Intro: 3D Printed Multitool/Pocket Knife
I love multitools; when I went to college I bought myself a Leatherman and I used it almost exclusively for many DIY projects instead of having to buy more tools. Multitools pack a lot of versatility to fit in your pocket that turns any maker into MacGuyver at the flick of a wrist. Recently, I've also become a fan of simpler, more focused multitools, like the Gerber Artifact, that aim to give you the bare necessities in a small package, trading versatility for portability. My goal with this project was to design a versatile and compact multitool that would only have the tools that I want to use. Additionally, I chose to 3D print it which is the easiest way for me to fabricate it but creates a few more challenges - most importantly, to make a strong enough tool. I have also tried to make the non-3D printed parts simple to source or find at home to make it easy to replicate.
As of right now, I have not been able to print it, but I will share the models and how to assemble it. If someone is inspired to make it, let me know how it goes!
Step 1: Design Concepts
To start, I tried to narrow it down the the tools that I wanted to include in the multitool. This would determine the shape and functionality of the tool. I came up with:
3D printing makes an interesting challenge with a knife. I didn't think I could 3D print a knife I would be satisfied with (except for maybe spreading butter) so I decided that it would have to have attachment for and X-Acto blade. This also lets me replace the blade easily when it dulls.
To me, having pliers or a wrench type of tool is a no-brainer. They are the most used tool on my Leatherman and I don't think I even own another pair of pliers besides that!
- Having different kinds of screwdrivers is also important for a multitool I think. To increase the versatility of the tool and save on size, I decided to use different hex bits to be able to swap out screwdriver heads.
Step 2: Bill of Materials
These are the materials you will need for this project:
- The 3D printed parts
- 5 M2 Socket Head Cap Screws x 15 mm long
- 1 M2 Socket Head Cap Screw x 3 mm long
- 6 M2 Hex nuts
- 2 small springs from pens
- Open up some click-style pens and take out their springs. They should be about 1/2" long.
- Superglue (optional)
Tools you may need
- Allen wrenches (1.5 mm to be exact)
Step 3: Print Your Parts
Download the attached STLs and print with your favorite 3D printer or 3D printing service. Choose your material wisely, as this is a tool that will come under stress. I would recommend ABS over PLA because it is stronger and more ductile (it will bend more before breaking, unlike PLA which is stiffer and will bend less before breaking). However, PLA will work too as it is a strong plastic, just be sure to have a high fill percentage.
When choosing your settings, again remember strength: fill percentage > 70% and thick walls.
Step 4: Assemble Base Plate
Take your x-acto blade, M2 x 3 MM screw, a M2 nut and the blade holder part. You can glue the nut into place in the printed part if you'd like. Then assemble as shown in the picture, with the screw holding the blade in place.
Then take the x-acto blade assembly, wrench top part, the trigger,the base plate, and the two springs. If you are gluing your nuts in place, now's the time to glue them in the back of the base plate.
Assemble as shown in the image, with the x-acto blade assembly and wrench piece fitting over their pegs with a little bit of clearance. If they don't fit or feel too snug, use fine sandpaper to sand down the peg until you get a fit that you like. These parts will rotate but should not be too snug. If they are too loose, don't worry, they will be tightened down later with screws. One of the springs will fit in the front of the wrench in the two matching holes on the wrench (see pictured).
Place the trigger on the rear of the tool as shown. It needs to fit in the hole fairly loosely so that it can rotate freely. Again, use sandpaper or a file if necessary. The remaining spring fits between the trigger and the tool base plate as shown.
Step 5: Assemble Top Plate
Take the top plate, lock piece, and door. The locking piece slides in the rail on top by the knife. This will be the locking mechanism to hold the blade in place either when closed or open. This should be snug enough that it doens't slide freely but loose enough to move by hand. Again, sand or file if necessary.
Align the door and the top plate so that the door fits in it's groove. Align the top plate with it's screw holes and start screwing it down. Adjust the screws so that your blade, wrench, and trigger mechanisms rotate how you want them too
Step 6: Assembled Images
To use the wrench, the trigger will lock it in place when you press on the end of the wrench handle and when you press the trigger down it will release the wrench again.
To open the blade, slide the lock down, then swing open the blade and slide the lock over it again.
The tool can use standard 1/4" hex bits or you can use the printed ones I provide. They can be stored by sliding open the door and there is a socket on the end of the tool and on the side for higher torque applications. The beauty of this is you can choose what bits you want for your multitool! You can use flathead, sockethead, torx, Allen wrenches, whatever you need.
Remember that the strength of your tool is dependent on the strength of your material. I am not responsible for what you do with this tool or if you break it or injure yourself. Know the limits of your tool; if it feels like too much torque or force then grab a different tool.