Wednesday, July 29, 2009

Progress on Campbell's "Glass Block" Building

I've started assembling the curved-front "Glass Block" building for the first time. The first photo shows the scribed 0.030 inch styrene walls. The upper cutout is the inner wall, and the lower one is the outer wall. I did two pieces so I could bend the walls easier, and the main window opening in the inner wall is smaller so that the scribed clear plastic can be glued in flush with the outer wall. The tile crosses at the top of the wall were scribed in lightly; the window and door openings were scribed twice, and the outer wall boundaries were scribed once. I snapped the plastic along the scribe lines.

That sheet actually had to be tossed out; I didn't scale it large enough in Sure Cuts a Lot, so it was about 15% undersize.

This second photo shows the model as it appears tonight. The roof and floor pieces were cut from 0.060 inch styrene by the Cricut; the notches around the edge gave me a place to glue styrene uprights to hold the floor and ceiling apart. The two layers of the building front then were glued to the floor and ceiling. Those nice tile crosses got messed up in this cut somehow, and I'm still not sure what happened. The storefront entrance at the right is multiple layers: the outer wall sheet forms the outer surface, a smaller inner piece (also cut on the Cricut) forms the inner window and door panes, and scale 4x4 styrene framed the doors and windows.

I've also scribed the glass block wall on clear styrene, and I'll glue it in after spray-painting the whole model with a base color. The roof will be finished with black construction paper to simulate tarpaper, hopefully cut on the Cricut to shape.

Saturday, July 25, 2009

Model Making Notebooks

Making models with the Cricut cutter isn't working so well. I'm halfway through another model of the glass block building in Campbell I mentioned last time, but I'm not completely sure that the cutter's helping me build any faster. On top of that, I just cut out another facade for the building that ended up at the wrong scale and too small, so I'm not in a good mood. It also turns out the software I'm using is having some issues with curves.

So let's get away from all those topics that might get me cranky, and talk about planning.

Building a large model railroad requires planning and making decisions long before you actually start building a particular scene. One common story describes how John Allen, an early model builder, laid wires for model house lighting in his basement's concrete ten years before he ever needed those wires. Different modelers have different ways of remembering those details: folders full of wiring diagrams, binders packed with historical photos, large track plans and maps pinned on the walls, etc.

In my own case, I keep a set of notebooks where I record progress and scribble occasional ideas, and I had some track plans describing what I wanted to build, but otherwise I keep most of my plan in my head. Occasionally, that causes a problem when I don't remember why I wired things in some specific way, but I've been doing ok with minimal designs.

For my historical modeling, I was most worried about matching historical scenes, and knowing where to look when I needed to see a picture of a particular area or read about the location. I occasionally scribbled maps in my notebook, but I couldn't always find them easy, and they were never precise. A couple years ago, I bought another notebook just for keeping track of such historical details. I sketched out a map of each town or scene, then went through all the books and photos I've got and marked the vantage point where each photo was taken.

These were great when I was trying to understand an area. Where was the telephone shack at Vasona Junction? I'd look at all my photos, make some conclusions about how they were related, and then draw my map and make sure all my assumptions agreed.

They were also useful after I figured an area out. When I started putting in the finished scenery at Wrights (at the top of Los Gatos Canyon), I remembered I'd seen photos of a car parked next to the station, but couldn't figure out how the car got to the station - it would have had to cross the tracks multiple times, and I didn't remember if there was a road from the station area to the road bridge. I flipped open my notebook, checked out all the photos pointing in the right directions, and noticed that there was an interesting fence protecting passengers on the platform from falling down a slope to a road below. It looked like the road dipped under the railroad tracks as they crossed Los Gatos Creek!

I never actually found photos showing the road dipping under the tracks, but the idea made sense, and I looked pretty much everywhere I could and found no better sources. I ended up tearing out a bunch of my nice scenery so I could route the road under the trestle. The great thing is that the road routing looks reasonable, and is a much more interesting scene than I'd been planning, either without a road or with the road just sitting on the same shelf as the railroad tracks. Again, trying to model a specific prototype gave me a much more interesting model than I would have imagined doing!

Monday, July 20, 2009

Using a CNC Cutter for Model Building, Part 2

(If you're directed here from TechShop's blog watch, you'll probably find my live steam locomotive experience more interesting. I was very happy to use TechShop's metal lathe to turn the wheels I couldn't make with my equipment at home.)

I've had a bit more experience with the Cricut CNC cutter and "Sure Cuts a Lot" scrapbooking software for the Mac. So far, I'm making some interesting things with the Cricut, but I think I'd still have better luck with a laser cutter.

To recap: I've seen some beautiful laser-cut model railroad structure kits, and I wanted to experiment with both designing structures flat, and hoped on speeding up my model building a little The Cricut scrapbooking cutter is a small standalone computer-controlled die cutter that can cut sheets of thin cardboard or occasional heavier materials. The Sure Cuts A Lot program is a third-party drawing tool for the Mac or PC that controls the Cricut cutter via USB.

My first experiences (in the last blog entry) showed a bunch of problems. I could draw cutting lines in a drawing program and import them into Sure Cuts A Lot, but found that it would tend to cut shapes with a continuous cut and round corners when doing so. It also wouldn't always cut pieces all the way through, so small pieces (like window openings) would need to be trimmed out by hand. None of this would be a problem if I was doing rounded shapes like letters and clip-art for scrapbooking, but won't work for small model railroad structures where I want sharp corners and need pieces fully cut out to reduce labor.

Luckily, SCAL imports vector drawings in the SVG format - an open, XML-based format, and one that's pretty easy to edit either by hand or with a simple computer program. I ended up writing a quick-and-dirty filter to take my cutting drawings, and massage them a bit so they work better on the Cricut:

* All multi-segment lines get broken into individual straight lines to force SCAL and the Cricut to only cut lines and not try to curve connecting lines.

* All lines get extended about .01 inches to try to cut all the way through at corners.
* Any lines colored red get cut twice, and get cut in opposite directions. I saw the knife didn't always bite through until it had been moving for a bit, so cutting the same line in different directions ensures the whole line length is cut through.

* Any lines colored green are considered scribing or embossing lines, and get placed at the front of the list to draw. After all the green lines are cut, a bunch of tiny lines in one corner of the drawing are added to get the cutting head off the drawing. By doing this, I can set the cutting blade (manually) at its minimum setting when I start, let it scribe all the lines that shouldn't cut through, then change the cutting blade to a deeper setting while the print head's doing the small lines.

If you try this at home, also be aware that SCAL silently fails to cut if any part of your drawing extends outside the cutting area. Make sure to keep your drawing inside the dotted boundary lines. Also make sure to measure your drawing at its largest point in your drawing program, then use SCAL's detail mode to enlarge the vector art to that size so you're cutting at exactly the size you want.

The different behavior for red and green lines is an idea taken straight from the laser cutters which already use different color to use different strengths or speeds of cutting.

By running my cutting drawing through my SVG processing program, I'm getting better results. I've actually used the cutter to scribe individual board lines in cardboard, and find the double-cuts in window openings ensures the pieces get cut through. The picture shows a building front in really thin cardboard. The board lines were scribed by the cutter, and the window openings pretty much fell right out.

The wood-frame office for the Hyde Cannery isn't the best demonstration for the cutter; it's all straight lines and minimal windows, and I know I could cut out all the pieces in an hour with a straightedge and Xacto knife.

A better sample project is this curved-front building next to the railroad tracks in Campbell. This building is visible in photos from the 1930's; the glass-block window in the front and inset tile crosses at the roof line are obvious details that are made for the cutter, either on clear plastic (for the glass block window) or scribed onto the wall itself (for the cross detail.)

I tried cutting pieces of this building out on the Cricut; the result isn't presentable yet, but it showed that the Cricut could actually help me with hobby projects. First, I made my model out of styrene, not cardboard - 0.020 inch for the walls (two thicknesses laminated together for a 0.040 thick wall) and 0.060 inch for a floor and curved form for the wall. I didn't expect the knife to cut through the plastic; I just made sure it scribed the plastic deeply, then I snapped the plastic apart along the cut lines. The curved floor piece (with a 2" diameter curve) required a pair of needlenose pliers to get the plastic to break, but generally the scribe lines from the Cricut were enough to snap the plastic apart. I also learned that the waste material I'd seen between pieces on laser-cut work wasn't needed for styrene; keeping the parts adjacent and snapping them apart saves a lot of work.

The problems with the curved-front building were mostly because of the thin material I used for the walls. The curved base cut nicely, but the 0.020 styrene for the wall didn't stay parallel when only glued to a curve at the bottom of the piece. (It didn't help that the 0.020 plastic I was using was already scribed to resemble individual boards, and the plastic cracked along one of those scribe lines.) For a second try, I'm going to need to cut a floor and ceiling piece (with supports between holding the two apart), then glue the walls to that armature so everything stays square. I'll also need to try to cut some small windows now that I'm getting cleaner cuts out of the Cricut.

So, that's my second week of experience with the Cricut. It's not a laser cutter, but it can do some interesting things. For my little one-off projects, it's not saving me a huge amount of time, but if I was making a lot of identical buildings, it could come in handy.

Sunday, July 12, 2009

Using a Cricut cutter for Model Railroading

[Hint: I got better results after this post. Check later blog entries for my experiences with the Cricut.]

Ok, here's my full first-day impressions of using the Cricut. I posted this to the ModelersCad mailing list at Yahoo as well.

I'd seen some questions on this mailing list about using one of the scrapbooking / vinyl cutting die cutter machines for model building. Here's my experiences after one day of experimentation. (See the previous post for pictures of sample cuts.)

Short answer: the machines are interesting, but they're not a substitute for a laser cutter. My cutter (like, I suspect, other die cutters) works best when cutting curved, closed shapes, and tends to put 0.050 radius curves on right angle intersections. Using non-meeting line segments didn't really help; the software with my machine sometimes ignored unconnected lines (that were probably below some size threshold).

If you're doing mostly curved shapes (such as cutting pieces for a model airplane's wing cross members) you could probably do some interesting work in thin wood. If you want to cut lots of right angles, you'll be less happy.

My cheap machine did really well with my modeling materials. 140 pound Bristol board (0.020 inches thick) cut cleanly. It could cut into, but not through heavy (0.050 inch) matboard. Cuts in paper were usually clean, though I did see minor tearing when cut lines intersected. The machine only scribed 0.010 and 0.020 inch styrene, but it was really easy to snap on the scribe lines to get a clean result. I suspect it would work really well scribing 1/16" styrene sheet.

I also tried it on 1/16" basswood with the "thick material" blade. The Cricut didn't cut completely through with a single cut, but it did score the wood pretty deeply so that cutting the pieces fully out would have been easy. The basswood moved around a lot even though it was taped down, so accuracy was a problem.

The other big problem is that while cutting curved letters by hand might be tedious, my models with lots of straight lines are much less work to do by hand. The die cutter helps if I'm doing multiple duplicate pieces, but tweaking cut lines and artwork when doing mock-ups is almost as much work as cutting a new model out of paper by hand.

Long answer:

I'm a model railroader, and I've been interested in doing my own laser-cut buildings in HO (1/87 scale). Unfortunately, I'm too cheap to buy my own, and too lazy to drive 20 miles to TechShop in Menlo Park to use theirs. I was curious if a vinyl cutter like the Klic-n-Kut would give me usable results.

I found a cheap way to start; the craft stores (Michael's, Joann's) often have the Cricut die cutters on sale. I got a 6" x 12" die cutter for $99 on sale yesterday. To use the machine, you place or tape your paper or cardstock on a sticky plastic cutting mat, feed it into the printer, then tell the machine the letters or shapes you want it to cut. The cutting blade is a tiny pointed blade on the end of a 2mm rod; a larger blade holder sets the blade to an appropriate depth that will cut the media but not the cutting pad. The holder stays stationary, but the blade can turn in the holder to handle changes of cutting direction. This turning (and a slight amount of play in the blade holder) means that cutting continuous shapes always results in curves at corners. This is great for lettering (which the machines are intended for), but less good for miniatures having lots of right angles. By contrast, laser cutters are great at square corners.

Cricut cutters only do fixed fonts and shapes, and require you to buy their cartridges ($45) to get new fonts. To use the machines, you type in the letters you want into an attached keypad, and the machine does the cutting.

The Cricuts do have a USB port, but their software won't let you cut arbitrary shapes. Luckily, a third party ( sells a program called "Sure Cuts a Lot" (SCAL) that lets you import SVG vector art from a drawing program and cut it on the machine. I had some problems with the SCAL software; it wouldn't connect to the Cricut when I used it with a computer running Mac OS X 10.5, but ran decently on Mac OS X 10.4.(Bzzt. I'd already installed a USB->Serial driver in the past, and it would grab the Crikut device when the OS booted. Deleting /System/Library/Extensions/FTDIUSBSerialDriver.kext got rid of the problem, though now I have to worry why the other driver was installed.) It also imports the art at a different size than my original drawing; I added a 1x1 inch square on my art so I could scale the drawing representing the cuts to the rough size I wanted.

My first project (after a few test letters with the stock Cricut) was a smaller building model. I'm trying to mock up a potential design, so I've been cutting cardboard models out of Bristol board, assembling them, and putting the models on the layout to check size and composition of the scene. Recently, I've tried to make the buildings more real, so I've been drawing the wall shapes and details in a vector drawing program, then printing out these drawings and cutting the pieces free.

Making this model requires some larger cuts for the walls and window openings, and finer cuts for pieces of the windows.

The walls come out ok. Sometimes, the rounded corners are pretty short; on other cases, the blade seems to have trouble finishing the curve and ends up with a spline-like curve that only ends up going straight after a tenth of an inch or so. Interior rounded corners are a little annoying, but can be cleaned up by hand (especially in styrene). Rounded corners on the outside edges are more troublesome; for model buildings, I might be able to cover these with trim.

To really challenge the cutter, I tried cutting the individual window panes out as a laser-cutter would, even though I've not been cutting these by hand. I really hoped the machine could do all the tedious cuts to do individual window frames and panes in a piece whose total size is an inch by 1/2 inch. The laser cutters do beautiful jobs with these sorts of pieces, and it's possible to build up some beautiful windows by layering together multiple pieces. Unfortunately, the rounded edges are a problem.

I also tried cutting the geared calling card available at Thingiverse. (I converted the PDF version of the drawings to line art in the Mac drawing program Intaglio, then exported the line art as an SVG file that could be read in by SCAL. Note all the curved surfaces are set up as line segments, so replacing them with arcs makes the cutting go much faster.) SCAL managed to cut the gears with a lot of up-and-down cutting action, but didn't actually cut through the cardboard fully. It made quick work of the non-gear parts, though. I'll need to try again another time.

So far, I'm not convinced that I can let the computer do all the cutting for my models; the die cutters (at least from what I've seen with the Cricut) just aren't intended for the right angle cuts that all my structure models require. Some of this might be the machine, but I could imagine that some of the problems are with the software that assumes you're cutting out rounded, connected letters. I could imagine tricks the software could do to do better on work like this. It could always do right angles as separate cuts, and do all cuts in the same direction at the same time to keep the blade pointed in the same way. The software could get the blade pointing in the correct direction by starting on a bit of waste material. Nearby cuts could be done at the same time to avoid losing accuracy over several cuts. It's too bad there's no open-source drivers for the Cricut available, or I'd be playing with driving the cutter in different ways to try to get better right angles. Other makers (such as Klic-n-Kut) might do a better job with different kinds of cutting jobs, for all I know.

My Computer Needs to Get Into the Model Railroad Hobby

After last week's work on printing paper models of the Hyde Cannery, I got curious enough about computer-controlled cutters to buy a Cricut Personal Electronic Cutter at Michael's for $99 on sale. This is a computer-controlled vinyl cutter, and can handle material up to 6x12 inches. It's intended only for cutting lettering, but CraftEdges "Sure Cuts a Lot" software lets you send arbitrary line art to the cutter.

I'll get into more detail later, but here's some photos of sample cuts:

Piece from the Cricut on the left, manually cut piece on the right.

Building front cut on the Cricut, made from 140 pound Bristol board (cardboard). The horizontal slices across the work are done by the trial version of Sure Likes to Cut; these wouldn't appear once I've bought the software. Note that sharp corners on the drawing are cut as small (0.020 inch radius) curves because of the way the blade works. I might be able to hide those behind trim, but the fact that the cutter can't do right angles is frustrating.

Sample lettering to show what the cutter does best. Top piece shows cuts in 0.020 inch thick styrene sheet. The cutter only scribes the styrene, but it's easy to snap the plastic cleanly on the scribe lines. The middle piece is 0.010 clear styrene, again not cut through but easy to snap. Bottom piece is 140 pound bristol board, cut very cleanly.

Windows and doors, comparing Cricut and laser-cut pieces. The upper right hand piece is a bit of laser-cut cardboard from an American Model Builder's station kit to show ideal results. The bottom line shows a freight house door (about 1" square); note the rounded edges on the door trim in the bottom left, and the rounded panel edges on the panel overlay piece. The piece just above shows how I tried to get cleaner corners by making sure the lines weren't continuous. The two upper rows show a window cut with continuous lines (with curves) and cut as individual unconnected line segments (neater, but a lot of work to clean up.)

Lettering cut out of 1/16" basswood sheet. The cuts don't go all the way through the wood, but the cut lines would easily guide an Xacto knife cutting the rest of the way through the wood. My biggest problem with the wood was that it tended to slip, even with the piece taped firmly to the backing sheet that fed it through the cutter.

Tuesday, July 7, 2009

Glenwood, nearly finished.

Here's the latest shot of the end of the Glenwood siding, with ballast and barbed wire installed. The static grass looks really nice!

Monday, July 6, 2009

All Roads Lead Back to Campbell

Now that the Glenwood scene's in good shape (with barbed wire on *both* sides of the field), it's time for me to choose my next project. Campbell's Hyde Cannery has been one of my problem areas, and so it seemed time to try again.

The Hyde Cannery, as seen from photos from the first half of the century, is a large, rambling set of buildings stretching all over the place. It's a fun mix. There's some small, wooden-frame buildings from the turn of the century. There's a huge brick warehouse from the 1870's. Finally, there's the modern cannery production line building, with concrete walls and wooden posts holding up a sawtooth roof with huge skylights. Best of all, Mr. Hyde wasn't shy, so his name appeared in huge letters on each part of the complex.

All those buildings are still there, sitting next to the railroad tracks. Some of the buildings have been turned into office space, others into restaurants and bars that were probably cool in the 1970's, but have lost their momentum to some of the newer places on the refurbished main street in Campbell.

The Hyde Cannery space on my layout is awkward; it's probably 24 inches long and 6 inches wide, stuck up against a backdrop and below a low upper deck. Still, it's one of the larger industries on the layout, and accounts for a lot of boxcars for the Campbell and Los Gatos-bound freights. I've tried mocking up potential building a couple times without a clear idea of what the area should look like. Most of my mockups are made from either matboard or heavy bristol board; I'll guess at dimensions, lay out the rough lines of the building in pencil, then cut the cardboard pieces out and glue them together. With a physical mock-up on the layout, it's easier to figure out if the building will really fit and if the scene looks correct.

The last couple mock-ups didn't go well. The large warehouse is an obvious focal point, but can't be so large that it crowds out all the other buildings. I knew I wanted the sawtooth cannery in the background, but wasn't sure how much room I'd have for it.

I'd also seen this picture of the office area next to the tracks. (This building is just behind the truck on the first photo.) It's a great building - wooden siding, different scale than the others, and more of a sense of being active - doors to the office, loading platform for farmers dropping off produce, signs, steps, etc. When I tried to build that building, I had poor luck. I'd get the dimensions wrong and it wouldn't fit, or I'd get the scale wrong. The half-done models get left on the layout til the next time I try to figure out the scene.

This time, I'd been distracted by some of the cool new tools that exist for model building: laser cutters and 3d printers. I've built a few laser-cut kits in the last couple years, and I've been amazed at how fast I could assemble a model from the neatly cut pieces, and how easy it can be to cut complex shapes as well as window and door openings. Laser cutters are out of my price range ($7,000 for entry level models). Looking at an instruction manual for one of them, I wasn't sure I'd want one even if they were cheaper. "Danger: improper use of this device can cause a fire which can destroy not only the machine, but the building containing it." Gulp. TechShop in Menlo Park has a laser cutter that you can rent time on, but I've never gotten around to taking their laser cutting course.

I'd also just heard about Makerbot, a do-it-yourself kit for a 3d printer that lets you draw 3d models on your computer, then let the computer fabricate the actual object by squirting out bits of styrene. It's a cool device, and I'm sure it would be useful for model building (though perhaps too coarse for the actual models.) However, I started thinking about whether there were other tools with Makerbot's computer-controlled table that might be used for physically cutting cardboard and matboard for model buildings.

I ended up finding out about a whole bunch of computer-controlled card and paper cutters (also known as "die cutters"). These are pretty much the same as the industrial vinyl cutters used for making signs, except they're smaller and intended for home use. They're really popular for the scrapbooking crowd; some brands are available at the chain crafts stores. These tools, like the laser cutters, basically work like large printers. You draw your shapes using a vector drawing program, using different colors for the different cutting intensities or depth. When you print the document, the computer runs the cutter along the lines you drew. Klik-n-Kut is one brand of the more beefy machines; they start at $600, but look interesting.

Wouldn't it be cool if I had a machine that would let me design models of buildings on the computer, then print and modify the models as often as I want? Sadly, there's some problems with this. I'm still not sure what weight of cardboard these cutters could handle. Cutting matboard and thin wood could be best; I could be designing and building my own kits like the old Suydam ones I grew up with. I don't know how sharp or ragged the cut lines are, or how well it could cut out square corners in window openings. I don't even know if I have enough models backed up to need the speedup. Sounds fun, but lots of research to do.

The die cutters got me thinking about the difficulty of designing my buildings flat in a drawing program, so I spent part of Sunday trying it out. I got out my drawing program (Intaglio for the Mac), drew the walls, colored them in, and marked the cut lines darker and thicker as I'd need to do with one of the laser cutters. When I was done, I printed the building out on heavy bristol board cut down to fit through the printer. Cutting the pieces apart was much faster than my hand-drawn kits, and my few mistakes and design flaws only required re-printing the offending parts.

Here's some pictures of the Hyde cannery office that resulted. If you'd like to build one of your own,
here's the original drawing for you to cut apart yourself! Unfortunately, the building didn't fit, and the extra color and board detail I added showed me the building is too low and needs to be raised up a couple feet. All I'll have to do is enlarge the walls on the drawing, then print out new copies and assemble another building. If I need to adjust the building more than once or twice, doing the drawing on the computer might actually be an advantage... and I could use the same drawings if I decided to try that laser at TechShop.

There's also programs for the PC that will print paper versions of buildings like these. I haven't tried any, but I suspect they're a bit easier than working in a generic drawing program.