User avatar
By EctoLabs
#4955586
Ever since my Ghost Trap build went quite well last year, I've been wanting to do another detailed prop build with all the bells and whistles. The obvious thing I am still missing is a pack, but I just don't have the time or the space for one at the moment. So, what about the Neutrona-Neutrino-Particle-Proton-Wand-Gun?

From this point, I'm just gonna call it the 'Thrower' because, let's face it - 'Wand' sounds a little too Harry Potter these days as well as being far too funny a word for someone with a childish sense of humour... like me. It may be a component part of the overall pack, but it's still a really interesting prop in its own right. Plus, it has tons of flashing lights, switches and buttons - and who doesn't love those?

Therefore, I've decided to build a completely standalone thrower from scratch with fully custom Arduino-based electronics. I want this to include include lights, sound and haptics with different FX modes, and be as visually accurate as possible according to the reference photos of the screen-used props. Sound effects will be self-contained as with the Matty and Hasbro wands, but with the ability to hook it up to a full pack at a later date. I'll use some 3D printed parts, but include as many metal components as possible. This also means incorporating a pop-mechanism via the green lever and a twisting (non functional) barrel.

----------

How hard can it be? Let's find out........

----------

Firstly, I began by looking for accurate 3D print files. There's no point in modelling the thrower from scratch if someone else has already done a great job. A search on Thingiverse brought up a few good looking models, so I did a few quick comparisons between the 3D parts of two or three models, and the tape-measured Sony Lobby reference photos here on GBFans. In the end I settled for notsabbat's files which seemed pretty consistent with the dimensions of the screen-used throwers as well as being better designed for use with aluminium tubes. You can find the set of files I used here: https://www.thingiverse.com/thing:3885923.


First up, was the main gun box. There are a few things I want to adjust with this model, but as I am working this all out as I go along, I opted to go ahead and print as is - any alterations can be done manually as I learn more about how the original props were designed and built.

The gun box was a long print, but came out perfect first time. I decided to print at relatively low resolution as I plan to smooth all the parts with a combination of body filler, filler primer and possibly UV resin. I printed this at 0.3mm layer height which produces quite prominent layer lines, but saves a considerable amount of time.

Image

I also printed the wing parts, the barrel lock, the fuse and control boxes and the front grip (which I modified slightly to better match the length of the grip on the reference thrower - this should be slightly longer than the rear grip which I will come to later).

Image


POP-MECHANISM & BARREL TWIST

Something of a mystery to me at this point was how the pop-mechanism was originally designed, but it was clear that it was the green lever that controlled this and not by the twisting of the barrel. I concluded that I would need three different sized aluminium tubes to make up the inner, central and outer sections. I had originally purchased three tubes with the same wall thickness, but a slight error in my calculations meant that one did not fit inside the other. In the end, I retained the largest tube and sent the other two back to the seller. I replaced these with an extending curtain pole which I found in a cupboard in my apartment. By chance, they were the perfect size and also allowed for easier cutting due to them being much thinner. They were painted white, but some acetone should be able to sort that out later on.

To assist in working out the mechanism, I measured the diameter of each tube and mocked up the barrel assembly in CAD so I could work out a design visually before doing any cutting and drilling. Thanks to the several existing pop mech kits out there, plus details of how the originals worked, I was able to come up with my own variation...

Image

The outer tube is 33mm in diameter (with 1.6mm wall thickness) and is cut into two sections. The first section is 75mm in length and has two holes drilled - one at the very top and the other at 90⁰ on the outside edge. This section was then attached permanently to the gun box. I needed to dig out the large hole in the front to allow the tube to pass right through:

Image
Image

This made it pretty rough as it exposed a lot of 3D printed infill, but a heady mix of filler, grab adhesive and super glue made sure that tube wasn't going anywhere. The most important thing was to make sure it was attached straight with the holes positioned in the correct place, otherwise the rest of the barrel would end up looking very wonky.

Image

The central tube is 28mm in diameter (with 1mm wall thickness) and has holes that line up with those in the outer tube, so the two can be bolted together. I then drilled two more holes in the same positions, only further down the tube. I used a hacksaw blade to cut out the section between these two holes to create a rounded slot - this is needed for the barrel twist. I removed most of the white paint by immersing the tube in pure acetone - this loosened the paint until it was possible to peel it off cleanly in large sections. I then added some electrical tape to increase the diameter of the tube in order to remove any wobble when inserted into the outer tube.

Image

Thinking of the mechanism as a whole, I knew I needed somewhere inside the barrel for an elastic band or spring to be secured. With this in mind, I designed a 3D printed piece that would hold a band in place, as well as doubling as a nut for the two bolts that fasten the outer and central tubes together. Because of its shape, I call it the 'pacman nut'. I glued in some M3 brass threads to prevent the holes from getting stripped:

Image

When secured in place, there is a gap around the rest of the pacman nut to allow the inner tube to run freely up and down the central tube, with a cut out to allow the wires from the barrel LEDs to pass through without getting caught. The photo below shows the pacman nut in place securing both the outer and central tubes together (this shot was actually taken before I glued the outer tube into the gun box so it's easier to see). One of the securing bolts runs straight through the pacman and a square hole in the centre means an elastic band can be wrapped around the bolt.

Image

The second section of outer tube is 150mm in length. This has just one hole that lines up with the slot in the central tube. My original intention was to add a bolt through these holes under the grip, but while routing through my nuts and bolts box, I found a metal dowel (supposedly from an Ikea bookcase to hold a shelf in place). Glueing this into the rear of the grip itself meant I could position the grip on the outer tube perfectly every time (the grip you can see below is after it had a coat of yellow filler primer - ignore that for now as we'll get to that later). The dowel passes through the hole and allows this section of outer tube to be rotated for the length of the rounded slot in the central tube behind. It also prevents the outer tube from slipping off. Win win!!

Image

Finally, the inner tube is about 25mm in diameter (with a 1mm wall thickness) and is 230mm in length. I have cut away half of the tube for 180mm of its length, leaving 50mm at the end intact. Removing this section means that it can travel up and down the central tube without colliding with any of the securing bolts. I made two holes at the rear end - these are for a bolt that will hold the other end of the elastic band, and a second bolt that will stick outward and be held by a catch that I will add later. A couple of layers of blue tape has been added to increase the outer diameter a little, and to make the tube's movement a bit smoother.

Image

Next up... acrylic action!
Last edited by EctoLabs on October 19th, 2021, 6:40 pm, edited 4 times in total.
tobycj, Nighty80, gchew liked this
#4955604
Nighty80 wrote: ↑September 14th, 2021, 6:52 am Can’t wait to see how you get on - your trap is a masterpiece, really high hopes for this πŸ˜πŸ‘
(No pressure lol)
Cheers. Here's hoping I can work out how to make it fire real proton streams. :twisted:
Nighty80 liked this
#4955608
FROSTED ACRYLIC TIP & BEVELLING

Okay, so on to the acrylic tip. For this, I purchased a basic 22mm diameter tube from Amazon. I had no idea how this was going to turn out, but the tube was just over 30cm long, so I figured I had enough for two attempts should I end up messing up. The first task was to create the two frosted rings by lightly sanding the relevant areas:

I used various reference photos to eyeball the position of the frosted sections on the tube, and wrapped some cable ties to mark the borders of the rings. I then used electrical tape in the other areas to prevent the ties from slipping as well as protecting the acrylic from any unwanted scratches. I figured that cable ties would be better than using masking tape, as sandpaper can easily cut through tape and might mess up the neat lines I wanted to achieve. The ties also give me a raised area that I could jut up against with the paper without risk of messing up the line. I can't remember the grit of paper I used, but it was pretty fine - around 1500-2000 - as the acrylic doesn't need much to get scratched and I didn't want it to look obviously sanded.

Image

I unwrapped the tape and removed the cable ties... success!! I actually couldn't believe how good it ended up looking and just the right amount of frosting which reflects the light brilliantly when placing an LED against the wall of the tube. I then shortened the tube to 150mm which leaves enough at the base to insert into the inner aluminium tube.

For the bevelled end, I decided to go with Astyanax's 'low-tech' method. I forgot to take any photos but you can read how he does this in his thread here: viewtopic.php?t=42799. I had to take it very slow with the acrylic as it can start to melt if you spin the drill too fast, plus it really eats through the sandpaper, often leaving black marks on the bevel. I was able to remove this by hand-sanding the bevel created by the angle of the funnel. I recommend using a scrap piece of acrylic tube to experiment with first, as this method could easily ruin your work.

Thankfully, i made it through without any disasters and finished off the job with a finer grit sandpaper to smooth the edge and... voila! Not a bad job. The bevel could be a little steeper, but this is dictated by the shape of the funnel you use. Nevertheless, I think it looks pretty good and certainly much better than leaving the tube flat.

Image
Last edited by EctoLabs on October 19th, 2021, 6:37 pm, edited 1 time in total.
darthbuster liked this
#4957752
POP-MECH CATCH

The first challenge of the build was working out how to incorporate a catch for the pop-mechanism. The gun body I am using has a reduced amount of space inside where the front tube attaches - this makes the tube nice and secure but does not leave much room to play with.

After a some trial an error, I came up with a 3D printed solution comprising of a two-piece latch and an 'L' shaped piece that attaches to a metal bar that forms the 'green lever':

Image

I riveted the two white pieces together so that the central piece can move freely. The idea is that a bolt attached to the inner tube slides between the sloped 'mouth' of the catch until it hits the back. An elastic band tied around the vertical arm snaps the central piece over the bolt and holding the inner tube in position.

Image

So, all in all, it's a basic catch mechanism, but nice and small that fits beautifully inside the gun body without needing much room. You can't see it here, but the free end of the elastic band attached to Pacman nut is stretched around the vertical bolt of the inner tube, so that the tube and barrel is pulled outwards.

Image

The metal bar slides through the gun body and the black 'L' shaped piece attaches to that using a screw. As the green lever is depressed the L rotates and pushes the white arm forward and the catch upward, releasing the bolt and popping the barrel. The other flat side of the L shaped piece hits the top of the hole in the body, preventing the lever from rotating any further than it needs to. The elastic band seen here will eventually be tied to the inside of the 'SLO-BLO' fuse box - this arrangement means that there is no need for any other spring or band for the lever itself.

Image
darthbuster liked this
#4957808
SMOOTHING AND SILVER COAT

Next job is to smooth out the 3D printed parts and get everything looking like metal. In order hide the print lines as much as possible I'm covering each part with body filler. I'm using a brand called 'Big Boy Body Filler' which, apart from the euphemistic name, is a bit nicer to use than the Isopon P38 that I've used before. I would use Bondo, but they don't sell it over here. This stuff sets hard fast and sands easily to help even out any low spots - this is pretty essential in order to get rid of the rough stepping on the curved corner on the gun body.

Image

I used 120 grit paper to sand down. Once done, you can see the low spots as white areas:

Image

As with my Ghost Trap build, I am using spray paints and primers from Halfords - this is the big automotive and cycle superstore brand here in the UK. I find that their own-brand paints are really nice and work really well with prop work, plus they are relatively inexpensive. I now spray a coat of yellow Filler Primer to further smooth out the surfaces - this is wet sanded down with 420 grit paper, followed by a second coat and then a second wet sanding.

Image

Once nicely smooth, I sprayed a coat of standard grey Primer to give a nice even surface for the paint coats:

Image

The process is repeated for the other parts before spraying everything with Rustoleum Metallic Silver:

Image

For the grips, I used the same smoothing process with body filler and primer, but decided to keep the second coat of yellow filler primer as the undercoat. The weathering to the grips on the screen-used hero props reveal a yellow/orange colour underneath so I felt that this primer would be a pretty good match for that. One happy accident is that, although there are still some 3D print lines visible, but their circular pattern is reminiscent of wood grain, so this should provide a nice little texture contrast with the rest of the parts:

Image

Next, I glued the barrel lock and the wing to the aluminium tube using a rapid two-part epoxy. To do this, I screwed both parts to the front grip and positioned the whole assembly on the tube - because the grip has the metal dowel that slots into the tube, I was able to get correct position while the glue set. I also used several cable ties to keep everything together until the wing and barrel lock were fixed securely in place:

Image

Finally, using regular screws for the time being, I put the entire thrower together. Now we're really getting somewhere...

Image
Nighty80, CaptainAssholay, mburkit and 1 others liked this
#4957846
mburkit wrote: ↑October 21st, 2021, 9:04 am For a 3D print, that looks great!
Thanks. There's really no reason why a 3D print should look (or feel) 3D printed if you spend the time with the finishing process. I want this build to rival any of the amazing fully aluminum throwers out there!
#4957850
FAKE WELDS & TOP COAT

Right then... let's tackle the fake welds. I did a bit of this on my trap build, but they were a bit more 'blobby', so I'd like to try an imitate the shape of welding beads a bit better. For this, I am using black Milliput and following Throwing Chicken's technique to create the welds (viewtopic.php?f=2&t=35951). I found using the flat edge of a large soldering iron tip worked pretty well for smearing the beads of putty. Bear in mind though... this stuff gets everywhere!

Image

I applied this to each of the relevant parts (gun body, wings, barrel lock and fuse boxes) and smooth it out a little with a thin layer of putty over the top. Looks a bit rough at the moment, but hopefully will look better once the black top coat is on...

Image

Okay, time for the black top coat. I'm using Halfords Matt Black here - this is a really lovely matt spray paint that has just the right amount of sheen without it being too shiny or too flat. However....

URRRGHHH!!! Those welds look absolutely horrible. Rough as anything and not convincing at all. After panicking a little after realising there would be no non-destructive way of removing them and starting again, I needed a recovery plan.

Image

My idea was to use UV resin that could be brushed over the welds to smooth them out. I'm using the water washable type that doesn't need rinsing in alcohol after use - this is great as any alcohol would risk attack the existing paint. I added the resin in thin layers with a fine artist's brush - you need very little resin to make a big difference as it magically self-levels as you apply it. With only a few seconds exposure to a 405nm UV light, it sets hard.

Image

I applied a few coats, curing between each one, until I was happy with the look of the welds. The resin has made them glossy, but this will be corrected with another coat of matt black over everything. You can see how much smoother the welds look after the resin. They are far from perfect and I definitely need to improve my technique with the putty, but they are now at least passable. Phew!

Image

*** ROOKIE ERROR ALERT ***

One thing I totally overlooked in all the excitement was making sure to correctly prepare the aluminium tubes before painting. Even though I want to weather the thrower, if you don't correctly prime the metal surfaces the black paint will not adhere properly. I figured I might be able to get away with it, but before long the black paint started chipping off with light handling. At one point, removing a piece of low-tack masking tape took off a huge section of paint under one of the handles and I swear it started flying off just by looking at it!

IMPORTANT! If you are doing a similar build - make sure you prepare and prime the aluminium correctly! First, scuff up the metal with 120 grit sandpaper and then again with some 420 grit. This gives the necessary texture for the primer to grab on to. Second, coat the aluminium with an etch primer before painting. Make sure you use etch primer and not regular primer as the etch contains a mild acid that helps create a permanent adhesion. Finally, leave for 24 hours before spraying your top coat.

I didn't take any pictures of this mishap but, suffice to say, it was a pain in the ass to correct, so make sure you do the etch priming before any assembly takes place. Anyhow, it's done now and the improvement is massive. I can handle this thing now without the risk of accidental weathering!
cristovalc liked this
#4957857
Amazing fill and sanding job on that wand as always! Looks like real aluminum! Shame you gotta cover it up...

I had the same problem with my welds, but came up with an artistic solution; once the milliput is nice and set, I took a small set of needle files and just started chiseling out the shapes I desired, then sanding over and between the grooves to remove the harsher looking bead edges. This works quite well because you can add way more fake beads than you could reasonably get just by placing them down on top of one another. If you don't feel like re-spraying the entire area, I just sprayed some of the semi-gloss spray-paint (or whatever you are using) into a small cup and brushed it over the surface, then polished it up with fine steel wool. Definitely get a nicer look of goopy smooth weld beads...
This Post Contains Spoilers
EctoLabs liked this
#4961684
FLASHBULB AND BARREL TIP

I want to replicate the flashbulbs used on the original throwers but don't fancy the idea of replacing the bulb every time it's triggered. Therefore, I am going to replace the insides of one bulb with an ultra bright LED which I can wire up to an Arduino circuit to simulate a quick flash when the Intensify button is pressed. I started by buying a pack of old Philips Photoflux AG3B bulbs - these can be found pretty cheaply on eBay and with 10 in the pack, there are plenty of spares should things go wrong.

Image

I then used a rotary tool with a diamond cutting disc to carefully remove the bottom of the bulb. I used the slowest speed setting and made sure to wear eye protection as a fair bit of glass dust is produced. Once the end was removed, I pulled out the magnesium filament and filed down the rough cut edge of the tube with the top side of the cutting disc.

Image

I also want to reproduce the look of the bulb socket so it looks less modified. To do this, I 3D printed a white cylinder with two holes running all the way through. Two solid wires are then inserted through the holes with a small amount protruding at each end before soldering the pins of an ultra-bright LED to the wires...

Image

The glass bulb needs be held in place, so I designed and printed a small ring that fits around the LED. This provides a lip that can be glued to the bottom of the bulb - no two bulbs are quite the same shape and they are not perfectly round, so I had to make this a slight oval to fit correctly. I glued this using some epoxy as I found superglue has a tendency to make glass cloudy with permanent vapour residue as it dries.

Image

Next, using transparent filament, I printed a tube shaped piece that is a little shorter than the white cylinder and sized to fit the inner diameter of the acrylic tube. The cylinder then slides inside to recreate the look of a ceramic socket. A positive and a negative wire (white and black) are soldered to the other ends of the solid wires and then fed back up through a hole along one side of the transparent section:

Image

Two holes are needed to be drilled into the acrylic tube - one for the two wires to escape through, and another for a set-screw to hold the 'socket' into place. I used the rotary tool for this, although I went a little too slowly with one of the holes and ended up creating a small crack. Arghh! Thankfully, this will be on the bottom of the tube so won't normally be seen. This could really bug me, so let's just pretend it's some deliberate weathering!

Image

The banjos I am using for this build are some nice machined brass replicas from Keymaster Props (https://www.ebay.co.uk/str/keymasterprops). For the wires to be fed through properly, extra holes needs to be drilled into the side of each banjo. As brass is a pretty hard metal, it takes a bit of work without better tools, but I got there eventually with a power drill and reasonably sharp bit. I replaced the Keymaster supplied bolts with more accurate slotted hexagonal bolts (the same used on the Ghost Trap pedal), although I needed to shorten one of them in order to fit the trigger tip...

Image

For the aluminium trigger tip, I went with the GBFans welded version (https://www.gbfans.com/shop/pack-parts/ ... igger-tip/). This fits perfectly and has enough of gap in between to hide the wire hole where they leave the tube. The wires are then fed through the hole in the banjo and out of the end - just as they do in the hero throwers. Finally everything is secured into place by a single set-screw to prevent the whole assembly from rotating or sliding up and down. All in all, I'm pretty happy with the look of this. Let's hope it will light up good and bright!

Image
cristovalc, tobycj liked this

    Folks on reddit said they had to give the DPCI num[…]

    OK everyone I also hear people that we don’[…]

    I wanted to update the photos I have of the red sw[…]

    so I guess we find out in a few days if we man[…]