Mojoptix 001: Digital Sundial
Tadam ! The very first episode in [ENGLISH] of the Podcast Mojoptix:
So we’ve just developed an invention, from the epiphany through the first test of a prototype !
As I mentioned in the video: it’s all Open Source !
You can find the Openscad script and the STL files on thingiverse: http://www.thingiverse.com/thing:1068443
Sundials and Kangaroos
There is a tiny subtlety if you want to use this sundial in the Southern hemisphere:
Try to visualize an kangaroo in Australia. Just like everyone else, this ‘roo has to orient the tip of its sundial toward the north pole. For him, that means having the tip of the sundial pointing toward the ground…. this doesn’t seem very practical. Our hinge mechanism doesn’t even allow to tilt the sundial below horizontal.
The trick here is simply to build a subtly different magical black box (also called a gnomon) for kangaroos: in the Openscad script you can set a flag that will simply rotate upside-down the whole swiss cheese inside the gnomon, and build a ‘Southern-hemisphere’ version of the gnomon. This way, the ‘roo can simply use this Southern-hemisphere sundial exactly the same way a cow or a penguin would use their Northern-hermisphere version the sundial, with just one difference: the ‘roo will have to point the tip of his sundial toward the *South* Pole.
Fun fact about this sundial
You will most likely never see it in a supermarket or a department store. The swiss cheese inside the sundial is so intricate, that you can’t realistically use injection molding, or some other mass-production method. 3D printing seems actually to be the only practical way to build this digital sundial ! (is that really true ?? let me know what you think in the comments !)
Open Source model
One day I might write a proper wall of text in this blog, about the zoology of business models based on Open Source hardware. By the way, I really hope space aliens are also fond of Open Source Hardware (otherwise we might not be allowed to copy their technology). Here, this digital sundial is an interestingly exotic case:
It seems almost perfectly well-suited for an Open Source Hardware business model. You can only craft it with hobby/prototyping tools, and only very slowly (one every 1.5 days): basically it’s ideal for ” High-Tech Artisans “.
…which (almost naturally) brings me to say a couple of words about my gift shop on Etsy :
It was envisionned with two types of public in mind:
— Makers without a 3D printer, or the patience for 35hours of printing (it is a somewhat challenging print). This should still give them the opportunity to build their own digital sundial, and then hack it / modify it / invent something else.
— Geeks that might be interested in a cool gadget that won’t be available anywhere else.
And at the same time, I am hoping it will help a bit with the financing of the R&D for the next few inventions/episodes !
If you like this episode…
… please consider supporting the podcast:
— Share it around !
— Leave me some feedback !
— Come and visit the gift shop.
From now on, I will aim to release both the English and French versions at the same time. This should limit any risk of spoilers before the release of an episode in English (:
This is absolutely amazing! Great idea, great execution.
Grazie mille !
This is really cool ! A very quick question . what is your process of designing this ? I mean how did you debug or simulate during your design to actually get to with awesome result ?
The Openscad interface is pretty usefull for debugging the gnomon (the magical black box).
If you look closely at the back side of the gnomon in the Openscad window, you can actually see the background color through some of the pixels: these are the pixels that would be ON if the gnomon was exactly between you and the sun. So when you rotate the gnomon, you can directly check that it does display correctly the time.
The main thing to check is that you’re not removing so much material inside the gnomon that some pixels are ON when they should be OFF.
There was “a little bit” of trial-and-error to find the best values for the parameters (size and shape of the gnomon, number of pixels, pitch between the pixels…).
I am impressed. The time-lapse video captivated me.
Thanks for the thumbs up !
Wouldn’t you als need also to adjust the angel based of the time of year? i mean the sund doesn’t get up so high in the winther.
That is a brilliant question !! And I am glad you asked.
Indeed the declination of the sun changes by as much as 47′ during the year: the sun will move along the longitude lines from one day to the next.
The “trick” to get the sundial to work throughout the year is really trivial actually: you just need to use very wide pixels (along the north-south direction). It’s a bit like seeing the sun from the bottom of a well: the wider the well, the longer you will see the sun at the bottom.
So ideally, a pixel should be wide enough to accept sunrays tilted (along the north-south axis) by as much as 47′.
In pratice I had to compromise a little bit with the 3D printed version: to keep it printable, I had to limit that angle to about 24′. So to use this 3D printed sundial throughout the year, you need to slightly misalign that sundial up or down by about 10′ every 6 months.
I was wondering the same. Thanks for the hack. This is brilliant – I’m very captivated by this incredibly simple design (well, aside from the complexities of the swiss cheese) – so clever!
Very cool idea !! Looking forward to your next video !!
Thanks ! I am really having a lot of fun with this next video (:
Penguins at the North Pole??
If you were a penguin on a touristic trip, where would you go for the Xmas holidays ?
At last a digital clock that will work after the zombie apocalypse. This is definitely going on my top 10 list of the coolest things to 3D print.
… and it should be Skynet-proof too !
I have no intention of ever building one of these, but I just had to pause and say how cool I think it is. And the video is a really entertaining learning experience! I have now subscribed to your English channel, and may even try to work through the French videos if I get too impatient while I wait for the next one.
Thanks for this really nice comment ! I’ll double down on the coffee intake to get the next English video out soon !
Your Sundial works in the southern hemisphere but you already knew that it would.
I posted pics of mine here. https://plus.google.com/+MichaelScholtz1/posts/bZhxKm3sZiZ
I printed mine in PLA as I prefer using it. I’ve printed other parts that spend all day in the sun here and fins that printing them in white or very light colours helps them keep cool. I printed mine in white and then decided to spray it with chrome reflective to help keep the heat from affecting it.
Congrats, it looks really cool !
And thermal control with PLA is a genius idea !
Interestingly, people designing sattelites are doing something similar. One of the trick they use is also to paint their satellite such that it reflects heat on the sun-facing side, and radiates heat on the other side. So maybe if you paint the back side of the gnomon (the side that was laying flat on the printing plate) in black, it might help cool it down even further.
It might be neat to create a sand casting of the 3D printed object to cast this in metal. It would hold up better in the elements, as plastic will deform over time.
Indeed ! plus it would leave something fun for next centuries’ archaeologists.
You could 3D print in wax and do a lost wax casting right?
Hi, very great sundial. I never saw a digital sundial before. I will print it.
Is it possible to project the digits on a wall or must it be mirrored therefore in any way?
It was designed to show directly the digits on the floor.
So you could also read these digits on a wall just behind the sundial as well (without any mirror).
I am printing now 🙂
When I project the sundial to a wall, the digits are placed vertically and I have to bend my head to read them. My aim is to have the digits horizontal.
My idea is to seperate the half-cylinder into 4 or 5 parts and arrange them side by side and the slits turned by 90 degrees.
Do you think that works?
Best regards from Germany
Hi Wolfang !
Sorry for the delay, I had a looong week-end away from any computer.
If I understand correctly: you want to read time horizontally instead of vertically, and you are trying to figure out which part to rotate (?).
With the current Openscad script, each character can only be displayed vertically. Even if you only have one digit, it still assumes that the sun will move along a specific path around the digit.
However, you could try changing the font used (it’s a bunch a matrices filled with 0 and 1 in the script): if you rotate each character by 90′ then each digit will display horizontal characters, while still being properly oriented with respect to the sun.
If you’d like I could do is upload each digit separately to thingiverse. It will still be the current type of digits (eg: the same font with vertical characters), but it might give you an easy way to test new arrangements, the LEGO way. Would that help ?
This is remarkable! I will absolutely be printing this when I get my printer.
Thanks heaps ! post pictures when you do !
My wife and I were captivated by the the whole experience: the concept, the design, the process, the resultant object (of course) and by the video presentation! Thank you so much for expending the extra effort to produce a version in English so that we could also appreciate the genius behind it all ( that would be you 😉 ) And, as if this were not enough, you’ve hinted that there are more to follow. We are now anxious to see what comes next! We’ll be watching an sharing your site with our friends!
Thank you for your kind words !
I am doing heaps of fun experiments at the moment for the next project.
I am hoping to have the next video ready by the end of the month !
Really great idea, and the video is amazing! Love the graphics. On my “must Build” list.
Would it be feasible to increase the time resolution to 10 or 5 minutes?
Look forward to your next video!
It should be possible indeed ! with a maybe a little bit of fiddling with the Openscad script.
But you might have either to print tinier details to get it to work properly, or alternatively to print it bigger (with the same resolution).
Note that you can always print the gnomon in several pieces if it becomes too big for your printing plate 🙂
Way cool, I love it. This the the first thing I’ve ever 3D printed. Just got the new Dremel 3D printer. Printed all in about 17 hrs. Am printing a second one now.
Why the break away on the top mount?
The teeth are really tricky to print properly without that breakaway part, at least on my printer. But if you don’t need that support, you can easily remove it in the Openscad script by setting the value FLAG_bottom_lid_support to 0 (instead of 1), at the top of the script. Then just hit F6 (to render) and File>>Export>>STL.
This is a genius idea. Thanks so much. I guess one could use the “time adjuster pivot” for correcting for the Equation of Time also. Thanks again. Great idea and excellent tutorial!!
Good point indeed ! It’s very similar to a typical equatorial sundial in many ways.
Do you have a source repository to be able to follow and fork the history of this project?
It’s only on Thingiverse at the moment.
The “Remixes” option could be seen as a very crude way of doing some sort of versioning already, if you squint your eyes enough.
Would you like me to add to github too ? (or do you maybe have another location in mind ?)
I know this is a late reply. A github repository would be great.
Truc de ouf!
Please be advised that you are bookmarked!
Thanks beaucoup !
Could the gnomon be made with a solid piece of metal, cutting the holes with lasers? I don’t know anything about how deep through metal lasers can/should cut…
I have a question about the material you recommended using. I am a complete newcomer to 3D printing. A website for finding print services offers “simulated ABS”. Is this the same thing? The site says that the material is sensitive to UV light, which made me think it may not be.
Along with a very cool video, and practical information on how you designed the digital shadow sun dial, it is a fantastic device! I will share it with all of the students and teachers that we meet.
Hey Julldozer, Great idea and its manifestation as an actual device! By the way, you are a great at conveying your message, I enjoyed your video as much as learning how you did it.
Here is what I foresee – the Chinese are going to mass produce this and sell it all over the world, really cheap – so before they do that, put your name on it (say something like “Down with Fascism Digital Sun clock”) and sell it yourself and make a little money for yourself – price it so you can sell in volume obviously, so you can dedicate your life to such wonderful projects. In any case, they’ll make a knockoff soon, so you have very little time. Hurry up!!
congratulation for the idea and for the super clear explanation 🙂
challenging question: do you think it will be possile to get the LAT and LON figures instead of the time? This would be a perfect “plan B” to have on board of sailing boats, in case all our nice electronics fade!
Given that it starts off assuming you know your latitude and longitude already in order to aim it right at your closest pole, I don’t see how that would be helpful.
Here’s one option in case your electronics fail:
you can print a sextant!
Fab!! great idea!! May you please share the stl file for the digital sun dial?
I posted the comment below to the Thingiverse site, but now here as well. After reading all the comments here, I realize that the below method could be used to create the form necessary to cast this in metal.
One feature of OpenSCAD is the projection command. One can translate the object in Z and “cast a shadow” in the workspace of that specific location. Export the SVG files. Consider that one can slice the STL in thickness of 3mm or 1/8″ suitable for laser cutting from cardboard or foam. Glue the slices together, protect the exposed surfaces (big job for the little holes) and cover it with fiberglass.
Result: Huge digital sundial suitable for one’s courtyard.
I was amazed watching this. Have you made calculations about how one should make the transformations to create a similar sundial that can be assembled on a vertical wall? That would be a proper stable place for the digital sundial.
Brilliant video, very well presented!
Does your sundial’s calculations include the Equation of Time so that the display is in Clock (Mean) Time, or does it display in Local Sun Time (meaning you have to know the day’s Equation of Time figure to convert to clock time)?
I work as a sience teacher in Sweden. I just love your digital sundial! Would love to show it for my students. Unfortionally we dont have a 3d-printer att my school yet. My vision is to get one…but we are not quite there yet…. Is it possible to buy one? How Munch is it? I have nerver bought anything here at etsy…so Im new to this. Tryed to sent a massage on etsy…but I dont think it whent through.
If you didn’t already buy one, this is the link to etsy: https://www.etsy.com/listing/248715228/digital-sundial
Looks like it’s a little under 700 kroner
This is absolutely amazing !!! Great idea !!!
Have you considered maybe selling it through shapeways? They can handle the printing, so you won’t need to worry about etsy stock.
…and, as a fellow tinkerer, I must say that this is an excellent project.
Would you be willing to share your Ultimaker 2 gcode? I have the same printer! I’d love to use it and see the profile you used.
Hey Julldozer, Great idea. The video was cool and with detail tutorial. Thanks for the idea.Making the same in India with least or no access to 3D printers is hampering my plan for making this Digital sundial. Any more such innovative ideas for overcoming for this sort of group.
Muy buen invento, que alegre ver como funciona en el Video, muchas gracias por compartir, cuando algún día logre ajustar para una impresora 3D estaré ansioso de hacer este proyecto.
What an absolutely brilliant idea!
Not only the sundial itself but more so the way you present the way from idea to completion. Great way to inspire creative thinking and new ideas!
Love it !
The concept, the visualisation, the manifestation, the resultant.
C’est magnifique – Bravo !!
I really enjoyed your video. The presentation was fun, the idea was very clever, and the thought process was straightforward. If I had seen this in high school I might have decided to be an inventor!
My only idea for mass production would be digging the tunnels with lasers somehow. It seems like this design ought to also work having a hollow core and precisely aligned holes where either end of the tunnel would be–should make scaling up much less materials-expensive.
Awesome. if I understand correctly you could make a huge one more accurate ( showing up the time every 1-5mn ), right?
A meta question here, what is the tool you used to create the video, really interactive and entertaining, I need something like this.
Très bon boulot – Bravo!
I just watched the episode and I really enjoyed it! Very inspiring, thanks! 🙂
Just watch the sundial video for the second time. Genius!!! Great presentation! For what it’s worth, there are no penguins at the North Pole. Polar bears, but no penguins. They are all at the South pole (and one species in the Galapagos, but I digress). Loved everything about your video. Your presentation was flawless. Loved your simple background. The animation was great. A very cool idea that makes one think 3 dimensionally. And the best line from the whole thing: “It’s really not rocket surgery.” I wish I was as relaxed when try to speak French as you appear speaking English. Chapeau, monsieur!!! I’m off to watch the French version now.
I have just received the copy of the digital sundial that I had ordered: https://www.facebook.com/photo.php?fbid=10208423187604645&set=a.10201549704771870.1073741827.1454798193 😀
Any possibility to buy one?
Just wanted to say that I loved your video. Very informative and entertaining. Your sundial is a stroke of genius !! Now I need to persuade my mate with a 3D printer to spend the next 2 days printing one for me !!
Can this be installed and used in a wall instead of a table?
This is a great idea. I have a digital sundial already, made with grates in plastic and reflected off a mirror. Your idea is quite innovative! My question ; what of some minor improvements, like a bigger shadow to improve visibility of the numbers ( like wings?)
Or using lenses to increase the light intensity?
Nice idea! I went ahead and ordered one, but I’m wondering how it deals with the declination of the sun, the angle between the path of the sun and the celestial equator. The sun only moves along the celestial equator during the vernal and autumnal equinoxes, the days when day and night are the same length. All the rest of the time it is above the equator (in the summer) or below (in the winter). It looks like the holes in the dial can only handle a limited range of declination. The sun can be up to 22 degrees away from the equator. I think this means that it won’t cast an image of a dot in the middle of summer or the middle of winter.
Wow! fantastic. How did you figure out the math as to the spacing and angel of each pixel with respect to the sun?
What a cool idea! Great! I live in Mexico City, do you commercialize the clock?
It is pretty cool. I might try printing one up using the 12hr instead of 24hr.
It may have been asked but, when at the equator, which do I need, the one for the Northern hemisphere or the reversed for the Southern hemisphere? Or something inbetween?