Long before GPS, satellites, or digital navigation existed, sailors and astronomers relied on handheld instruments called astrolabes to navigate using the stars.

For centuries, these remarkable analog devices helped navigators estimate latitude, measure the altitude of celestial objects, and track the movement of the heavens using nothing more than rotating measurement tools and careful observation.

For this project, I recreated a historically inspired medieval astrolabe using layered 3D printing techniques, engraved navigation scales, and interchangeable astronomical sighting arms to capture the elegance and practicality of these early scientific instruments.

Rather than building a fantasy prop or a decorative replica, I wanted this version to feel like a believable reconstructed scientific tool — something a navigator or scholar from the Middle Ages could realistically have carried while observing stars like Polaris to estimate position and direction.

To make the astrolabe easier and safer to demonstrate today, I created two interchangeable arms:

Stellar Sighting Arm

(Historically inspired)

This arm uses front and rear mountain-style sights to align stars by looking between the peaks.

Solar Projection Arm

(A modernized educational adaptation)

This arm uses removable straws and projected sunlight on cardstock to safely demonstrate solar elevation without looking directly at the sun.

The finished astrolabe includes:

1. Engraved degree scales
2. Interchangeable astronomical arms
3. Rotating celestial measurement system
4. Functional stellar alignment
5. Solar projection capability
6. Historically inspired astronomical design

What You’ll Make

In this project, you’ll create:

1. A handheld medieval astronomical instrument
2. An engraved angular measurement scale
3. A Stellar Sighting Arm for observing stars
4. A Solar Projection Arm for solar elevation demonstrations
5. Interchangeable rotating components
6. A historically inspired scientific instrument

The finished build should feel:

1. Precise
2. Interactive
3. Mechanical
4. Historically grounded
5. Educational
6. Museum-inspired

How an Astrolabe Works

Astrolabes were some of history’s earliest analog computers.

Navigators and astronomers used them to:

1. Measure star altitude
2. Locate Polaris
3. Estimate latitude
4. Determine direction
5. Track celestial movement

This simplified recreation focuses on one of the core navigation principles of historical astrolabes:

Measuring the elevation angle of celestial objects

Historically, navigators rotated a sighting arm called an alidade and aligned stars or the sun using sighting holes or visual alignment markers.

This recreation uses two interchangeable arms:

Stellar Sighting Arm

The Stellar Sighting Arm uses mountain-shaped front and rear sights.

By looking between the peaks, you can align celestial objects like Polaris.

This approach is historically inspired and preserves the visual alignment principle used in medieval instruments.

Solar Projection Arm

The Solar Projection Arm uses removable straws and projected sunlight on cardstock.

makerworld Print profile link

https://makerworld.com/en/models/2777908-medieval-astrolabe-navigation-instrument#profileId-3086825

3D Printing

1. Copper Silk PLA filament
2. Matte black or dark bronze PLA
3. 0.4mm nozzle

Hardware

1. 1x M3 bolt
2. 1x M3 locking nut
3. 2x washers

Finishing Supplies

1. Black acrylic paint
2. Fine paint brush
3. Paper towels
4. Cotton swabs
5. Matte or satin clear coat spray
6. Fine sandpaper (220–400 grit)

Other Materials

1. Plastic drinking straw
2. White cardstock

Printed Parts

1. Mater (main body)
2. Stellar Sighting Arm
3. Solar Projection Arm
4. Decorative center cap

The goal of this project was to create a simplified but believable medieval astronomical instrument.

Rather than recreating every complex feature found on historical astrolabes, I focused on the parts most closely connected to navigation and celestial measurement:

1. Engraved scales
2. Rotating sighting arms
3. Stellar alignment
4. Solar elevation measurement

I based the overall design on medieval Islamic and European astrolabes because they combined practical science with elegant craftsmanship.

The design intentionally uses:

1. Concentric rings
2. Dense radial markings
3. Engraved scales
4. Rotating components
5. Layered geometry

These details help the instrument feel historically grounded without requiring extremely complicated engineering.

Design Size

The astrolabe was designed at:

200mm diameter

This size feels:

1. Substantial
2. Handheld
3. Realistic
4. Visually impressive

Mater Thickness

The mater is:

5.5mm thick

The recessed center is cut down slightly, leaving a raised outer rim for the engraved scale.

Important Design Choice

I intentionally created two interchangeable arms:

Stellar Sighting Arm

For observing stars

Solar Projection Arm

For solar demonstrations

This modular system makes the astrolabe feel more like a historical scientific instrument kit instead of a single-purpose prop.

The mater forms the main structural body of the astrolabe.

This layer contains:

1. Engraved degree scales
2. Rotating center pivot
3. Recessed center section
4. Raised outer measurement ring

The engraved scales were cut directly into the model so black paint could later settle into the grooves and dramatically improve readability.

Create the Main Disk

1. Add a cylinder to the workplane.
2. Set the diameter to:
3. 200mm
4. Set the height to:
5. 5.5mm
6. Increase the side count as high as possible.
7. Center the disk on the workplane.

This creates the main body of the astrolabe.

Screenshot Recommendation

1. Full 200mm disk with dimensions visible

Create the Recessed Center

1. Duplicate the main disk.
2. Keep it centered.
3. Change the duplicate diameter to:
4. 160mm
5. Convert the duplicate into a hole shape.
6. Raise the hole slightly so it only cuts into the top surface.
7. Cut approximately:
8. 1mm deep
9. Group the shapes.

This creates the recessed center while leaving the outer measurement ring raised.

Tip

Do not cut all the way through the disk.

You only want a shallow recessed center.

Screenshot Recommendation

1. 160mm negative cylinder before grouping
2. Side profile showing recessed cut

Create the First Large Tick Mark

1. Add a thin rectangular box.
2. Set dimensions approximately:
3. 1mm wide
4. 30–35mm long
5. 1mm tall
6. Position it across the outer rim.
7. Convert it into a hole shape.
8. Lower it so it cuts:
9. 0.5mm deep
10. Place it at the 0-degree position.

This creates the first large 5-degree notch.

Screenshot Recommendation

1. Close-up of first notch placement

Duplicate the 5-Degree Marks

1. Duplicate the notch.
2. Rotate it:
3. 5 degrees
4. Continue duplicating until:
5. 90 degrees
6. Repeat in the opposite direction using:
7. -5 degree rotation

This creates the large notches every 5 degrees.

Tip

Keep the rotation point centered perfectly or the scale will drift.

Screenshot Recommendation

1. Multiple large tick marks before grouping

Create the Smaller 1-Degree Marks

1. Duplicate the original notch.
2. Reduce the width to:
3. 0.5mm
4. Shorten the length slightly.
5. Rotate duplicates every:
6. 1 degree
7. Continue between the larger marks.

This creates the smaller precision notches.

Screenshot Recommendation

1. Large and small marks together

Group the Cutting Geometry

1. Select the disk.
2. Select all negative notch geometry.
3. Group the shapes.

The outer ring should now contain:

1. Large 5-degree notches
2. Smaller 1-degree notches
3. A recessed center
4. A raised engraved scale ring

One of the most important parts of this project was designing around real physical hardware instead of guessing dimensions.

To do this, I measured the actual components using calipers and recreated them directly inside Tinkercad.

This dramatically improved fit accuracy.

Measuring the M3 Bolt

1. Measure the real bolt diameter using calipers.
2. Recreate the bolt hole digitally.
3. Convert the digital bolt into a hole shape.

Final Hole Size

Although the bolt is an M3 bolt, I designed the hole at:

3.25mm

This gives enough tolerance for smooth assembly after printing.

Screenshot Recommendation

1. Caliper measurement of bolt
2. CAD hole geometry

Measuring the Straw Diameter

1. Measure the straw using calipers.
2. Recreate the straw diameter digitally.
3. Convert it into hole geometry for subtraction.

Measured Straw Diameter

1. 7.7mm actual diameter

Final CAD Hole Size

1. 8mm

This gives the straw a snug but removable fit.

Screenshot Recommendation

1. Straw measurement with calipers
2. Straw hole geometry

Why This Matters

Designing around real measured hardware improves:

1. Print accuracy
2. Fit consistency
3. Rotation smoothness
4. Assembly reliability

It also makes the astrolabe feel engineered instead of decorative.

What You Should See

The hardware and straw should fit without excessive force while still remaining secure.

The Stellar Sighting Arm is the historically inspired arm used for observing stars.

This arm uses front and rear mountain-style sights that allow you to align celestial objects by looking between the peaks.

This preserves the same visual alignment principle used in historical astronomical instruments.

Create the Main Arm

1. Add a rectangular box.
2. Set dimensions approximately:
3. 160mm long
4. 2.5mm thick
5. 2.5mm tall
6. Center the arm across the mater.

Screenshot Recommendation

1. Main arm dimensions

Create the Center Pivot

1. Add a cylinder hole.
2. Set the diameter to:
3. 3.25mm
4. Center it on the arm.
5. Group the shapes.

Screenshot Recommendation

1. Pivot hole close-up

Create the Mountain Sights

1. Add triangular or peaked geometry at both ends.
2. Create matching front and rear sight peaks.
3. Align them carefully along the same axis.

The peaks create a visual sightline when looking through the arm.

Important Tip

Small misalignment between the peaks becomes very noticeable during use.

Screenshot Recommendation

1. Mountain sight close-up
2. Looking through aligned sights

Smooth the Edges

Lightly bevel or taper the arm ends to improve:

1. Appearance
2. Highlights
3. Historical feel

What You Should See

The Stellar Sighting Arm should feel:

1. Thin
2. Precise
3. Mechanical
4. Historically believable

The Solar Projection Arm is a modernized educational adaptation designed for safely demonstrating solar elevation.

Unlike the Stellar Sighting Arm, this version uses removable straw sights and projected sunlight.

Create the Main Arm

1. Add a rectangular box.
2. Set dimensions approximately:
3. 160mm long
4. 2.5mm thick
5. 2.5mm tall
6. Center it across the mater.

Screenshot Recommendation

1. Solar arm dimensions

Create the Pivot Hole

1. Add a cylinder hole.
2. Set diameter to:
3. 3.25mm
4. Group the shapes.

Create the Straw Holders

1. Add cylindrical holders at both ends.
2. Position them along the same axis.

These hold the removable straw sight tubes.

Screenshot Recommendation

1. Straw holder close-up

Create the Straw Channels

1. Add cylinder hole geometry.
2. Set the diameter to:
3. 8mm
4. Cut through both holders.
5. Group the shapes.

The straw should slide in firmly while remaining removable.

Screenshot Recommendation

1. Straw hole geometry
2. Straw fit test

Create the Projection Holder

1. Add a small cardstock support near the rear sight.
2. Keep it thin and lightweight.
3. Align it with the straw sightline.

The projected sunlight will appear on this surface.

Screenshot Recommendation

1. Projection holder close-up
2. Side profile

Test Solar Projection Alignment

1. Insert the straw.
2. Shine a flashlight or sunlight through it.
3. Adjust alignment until the light projects onto the cardstock.

What You Should See

A bright projected point of light should appear on the cardstock.

This is one of the most satisfying moments in the build because the astrolabe suddenly starts behaving like a real scientific instrument.

Once the CAD work was finished, I exported all components into Bambu Studio.

I used the auto-arrange feature to position the parts flat on the build plate.

Printing the arms flat improves:

1. Surface quality
2. Strength
3. Consistency
4. Scale readability

Slice the Parts

Import:

1. Mater
2. Stellar Sighting Arm
3. Solar Projection Arm
4. Decorative center cap

Arrange the parts flat.

Once the prints finished, I lightly cleaned:

1. Edges
2. Seams
3. Rotation surfaces
4. Engraved grooves

The goal is not perfection.

The goal is improving:

1. Highlights
2. Surface quality
3. Movement
4. Realism

Clean the Edges

1. Remove any brim remnants.
2. Lightly sand rough spots.
3. Smooth rotating contact surfaces.

Important Tip

Avoid aggressive sanding on Silk PLA because it can dull the metallic finish.

Screenshot Recommendation

1. Raw vs cleaned comparison

Clean the Engraved Grooves

1. Use a soft brush or hobby knife.
2. Remove filament fuzz.
3. Inspect the scale carefully.

Clean grooves dramatically improve paint filling later.

Screenshot Recommendation

1. Groove cleanup close-up

Test Rotation

1. Assemble temporarily.
2. Rotate both arms across the scale.
3. Check for scraping.

What You Should See

The astrolabe should already start feeling:

1. Mechanical
2. Interactive
3. Functional

This is one of the most dramatic transformation steps in the entire project.

The black paint instantly transforms the astrolabe from:

“3D print”

into

“historical scientific instrument”

Apply the Paint

1. Brush black acrylic paint heavily into the engraved grooves.
2. Work in small sections.

The goal is to flood the engravings completely.

Screenshot Recommendation

1. Paint filling grooves

Wipe the Surface

1. Use paper towel or cloth.
2. Wipe the flat surfaces clean.
3. Leave paint only inside the grooves.

This dramatically improves:

1. Readability
2. Contrast
3. Precision
4. Realism

Screenshot Recommendation

1. Before/after wipe comparison

Inspect the Scale

The engraved markings should now appear:

1. Darker
2. Sharper
3. More precise
4. More metallic

What You Should See

Dense engraved markings create a surprisingly convincing illusion of complexity.

Now everything comes together.

Assemble the Pivot

You’ll need:

1. M3 bolt
2. M3 locking nut
3. Washers

Assembly order:

1. Mater
2. Selected arm
3. Washer
4. Locking nut
5. Decorative cap

Screenshot Recommendation

1. Exploded hardware layout

Adjust the Rotation

1. Tighten the nut gradually.
2. Test the arm rotation repeatedly.
3. Stop tightening once the arm rotates smoothly while still holding position.

Important Tip

Overtightening causes scraping and stiff movement.

Swap the Arms

The interchangeable system allows the astrolabe to switch between:

1. Stellar observation
2. Solar elevation measurement

Simply remove the center bolt and swap the arms.

What You Should See

The completed astrolabe should feel:

1. Interactive
2. Functional
3. Historically inspired
4. Surprisingly substantial

Using the Stellar Sighting Arm

1. Hold the astrolabe vertically.
2. Rotate the Stellar Sighting Arm.
3. Look between the front and rear mountain sights.
4. Align a star like Polaris between the peaks.
5. Read the angle from the engraved scale.

This demonstrates the same core alignment principle used in historical celestial navigation.

Screenshot Recommendation

1. Looking through mountain sights

Using the Solar Projection Arm

1. Install the Solar Projection Arm.
2. Insert the straw.
3. Aim the straw toward sunlight.
4. Watch the projected light appear on the cardstock.

Important Safety Note

Never look directly at the sun through the sights.

Even though the astrolabe is mechanically simple, the engraved scales, interchangeable arms, and celestial alignment system make it feel like a real early scientific computer.

That tactile interaction is what makes projects like this so satisfying.

Money Shot Recommendation

The strongest final image is:

Holding the astrolabe toward the sky while sunlight passes through the Solar Projection Arm.

That instantly communicates:

1. Astronomy
2. Navigation
3. Science
4. Interaction
5. Historical craftsmanship