An open design pen that supports different refills. “One pen to house them all.” A design for the Trikka system.
One afternoon in the Mifactori workshop. A question comes up: How about an open circular design pen? A bit later the key solutions were found. We share in this post a couple of iterations. And explain the trick that makes O:pen extra circular!
Update: Version 3 was added to the Trikka catalog.
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Circular: One pen to house them all
It happened to most of us: Our favourite ball point pen is suddenly out of ink. We search for another ball point pen to swap the refill. Only to discover: the refills are different. The new one does not fit. Well if O:pen No1-No4 is your favourite pen this won’t happen again that often.
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O:pen is designed to have space for all available refill sizes. The locking screw keeps the refill in place.
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Versions
All pens are around 130mm long.
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№1
The first attempt. The outer tube has two internal threads (M3).
Click below for more pics and info ↓
If you chose the right diameters for the parts this pen holds most available refills.
Howto:
- The small inner tube does not have a hole here.
- The outer tube has two internal threads.
- The locking screw in the back allows to adjust the size of the inner space and presses the refill on to the inner tube.
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№2
The outer tube has one internal thread. The inner tube has just a hole.
Click below for more pics and info ↓
If you chose the right diameters for the parts this pen holds most available refills.
Howto:
- The outer tube has an inserted thread for the M3 locking screw or locking bolt.
- The bolt reaches through the hole in the inner tube and presses down the refill to fix it.
- The images show a nice way to make a cap. Just take some silicon tube and pull it over the pen.
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№3 * Trikka
The outer tube has just a hole. The inner tube has an internal thread.
Click below for more pics and info ↓
If you chose the right diameters for the parts this pen holds most available refills.
Howto:
- This works like No2 just the other way around. The outer tube has no inserted thread the inner one does.
- The locking screw presses down the refill to hold it in place.
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Parts
IP Protected
No and not planned. Date of publication March 8 2023.
This is easily done with printing your brand on it.
Purchasable
Currently only as Local Make (1 €/$ donation per make)
Support the designer: Your donation address
Manufacturer Contact
hello@mifactori.de
Post license
This post is shared under the Creative Commons Attribution 4.0 license
Disclaimer
This product is just a concept and not fully tested. You should not assume that it works as indicated and I am not saying that it does. I disclaim any responsibility or liability for any damage caused during the construction and use of products based in whole or in part on the concept shown here. All information is provided for your use at your own risk.
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№4
A rubber tube at the front prevents the refill from falling out. The bolt at the back prevents it from being pushed out.
Click below for more pics and info ↓
Unless you make the bolt in the end really long this version can’t deal with refills that have different lengths. You are more or less bound to one length.
Also refills with a thick centre body have a diameter of 6mm there. You would then have to use screws M7 or M8 in the back. This quickly makes the pen very large and unnecessarily heavy. So you usually have to rely on thin refills.
Howto:
- Cut a thread in the back for a fitting bolt. In the pictures you see M5 & M6.
- The part in the front should have an inner diameter of 3mm (that’s what refills come out to) and an outer diameter that fits tightly into the outer tube.
- Friction is what prevents the refill from falling out. To change it, you just pull it out in the front.
- In the pictures you see a version with a body from softer plastic. In this one we could just screw in a bolt in the back without having to cut it first.
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№5
The outer tube just has a hole. Combine it with an off the shelf set collar and be ready.
Click below for more pics and info ↓
This version is only for thin refills which have a diameter of 3mm. This allows you to have an outer diameter of 5 or 6 mm for the outer tube. You should not go larger because the set collars might grow quite big and heavy quickly.
Howto:
- Drill a hole in your tube. Shop a set collar. And be done.
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№6
Just one tube with an internal thread.
Click below for more pics and info ↓
Just suitable for thin refills.
Howto:
- Just find a tube part with an inner diameter between 3,5 and 5 mm which is thick enough to add an inserted thread.
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More Images from these pens (full Flickr album)
