Project: Fan speed selector cap

How is a 3D printer actually used? Where do we get the parts from? I hope this blog post gives a better overview of what the entire process is like.

The problem: self-explanatory.

2015-06-12 15.07.01

The solution: design a replacement! If you don’t know how to use a vernier caliper, now is the time to find out. (Ask your science teacher.) Let’s talk about how to do this designing in another post.

fan speed selector switch

Easy-peasy. Let’s just print it out and use it, right? Not quite:

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It turns out that what is printed does not always match the original design exactly. In this case, it seems to add about 0.2mm on all sides, making the centre hole smaller than expected. I couldn’t force this cap in any further without risk of breaking the stem.

Other issues: the fan speed indicator is slightly too small as well. Try to spot the little dimple:

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Fortunately, scaling up a print in FlashPrint is easy enough:


The cap is now slightly wider—that’s okay. But the stem is now too long—that’s not okay!

Three test prints later:

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That’s quite a bit of plastic wasted. We should find a way to test with less wastage.

What can we do now? Redesign it from scratch? Too much trouble. Let’s split it into two parts, the stem and the cap, instead. Now we can print just the stem to test for fit, and resize it separately from the cap. And we can print a few of these at a go, to slightly different sizes, to save time:

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Another problem: the stem is being printed too quickly. Each layer of the stem doesn’t have enough time to cool before the next layer is printed on top of it. The result: warping. This causes our stem to be about 5% thinner than it should be. No wonder the test print wasn’t fitting!

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Printing at 40% speed finally yielded a good fit. We would be able to print at 100% speed if making multiple copies, since the layers will have more time to cool as the printer travels back and forth creating multiple copies of each layer.

With these settings, it takes about 35 minutes (including nozzle heating time) and 2 metres of filament (roughly S$0.25, with our current supplier) to print one.

Time spent so far: 5 days

[15 June 2015: Project went on hiatus until 12 August 2015]

Finally, I got the Flashforge Dreamer set up to print with white ABS filament. This makes the cap look more natural:

Photo 12-8-15 15 32 32

It’s a snug fit!

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Job complete! Final print time 30 min – 1 hr.


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