Alto Rebec

20.06.2023    Added an alternate Soundplate with bass bar, which gives the instrument a fuller sound. Just add a lower saddle andf replace the old soundplate with this.

(scroll to bottom for technical drawings!)

Sound samples:

https://vocaroo.com/1mTpZ0LNSlIF

https://vocaroo.com/1d4PDWcNos6v (alternate tuning with low C string, C-G-D)

Print instructions:

The most difficult part is the neck joint to the body. Print the joint test in the respective folders first, before printing the whole parts. If you have trouble joining the parts, there is a “High Tolerance” folder with slightly higher clearance for the dovetail joint. A tight fit is desireable, use small files to rework the dovetails if nessecary.

In general:

Print slow. I recommend limiting flow rate to 8mm³/s for PLA; and 6mm³/s for PLA-CF.
Print orientation is important - print as shown in the photos. The nut has to be printed upright to make the strings glide better.

Body:

Print the body with enough perimeters that there is no infill in the walls of the bowl. Use 30-40% rectilinear or grid infill, top/bottom shell minimum 1mm. Use organic Supports.

Neck:

Print with minimum 7 primeters, top/bottom shell 1mm, rectilinear or grid infill, 30-40%

Fingerboard:

Make sure top shell is minimum 3mm. I recommend printing variable layer height, the curved part with 0.07mm; or even 0.05mm layer height.

Small Parts: 

print these massive, without infill; in the recommended print orientation (see photos)

Soundplate:

Print massive, without infill in the recommended print orientation (see photos)
For improved sound, print the solid plate with normal PLA, and the Ribs with PLA-CF. You can do this with intermittend print pause and filament change or using an MMU.

Assembly and setup:

This Rebec uses ¾ Violin strings and is tuned G-D-A

1. Put the Body on a flat surface, then push the neck dovetail into its counterpart on the body. If you can get it ¾ of the way in, you can hammer it down with your hand or a soft object. Otherwise, rework it with a small file. If the joint sits tight, then there is no glue necessary.
2. You can now insert the tuners into the pegbox, make sure the small pin aligns with the small hole above the 10mm hole for the tuner.
3. Glue the fingerboard to the body and neck, make sure it it sits flush with the outline of the instrument.
4. Glue the nut to fingerboard and neck - the higher part facing the fingerboard. Use only a small drop of glue, so you can pry it off later for repairs. Its mostly held in place by string tension.
5. Glue the tailpiece nut to the soundplate - the thicker part of the “L”-shape on top of the plate.
6. Take the tailpiece and wind a few loops of fishing line through the bottom holes - see photos.
   Then tie a knot on the top side.
7. Now you can put the soundplate on the body
8. Pull the strings through the underside of the tailpiece. Attach the fishing line to the button on the body and the string ends to the tuners (see photos), make sure the fishing line sits on the tailpiece nut, and the strings in the grooves on the nut at the fingerboard.
9. Pre tension the strings, until everything is held securely in place.
10. Now carefully insert the bridge, thin part on the side of the highest string and push it toward the position indicated on the drawing.
11. Now you can bring the strings to tune -wear eye protection: every printing mistake might result in a string or the tailpiece snapping!
12. Tighten the Phillips head screw on the tuner for the lowest string to prevent it from being rotated by string tension.

If you have problems with the built, please describe them in the comments; and tell me your printer and slicer! I will upload an updated file or try to find a solution for you.

Drawings

Assemble and glue the parts according to this drawing:

The Rebec uses three Banjo tuners. Make sure the ones you buy comply with these measurements:

Place the Bridge like shown in this drawing:

Here are some general measurements of the instrument: