening arrangement. I also need to finish designing and adding the bracing for the forward extension of the module, where part of it will drop down to allow for the water-level change at the dam.

With the main deck and bridge mocked into place, the module so far looks like this:



I haven't cut the below-the-dam part of the deck out yet, but this picture shows how the forward extension of the module is sort of hovering above the frame at the moment.

This picture also shows the first hint of "water" on the module. The plywood is covered with a sheet of fluorescent light panel--the kind used to hide the lights in drop ceilings--in a "cracked ice" pattern. The pattern is pretty much random, and while the "front" side of the panel is far too jagged and geometric for water, the "back" side has a nice rippled surface. I plan to put the "back" side up, and paint the underside a Pennsy-Green-ish shade of black. It's a bit of an experiment, but if it works, it'll be Yet Another Way to model bodies of water, up to 2 by 4 feet, with no seams and no messy liquids.

[Zox]

Between Monday evening and tonight, I was able to get the leg-latching mechanism installed.

I cut four pegs from 3/16" brass rod, and four sleeves from 1/4" brass tubing. The pegs are about an inch long, and the sleeves are about half an inch long.



I inserted the pegs into the tops of the legs, and the sleeves into matching holes in the bottom of the frame, to serve as alignment points. I then added a "pull latch" (what I'd call a trunk latch) to draw the legs and frame together. Here's what the combination looks like:



Unfortunately, one of the latches interfered with the legs folding flat against the bottom of the module. So I had to, um, improvise:



Now it folds just fine.

[Zox]

Back on Monday, I went to a friend's house and borrowed his drill press, so I could install levelers into some bottom spans for the module legs. Tonight, I installed the spans on the legs.

Since the legs are at an angle, I had to make what's called a "bird's mouth" notch in the ends of the legs to receive the spans. I used a template to make sure they were laid out consistently, cut the notches with a jigsaw, and installed the spans.



As is common practice at our club, I use eye-bolts for levelers. It's much easier to stick a screwdriver through the eye and use it to spin the bolt, than it is to try to use a wrench at floor level on a normal bolt. Trust me, your knuckles prefer eye-bolts.

I've found a fastener at Home Depot that's similar in function to a T-nut, but should work much better for holding the levelers. It's called an "insert nut," and here's a Web site describing it:

http://shop.comdir.co.uk/Products.aspx?intGroupID=1001&strProductID=ddfxtxmtsb&strWebTemplate=C

Since it threads into the hole, it won't work its way loose the way a T-nut can. Just make sure you have a 6mm Allen wrench to install the insert nut with (the package says 5mm, but that's incorrect), and don't try to use an "almost-right-size" 3/8-inch. The nuts are made of soft metal, and you will strip them out unless you use the right wrench.

[SAH]

As is common practice at our club, I use eye-bolts for levelers. It's much easier to stick a screwdriver through the eye and use it to spin the bolt, than it is to try to use a wrench at floor level on a normal bolt. Trust me, your knuckles prefer eye-bolts.

I've found a fastener at Home Depot that's similar in function to a T-nut, but should work much better for holding the levelers. It's called an "insert nut," and here's a Web site describing it:

Eye-bolts.  Excellent idea.  Why didn't I think of that?   :  Thanks. 

I've used insert nuts a number of times.  One of those good "problem solver" type of products.

[TrainCat2]

Rob,
Nothing wrong with improvisation. Adapt, conquer and overcome. HooRaaah!


Bob