Alternative Door Lock

grabcad

Intro:This entry is a 30% scale model of an alternative door lock. The inspiration came, unfortunately, from the recent school shooting. We thought that an extra lock to slow intruders down might be life-saving in schools that have yet to be retrofitted with the latest security measures. From there, the idea ballooned into a way to add security to rented rooms while traveling, and keep people (especially young children) out of bedrooms and bathrooms that don't have built in locks.Inspiration:The design is meant to be quick and easy to use. All you have to do is open the door, place the vice so the door is between the end plates, then pull the door shut, and slide the vice sideways to hold the door jam. After that you simply push the rod in until the vice is tight, and pull the lever down to lock it in place. A lock rod on the side can also be slid over the lever for added security.Design Process:We began our process by brainstorming problems to solve. We put a week into asking people what problems they needed solved by a customized part. We then spent several hours coming up with our own ideas, and refining ideas others had pitched. Once we had decided on a project, we created a series of isometric and orthographic sketches on paper to use as a guide for the design. We examined several doors to decide on dimensions and necessary parts. Then we created CAD drawings of each piece. Finally, we put all the pieces together in an assembly and scaled them down to fit the size requirements.Scaling:The original design was meant to fit a door jam anywhere between 2.5 and 9 inches, but we have scaled it down for this challenge. We have included dimensioned drawings of both the full size and 30% scale model, but the submitted CAD files are all the smaller size so as to follow the size requirements. Some dimensions were adjusted in the scaled down version to maintain structural integrity. Drawings of the design in its original size are available upon request.Innovations:The design is based on a cam vice, but we modified it to optimize its performance. The cam itself is contained in a removable box at the back. This box can be unscrewed and placed on either side of the track. We avoided having it centered because this would put more pressure on the end plates. By having the rod offset, pressure can be applied directly over the door jam, preventing excessive stress being applied to the plates. This means that the design works just as well whether the door opens from the left or right. Because of how easy it is to set up, a user can put the vice on the correct side as soon as they know what door they are going to use it on. Then it is ready at a moments notice. The removable box also allows for more compact storage, since the box can be taken off and placed between the end plates. A removable stand can be screwed onto the side that is not on the track. This stand makes sure that the vice box remains level. The addition of a lock rod to slide over the lever also means that this alternative locking device can be used on doors that open in and out, since the lever cannot be forced up from the outside.Cam:The size of the cam and how far its axle is offset from its center can be adjusted relative to the strength of the material making up the rod.Materials:Outside of the screws, the entire design can be 3D printed. However, we had specific materials in mind for each piece. The rod that holds the end plates against the door jam should be made out of metal, since it is under the most stress. Our preferences would be stainless steel for the rod, TPU for the cam, the handle of the rod, and the inside of each end plate, and ABS plastic for everything else. The screws and nuts should be store bought. The support filament would need to be dissolvable in the scale model, and it would be preferable to use dissolvable filament in the full size model, but it could be printed in ABS plastic with the rest of the design.Print:The 3D printing method that the design is made for is Fused Deposition Modeling (FDM). We chose FDM printing for multiple reasons. The first is that it is the kind of printing that we have had experience with in the past, so we are more familiar with the limitations of the plastic and the minimum dimensions that pieces can be in order to successfully print. The second is that it is more widely used by individuals and schools so that it is possible for more people to print the design themselves. The cam and cam assembly would have to be printed together as a single part with multiple filaments.Submitted By:Yana Burgess, Age 16 and Billy Wencl, Age 16Saint Peter Area Robotics Advisor: Teresa Burgess