Make Your Own Pen With a Built-In Ruler

Howdy!

I always enjoy solving problems that no one has, so today we'll try and make a pen that has a built-in ruler. Not only does it solve a problem, I'm sure three people have had before, it's comfortable to use, easy to assemble and convenient.

This is the second pen (and a massive improvement from the first) I've used a 3D printer to make. Before this, I've made a multitude of pens with my father on our lathe. All of those pens were more art pieces than useful and were always static. With a 3D printer, I can make pens that have moving pieces and can serve complex purposes beyond looking great (which this also succeeds at).

This pen didn't require a lot of knowledge in CAD, Fusion360 for me, and is simple to 3D print on either an FDM or SLA printer. For this pen, I used a hybrid of plastic and resin so that the pieces I needed to be durable and easy to replicate are made on my FDM printer and the higher detail parts on my SLA printer.

I hope that if you decide to print this pen or if it inspires you to make something similar, it'll be a worthy addition to your pencil bag or wherever you store your pens.

Thanks for reading!

This pen only requires a Sheaffer ink refill and pen springs. All other components are 3D printed and, if you want, you don't even need to buy glue. Besides the ink and springs, you will of course need either resin or PLA, the materials I used on my printers.

Supplies:

• Sheaffer K-Style Ballpoint Ink Refill (So long as it's K-Style, any color will work)
• Pen Springs (You use any spring that fits, it's all up to your preference)\

3D Printer Supplies:

• SLA/Resin 3D Printer (Anycubic Photon Mono 4k)
• FDM/Plastic 3D Printer (Ender 3 V2)
• Filament (Any PLA will work)
• Resin (Inland Plant Based 405nm Resin)

Tools:

• Nippers (For cutting supports)
• Sandpaper/Sanding sticks (For cleaning supports)
• Mask

Creating the Model:

To create this model, I used Fusion360 and will try to create another instructable that goes over the entire design process but for now, I'll link the 3D model. The model is already organized into labeled groups so feel free to download your own copy and change it up to make your own!

https://a360.co/3QfFoUP

Some notes about the model for editing...

• There is a disabled group, "Initials Sketch," that has a sketch and extrusions on the cap where you can add your initials and make sure you know which pen is yours.

• There is a space between the pin and ink cartridge where a spring will fit. I found it felt better with a spring, but you can always adjust the extrusion in the group "Pin Block" so that there's no space or more space for a spring.

• The group titled "Measurements Cut", especially the sketches, use a lot of processing in the operations. If you are going to edit the outer shell, I would recommend disabling the group to make any edits smoother.

If there are any issues with the model, feel free to comment and I'll be sure to fix it ASAP. Now then, we've finished making the pen in the digital world so all that's left is to see it in the physical world!

What Slicers to Use?

For all parts listed, I used a 3MF file and used the latest version of Cura for all my FDM prints and a combination of Prusa Slicer and Photon Workshop for my SLA prints.

I used a custom bed preset on Prusa Slicer that used the SL1 preset with a different bed. In my experience, Prusa's auto-supports are much stronger and more reliable than Photon Workshops and you can export the models from Prusa with supports, making the whole process much easier. Your choice of slicer is completely up to you and this is what worked for me for what I had.

Now for printing...

What Parts To Print? All of them!

All the parts listed below are straight from the Fusion360 model and require no extra prep to print besides support. I recommend printing "Ruler Pen Pin" and "Ruler Pen Cap Cover" on an FDM printer if available. Both have no detail or are suitable for an SLA printer. Do know that after you print both "Ruler Pen Cap Cover" and "Ruler Pen Cap," you will need to glue the 2 parts together (Will go over that in Step 3)

For FDM Printers:

If you don't own an SLA printer, the pen can be printed on an FDM printer without issue. My first drafts of the pen were all FDM and I encountered no issues using my stock Ender 3 V2 with a 0.4mm nozzle. The only con of printing with FDM is that tolerances will be tighter and you will be missing some detail but I'm sure that with a few tries, it can come out looking great.

For SLA Printers:

For all SLA printers, I would recommend not angling "Ruler Pen Inner Shell" and "Ruler Pen Outer Shell" to save on resin and making assembly easier. Printing them vertical will increase print time, but allow for all the parts to fit on a smaller printer bed.

Being Mindful of Tolerances:

Assembly consists of one step - insert the ink, spring and finally lock the pin inside the inner shell. Doing this requires some delicate tolerances, especially with the ink and pin. Before committing, I would recommend checking the inner diameter to make sure that there is clearance for all the parts. I will admit that I ruined an ink cartridge by getting it stuck in one of the pens and having to use drill bits to get it out, so I would rather not have ya'll repeat that.

When assembling, I would recommend going through the following process without the "Ruler Pen Outer Shell" on the pen. The Outer Shell can only be locked in place once the pin is added and trying to lock the pin while the "Ruler Pen Outer Shell" is unlocked will make it slip out. Once the pin is locked inside, it can be rotated to let the Outer Shell slide on before rotating more to lock it.

When assembling the caps on my pens, I printed "Ruler Pen Cap" on my SLA printer and "Ruler Pen Cap Cover" on my FDM printer. Doing this means that the two pieces will need to be glued together, but the process is fairly simple. The cover is aligned by angled cuts on the bottom that match with the hole on the cap. There are 2 ways to glue the pieces together - traditional super glue or the resin from your SLA printer. For all of my pen caps, I used the resin already in the vat.

Cleaning SLA/FDM Print:

Please wear a mask and gloves when dealing with resin, especially while sanding

When cleaning prints, I recommend using your choice of sand paper/sanding sticks to go about smoothing any imperfections. When working with resin prints, I use high-grit sandpaper covered in water. When the sandpaper is damp, it'll hold onto the resin dust particles instead of flinging them all over your workplace, reducing the chance you might breathe it in. You have to be careful when sanding, as too much and you could remove details. It is much easier to clean supports off of an FDM print but with the sacrifice of details straight off the print bed.

Order of Operations (Assembling Pen):

1. First, insert the K-Style Ballpoint Ink Refill into the Inner Shell. Assuming there is enough clearance, it should fall straight through and stick out just enough.

2. Drop the pen springs in right after. It's a little bit unorthodox to have the spring in pushing the ink forward instead of backwards, but this allows the pin to be under the most tension and makes the whole mechanism much tighter

3. Insert "Ruler Pen Pin," making sure that the key will line up with the slot in "Ruler Pen Inner Shell". Once the key is in the slot, the spring will be under tension and will want to shoot the pin back up, so be sure to hold it in when rotating it.

1. The pin will be able to turn 180° to lock the Outer Shell in place.

4. Rotate the pin 90° counterclockwise so that the tongue is in line with the pattern on the "Ruler Pen Inner Shell". When the pin is positioned like this, the "Ruler Pen Outer Shell" can be slid on.

1. Once the "Ruler Pen Outer Shell" is on, rotate the pin another 90° counter-clockwise to lock the parts together.
2. To remove the "Ruler Pen Outer Shell" and use it as a ruler, repeat the step backwards, making sure to only rotate the pin 90° from the locked position or the pin will fall out with the spring and ink (Might be shot out because of spring tension).

Order of Operations (Assembling Cap):

1. (For super glue) Apply the glue onto the rim of the hole on top of the "Ruler Pen Cap". Place "Ruler Pen Cap Cover" on top and hold down until dried. Clean up any excess glue that might've leaked out of the gap.

2. (For resin, before UV treatment) Use a toothpick to apply the resin onto the rim of the hole. Place "Ruler Pen Cap Cover" on top and hold down to clean all excess resin that might leak out. The cover will not be secured to the cap yet, so don't drop it.

1. Like with any resin print, put the assembled cap into your UV chamber and turn on for however long you deem necessary for the part (I did it for 5 minutes). The uncured resin securing the cap will cure and bond the FDM cover with the SLA cap, creating a secure connection.

Have Fun Writing!

Send any questions or comments you have and I'll be sure to respond!