#4945053
Hey All,

Building a trap has always been one of those bucket list things that has been gnawing at me ever since the late 80's when attempts were made using lego, cardboard, and even paper mâché. With the purchase of a new 3D printer, the ability to see that dream come to fruition has finally come.

Part of what convinced me to purchase a 3D printer was seeing the Charlesworth Dynamics trap featured on Tested a few yeas back. I quickly downloaded all the files where they sat, just waiting to be built.

With the last of my orders trickling in for my GB trap, I figured it was time to get started. This thread will be a bit of a documentation / review of the kit and the process. It is important to note that my criticism and thoughts may sound harsh and direct, but it is done with the upmost appreciation for what Sean has done.

Also keep in mind that my methods and ideas are often a little... err, outside of the box so don't be surprised if I go off on tangents that leaves everyone scratching their heads in confusion.

I hope that this helps others and sparks some conversation along the way. I appreciate any feedback and thoughts as well, but I ask one thing. Be honest, be harsh. I don't need you to hold me tightly by the fireplace while you whisper how proud you are of me. I want honest and helpful criticism to make my trap the best it can be.

With that little intro out of the way... let's get started.
#4945055
The Goal

My goal is to create a trap that would have been seen somewhere between Ghostbusters 1 and 2. A trap that is mostly the style from the first movie, but with elements and upgrades that would have happened in the time before the second. A hybrid if you will with a heavy influence to the first version.

While I am 3D printing the majority of parts, I opted to use real world parts where available. For example, I have an order of knobs from this website on the way. I also purchased the deluxe kit from Charlesworth Dynamics (review to come later) which provided some of the actual parts used on the traps.

The CD (Charlesworth Dynamics) trap is designed to incorporate lights, sounds and smoke. I will be mostly following that plan, but after seeing a few other traps people have created, I have decided that I want mine to more closely resemble the movie version. Therefore I will be doing things a little differently in terms of lighting and sounds.

The hope is that I can make it as accurate as possible within the scope of what I'm trying to achieve.
Last edited by ImperialWalker on January 26th, 2021, 5:27 am, edited 1 time in total.
#4945059
The Hose

Going off script right off the bat I decided to start with the construction of the hose. I figured that it would be a good starting point to get brush off the soldering cobwebs and to tackle something I could complete in a weekend.

I started out by following the directions and disassembling the female connectors. The first step is to cut out some electrical tape to isolate the metal spring inside from the casing.

I tried using the method shown in the directions, but wasn't happy with the result.

I tried modelling and 3D printing an insert, but even at the finest quality my FDM printer couldn't print a wall thin enough to work. I ended up printing a template created in Illustrator which I taped on top of electrical tape stuck down to the cutting mat. I could then get accurate inserts with notches cutout to allow it to curve up the sides a bit.

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After fiddling with this a bit I got it perfect. Which brings me to my first criticism.

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Connectors and Plunger

The goal here is to isolate the metal spring from the housing allowing the signal from the peddle to work. CD has opted to use glass tape, but recommends electrical tape or heat shrink as well. The problem is that the build order of this means that in the next step you'll be applying huge amounts of heat to the brass connector. This heat, as you can imagine will mess with the heat shrink and electrical tape.

I found this out the hard way as I had to go back and redo the electrical tape after soldering the wire. The build order really should have the electrical tape being the last step.

That said, I also think electrical tape/heat shrink isn't the best solution. If the goal is to isolate the spring, I think a much easier and more effective way would be to apply a non-conductive coating to the spring itself. A coating of liquid electrical tape or rubber would not interfere with the movement of the spring, but would make it so much easer to apply.

The next step is to remove 1/16 of this part called the plunger. It is a tiny metal part that attaches to the spring. The idea I believe is to remove 1/16 of the metal plunger and then extend a 1/16 brass rod from the male connector to connect with this.

Now, I only sort of tested it, but I am not convinced this is going to work that well. The reason is that the part that you take off results in a very small surface area. This means that when the brass tube comes into contact, it must find this little ridge and maintain a strong connection.

These connections are also designed to spin. This is a good thing as it allows the trap to spin around on the hose reducing pressure and keeping the hose free of twists. In one of my initial tests the brass rod slipped to one side not allowing the connectors to spin freely. This could put a lot of pressure on the parts and ultimately cause failures.

My suggestion would have been to either completely remove the fin on the plunger (and extend the brass rod), or increase the surface area of the top of the plunger using another method. This would create a flat, large surface area for the brass rod to find.

Time will tell if this will hold up.

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The Wires... Don't cross the streams

The instructions call for soldering a blue wire to the plunger and a black wire to the connector.

Now, perhaps I am totally screwed up but, it appears to me that CD has this completely mixed up. I've attached a diagram of what the directions call for.

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Now, again I might be looking at this incorrectly, but it appears that the wires are reversed along the inside of the tube. Not a huge deal as a wire is a wire, but it had me super confused after I tried troubleshooting a connection only to realize I was working on the wrong wire. My perfectionism makes me want to go back and rewire it, but I'll leave it for now.

As you can see from the diagram above, the directions call for soldering a wire to the barb of the female connector. This is no easy task and brought me back to my days in art school when I got the brilliant idea of soldering together a giant brass lantern. The issue is that to avoid a cold weld (a weld that doesn't actually adhere to the metal) you have to heat the part. The part of course won't just heat up in one spot and will dissipate the heat to the rest of the object, the vise, the leather you're using to hold it in the vise and everything else.

What I don't like about this is that you solder a small wire to the end of an edge, where there is the most amount of flex and strain on the hose. This came back to bite me later when I attempted to insert it into the clear tube and my wire broke off in the process.

I should have went with my gut feeling and dealt with it then and there.

I think a better solution would be to take the wire and wrap it around one of the upper parts on the barb and solder it there. Then, taking a heat shrink tube, cover both the blue and black wire, as well as the barb and solder point.

After shrinking the tube this would lock both of the wires in place and create a strong, flexible stress point at the end of the barb. It would also hold the wires onto the barb not allowing them to pull out as easy with stretching that likely comes while rolling out the trap.

This is really bothering me because I am concerned that black wire will eventually snap in the tube requiring me to take most of it apart and heat up the brass which has already discoloured due to heat.

...

We Be Tubin'

With the connections made, it was now time to put the wires in the tube.

An old electricians trick is to use a vacuum or your mouth and suck a piece of string through the tube. Then, you attach the wires and pull it back through. Clever!

The instructions call for slicing the tube lengthwise and manually feeding the wires inside and I wanted to avoid this if possible. The less chance of moisture, mud, dust, and such getting inside the plastic tubing the better.

Hmmm... The problem is that the tube provided in the kit has a very small inner diameter. This means that while the wires do fit, they cannot be pulled through as the friction becomes so great after a few feet that it is impossible to move. I tried doing one wire at a time. I tried different rigs, but in the end I ended up slicing the tube as directed.

To do this, I created a simple little jig.

Using a piece of plastic tube the same diameter, I poked a knife through just enough so it would slice one side. I then taped that knife down to the table.

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I could then feed the tube in and pull it the entire length. What I like about this method is that the tube naturally twists meaning that the cut is spiralled along the entire length meaning that it does not easily buckle open.

The inner diameter of the tube once again became an issue when trying to connect them to the barbs at the two ends. To fit them on the ends the tube needs to be sliced, but this creates a really weak connection due to the tube only covering about 3/4 of the diameter of the barb.

Once taped and zip-tied it seemed to hold, but I think this could all be avoided with a more appropriately sized tube.

...

Eventually you'll need to connect the wires from both sides. This is just a small nitpick, but while the directions show a staggered connection of the wires (meaning they don't connect at the same spot), there wasn't any little notes to point this out. I wasn't thinking and I connected the black and blue wire in the same spot, only to realize that they wouldn't fit into the tube with the addition width of the heat shrink.

I ended up having to redo one of the wires further along so the connection points were not in the same spot. Not CD's fault, but one of those quality of life notes that would have saved me a half our.

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Fosters Male Connection

To shield the connector from electricity, a 3D printed part is inserted into the Foster connectors. Then, a brass rod is inserted, cut to length and soldered to a wire. This allows the connection to be made with the plunger inside the female connector and then through the tube.

The directions say to solder a wire to the end of one of the brass rods, then insert it into the 3D printed part. Then, when 1/16 is poking out the top, glue it in place add some heat shrink and call it a day.

Again, this doesn't sit right with me. Not only am I obsessive about cable management and clean looking parts, but I didn't like that it caused a stress point with uncovered wire. The reason for having to use heat shrink is because once the wire is soldered to the end, it becomes too bulky to fit into the 3D part.

To solve this, I took the rotary tool and a disk and carefully created a notch at the end. Then, I filled this with solder and laid the wire inside. This resulted in the wire coming straight out the back of the brass rod. With a little sanding and scraping with the hobby knife, I was able to create a clean, strong connection.

The best part, is that it could now be inserted into the 3D part and glued in place leaving the wire to come out the end. I think it not only looks cleaner, but most importantly is not stressed.

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That said... I am concerned about this part holding up. When the male and female connectors are inserted into each other... Hmmm, err... Well, the little brass rod presses on the top of the plunger and spring. I suspect in the normal operation this pressing action opens the valve. In this case it keeps the two connections tight together. The concern I have is that the spring, which is already super compressed will not have enough give and will push the pin and / or the 3D printed insert out of the Male Foster. CD recommends some glue, but in my experience when you introduced two immovable objects then something has to give. The spring and brass rod won't, but the fragile 3D printed part and the glue likely will.

If it ends up becoming a problem, I may end up replacing the spring and plunger and opting for a connection with larger contact points and a weaker spring. Something that will keep the pressure together for a good connection. Or... I might just permanently wire the thing up as I'm not sure when I would remove the hose anyway.

...

Result

After finishing up the final steps I put it together, taped up the ends to fit the GB1 style and put on some zip-ties. I gave it one last test with the multimeter and it seems to be functioning as intended. It needs some weathering of course, but I think it turned out quite well.

I am still concerned with the connection points and how they'll hold up over time, but hopefully they don't become an issue.

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...

TL;DR

I think overall this part of the instructions were easy to follow and accomplish. There does however seem to be some mistakes in the directions which could cause issues down the line when troubleshooting. Some quality of life notes in the instructions would make things a little more clear in some parts as well.

I think the solution to making the pedal work is really clever and full credit to Sean for coming up with this solution. I would like to see a few improvements made to assure the connections are more robust.

One of the biggest things I would like to see changed is the diameter of the rubber tube. A thinner one might not feel as hefty, but it would go a long way to making the process a lot more user friendly. It could also mean that the tube does not need to be cut, which would help keep out moisture, dust and other things that could work themselves into the tube and mess with the wires.

Anyway, I had fun!

Three Venkmans out of 5
:cool::cool::cool:
Kingpin liked this
#4945429
You can’t Handle the truth!

When I was young and attempting to create a trap out of LEGO and cardboard, one of the failure points was always the handle. No matter what it would always bend or break off. This of course lead to many LEGO traps smashed into a hundred foot murdering pieces.

When I started building this trap the second I looked at the directions I knew the handle was going to be one of those trouble spots. I printed the handle part with a 90% infill just to be sure it wouldn’t snap (I have no idea how heavy this trap will be).

I then then attempted to thread the socket screw into the hole. As expected it is really difficult to keep downwards pressure for that long of screw. The hole in the model is also not very long and I am sure I bottomed out. This caused the entire thing to be stripped. I considered gluing it, but it just didn’t feel right.

The handle is basically attached by one small screw with tiny threads, on a single pivot point that wobbles because the holes in the aluminum handle have larger tolerances. I thought about how I could replace the small screw with a hefty one that would go well into the handle. It occurred to me that most of my IKEA furniture has what are called Dowel/barrel Nuts. They work by being inserted into a hole that crosses the bolt. When the bolt is inserted, the nut tightens inside.

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1/4-20 1/2" Barrel/Dowel Nut

However, the problem was that the 3D printed model doesn’t have a hole for the bolt, or the nut. So, the next thing was to adjust the 3D model to allow a bolt to pass through and connect with the nut.

10 hours later it came off the print bed.

The bolt I used is a — 1/4-20 x4 Stove Bolt Round Socket Head

This gave me the length I wanted and basically created a metal core in the handle.

The problem now was figuring out the handle. The head of the bolt is much too large to fit through the existing holes, and I was concerned that without some kind of support inside the bolt wouldn’t sit square and put uneven downwards pressure on the handle. I also didn’t want the handle to be able to spin or wobble at all as I felt this would eventually lead to it failing.

So, once again I turned to the 3D printer.

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I designed a little insert that holds the bolt in place and distributes the downwards pressure evenly. So far, so goo… well, of course. I needed to widen the hole to 1/4” and take a slot out of the aluminum tube to allow the bolt to slide into place.

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With the bolt in place and tightened the handle was now feeling really sturdy. Now we have to deal with the original screw and the cap. I thought about how I could do this and realized that if I combine the cap and the screw that they would not only slide into place and further secure the bolt, but when the screw was inserted it would lock the cap in place allowing for it to be removed later if need be.

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The original socket screw is obviously way too long now and so I will have to replace it with a much shorter one… which I hope I can find, or I’ll have to chop off the old one and hope that works.

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Maybe this is overkill and maybe I could have just lathered epoxy on the original design and it would have been fine, but I never wanted to experience the momentary dread as the handle snapped off and the trap fell in slow motion to the floor. I am confident that this will be sturdy and gives me peace of mind. If you would like to use this with your trap, feel free to download the files on Thingiverse here.

https://www.thingiverse.com/thing:4747034
robandliv, Couture liked this
#4945718
You just came up with a great solution to a problem that I've been worrying about with my build! Years ago I bought a really beautiful trap and the handle broke off in that exact place from hanging the pedal on it while costuming. I've since been super weary of that stress point and worried about how I was going to reinforce it on my printed trap to avoid it happening again. I'm definitely going to go in this direction.
#4946350
Pedal Remix

This part of the build has been... interesting to say the least. After a week of printing, the pedal base was the last thing that I needed to print.

Knowing that it would take some wear and tear and because I wanted it to have some bulk to it, I opted to print it with a fairly high infill. This of course increased the print time to about 15 hours. Little did I know that 15 hours would turn into days.

Living on the West Coast means that a lot can happen weather wise in 15 hours and where I live ocean storms often roll in causing trees to fall and the power to go out. This happened not once, but twice as I was attempting to print this part. Needless to say, I was unimpressed. Not only that, but I was super unimpressed that the power outages happened at the same time in almost the same layer of the print.

Eventually I got a near perfect print and started putting it together. But...

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...

Not Feeling It

I had the entire pedal together, and no offence to CountSpatula but, I just wasn't feeling it. After researching the pedal more, it started gnawing on me that there were so many inaccuracies. I also didn't like that it wasn't very detailed.

Some of the things that were bothering me:

- The extension on the left side (small box) was missing

-I understand the designer logo being on there and I appreciate that he tried to hide it under the vector plate, but I could see it and it made it feel like a toy.

- The screw holes on the bottom to keep the plunger on didn't seem accurate to me

- There was no metal trim on the front and there was no separate aluminum bottom

- The acorn nut also was inaccurate and needed to be replaced with a bullet latch.

- There was no cutout in the centre and the tubes just kinda went into holes.

- The hinge sat too far back and hung off the edge

I attempted to salvage it by filling the designer logo and I was going to try and scribe in some lines to make it appear like there was attached metal parts, but in the end I just felt it wouldn't look how I wanted.

...

Pedal to the Metal

I felt like the only way I was going to get it more accurate was to make it from scratch. Now, I was a little limited in that I had already drilled all the holes for the project boxes, so I had to steer towards the GB2 pedal.

Unfortunately the Countspatula design in its attempt to be a hybrid between GB1 and GB2 has created a situation in which it is very difficult to commit fully to either one.

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I kept many elements of Countspatula's design as I needed the electronics and plunger to work as before, but I used dimensions from the information I found in these forums. The following modifications were made.

- Removed designer logo (sorry Count) and added the centre cutout.

- Adjusted the overall dimensions to be more accurate

- Added the GB2 extension on the left (small project box) side

- Added the wrapped metal to the front

- Added a faux aluminium plate to the bottom with "nubs" for the faucet feet

- added a hole for the Bullet Latch

- Moved the hinge holes up so it sits closer to the movie version

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...

Bullet Latch

The bullet latch was a part that I just couldn't source. Well, to be more accurate, I could source it but for some reason it was impractical to get shipped to Canada.

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Countspatula offered to sell me his which I super appreciated, but unfortunately I wasn't sure it was the correct model and passed on the offer. Instead, I opted to simply model it and print it with my new Elegoo Saturn resin printer.

Thanks to the help of WESTIES14 I was able to model it up and with some additional help from another forum I was able to get it as close as I could.

I printed a few and was happy with the result. Feel free to download and print your own.

https://www.thingiverse.com/thing:4772769

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...

New Pedal

While I modelled the front metal piece to be 3D printed, I wanted actual aluminum to give it a bit of strength and to allow me to eventually weather it.

To make sure I had the holes lined up, I cut the pedal base model which gave me a template to work on. Starting on the right side I drilled the holes which I secured with screws allowing me to make a nice crisp bend around the corner. I continued this until it was all the way around.

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Once that was competed I put it all back together. I replaced the FDM Banjo with a resin one, added a newly printed Bullet Catch and added a resin resistor to the middle.

I plan on working a bit more with the middle part to make the tubes connect logically and like the film, but for now I'll leave it there.

If you want to print your own, feel free to head over to Thingiverse ( https://www.thingiverse.com/thing:4780037 )

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Last edited by ImperialWalker on March 31st, 2021, 10:46 pm, edited 1 time in total.
cristovalc liked this
#4947448
Pedal Electronics

Having completed the prints for my pedal it was time to start looking at some final details. I'll be updating this post a bit more when complete, so check back.
...

Tubin'

In the original CountSpatula design the red and yellow tubes were attached by press fitting them into two holes modelled into the base.

When I remodelled the base (post above) I cut the middle part out to be more in line with what was seen in the movies. The issue was that now there was nothing for the tubes to actually attach to.

While looking at the reference material, others had pointed out on the GB1 trap, there seemed to be a resistor ( same as on the side of the trap ) that the tubes were attached to.

In CountSpatula's files he does include a nicely detailed resistor, which I initially resin printed.

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I drilled out the centre hole and inserted a metal rod to attach the yellow tube.

I then realized that I didn't really have anything for the red tube... hmmm...

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Artistic Licence

For the most part I have been trying to stick to as accurate as possible, but in this case I decided to take a little bit of artistic liberty. Why? I dunno...

I wanted the red tube to have somewhere to go that seemed practical, while also keeping it in the right position. So, I headed into Blender and started adding random greeblies to give it some subtle texture and tech looking stuff.

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The idea was to keep the resistor as the main focus, but have some detail (to be painted black) that would, if looking close enough give a bit more detail instead of a flat bottom.

I also wanted it to be removable in case I decided at some later point it was a little much. So, with an excuse to use the resin printer, I printed out a few versions.

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The hope is when painted the same flat black as the pedal, with a few subtle dry brush highlights it will just give a bit of interest without being too obvious.

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...

Issues

I am going to make the file available for download if anyone wants, but I have to fix some issues.

First, my resin prints are super brittle. I have no idea why, but these prints are warping post print and eventually become so brittle they snap. I am still trying to dial in my printer settings.

The model is also not manifold (meaning it has holes and issues that could mess with the print). I need to sort those out, but when I do I'll make it available for download.

Again, I realize it isn't accurate, but I think it's kinda fun.
cristovalc liked this

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