Introduction: Baroque Alto Recorder in F
In this first instructables I write I'm covering all the details to print, post process and assemble this fully working alto recorder. The recorder can be printed in any standard RepRap printer or commercial home printer such as ultimaker or makerbot. As long as your max build height is greater than 190 mm you are fine (most RepRap printers can print up to 200 mm in height).
As for the recorder itself, it has a fairly good quality. It can produce tones for two full octaves and a little bit of a third. The fingering is the modern English fingering, also known as baroque fingering. In this page you can find the complete fingering chart for this recorder.
Go ahead download the thing and continue reading this instructables.
Step 1: You'll Need...
- The thing from thingiverse (I recommend to download the source zip).
- A small flat file, around 12 mm width on the tip is ideal.
- A pair of pliers.
- A calliper (optional).
- Acetone (optional).
- A 3D printer (duh) and ABS plastic.
You can try and use other type of plastic, but some steps in this process use acetone to weld and polish the plastic, so I recommend to use ABS. The parts are basically thin, tall cylinders so you shouldn't have any trouble with warping.
Optionally you'll also need the following software:
This software is necessary if you want to compile the source, which is necessary to print a calibrated recorder. You should be familiar with the use of that software, as this tutorial doesn't cover the details of their use.
Step 2: Print Settings
To slice the parts, I recommend to use a thin layer height, like 0.1 mm. It's rather slow, but you'll get the most precision you can from your printer. Some parts of the recorder, such as the labium, are delicate and will greatly benefit from the thin layer height.
As for other settings, I've used "normal" print speed (around 50 mm/s) and 30% infill, although I think those things don't really matter. Just use the settings you are comfortable with.
Pay attention to the joints. You want them to be as solid as possible. Some slicers (like slic3r) tend to leave gaps in thin walls like those, so experiment with the perimeter extrusion width to get the best results.
Don't scale the recorder. If you are wondering, you can't get a soprano recorder by just scaling it down to 66%. Not all measures shrink the same amount to get it tuned.
Step 3: Calibrate Your Printer
To achieve the most accurate tone the recorder needs precision sized holes. Most printers tend to print undersized holes, so it's a good idea to calibrate the size of the holes printed by your printer before printing the whole thing. To calibrate, you'll need to compile the sources, so you'll need OpenSCAD and Python.
If you know your printer prints accurate sized holes or don't bother about tone accuracy, you can go ahead and print the STL's from thingiverse directly. Otherwise follow the following steps to calibrate.
- Print the file "calibration.stl" using the slicing settings you'll use in the final print.
- Measure the small lateral hole and the inner bore. The hole should be 6 mm in diameter, and the inner bore 16 mm. The outer diameter is 25 mm. If you get less than that, you need to compensate. For example, if you get 5.70 mm for the small hole (like in the picture) you need a compensation of 0.3 mm.
- Uncompress the file "source.zip" in some place on your computer and open "barroca.scad" with OpenSCAD.
- Change the variable "internal_compensation" to whatever value you measured (in my example, 0.3).
- Uncomment the line with "calibration_piece()" and compile a new calibration piece.
- Print using the exact same slicer settings you used before.
- Measure again. You should now get correct (or close to correct) measurements.
If you are wondering what the "external_compensation" variable is, it is intended for "external" features, such as the width of a cylinder. If you measure more (or less) than 25 mm in the cylinder width of the calibration piece, you should change this value as well, although I've found most printers are accurate for exterior perimeters.
Once you got the new calibration piece printed, you need to make a final adjustment. Open the file windway.py and change the variable "internal_compensation" to the value you obtained before. Save and execute the script. It should generate a new "windway.scad" file. Now you can compile and print all the pieces with their measurements calibrated. Just uncomment "full_plate()" and you are ready to go!
Step 4: Print
Now you are ready to print the recorder. In my case it took roughly 13 hours to finish, so go get some snacks while you wait.
Step 5: Remove Support Bridges
You've probably noticed that the bore of the three main pieces are obstructed by one or two layers of plastic (depending on your slicer). Those bridge layers are there as support. Remove them using the pliers. Doesn't require much effort.
Step 6: Sharpen and Polish the Labium
The labium is the sharp edge where the air stream strikes, producing the sound. Ideally, the edge should be as sharp as possible, and the surface should be smooth, but the typical printer has a 0.4 mm extrusion tip and produces rough walls. You can see the edge is not sharp at all.
Before sharpening, do a quick test of the sound. Assemble the mouthpiece and blow while you cover the bore with your hand. As you blow harder, you'll notice that it squeaks very unpleasantly (check the video). This is what we want to eliminate by sharpening the labium.
Using the file, sharpen the edge and polish the roughness of the labium. try to file equally in the outside and inside of the bore to keep the edge centred.
Go slow and gentle, it is really thin and easy to break. Notice also that the edge is slightly curved outwards. Try to keep that curved shape as you file.
Get the edge as sharp as in the picture. Then, using a cloth wet in acetone, do a final polishing. The acetone will give the surface a nice shiny finish.
Do a test again. It shouldn't squeak like before (it should sound as in the video).
Step 7: Make the Windway Bevel
After polishing the labium, you can still hear kind of a warble in the sound test. This warble will make the recorder unable to reach the higher register notes, so we want to get rid of it!
Turns out you need to make a small bevel to the exit of the windway. I don't really know what's going on here, but it works. I also failed to get the bevel directly from the print, for some reason it just doesn't want to work if not done manually.
Using the square tip of the file, make a small bevel. Use the pictures and video as reference. The bevel should be around 0.5 to 1mm deep. Make sound tests periodically until you can't hear warbling any more (just as in the last video).
Step 8: Assemble the Fittings
The fittings (the two small cylinders) need to be glued to the main body. Probably you can't quite fit them into the grooves, so file them down until they fit tightly. Then, using a little bit of "ABS juice" (ABS plastic dissolved in acetone), weld the fitting into place. Be sure to fit the piece all the way to the bottom. The ABS juice sets really quickly, so be careful!
Step 9: Sand and Polish the Fittings
The fittings are intentionally slightly thicker than the bore where they fit. This is to give room to sand and polish them to get a tight seal.
Smooth the inner bores using a cloth wet on acetone. One or two passes will do.
Sand the fittings using the sand paper until they barely fit into the bore. Then smooth them down using acetone on a cloth. Use some kind of lubricant to fit the pieces together. I had some "recorder cream" from a Yamaha recorder, but vaseline works just fine. If it doesn't quite fit, just sand a little more and polish again.
Once this step is complete, you can assemble a play the recorder for the first time!
Step 10: (Optional) Weld the Mouthpiece
Optionally you can weld the mouthpiece to the upper segment using ABS juice. I designed the mouthpiece to be welded together, but I found that the recorder plays just find without welding, and it is easier to clean if you can remove the mouthpiece, and you can experiment with modification on the labium too. But, if you feel the joint is too loose, just weld and forget about it.
Step 11: You Are Done!
Enjoy your new alto recorder! Check the video to see it working once finished!
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