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Mechanical Linkage Pen MKI

by blackdynamics Aug 26, 2019
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So after using this for a while and using the lever to fidget with, the bit that holds the level starts to weaken and the pen retracts whenever pressure is put on it to write.

Great design though.

This is a great looking pen! It's the perfect instrument for a makerspace, too. Are the bolts threaded directly into the plastic or are there nuts involved? It appears there aren't many bolts, but could we get a bit of a bill-of-materials?

It appears to be something like this:
M3x6 cap head
M3x6 button head
M3x4 button head
M3x12 button head

One each of the above?

If you don't mind me saying so, you've underpriced your art on Etsy. It's easily a six dollar pen or more!

Thanks for the feedback! I have the screw types in the instructions, but you’re right it would be easier to break out in a BOM. I am just selling them at cost, since I just want others to enjoy my inventions.

I appreciate the quick reply. I saw the types in the instructions, from which I created the list in my comment, but my question is it only one of each length and type of screw? I suppose it will be obvious if I print the pen, but I like to be prepared, generally speaking.

That’s correct, it is just one of each. Others have just used all cap screws, if that is all that is on hand.

Hello, I have a question regarding the print orientation of the main body part.
Is this the correct way? https://imgur.com/gallery/gNnWW6U

Hi, that is the correct orientation.

Love this design, any chance you could release the source files?

What kind of pen inserts would you recommend?

I remixed the plunger to make it longer to work with pens I had on hand,
I also remixed the handle so no cap screw is needed.

I love this gadget! Thanks blackdynamics.

@DanMann, I've run into a similar snag. The OfficeDepot version of these pens appear to be the same, but the pen doesn't extend from the tip. You note that you made the plunger longer (6 mm?) but in my assembly, the compression spring reaches the maximum and won't compress farther.

Would you think it's then necessary to slice the 6 mm from the main barrel near the tip to get the pen to extend enough for use?

I shortened the spring. I had thought of shortening the pen barrel. I think tinkercad reduced allowed file size so I could not alter.

I hadn't thought of cutting the spring. I just came back from the garage after drilling 7 mm diameter hole 6 mm deeper and then also drilled the tip to give clearance that wasn't there previously. With a 6 mm increase on the end plunger and careful drilling, I might be okay.

I probably would use Meshmixer to slice the 6 mm out of the barrel length, but drilling and not re-printing is a lot easier. Shorter spring is even easier!

Have you noticed anything not going well by cutting the spring? I might try that with the next iteration.

no problems with the shorter spring. One thing I noticed when I remixed the first arm was that the nib that replaces the screw was a bit too tall. When released to close the pen the arm would snap and stay in place due to a friction fit. If this can be perfected then one could eliminate the slide lock.

Alternatively, I wonder if the linkage or arm was modified that the spring pressure would hold the arm into the body tight. It seems the current geometry makes the arm kick out, thus requiring the slide lock

You might want to also check the clearance between where the ballpoint pen exits the pen body. It is a close fit so that it doesn't wiggle around when you're writing, so you may need to bore it out a tad. You can check by putting the ballpoint pen into the writing end of the pen body to check clearance. Glad to hear you're up and running though!