Key Holder

In this tutorial, I will be teaching you how to make assistive car keys. I will be showing everything from the design to the printing to the postprocessing. My inspiration for this project came from makers making change where I was inspired by one of their assistive car key turners. Below is my first step to showing you how to make an assistive car key holder

Tools/software that you will need for this project:

• Autodesk Fusion 360
• a 3-d printer
• rubbing alcohol
• paper towels
• tweezers

The first step in completing the main body is to create a sketch and select the rectangle tool. Select the rectangle tool and click on the origin, then draw a 80mmx30mm rectangle. Then select the 3 point are and create a 16mm diameter arc on both 30mm sides of the rectangle. After that you are going to want to extrude the rectangle part of your sketch 50.8mm (you will later make this a parameter). Then extrude one of the arcs 10mm and the other one the length that you extruded the rectangles which is 50.8. Lastly, on the side where you extruded the arc 10mm, you are going to want to make an identical arc on the other side and extrude it the same length (10mm)

The second step is to create the tabs for your keys. To do this create a new sketch on the y-axis and draw a rectangle that is 17mmx30.8mm. Add sketch constraints to your key holder so that this rectangle is 10 mm from each side of your key holder and the top edge of the rectangle lines up with the top edge of the key holder. Then extrude this so it cuts through the entire key holder. this created the part that would hold the keys.

The third step is creating tabs in the section that you just cut by extruding the 30.8mmx17mm rectangle. Create a new sketch on the top face of the rectangle that you cut. Select the rectangle tool and create a new rectangle that spans from the beginning of your extrusion to the other edge of your extrusion. Add a sketch dimension that makes this rectangle 2mm away from the edge of the rectangle. Extrude this rectangle by selecting the to object feature on the extrusion object and selecting the top edge of the key holder.

Now that you have one tab, you are going to use the rectangular patter tool and select the amount of tabs that you want depending on how many keys that you are trying to hold. I chose 7. Depending on the amount of tabs that you pick you will have to change the distance of the sketch constraint that you added in the last step so that the distance between all the tabs is equal

The 5th step of this project will entail making a hole for your thread. Do this by creating a new sketch on the semicircles that you did not extrude all the way. Then select the circle tool and make it 4mm. We will make this a parameter later. Again, add two sketch constraints to the circle one where the circle is 18mm from the base of the key holder and another where the circle is 12mm from the top of the key holder. Lastly, extrude this circle so that it cuts through both the semicircles on both sides of the key holder.

This step is optional however recommended. Fillets can be a good way to make a design look better and be safer. They are not required but if you would like you can select the fillet command and add a slight fillet on edges that you see fit.

As of now your main body for the key holder is done, the next things you must do is create your second component, the threads. Start by selecting the solid cylinder tool and creating a cylinder that is 3.8 in diameter and 8mm high. Then you are going to want to add threads on the outside of the cylinder. There are so many different setting that threads could have so instead of listing them out I will add a picture.

In this step you will be creating the nut for the threads. On top of the cylinder that you just made, add a sketch on the top. Select the circumscribed feature and create a hexagon that is 5mm wide. You are then going to want to extrude this nut down by 4mm and add threads on the inside of it too. Ensure that the threads are on the inside of the hexagon and not outside. Again I will add a picture of the thread settings for the nut. After this move the nut off of the cylinder and duplicate it.

To finish the threads add another sketch on top of the cylinder (in the same place where you made the hexagon) and add a circle that has a diameter of 3.8mm. Once done, add an offset plane that is 25.4mm above the TOP EDGE of the cylinder. Then reflect the 8mm threads that you made across this plane. Now you should have two 8mm threads about 50.8 mm apart. To connect them extrude the circle that you made on the top of the cylinder that was on the ground and extrude it to the bottom edge of the 8mm cylinder thread on the top

In this step you will be adding three parameters. You can add more but these were the only three that I thought were necessary. You will be adding one for the width of the keyholder, another for the length and one more for the threads. This is so your key holder depending on your key's size, can fit your key, no matter how long, wide, or thick the hole for the key ring may be. Begin by selecting the modify dropdown menu and selecting change parameter and add three user parameters. Make one say length of keys, another width of keys and another say diameter of threads. Now go back into your designs add the length of threads parameter to the diameter of the hole for your threads and add the length of your threads-.2 to your cylinder with threads and the cylinder that connects them. This is so that your threads with fit into the hole. Then add the length of keys to the length of your key dimension and the width of key dimension to your width of keys. The one thing about the width parameter that is a little hard is that you have to change the amount of tabs you have because there is no way to constrain or add tabs as you change a parameter so be conscious of that

You can print this by exporting your fusion files as STLs and sending them to some slicing software. It really doesn't matter what slicing software that you use. I used Prusa slicer. Whatever you do just ensure that you put supports everywhere otherwise your print may fail.

Again you can print on any type of 3-d printer just make sure that you wipe down the bed with alcohol so that you filament will actually stick to the bed. Also a good rule of thumb while 3-d printing is to watch your first layer. Usually, if a print fails, it fails on its first layer. If you watch the first layer, you could save yourself a lot of time and money.

This design requires very little postprocessing. The only thing that you should have to remove is supports from the holes where your threads would be. After that you are done and should have a fully functioning key holder.