Dangerous Ladies' 3D models for twist-lock PVC pipe connectors.
Model by Jennifer Rezny (@quicksparrows)

.stl format. Should fit on any printer. Print with REALLY thick walls if you want them to be super durable!

A great way to make props collapsible is to split the PVC pipe and install a joint, but commercial joints tend to be either difficult to find or bulky, as they fit to the outside of the tube. 

PVC pipe, as you may have noticed, also comes in different sizes. It's measured by inner diameter, but that varies slightly depending on whether the pipe is schedule 40 or schedule 80. Annoying, right?! It can make it really hard to find something that slots into each end snugly without being too loose or too tight.

This file solves that, and adds an extra bit of security for separation: it's a twist lock! These printable tubes and sheaths slot into each end of the PVC pipe, so you can glue it in one side and then slot that into the other part to take it apart or put it together. Part A has a nub that slots into part B and then rotates 3/4 of the way around so it cannot slide back out until you rotate it back.

You can figure out which size you need to print by looking at your PVC pipe; it should be printed right on it whether it's schedule 40 or 80.

To install, the sheath should be flush with the edge of the pipe, and the connecting tube should sink in until the split between the thicker part and thinner part.

You might also find they are a smidge tight or a smidge loose; sometimes this is because pipes can vary very slightly from company to company, and sometimes because your printer isn't calibrated well or is printing too fast to do accurate dimensions. That's okay! You can just scale the print up or down very slightly as needed.

Files include:
- Photos
- .STL files

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HOW STRONG ARE THESE?

Obviously 3D prints are only as strong as their print settings and print orientation. There is important information below that will help you print the best twist lock possible!

For the standard twist locks, the part that needs the strongest printing is the "B" side, which slots into the "A" side. This is the part that sticks out of the end of your PVC pipe and thus is most susceptible to damage.

We suggest printing with 1.6mm walls (4 walls on a 0.4mm nozzle) and a 30% infill minimum, but you can thicken that if you want. At those thicknesses, they should be nearly impossible to break with you hands without using something as deliberate leverage, such as snapping it against a table edge. We have put these pieces with these settings into a vice and beaten them with a hammer; it takes a few strong strikes to damage the print. 

Obviously when you are taking your prop through transit or at a convention, you will not be beating it with hammers. (Ideally, anyway.) However, there are many ways a prop can experience brute force, such as being stepped on, or snapped in a crowd. In my opinion, any damage sustained in these scenarios by the twist-lock would likely be the same for most other connections. In fact, it might be better for the twist-lock to break under extreme stress because you can drill it out and replace it, whereas a completely rigid joint might prompt the prop to break in a place that's harder to repeat.

That said, there are a few variants to this file you can use to print stronger twist locks:

BASIC
This is the basic Part B. It's strong with good print settings, but you can make it stronger without any modifications by simply off-setting the whole joint in the pipe by 1/2". This means the thicker part of Part B will jut out of the PVC pipe by 1/2", and Part A will be sunk in by 1/2". When connected, the spike of Part B will be protected from vertical torque (downward force when the prop is held horizontally!) by having the thicker part passing into the other pipe.
Pros: Stronger
Cons: Lining the pieces up accurately can take a little bit more care, as it has to line up. I suggest gluing Part A in place in the first PVC pipe first, locking Part B into it, and then attaching Part B into the second PVC pipe while they're attached so you're guaranteed a clean alignment. Just be careful not to glue the two together!

HALF PRINTS
These versions allow you to print Part B in two parts, a top and a bottom.
Pros: As it's printed flat on its back, the filament runs side to side along the long part of the piece, making it much, much stronger than if it were printed vertically.
Cons: You have to line these pieces up accurately, and they are generally too small for alignment keys without introducing new weak spots.

FLAT BACKED
These versions allow you to print Part B flat on its back, making for a much stronger print with no alignment issues like the Half Prints.
Pros: As it's printed flat on its back, the filament runs side to side along the long part of the piece, making it much, much stronger than if it were printed vertically.
Cons: While the missing chunk does not create structural issues and still goes into Part A just fine, it means there is less surface to glue the base inside the pipe.

SLOTTED
These versions print vertically like the basic Part B, but it has a channel inside for a support beam, which you can print flat (long side against the bed) and then slot into the main Part B piece. The listing video shows how to insert the support beam!
Pros: The support piece adds a huge amount of additional strength.
Cons: Depending on your printer's tolerances and calibration, the support piece may be slightly loose or slightly tight. If tight, sand down a bit so there's space for glue, and put in place. Hammer gently if necessary. If too loose, try printing the support piece at 100.5% scale, or use a high volume glue to fill in space.

CAN I PUT A NAIL OR SCREW IN IT FOR STRENGTH?
You could, but the reason I don't offer this as a file variant is that there are hundreds of different screws and nails out there in multiple units of measurement, and there is no way to account for all the different options, sizes, etc without introducing a huge headache in finding the appropriate hardware. I designed these so they can be made entirely 3D printed with no need to scour a hardware store for something specific, which can be an accessibility issue and/or point of stress for many cosplayers, who prefer to DIY entirely at home.

You're welcome to modify these files for personal use, of course!

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SUPPORT SETTINGS
If your printer is very good at bridging, you can print without supports. Bridging is your printer's ability to cross chasms without support underneath and provide a good result. If the bridge sags, it'll change how Part B slots into Part A. You can find many "bridging stress tests" online on sites like Thingiverse; these are prints you can run to see how well your printer can pass tests bridging greater and greater distances.

If your printer is not so good at bridging, I suggest printing with tree supports. You can knock these out afterwards with a tool, preferably a small metal hook or pick. If there are tiny pieces left behind, it's okay; just insert Part B into Part A and twist until you feel resistance. Oftentimes these locks are stiff at first, but as you twist them back and forth (and periodically open them up again to dump out loosened plastic) you should be able to clear the path.

If you can't get the lock all the way to the end of the channel (5/6 of the way around) then that's okay! It really only needs to go the first bit to lock in place, it's just more secure if it goes all the way around. The tolerance is tight enough that it should never fall loose; it will always take some level of manual twisting motion to loosen.

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Please do not redistribute or resell. Intended for personal use only. Commercial use must buy a new copy for each item produced.

Feel free to tag us to show us what you print and make! We love to see finished works.

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