Drawing Machine Which Can Draw More Varied Patterns Than Spirographs
by NovemberKou in Workshop > 3D Printing
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Drawing Machine Which Can Draw More Varied Patterns Than Spirographs
Have you ever played with a Spirograph?
It's that toy where you insert a pen tip into the holes in the gears and spin them around to create geometric patterns.
While the patterns created by a simple Spirograph are limited in variety, ”Wild Gears” offers a solution to this issue. I tried 3D printing one myself, but it was quite challenging to draw patterns without the gears coming apart. So, I set out to create a machine that could draw similar patterns simply by rotating the gears. After over two months of trial and error, I finally completed the machine I am introducing here.
Supplies
3D-printed parts
This machine uses five types of gears: center gears with pinion gears, side gears, sun gears, and planetary gears. Of these, the sun gears and planetary gears are designed to be interchangeable.
To increase the variety of patterns, gears with different numbers of teeth are required. Additionally, structural components other than gears are also needed. As a result, there are approximately 70 types of parts to be printed. Therefore, it is simpler to download the files that can be read by the slicer software rather than listing each part here.
Printing profiles for BambuStudio are available on the following website.
The files for PrusaSlicer are available on the following website.
Other parts
- Round magnets with a diameter of 6mm and a thickness of 3mm: 8 pieces
- Used to hold paper in place.
- M3x8mm cap bolts: 5 pieces
- M3x12mm cap bolt: 1 piece
- M3 nuts: 7 pieces
- 6mm diameter steel balls: 4 pieces
- R188 bearing: 1 piece
- https://www.amazon.co.jp/dp/B0CMJ2K8K1
- Ballpoint pen refill: 1 piece
- I recommend ZEBRA's SARASA. The one I purchased is RNJK5-BKRBLG-8AZ.
- https://www.amazon.co.jp/dp/B0D631QZ39
Assembly Instructions
Since explaining the assembly instructions in text would be lengthy, I have prepared a video.
About Pinion Gears
Pinion gears are important. If they are omitted, the pattern drawn will change. During development, I was troubled by a problem where the pattern drawn was different from what I had expected, but this was the cause.
How to Change the Figure
As shown in the video at the beginning, changing the gears will change the figure.
There are also the following methods.
- Change the position of the pen.
- Change the phase of the planetary gear.
- Change the phase of the side gear.
- Change the fixed position of the planetary gear bar.
During development, I struggled with how to parallel transfer the motion generated by the side gear, sun gear, and planetary gear onto paper. Initially, I used a linear guide, but it did not move at all when force was applied diagonally, so I abandoned this method. Next, I considered using a pantograph, but it made the machine very large, so I rejected this method as well.
Ultimately, the method that worked was a rather unsophisticated approach of preparing two pairs of side gears, sun gears, and planetary gears. However, this allowed us to implement methods such as “changing the phase of the planetary gears” and “changing the phase of the side gears,” so this method also had its advantages.
Change the Pen Position
This method is simple but effective, and cannot be done in Wild Gears. The change in figure produced by sliding the pen holder is different from the change in figure produced by inserting the nib into the different holes in the gear.
In this method, the pen position is determined analogously, making it difficult to produce the same figure!
You can use a pen holder with a single refill and draw it several times in different positions, or you can use a pen holder with multiple refills and draw them all at once.
By using Grapher's animation function, you can understand the relationship between the pen position and the figure. This will be explained later.
Change the Phase of the Planetary Gear
Change the Phase of the Side Gear
Change the Fixed Position of the Planetary Gear Bar
This is equivalent to changing the hole where the ballpoint pen tip is inserted in a spirograph.
About Ballpoint Pen Refills
Not all inks work well
I had a hard time choosing refills. Even though there are some differences, I thought that no matter which one I used, there would be no problem in drawing patterns. I was wrong.
In the early stages of development, I used Mitsubishi's JETSTREAM, but it produced excessive ink, so I had to try different refills. Next I tried PILOT's Acroink, Pentel's ENERGEL, and ZEBRA's SARASA. The only one that worked well was SARASA.
All of these products work well with handwriting. What I am saying is that they do not work well with this drawing machine.
Ballpoint pen refills with Acroink produced excessive ink and the ink pooled at the point where I finished drawing the pattern, staining the paper.
ENERGEL produced too little ink and broke up the lines.
SARASA worked well, perhaps because it is a water-based ink. If you do not have access to SARASA, you may want to try water-based ink instead of oil-based ink.
Thick mechanical pencil lead
I also tried a mechanical pencil lead with a diameter of 2 mm. However, both HB and 2B lead had disappointing results as the pattern became lighter, so I decided not to adopt them.
The problem with mechanical pencil leads is that the tips become rounded and the entire pencil becomes shorter as it is used, which is another reason why I did not adopt this type of pencil lead.
How to fix the refills
The refills were initially screwed in place, but it was difficult to adjust them to the optimum height, so I changed to a spring system. I have only checked the spring with PETG, so it may not work well with other materials.
Refill size
Refill size is assumed to be 3mm in diameter and 98.2mm in length. This is a thin refill for multicolor ballpoint pens.
Table Sizes
Three table sizes are available: 180mm, 150mm, and 120mm in diameter.
The size of 180mm was determined based on the limit of what a small 3D printer can print, 150mm is the size to cut two circles out of A4 paper, and 120mm is the size to cut three circles out of A4 paper.
To cut the paper into circles, a circle cutter is useful. I use an OLFA ratchet compass cutter.
Information Needed to Make Gears With Different Numbers of Teeth
I have prepared quite a few types of gears, but I believe this is not sufficient. I understand that you may wish to have gears with different numbers of teeth, so I am providing the information necessary to create them.
The gears were created using the Helical Gear+ add-in in Autodesk Fusion.
The gear thickness is set to 5 mm. However, only the center gear is 5.2 mm.
Module is unified at 1mm and Helix angle is set to 0 degree to create spur gears. Backlash is set to 0.4mm.
Please refer to the f3d file for information on how to process the gears after they have been created with the add-in.
Simplification
The “no gear shaft” and “no gear shaft base” can be used to simplify the gears by replacing two sets of gears with one set. Use M3x12mm bolts for connection to the supporter guide.
Check the Figure in Advance
The application Grapher, which comes with macOS, can now reproduce the curves drawn by this drawing machine. I tried to attach the “144_140_63_36.zip”, but Instructables did not allow me to do so, so please download it from Printables.
However, it is limited to the case where the initial phase of the side gear is zero.
If you cannot use Grapher, try to find software that allows you to enter a formula and draw a graph.
The shape of the curve is almost reproduced. The meanings of the parameters are as follows.
Number of gear teeth
n0 to n3 enter the number of gear teeth. n0 is the center gear, n1 is the side gear, n2 is the sun gear, and n3 is the planetary gear.
Initial phase of planetary gear
Enter the initial phase of the planetary gear in t3ini. The unit is radians.
Screw position
p is the value for the position of the M3x12mm screw to be attached to the planetary gear. Enter the distance from the center of the planetary gear to the screw divided by the radius of the planetary gear.
Attached is a list of the maximum values of p for each planetary gear as an image. This value is obtained when the screw is installed outermost.
Pen position
Changing the value of offset is equivalent to changing the position of the pen. Try changing it as long as the size of the curve does not exceed the size of the table. Click the Play button to see an animation of the effect of the OFFSET value.
Center Gear Revolutions
T represents the number of revolutions of the center gear. The formula to calculate how many revolutions to make exists, but I could not use the function to find the greatest common divisor in Grapher, so I could not calculate it. Since I had no choice, I have included a larger number. If it is not enough, please increase it.
Effect of the Pen Position on the Figure
If the number of teeth is 144 for the center gear, 140 for the side gears, 63 for the sun gear, and 36 for the planetary gear, the figure will change as shown in the animation in this step when the offset is changed from 0 to 28.
Referenced Information
The following is a blog that was used as a reference in the creation of this drawing machine.
You can see a video of the drawing with Wild Gears at the following website