Introduction: A Homemade DIY Great Bass (ie Viola-Range) Recorder for $30-40

Picture of A Homemade DIY Great Bass (ie Viola-Range) Recorder for $30-40
In the recorder family, the great bass recorder has a range starting at the C below middle C (that is, the viola range). Instruments in this range provide much-needed bass support for wind ensembles.

Because the recorder's size necessitates keywork, which must be made precisely, commercial great bass recorders sell for $1000 - $2000. Now you can create your own for about $30-40.


Note: the prototype in this video reflects an earlier revision of hole placement. The revision in this Instructable features better tuning.

Materials:
- 1.5" nominal Schedule 40 PVC pipe (e.g. from Home Depot for $5 per 10' length) x 4'
- 2" nominal Schedule 40 PVC pipe (for the key segments) x 3"
- Several 3D-printed parts (for fipple and key mechanisms; see https://www.shapeways.com/designer/ssngai)
- 2mm craft foam (for key pads) 
- 3/16" diameter wood dowel (from Home Depot) x 5"
- Size 16 standard rubber bands (a very common size) x 5
- Tacky glue (e.g. Aleene's Original Tacky Glue)
- Hot glue

Tools:
- Free online electronic tuner (http://www.seventhstring.com/tuner/tuner.html)
- 3/8" drill bit (I use an Irwin Speedbor spade bit intended for wood--yes, wood.)
- Small round file (for insides of holes)
- Flat file (for surfaces)
- Tape measure
- Calipers (optional)
- Masking tape
- Hacksaw

Note: For updates and improvements, and also to learn of other alternatives for various steps, please contact the author.

Step 1: Prepare the Body Tube

Picture of Prepare the Body Tube

Cut pipe to 48.0". (Note: the previous version specified a length of 48.25".)
If you do not cut the pipe squarely (perpendicularly), the fipple piece may not fit, or there will be some uncertainty as to the proper location to drill the toneholes. Obviously, as one of your two cuts you can use the pre-cut side of the 10' length. 
Use the file to remove burrs.
Use the better-cut side for the bottom of the instrument (bell).
Before you proceed, it might be a good idea to wash the pipe a little.

Mount the endcap fipple with masking tape.
Excessive air leakage may cause distortion of tuning. As long as the cut was fairly straight, one strip of tape on each side should hold it down well enough.
Don't glue the fipple down yet. You will need to remove it during tonehole drilling and mount it again at the end.
The best orientation is rotated 90 degrees right of centerline. In my opinion, that makes for the most comfortable playing position, which is illustrated in the video.
If you want, you can swab the pipe end with alcohol. You don't know where that thing's been.

Blow to play your first note (the bell note or base note)!
Confirm that the pipe plays within about 10-20 cents of 130.81 Hz (C below middle C).
Any frequency within this range is pretty much acceptable, since frequencies will vary as much as 30-40 cents with your blowing pressure.

Step 2: Mark and Drill Toneholes

Picture of Mark and Drill Toneholes

Identify the line you want to be the front (centerline).
Often the PVC pipe will have a line of printing. You probably want this side to face you.
Orient the diametrically opposite side to be the front.

Measuring from the bottom of the pipe, mark and drill the following 3/8" toneholes:
258mm: 90° right of centerline
385mm: 40° left
454mm: 10° left
529mm: 40° left
637mm: 40° right
708mm: 10° right
790mm: 40° right

(Previously published measurements for 48.25" tube follow:
260mm: 90° right of centerline
390mm: 40° left
455mm: 10° left
540mm: 40° left
645mm: 40° right
715mm: 10° right
795mm: 40° right)


(Tonehole positions are determined by a combination of complicated mathematical algorithms... plus some good old-fashioned error compensation by estimation. More information is available from the author.)

Using the round file, clear the burrs from within the holes.
Also file lightly over the tops to eliminate burrs that would keep the keys from seating properly. But don't file too aggressively -- you don't want to distort the round profile the key is designed to seat against.

From here on out, it's all about the keys.
It is crucial that the keys seal their holes perfectly, or else the instrument will play poorly.

Step 3: Cut Key Segments 2, 3, and 4

Picture of Cut Key Segments 2, 3, and 4

Cut a 3" length of 2" PVC pipe and split it into three 120° segments.
Make both longitudinal cuts and transverse cuts as straight as possible! This will make future steps easier.
For better control of the cutting process, you may find it easier to cut the three segments partially before making the 3" cut.

(Why are we using a 2" pipe? A lucky coincidence: it so happens that the inner radius of 2" pipe and the outer radius of 1.5" pipe are discrepant almost exactly by the thickness (2mm) of a craft foam keypad. So rather than 3D-printing all five of our keys, we save some money.)

Step 4: Prepare Keys 2, 3, and 4

Picture of Prepare Keys 2, 3, and 4

Get spare segment of 1.5" diameter pipe to use as a gluing template (like a dowel or mandrel).
Very carefully pencil in longitudinal marks. You will use these as a reference for aligning the hinge pieces.
If these lines are significantly off, and your hinge pieces are off, the hinge won't swing correctly, and your recorder won't speak properly.
Any text that is printed on the pipe may help you draw the longitudinal lines. Keep in mind that not all letters in text rise to the same height! To create the illusion that all letters are the same height, round letters often protrude a tiny bit higher (unless you are a typographer, you probably didn't know that!).

Cut a rectangle of craft foam measuring 2.625" x 1.25".
You may be tempted to think that increasing the 1.25" measurement may improve key sealing, but it won't.

Find the better (flatter and more perpendicular) edge of your 2" diameter pipe segment. Glue rectangle into inner surface of segment, applying it close to that side.
You can move the foam a few times from side to side to even out the glue and work out any excess.

Place just-glued assembly on 1.5" diameter pipe as template and weight down with a few heavy books.

Allow 3-4 hours to dry.

Detach 3-D hinge pin pairs.

Sand down the nub left over from the cutting so that, once installed, it will not obstruct the free swinging of the key segment.

Align and glue 3-D printed hinge pins toward the flatter side, where you recently glued the foam.
The hinge pieces are custom-designed for this application -- 2" PVC on 1.5" PVC.
Using the line you drew earlier, make sure the two hinge pieces line up, or the hinge will not operate correctly!
Also make sure the hinge is close enough to the edge that no part of the key segment will obstruct the free swinging of the key.
Use tacky glue to temporarily hold the hinge pins in place before hot gluing them down.
Ensure the critical parts of the hinge assembly are not obstructed by glue.

Repeat for all three segments.
If this is your first time, you might want to do just one first to make sure you don't screw up all three at once.

Step 5: Prepare Key 1 and 5

Picture of Prepare Key 1 and 5

Key 1, the highest key, and Key 5, the lowest key, are 3-D printed. Refer to diagrams.

Sand or file down the arch pieces so that they hold the axle snugly against the tube body.
They're all purposely a little longer than necessary so that you can do this.
Of course, you don't want to over-shorten the arch; if you do this by accident, I suppose you could just float it up on a little glue.

Cut two squares of craft foam measuring 1" x 1".

Using same process as in the previous step, apply the craft foam to the 3-D printed keys. Let dry.

For Key 5, install wood dowel to connect proximal and distal key segments.

Measure proper length of wood dowel (about 5") by laying parts out against the main tube.
The fit is designed to be tight. It may be necessary to sand down the dowel ends slightly.

Step 6: Mount Key Assemblies

Picture of Mount Key Assemblies

Mount keys 1 and 5.
It's easier to install these keys first before the other keys keep you from laying the tube flat.
Use the diagram as a reference.
To fix the hinge pins in place, use the supplied hinge pin guide pieces (A, B, C, D).
Fix in place with hot glue.

Mount key assemblies 2, 3, and 4.
Use the diagram as a reference.
Hold the key assembly snugly in its final place on the main tube.
Apply tacky glue to the hinge wings and slip the wings into position. The wings should be a perfect height to accept the hinge pins.
Fix in place with hot glue.

Install rubber bands and key travel limits.
I have specifically chosen rubber bands over springs because they are more cheaper and plentiful than springs.
Moreover, their movement is easier to control; elastics pull back reliably along their axis, whereas compressed springs often push back off-axis.

Step 7: Your Great Bass Recorder Is Complete!

Picture of Your Great Bass Recorder Is Complete!

Reattach the fipple cap.
I recommend it face 90 degrees right of centerline.

Fingering (preliminary):
Top --> bottom
x x x   x x x   x = C
x x x   x x x   o = D
x x x   x x o   o = E
x x x   x o x   o = F
x x x   o x x   o = F#
x x x   o o o   o = G
x x o   x x o   o = G#
x x o   o o o   o = A
x o x   x o o   o = A#
x o o   o o o   o = B
o x o   o o o   o = C
o o o   o o o   o = C#
o x x    x x x   o = D
o x x    x x o  o = E
o x x    x o o  o = F

Accidentals produced by cross-fingering.
Key 1 doubles as a register key (though the upper octave may also be produced with the hole closed).

Comments

GrogB (author)2017-01-31

I am a bit lost with:

Several 3D-printed parts (for fipple and key mechanisms; see https://www.shapeways.com/designer/ssngai)

What exactly should I order?

I have everything else and am ready to go.

dave_bryan (author)GrogB2017-08-20

Did you get a reply GrogB

dave_bryan (author)2017-08-17

I can't work out which 3D printed parts I need for the 1 1/2"version, whether they are available as files or ready made and where the rubber bands attach.

rimar2000 (author)2014-05-09

Very good work, thanks for sharing it.

jexter (author)2013-10-30

Nice work! That's got a great sound. The graphics are great, but could you include a close-up photograph of one of the key assemblies on the instrument? I think it would help to see the actual key/rubber band finished setup as well as the diagram.

Thanks for sharing this!

stubbsonic (author)2013-10-29

This is amazing. You seem to have done the impossible.