Assistive Jar Opener

Opening a jar or bottle is a daily task that most people take for granted. However, for individuals with limited mobility or limb differences it can be a frustrating hurdle. Our team designed this cost-effective assistive device to change that, allowing users to open a wide range of containers independently using only one hand.

The device works by securely anchoring the container in place, freeing the user to twist off lids without needing a second person to help. In this Instructable, we’ll walk you through the design process, the materials needed, and step-by-step instructions so you can build your own and help make everyday life more accessible.

Materials

1. PLA filament: Creality High Speed PLA Filament 1.75mm
2. Dycem: Non-Slip Material Roll, Black
3. Poly Foam: Cushioning Material

Tools

1. CAD software
2. 3D printer
3. Superglue: Gorilla Super Glue Gel XL
4. Sandpaper: 120/150/180/240/320/400/600/800/1000/1500/2500/3000 Grit

Our team began the design process by researching existing automatic jar and bottle openers to gather inspiration and identify key features that might be useful for our application. After an extensive online search, we realized that most available products were either overly complex, reliant on electronics, or were designed for users with full upper body functionality.

After evaluating the specific needs of our client, who retains full use of one arm and hand, we concluded that a fully hands-free solution was unnecessary. Instead, we transitioned our plans toward developing a simple, assistive device that could enhance independence without adding unnecessary complexity.

To prioritize simplicity, affordability, and ease of use, we opted to leverage the user’s own body for stabilization. By using the torso or hip to hold the device in place, and the users fully functioning limb to twist open the desired object, we were able to eliminate the need for motors, wiring, or batteries entirely.

From there, we focused on designing a low-profile clamping base that could securely hold jars or bottles in place while the user twisted the lid open with one hand. The frame includes:

1. A curved back support to provide surface contact and resistance
2. Two L-brackets to stabilize the base laterally
3. A sliding shaft that adjusts to various container sizes
4. And a retaining ring to ensure the sliding mechanism stays in place during use.

Materials such as super glue and Dycem were chosen for their effectiveness and accessibility, enhancing both the grip and durability of the assembly. The result is a lightweight, affordable, and functional assistive device that meets the client’s needs without overengineering the solution.

A total of four different parts were designed and manufactured through 3D experience. The parts were made so that every edge was not harmful to an individual, such as sharp edges or material choice. This ensured that even if the leverage device were used incorrectly, it would not harm the operator. All fillets in the 3D modeling are 0.1-inch radii.

Table Holder

The table holder is just an L bracket that connects to the top of the base section. This prevents the device from moving on the table when pressure is applied. The specific file linked below features a holder that is half an inch by half an inch in cross-section. It is also 5.5 inches long and 3 inches tall.

Automatic Jar Opener Rod

The jar opener rod features a base that is big enough for the user to apply pressure on with their body. The base section is around 3 inches by 1.5 inches. This is sufficient to apply enough pressure to hold the jar. Also, it features a shaft that extends through the jar opener base, which is 7 inches by 1.25 inches by 0.75 inches and features a 5-inch radius on the end to hold most jars.

Jar Opener Base

The jar opener base is the object that holds everything together and in place. It features a large 5-inch diameter jar section that is capable of holding almost every single jar on the market. Other than that, it is just a 7.5-inch by 6.5-inch by 0.5-inch base section that has support walls to help keep the jar in place. This wall is approximately 2.5 inches tall to accommodate short and long jars. The last section of the base features the hole where the jar opener rod connects to allow the leverage device to work. The hole is the same dimension as the rod above to allow for no lateral movement while using it.

Jar Opener Rod Holder

The rod holder is just a ring that glues on the end of the rod to hold it inside the base's hole. The ring has a 0.2-inch tolerance on it, allowing it to slide on easily and glue where the user wants it. The hole in the middle is approximately 1.27 inches by 0.77 inches and features a 1/8 inch offset.

All 3D-printed components for this project were designed using standard 3D modeling print settings. The team used Bambu Studio to orient, slice, and adjust print settings for each part. Printing was performed using a Bambu Labs 3D printer.

1. Material: PLA
2. Layer Height: 0.175 mm
3. Infill: 15–20% (Grid or Gyroid pattern)
4. Supports: Tree (auto) only within the loop of the main base everything else should print directly onto the plate

Print times will vary depending on the printer and print settings selected, but most components are relatively quick to produce. The parts were designed with a focus on structural strength and ease of manufacturing, aiming to balance durability with reduced print time and efficient material usage.

When 3D printing you will need to put internal supports into the ring in the main base. Any slicing software should automatically apply these support structures. Upon removal from the 3D printer you may need to cut out this internal structuring piece using a box cutter or scissors if you cannot just break the structuring out easily.

This project consists of five 3D-printed components:

1. The main base with a curved back section
2. Two L-brackets
3. The sliding shaft that fits through the hoop
4. A retaining ring that secures the shaft in place
5. Attach Foam on the end of the rod

Step 1: Assemble the L-Brackets

Attach the two L-brackets to the left-hand and right-hand sides of the main platform using super glue. Ensure the edges of the brackets are flush with the edges of the main platform.

Step 2: Insert the Sliding Shaft

Slide the shaft through the rectangular hoop in the main platform. Ensure the shaft moves freely before proceeding.

Step 3: Secure the Shaft

Attach the printed retaining ring to the end of the shaft using super glue. This prevents the shaft from sliding completely out of the hoop.

Step 4: Apply Dysem for Grip

To prevent slipping, attach Dycem using super glue to 5 key areas:

1. The back of the curved section on the main base
2. The curved end of the sliding shaft
3. The legs of the L-brackets
4. The bottom side touching the table of the main platform
5. The bottom semi-circle shape of the main base

This improves stability and ensures the assembly remains secure during use.

Step 5: Attach foam to the end of the rod

Cut the foam to the desired size to be placed on the outer edge of the rod that will contact the body. Super glue the foam to the end of the rod.

Let all super glued components dry completely before using the device.

For future work, the team expects the materials to be:

1. Lego gears
2. Simple grip extender
3. PLA filament
4. Batteries
5. Two push buttons
6. Foam
7. Dycem

The team had started prototyping an automatic handle that would grip any lid and make it easier to untighten using leverage. A 3D-printed grip would be made that includes the simple grip extender and a screw system to open and close the extender.

The design included a screw that would be set inside of the casing with a small square piece that would move up and down the screw. This square piece would be connected the one of the edges of the teethed area that closes around the lid. The screw itself would be mounted to a motor that would be controlled by two external push buttons. The button will control which way the motor spins therefore spinning the screw and opening or closing the square piece and thus the closing piece around the lid. This would be powered by replaceable batteries as well. Lastly this will all be contained inside of a larger 3D print casing so that the action would be similar to an automated monkey wrench.

Inspiration for Other Creators

1. Stationary Jar Lid Opener
2. This jar opener is put onto the bottom side of a counter, allowing the user to twist the jar. Once the user twists the jar, the lid grips onto the spikes that pop the lid off
3. Not good for small water bottles or any bottles that could be damaged
4. Automatic Top Jar Opener
5. This jar opener uses motors and rubber grips to grab onto the jar's top and side. Then it twists the lid off one way while twisting the bottle the other way.
6. One issue was the jar twisting, not allowing the lid to pop off easily. If there were some way to hold the jar stationary, it would work better. This helped the team come up with the leveraged body weight-activated holder.
7. Top Clamp Opener
8. This device requires a clamp that can be squeezed with the user's hand to tighten to the lid's size, and it would lock into place. Then the bottle would have to be held with one hand while the top clamp had to be twisted with the other.
9. The team's goal was to use one hand to be accessible to all types of people who might struggle opening jars. This also inspired the team to create the jar holder on the table to allow the user to use one hand. This device might damage jars, too, with the teeth it has.
10. Sticky Surface Jar Opener
11. This is a common tactic that people can use in their homes all the time. Getting a board with a stick surface on it, then applying pressure down with the jar to open the lid with one hand. An example of this material would be Dycem.
12. This inspired the team to use a grip surface because if the user did not have a way to put high amounts of force down, then the jar would just spin. This inspired the use of Dycem on the team project to ensure this would not happen.