[Shwalamazula]

A couple months ago someone asked in one of the Facebook Ghostbusters groups if anyone could model up some doors for the 1989 Kenner, The Real Ghostbusters, Ghost Trap. I offered to make the part. The project was so much fun that I decided to buy a functional trap off eBay so that I could tear it down to model all of the parts to make them available to the community for rebuilding/restoring of existing traps.

Completed Parts:
Doors

• https://www.thingiverse.com/thing:4973211

• https://www.prusaprinters.org/prints/82 ... trap-doors

Wheels

• https://www.thingiverse.com/thing:5034525

• https://www.prusaprinters.org/prints/83 ... rap-wheels

Handle

• https://www.thingiverse.com/thing:5034514

• https://www.prusaprinters.org/prints/83 ... rap-handle

Red Nubbin

• https://www.thingiverse.com/thing:5034509

• https://www.prusaprinters.org/prints/83 ... red-nubbin

Pump Assembly

• https://www.thingiverse.com/thing:5100733

• https://www.prusaprinters.org/prints/85 ... p-assembly

Belt Clip

• https://www.thingiverse.com/thing:5103934

• https://www.prusaprinters.org/prints/85 ... -belt-clip

Rear Light

• https://www.thingiverse.com/thing:5115709

• https://www.prusaprinters.org/prints/86 ... rear-light

Foot Pedal

• https://www.printables.com/model/120764-rgb-trap-pedal

Parts in Queue:
Upper Body
Lower Body

I'll use this topic as a project log and maintain this first post to track the progress of the build. I will be providing a replica part that is as accurate as I can make it. I will also try to provide some parts that are either optimized for 3D printing or modified to address deficiencies with the original toy.

Please add any information that would be helpful in the build.

Sections:

• Teardown

• Doors

• Wheels

• Red Nubbin

• Belt Clip

• Handle

• Pump Assembly

[Shwalamazula]

The most useful information from the teardown are the screws and sticker.

On the trap there are 6, Philips-head, screws. The screws are all the same. I am guessing these are American screws. Measuring them, the thread diameter is 1/8" (≈ 3mm). This relates to a standard #5 American screw. The thread length is 3/8" (≈ 9.5mm).



There are 5 exposed screws on the base of the trap and one more that is buried in the upper body. The screws in the base are all located on the bottom of the trap. The screw locations are:

• 2 next to the belt clip

• 2 between the rear wheels

• 1 on the hose retainer

Once the 5 lower-body screws are removed, the only thing holding the trap together is this sticker on the right side of the trap:


I took a hobby knife and cut the sticker along the mid-seam to take the trap apart. Peeling the sticker would have deformed the sticker or potentially ripped it. Cutting the sticker seemed like the least damaging option.




When you pry the trap apart, you will notice there is nothing securing the wheels. The red nubbin on the right side of the trap is also not secured and will fall out.

The last screw is in the upper-body of the trap. To access it, you need to remove the pump housing and piston. The piston is connected to the trap doors with a pair of tabs. These are fairly easy to wiggle out of the way. There is no need to force them. Once the pump hardware is out of the way, you can access the last screw, which holds the handle to the trap.




The last two parts to take off are the red plastic piece under the handle and the belt clip at the front of the trap. The belt clip just wiggles out of the lower-body of the trap. The red plastic piece just has a pair of clips.

[Shwalamazula]

The doors were fun to model. I only ran into a minor problem while modeling them. In order to save some time and to ensure that my parts were symmetrical, I just mirrored the part along a mirror axis. While the doors worked, they were not accurate with the striping.

Trap


Inverted Door


Corrected Door


I was able to easily correct the issue. Instead of getting rid of the inverted doors, I created a second door with proper striping and inverted that as well. Now, people can mod their trap, if they want, with a chevron pattern on the doors. Because both doors were inverted, you can choose to have the chevron point toward the handle or toward the belt-clip.

[Shwalamazula]

The wheels were crazy simple, just a bunch of circles.



I did notice that there is a seam going down the middle of the wheels. This would make sense for injection-molded pieces, where this would most likely be the seam where the two dies met. I ended up providing a second file for the wheels that had them split in half. This will be more useful for FDM printers or folk trying to make the parts look as authentic as possible.

One part of the wheel does have me a bit confused. There is a hole going thru the middle of the wheel. As you can see in the picture below, there is no axel on the trap. The wheels are aligned with a slit in the bottom of the base and are kept in place by curved geometry in the upper body.



I am guessing that the holes are there for injection of the plastic into the dies or for manufacturing locators. I think they will be useful for anyone printing the wheels in halves and then gluing together. The hole is 4.5mm in diameter. A small dowel will help in aligning them while the glue sets.

[Shwalamazula]

I am still not sure what the square feature on the right-side of the trap is, so it will stay as the Red Nubbin.

The Red Nubbin is only held in place by the upper and lower body of the trap. On the bottom of the part, there are a pair of protrusions. The protrusions butt up to the box under the trap doors. This geometry seems to only be there to keep the part from wiggling all over the place.



I made a replica of the part and a version optimized for 3D-Printing. The base was extended and the inside filled. This makes it much easier to print and since the modified geometry is inside the trap body, there is no external visual difference.

[Shwalamazula]

The belt clip was a challenge to model. This is because the part has a lot of angles and reference faces were not easy to locate. Instead of building the model from the base up, I took the sculpture approach. I took the max height, width, and length of the part and created a solid block. I then started cutting the geometries out of the block to get to the final part.





I am not sure how with will fare with a resin print unless something is added to the resin to increase the flexibility of the material. As for FDM, the geometry and loading suggests that printing the part on its side will be the best. Printing at 45 degrees may be a decent compromise in strength vs support cleanup.

Side


45

[Shwalamazula]

The handle is the part that I see broken most often on old traps. This also happens to have been one of the more annoying parts for me to model. The handle has a stepped profile on the underside and a smooth profile on top. The top profile tapers and has a larger major diameter than the underside.

There were multiple times where I had to make a geometry that would extend into the profiles of the handle grip and I had to use the base profile to clip off the protruding parts. I think I made the part pretty accurate. I made a second part with the inside completely filled in and I extended the screw hole further into the handle so that a longer screw can be used to make the handle attachment sturdier.

[Shwalamazula]

Tearing down the pump assembly was interesting. The pump has a barbed inlet that the hose connects to. Stepping on the pedal forces air into the inlet and pushes up a piston that moves the trap doors. The pump assembly has geometry to hold the rear wheels in place and also has a pair of locator holes that align with the rear pair screws.



Taking the asseembly apart revealed that there are only 2 main parts. The main housing and the piston. The piston is comprised of the main piston, a sealing film, and a cap.



The bottom of the piston was also covered in some kind of grease. It looks like lithium grease. After cleaning off the grease and taking the assembly apart, I was able to take measurements of the film. The film feels like it's about the thickness of a sandwich bag. The film is 25mm in diameter. The inner diameter is about 4mm.





Modeling this wasn't difficult, just tedious. Once I finished the model, I was able to print it to test it and see if it worked. The first print ended up with too much friction between the piston and the body. I expanded cylinder diameter by .25mm and that made it work just fine. I also opened the air inlet to 2mm vs what I am guessing was a diameter of 1mm on the original piece. Unfortunately, I do not have tools that can accurately measure the inlet diameter, so I had to eyeball it as best as I could. Finally, I raised the floor of the main cylinder .2mm to give a little extra room to make it air-tight (there is more than 20mm of air when the piston is fully seated) and chamfered the tips of the wheel cradles.

I found that printing the main body with the cylinder mouth on the bed was the best orientation. The small features of the wheel cradles survive better with them unsupported. The cylinder base will also bridge just fine without support.

The piston was easy to model but printing it is annoying. The best way to print it is in its base orientation with the alignment arms on the print bed to reduce the amount of roughness on the arms. You also need to put supports everywhere to support the ribs. After I finish the project, I'll likely go back and create another piston that is just functional and not a replica. I can then remove the ribs to make it easier to print.

I also learned how to do rendering better with Fusion 360. Now all my models can be pretty!

[BrandtFX]

This is an awesome project! This was a dream toy as a kid. My cousins had one but I never did. lol

Just out of curiosity, are you using fusion 360 for modeling? Sorry, if I missed it if you mentioned it.

[Nighty80]

Great work and an amazing resource! Thanks for sharing

[Shwalamazula]

This is an awesome project! This was a dream toy as a kid. My cousins had one but I never did. lol

Just out of curiosity, are you using fusion 360 for modeling? Sorry, if I missed it if you mentioned it.

Yes, Fusion 360.

[OBEdaGB]

Waiting anxiously for the body files , if the stomp pedal can be printed in a soft material a full replica will be within reach.

[Shwalamazula]

A lot of things got in the way of finishing this project. I need to jump back in the saddle and finish this up. I'll put a writeup of the pedal build and testing next week. I know I made a writeup and stored it in a document somewhere. It was frustrating enough that I can rewrite it, if needed.

I will say that the pedal really is not good for 3D printing. You can print it in TPU and get a couple stomps on it, but the layers will eventually break down. I think if you wanted a functional replica of the pedal, it would be best to print to make a mould and then cast the part.

[Shwalamazula]

Now I remember why it took so long to get to the body. This thing is a pain in the butt to replicate. Part of me is thinking I should do what I did with the clip and just carve the thing out of a block. The other part of me is saying I'm nearly halfway there and to just keep going.

[SilentSpanky]

Is there a update for this? I am dying to know!

[Shwalamazula]

Life got in the way and I honestly forgot all about this project. I'll fire up Fusion tonight and see where I left off. Thank you for the reminder.