Static grass applicator from a bug zapper

Static grass is a method of applying little strands of nylon to a board, to give the appearance of a field or grassy area. The nylon strands are given a static charge before applying, to encourage them to stand up on end, rather than lay flat in a straggly, messy way.

There are plenty of static grass applicators on the 'net and, priced at about £20-£25, they're not exactly going to break the bank. But there's something a bit "suspect" about them.

The idea is that you fill the tea strainer with static grass, connect the other, exposed wire to the board you're applying grass to (usually by driving a small nail or pin into a patch of wet PVA glue) switch on and give it a shake.

The high-voltage potential difference between the (metal) tea strainer and the wet area of (negatively charged) glue creates a static effect, causing the nylon strands (static grass) to stand on end.

It's a relatively simple job, and a relatively simple tool. But there's something about that applicator that looks a bit familiar....

In fact, many people have indeed made their own static grass applicators from a metal sieve and a bug zapper. So we hit the local Aldi and picked up both for less than a fiver!

Opening up the zapper reveals a relatively simple  circuit, containing a transformer, transistor and a few capacitors. One side of the output coils of the transformer are connected to the outer mesh of the bat and the other side connected to an inner mesh. The idea  is that a bug getting caught between the two meshes is instantly "zapped".

Whenever we see a power source, with capacitors and a transistor, already we're thinking "oscillator output". The transformer is a twin coil affair, with a massive step-up effect. The remaining capacitors create a "charge pump" effect, to allow a large voltage to be created from a relatively low voltage source (2 x AA batteries).

In fact, this particular bug zapper creates a pulse of about 800V. From experience, we quickly learned that you don't really want to go touching the two output wires while the device is being powered!

Looking at some of the static grass applicators online, it's obvious that some of them are little more than a "hacked-up" bug zapper - with the zapper meshes removed and a metal sieve connected to one side of the transformer, leaving the other side free to connect to a pin or small nail. It took us less than five minutes to get a similar thing soldered up and re-assembled; giving us a static grass applicator for less than five pounds and a total of about ten minutes work.

So how does it perform?
Here are the results.


It's not bad. But some of the grass looks like it's "wilted over" a little bit. Since the circuit is simply a step-up transformer and a few caps, and given we're pulsing the output, rather that leaving on continuously, we thought we'd push it a little bit and see if it could cope with a higher input voltage (the idea being that we'd get a higher output voltage, and thus increase the static effect). Instead of two AA batteries, giving us 3V, we stuck a PP3, 9V battery on the supply.

The results:

Interactive sci-fi terrain

The long Easter weekend gave us plenty of time not just to mull over a few wacky ideas, but also afforded a few hours to actually put them into practice.

One of the things we looked at was creating some laser cut sci-fi terrain for our larger, 35mm grids.

This meant simply drawing up some vector shapes in Inkscrape and preparing them for laser cutting. It started out pretty simple - some double-length walls, about 68mm long, some inter-connecting pillars (for joining the wall sections either in a straight line, at 90 degrees, or combinations thereof) and spacing them all out onscreen so that, when clipped together, the fit perfectly in our 35mm grid system.

Instead of the relatively chunky 3mm, we designed these to be cut from 2mm MDF. The wall sections are pretty small and fiddly anyway, and we didn't want to make them more difficult to handle, by making them from extra-chunky stock.

Then something went a bit weird. Without even breaking out our favoured ExpressPCB, pads and circuits just appeared on the drawing....

What if, instead of being cut from 2mm MDF, the whole thing was cut from 2mm copper-clad PCB board? That would mean we could put some surface-mount LEDs on them.

And what if we could control individual LEDs? A simple shift register should suffice, allowing multiple walls to be daisy-chained together, all individually controllable from a single source. What if each panel had a few different coloured LEDs placed on them, so that, at the touch of a button, you could - for example - make an entire board area turn red to indicate "red alert"? Or door panels with red and green LEDs to indicate whether the door was locked or open?

Suddenly there was a world of possibility with this "interactive sci-fi wall panel" idea. In fact, since our board game is dependent on some hardware to act as a bridge between a smart device (phone/tablet/PC) and uses serial messages to pass data around, we could re-use the same technology and simply build a stand-alone app, to allow the user to switch lights on and off around their playing surface....

There was nothing for it: we had to crack open the Ferric Chloride!

One thing we hadn't considered (until it came to actually trying out a single wall panel) was that using 74HC595 shift registers meant that every panel needed a five-way connector (power, ground, clock, data, latch lines).

This was a rather chunky connector, and wouldn't work at all well with lots of tiny little, fiddly interlocking pieces. We needed a way of getting that pin-count down.

The Roman Black website has some great ideas for doing just this kind of thing. His site gives a great, detailed explanation about how you can use capacitors and resistors to create an RC circuit, to delay triggering the data/latch pins from a single clock source.

In theory this all sounds great. There's no reason why we couldn't mount a few discrete passive components on each board, and dress them up to look like sci-fi panels on the walls. In practice, things weren't quite so straight-forward.

Here we've connected two shift registers, one cascading into the other (yes, there are three on the breadboard but only two are actually connected together). While the PIC correctly activates the appropriate output pins on the first shift register, the cascade effect fails to send the data on to the second (and, if there were more than two, any subsequent) registers in the chain.

So a single-wire approach is achievable - but only at the cost of losing the cascade ability (and without being able to cascade data from one wall section to another, it'll be really difficult getting any except the first panel to light up!) Maybe we could tie the latch and clock pins together, and reduce our connection count to four pins, instead of five?

By tying the clock and latch pins together (it even suggests you can do this, in the datasheet), we need to provide on extra clock-pulse at the end of sending our data (since the latch is always one clock pulse behind the data). This worked fairly well, but we then discovered the downside of the shift-register approach:

Each shift register is able to source only about 16mA-20mA across all its outputs; roughly the same as the total output of a single PIC i/o pin. That's no problem if we're only lighting one LED at a time. But if we want to light up multiple LEDs, each one gets progressively dimmer, as more are lit at the same time. This could prove to be a real problem, as we've no idea which lights (or combination of lights) the user is likely to want to illuminate at any one time.

What we really need is some kind of constant current, multi-channel, LED driver....
Sometimes you need to invest a bit of time to discover what isn't going to work, in order to work out what is the best way to proceed with some projects.

This weekend we've done just that. We know that not only is a single-wire shift-register unsuitable for, let's be honest, a bit of a crazy whim idea. But investing a bit of time into trying alternatives demonstrated that shift registers aren't exactly the best idea for what we want anyway.

So we've a few TLC5916 LED drivers on order from Farnell.
Etching some PCBs should be straight-forward enough - though quite how we'll cut them into those strange shapes remains to be seen.....

Making 28mm terrain from greenstuff and home made moulds

Recently a few of the nerds were quite taken by a Kickstarter project called Basius. It's a set of resin moulds from which you can create interesting-looking "base toppers" for 28mm miniatures. A few of us even pledged for one, to see what they were like.

Having spent the last few days in front of a computer screen (whether for real work, or debugging the latest nerd project) it was nice idea to get away from the computer for a few hours and make something a bit more "arts and crafts-y". There's quite a bit going on, other than just nerding about, at Nerd Towers at the minute, so a bit of escapism is always welcome!

Using the Basius project as inspiration (and being impatient because the campaign is still running and the products aren't likely to be shipped for a few months yet) we set about creating our own simple moulds, from some "junk masters".

The first thing we did was stick some "industrial" looking bits of plastic to a base. These are easily picked up at local hobby shops, by rummaging around through junk boxes, or raiding charity shops for old, broken toys. As we're going for an industrial look, anything with plates and rivets was fair game - along with some herring-bone patterned squares (which looks like the metal diamond floor covering on gantries and the like) and various doors and hatches. We even dismantled a cheap metal sieve (not shown) to get a nice, textured effect for a floor.

Next, we used some Instant Mould. This is a low-melting point thermo-plastic and has a variety of different names, such as Polymorph, PolyForm, Shapelock, and the super-catchy sounding Polycaprolactone. Basically you bung this into a cup/pan of boiling water for a few minutes, and it goes all soft and sqidgy. Take it out, and you have maybe a minute or two, to form it over your "master" shapes, to create a negative mould.

Here we were probably a little stingy with the Polymorph - a thicker layer over a smaller area would have created a much more rigid/easy-to-use mould in the long run.

Douse the plastic in cold water to help it set more quickly.
This stuff is amazing. Hardly anything sticks to it - not even superglue!
As a result, it pops off the master really easily.

Although the top surface is uneven and it doesn't look particularly brilliant from this side, on the underside - where the business end of things is - it has captured even the tiniest of details perfectly:

So all that's left is to try out our new moulds.
Using some two-part epoxy putty (often called kneadatite, or simply green-stuff) we made up some little balls of green goop and pressed it onto a couple of 28mm bases

This stuff is really sticky when fresh, and is hard to weed out of little nooks and crannies - which also makes it great for picking up detail from small moulds. So we simply wet the top side of the green stuff (the side that was about to come into contact with the mould) and then smooshed it into the negative (is smooshed even a word?)

For a first attempt, these didn't come out too bad.
The one on the right is a bit warped, as we bent the mould while we smooshed the green stuff into a relatively deep pocket on it. Using a bit more Polymorph would have made the moulds a bit thicker, and given extra support around the areas where the walls of the mould get a bit thin (and are liable to bending under any amount of pressure). But, for a first go, it didn't look too bad at all!

We compared our efforts to some resin-case bases to see how they lined up. After spraying the green and resin bases a uniform black it was tricky to tell them apart.

A heavy drybrush with gun-metal, followed by a lighter coat of shining silver acrylic paints, and the bases are ready for the miniatures to be mounted onto them.

If you look closely you can tell which are the resin cast bases, and which are the home-made ones. But you have to look twice to tell them apart. And for that reason, we're going to call these a success.

From the top-most base, running left-to-right, top-to-bottom, we have: homemade, resin, homemade. On the next line, resin, homemade, homemade and the base at the bottom of the photo is a professionally produced, resin-cast one.

A few hours work, some left over junk (that would otherwise have gone to landfill) and a bit of putty, and we've got some really nice bases for our playing pieces.

And the best part?
The polymorph is completely reusable. Once we've finished casting these industrial style bases for our space-soldiers and starship inhabitants, the plastic can be dropped into hot water, and used to create a whole new set of base moulds, in a completely different genre. That's the best £8 we've spent this month!

More laser cutting 28mm terrain, wild west buildings

We've decided to have a bit of a push with our wild west terrain (if only so we can get it done and move onto the next massive laser-cutting project, a football stadium, but more on that later!)

We've already got a few "standard" building shapes, which can be mixed-and-matched to create a variety of different buildings. But if we simply repeated our few building designs over and over, we'd end up with a pretty boring looking wild west town! So we've been getting a little bit more adventurous with our designs.

All of our building designs start out like this - a reference photo and lots of overlaid, overlapping parts, drawn to try to give some idea about how they all fit together. Then we produce a "cleaned up" version of the drawing, and send it to the laser cutter:

Given we've had such a miserable "last-bank-holiday-before-Xmas" and the summer seems to have deserted us even before August is out (thanks, Hurricane Bertha) we've spent a bit of time stuck indoors. But it's not all been watching New Tricks and Great British Bake Off. No, we've been busy designing loads of "interesting" looking buildings for our wild west town.

And last night, managed to spend a good few hours at the laser cutter, cranking out kits for our miniature buildings. As yet they're untested, so it's likely that we'll have to amend the final designs. But so far, things aren't looking too bad....

(what's with the half-uploaded files, Google? There are more than just a couple of photos turned out like this in recent weeks)

As well as our standard, 3-inch-wide buildings (tall and short) we found a photo of a tobacconist, squeezed between two larger buildings, so set about creating a super-small building that we could use as a trading post, a telegraph office, tabacconist and so on, by simply changing the top part used to display the signage.

To add a bit of character, we even created a windmill and a water tower for our miniature town.

We've got a jail building on the maker-table too - made entirely from lollipop sticks, to simulate a log cabin (it's hard to create an interesting looking textured surface out of flat, laser-cut planes) so we squeezed some jail bars onto the relatively small windmill section

After cutting out the pieces, we thought that the windmill blades looked far too "chunky" for the model (in truth, the uprights don't look quite right carved out of 3mm mdf, when the design was built for 2mm stock, but it'll do, as a test piece). So we quickly transferred part of the design onto some 0.8mm birch

As we'd run out of "laser-friendly" mdf, we started using some cheap-n-cheerful 3mm mdf from Wickes. Unlike the laser-friendly stuff we got from an online supplier - which has an almost fluffy, untreated surface - the Wickes mdf was really nasty to work with. Both sides are really smooth and shiny, and left a sticky yellow film over everthing - the surface of wood being cut, the cutting bed, the insides of the laser cutter - it got everywhere!

Just before finishing up for the evening, we quickly hacked out a toilet/dunny from a piece of scrap!

With about five "structures" (a few of buildings, a windmill, a water tower and a dunny) bagged up (to keep the different parts separate) we set about cleaning up. The sticky yellow film took quite some removing on its own, so we ended up resorting to some Mr Muscle.

Hopefully this hasn't leaked under the bed. And if it has, let's hope it doesn't do anything drastic like make the belt perish!

After about two and a half hours of lasering almost non-stop, it was time to give the laser cutter a rest and bring our home-made Airfix-a-like model kits home. As each one takes anywhere between 30 minutes and an hour to assemble (including glue drying time) there's probably a full day's work in putting them together. So, softly, softly, over the next few nights, we might actually make some progress....

More 28mm wild west terrain buildings

Inspired by examples of laser-cut buildings, and given the (relatively) quick results we've had from cutting our own wild west themed buildings, and decorating with stickers (rather than modelling and painting them from scratch) we're going all out to produce a "town" of about eight different styled properties.

Which means, given that it's the bank holiday, more laser-cut goodness!

Our buildings are quite small, compared to some of the "proper" manufacturers out there (like 4Ground or Sarissa) but there's a reason for that: since we're building boards which are 6" x 8" and each playing square is one inch, we're trying to keep our buildings to about three inches across, and only sometimes going as large as four inches across.

This means that a board placed "long-ways" could have two buildings along it's long edge, separated by a single or a double square. Or we could place a 4" wide building in the middle of the short edge, leaving one square either side of the building (or two squares between buildings, if two playing surfaces are placed against each other, and a 4" wide building placed in the centre of the short-edge of each).

While not exactly huge, our buildings fit quite nicely with the 28mm scale that most miniatures manufacturers produce. We're not looking to make a massive playing surface - we just want a few buildings to make an otherwise plain-looking playing surface look a bit like a town from the wild west.

With all this in mind, and using various online sources for inspiration, we've managed to design, cut and assemble another western-style building in less than a day. This time, it's a hotel-like building, with a balcony around the second floor.

As ever, all the drawing and layout was done in Inkscape:

Our trusty LS3020 made short work of buzzing through some 3mm mdf (ideally we'd like to make the buildings from 2mm mdf, but we have a stock of 3mm so that's what we're using!)

We've decided to go a stage further this time - although we've no plans to use our buildings for anything other than a showcase game for our generic electronic board gaming system, a few people have already asked about having some of these buildings made up for their own gaming. And if others are likely to want to use these plans, then it seemed sensible to add in some extra little features:

Like a detachable roof, and removable interior floor for the two-storey buildings. It's a bit late for our early single-storey "stores" building (since the roof has been glued on) but we can always retro-fit a removable roof to our "hotel" building (and even add in some supports for a removable second storey floor). For this building, we've planned for them from the start.

When assembled, the lip going around the inside walls will allow us to drop a 3" square floor in through the roof - effectively creating two accessible, interior rooms where players can place their miniatures to indicate that a player is inside the building. It's not something we've coded for in our electronic games, but the if the buildings are used in any other game ruleset, at least we can accommodate this, should anyone need it.

Here's our latest creation (above) alongside the previous buildings, just awaiting some stickers to jazz it up a little. Since this building is in the style of a wild west hotel, we're probably going to have to change the signage on the other building!

Both of the two-storey buildings have been designed with detachable fronts. This will allow us to make a range of different building styles using a basic template for the building construction. It also means that, when used in a tabletop game, getting access to the miniature playing pieces placed around the buildings can be made a little easier, by removing the front canopy of a building.

An unexpected benefit to this approach is also the ability to "mix and match" different building fronts, onto different building styles

We're getting a little impatient to see our wild west building actually appear on the tabletop, so we may yet just cut another of each of our buildings to date, and have a simple, small town of just six or so (very similar looking) establishments.

Sure, laser cut buildings don't have the same detail as scratch-built ones. And stickers will never give the same impressive appearance as a properly built, painted, inked-and-drybrushed piece of terrain. But they are a pretty easy way of building a relatively large playing terrain, quickly. And for that reason, we need to focus on getting our wild west town finished, rather than worry too much about them not being "real hand-built terrain"!

Laser cut terrain buildings - 28mm wild west contd

Steve had a great idea about our laser cut wild west buildings - CraftRobo stickers. We'd forgotten all about our trust little blue-and-white cutting machine; it's been sitting in a box in a corner for a while now.

Luckily it can import .dxf files as cutting lines, and accurately place these over a pre-printed image. So all we needed to do was create a series of jpegs (one for each section of the building) and place the cut lines over them (the same cut lines we drew in Inkscrape for the laser cutter, though modified slightly in places).

The most difficult part is resizing the jpeg images in the CraftRobo software; the only information we have about the jpegs is the height and width, as measured in pixels. The CraftRobo software, RoboMaster, only uses only millimetres as units for resizing images, so we had to do some quick conversions.

Our bitmaps/jpegs were created at 600dpi (to get the best quality printed output). So the size of the image in millimetres is: size of image in pixels / 600 * 25.4

Creating the A4 sized sticker sheets was a relatively quick process: create a jpeg and import into RoboMaster. Import a dxf with the original cut lines as sent to the laser cutter. Resize the images in Robomaster to their actual size (using the formula above). Place the cut lines over the correct parts of the images. Each sheet took less than half an hour to produce:

Our CraftRobo is the old-style blue model - one of the very first imported into the UK a number of years ago. As a result, it doesn't have particularly good downward cutting force - it struggles with anything more than even just thick paper. But for sticker inkjet paper, it cuts just fine.

Each cut goes cleanly through the sticker side of the paper, while leaving the backing paper intact - perfectly cut stickers every time!

Some of the stickers needed to be adjusted slightly to get them to fit onto the building, but for a first try, the results were surprisingly effective.

The 28mm playing piece shows the overall scale of the buildings in relation to a board game playing surface.

We're not quite sure how the buildings will work with stickers on the walls and our laser-cut roof shingles (and a mix of painted and non-painted parts) but the stickers seem to work well enough to use on other parts of the building - the roofs and sides of wooden planks on the building fronts, for example.

The plain wood coloured shingles look quite nice on the single-storey building. And the etched planks on the double-storey building canopy could be left as they are - the colour of the 0.8mm birch contrasts quite nicely with the wood-effect patters on the stickers

We'll have to try painting and dry-brushing the "textured" parts of the buildings, and see how they look with the stickered walls. But so far, things are looking very encouraging.

The overall scene will look all the more convincing once we've got a proper floor down, and maybe a few more buildings around the place. But, of course, the whole point it to furnish our electronic board game - so perhaps it's time to park little wild west buildings for a bit, and get on with actually manufacturing something!

Laser cut 28mm terrain buildings - wild west

A while back, we made some simple 28mm buildings for a wild west shoot out miniatures board game. Having turned our backs on the laser cut buildings that seem to be flooding the board gaming market in recent months, we decided to "scratch-build" our buildings from lolly sticks and coffee stirrers.

The results were quite nice, but the overall process took far too long. So we tried a half-way house - laser cutting rows of shingles for the roofs and cutting planks to make the walls of the buildings. Again, a successful trial, but still making a complete building - even a relatively small, single storey one - was tediously slow.

So now it's time to give laser-cut buildings a try. We know that scratch-building gives impressive results. Shingle roofs and plank-built walls look great when painted up and drybrushed, but - to date - we've nothing to compare them to. So we thought we'd at least put some buildings together, and compare them to our scratch-built ones.

Using photos of existing models on the 'net as "inspiration" we got busy with Inkscrape

We designed and cut a small, single story building (with 3 inch sides, 3 inches deep)...

...and a larger, two-storey building, again with a 3 inch square footprint:

Being impatient, we cut the doorframes and windows from regular 3mm mdf - ideally these would be cut from 2mm, as the 3mm gives them a slightly cartoon-chunky look

The pieces fitted together easily. Unlike a lot of mdf laser-cut buildings, we tried to keep the number of interlocking tabs to a minimum. We're using PVA glue to assemble our parts, which means putting a few sections together, then leaving overnight to dry before further assembly.

Superglue (the real stuff, not the nasty knock-off clone from Poundland) does a pretty good job of gluing mdf together, with the advantage of not needing to be left for a few hours to try before putting more pieces together. But it does suffer from "instant grab" which means you need to be pretty accurate when placing each piece.

Because we hadn't yet tried a full fit of all the pieces, we decided to stick with PVA - to give us time to slide pieces around if they didn't quite line up, first time.

The finished double-storey building looks pretty good. There are a number of first-time design faults that need to be addressed in the second version, but for a first time try, it looks ok.

For a start, things like the top plank isn't wide enough to sit on top of the decorative false-roof parts. This can easily be corrected in the next iteration. The window frames are too chunky, and we designed the canopy supports to line up when cut from 2mm mdf, not the thicker 3mm stuff we had to hand. But these are simple design problems that are easily fixed. The actual, finished building looks quite nice - and even though it has a relatively small 3" footprint, still looks a decent scale for the "heroic 28mm" (i.e. 32mm high) miniatures from Black Scorpion.

Unfortunately, it still looks like a flat, laser-cut building. We're going to try drawing (heavily) on the wood to create a grain effect, before painting over the whole thing with a primer and base coat, to give it a little more character.

 Perhaps a computer-printed sticker for the canopy sign and some posters to go along the sides of the building are the finishing touches it needs? According to some sources, advertising was just as prevalent, garish and clever as today's efforts to get people to part with their hard-earned. Except instead of pasting adverts all over the internet, they just pasted them onto their buildings!