Electric Hurdy-gurdy

Sound sample

3d printing tips

I printed most of the parts using a layer height of 0.2mm. But for the bigger pieces, I bumped it up to 0.25mm. This change helped speed up the printing process without compromising the strength and overall quality. 

 I used default print settings for most of the parts. For the wheel and tailpiece I increased the count of wall lines to 5. 

 Support

 Support is strongly recommended only for body_03-pickup_base. 

 If your printer does not handle overhangs well, you may also consider enabling support for keyboard_backplate. 

Key caps can be printed in two orientations:

• on the front - as they are uploaded -  the keys will have the bed texture on the front  - the drawback is it may produce small overhangs that have to be removed before assembly. 
• on the top wall - no overhangs but also no nice bed texture on the front :) 

The tailpiece and the bridge have to be printed on a side, so good bed adhesion is required.

Non printable parts:

• Violin strings - The hurdy gurdy is designed to be compatible with 1/8 scale violin strings, but using longer strings also works well. In my experience, D strings (0.53mm) tuned to E produced the most pleasing sound, but I encourage you to experiment with different setups to find your preferred tone.
• 6mm rod, 12-14cm. It is used to connect the wheel to the crank. A steel threaded rod is recommended.  I also tried a wooden 6mm rod that was previously an ice cream stick and it worked quite good, but it got wobbly after I reassembled the gurdy with a different wheel.
• 2 x 608z bearings  (8x22x7)
• 2 guitar tuning pegs - the current design is compatible with symmetric pegs (as in Les Paul type guitars)
• Hambucker pickup and an electronic kit for connecting the pickup (volume and tone controls & jack input) You can find it on amazon. I paid less than 30€ for kit with two pickups and the electronic for connecting it. 
• Rosin -  I'm use natural rosin for violin that can be used with synthetic bow hair.
• Cotton - little bit of it is needed to apply on strings in a place where they touch the wheel.
• Screws:
  • 36 x  M3x10 - with a cylinder head
    • 28 - for the keys - the cylinder heads are used as tangents
    • 4 - tail piece
    • 4 - bridge
  • 2 x M3x5
    •  - wheel cover
  • 4 x M3x4 distance screws
  • 13  x M3x30 
    • 5 - body_05-top
    • 3 - body_04a-internal_frame
    • 6 - body_02-wheel_base
  • 4 x M3x25
    • 4 - body_06-headstock
  • 11 x M3x16
    •  5 - body pickup - you may longer ones (30mm max)
    •  3 - wheel
    •  3 - body shell
       

Assembly

Body

• Tailpiece and the bridge can be mounted at any stage, even just before putting on the strings. 

• Put bearings into body_01 and body_02-wheel_base:

• If the humbucker pickup is already soldered together with the electronic components, you will need to pass the volume and tone dials, along with the jack input, through the hole in body_02-wheel_base as illustrated in the provided picture.:

• Mount the electronic components:

• Mount the rod lock approximately 15 mm from the end of the rod. Next, position the wheel around 55 mm away from the lock. Secure the rod lock in place by screwing the distance screws, ensuring a stable attachment. However, refrain from locking the wheel at this stage, as it will be adjusted later in the assembly process.

• To mount the rod, carefully insert the rod lock into the body_01 bearing. Ensure that the cables are not touching the rod to prevent any interference. You can use tape to secure the cables in place, keeping them away from the rod. Next, screw the body_02-wheel_base to body_01. Finally, position the wheel in the middle of the hole and fix it securely in place.. 

• Mount body_03-pickup_base to body_02-wheel_base and lock the rod using second rod_lock. 
• Mount the guitar pickup (it may be little bit hard as the rod lock may be getting in the way, but the springs can be squished :))

• Mount body_04 and body_05_top:

• mount the body_06-headstock.
• mount the crank.

Keyboard

• To mount the keyboard_base, use a minimum of 2 screws in the central row.
• Mount the keyboard_frontplate
• Mount two 10mm screws into each key as shown on the picture above.
• Put the keys in the front plate:

• Proceed by adding the backplate and keycaps to the hurdy gurdy. Take care to ensure that each key is properly locked into the backplate, securing them in place. 
   

keyboard_top_plate and wheel_cover should be mounted after setting the hurdy up.

Setup tips

The wheel has to be super smooth so it a good idea to sand it. To keep it round you can sand it while rotating it. 

We also need some friction between the wheel and the strings. You can achieve this by putting rosin on the wheel and placing a little bit of cotton between the strings and the wheel.

You can use a guitar pick or similar object to mute the strings while applying the rosin. 

Too much cotton or too much rosin may make it sound bad, I advise you to approach it with some experimentation. Find the right balance by trying different quantities of cotton and rosin until you achieve the desired sound.

Using guitar tuner mounted to the keyboard back plate was the most convenient way to tune it.