Session 34

We have started to get students and teachers involved in make instruments.  The trombones players in the Small Band are in the process of making PVC trombones with 3D printed mouthpieces and bells.  A prototype of the mouthpiece has been made that is more of a large tuba size so it has been resized and is being reprinted.

 

A group of teachers have also been working on “box-style” ukuleles and learning more about using the laser cutter to add art work to the instrument.

 

Finished printing the resized mouthpiece which seems much better.

Session 33

Put together a display of some of our instruments in the school for students and others to see as school gets back in session.  Tried casting a brass bell.  The ~2000 degree brass did melt away some of the plastic, but the brass cooled off too quickly so it became solid before brass could melt away all of the plastic.  In the future the bell will have to be cast with a 1 layer thick outside shell and minimal supports to the metal can burn the plastic off before cooling too far.  The other option is to use a 3D printed mold for the pewter or a 3D printed mold to create a wax bell that can then be melted away with the brass.

Session 32

Finished 3D printing two more mouthpieces for the tubes.

Also started working on casting.  Started with pewter which has a lower melting temperature (>600 deg F) which wasn’t hot enough to burn off the plastic of the 3D printed bell.  Tried another method that used the plastic bell to create a shape in the sand and then used the bell offset up a little to create a cavity.  Unfortunately the metal flowed through a small hole in the bell to end up inside and outside the bell.  The plastic still didn’t melt away but the bounds between the layers of the print broke apart when trying to separate it from the bell.  There are two more printed bells, but they were still at school so we will have to try this again with the higher temperature metal.

Traced a tuning fork shape in the sand and cast it with pewter.  It does ring some when hit.  With a better shape it should work okay.

Also cut down scrap metal obtained from St. James bell tower that appears to be brass.  This melts at a much higher temperature ( >1900 deg F).  This should be hot enough to burn away the plastic in the future.  Cast two rough shaped tuning forks using this metal.  One rings okay.  The other one doesn’t ring much – probably due to the short handle which makes it hard to hold without damping out the vibrations.

Session 31

The set of tubes are finished.  They have different notes and sounds.  The tubes were played with a saxophone reed and “trumpet-style”.  The tone gets less clarinet like and more saxophone like as the cone part gets larger.  With the saxophone reed it was possible to get lower and higher harmonics for the more conical shapes.  Using a lip reed it was not possible to get the lower harmonics.  Also with the sax reed, it was more difficult with one of the middle tubes (about half cylinder – half cone) to hit the harmonics cleanly.  We experienced a similar problem at the beginning of the summer with our homemade clarinet (from rings).  As we increased the cylinder to conical ratio the harmonic structure changed. The videos of the tubes being played can be seen here:

video1 (lip reed)

video2 (saxophone reed)

Session 30

Finished printing two more of the cylinder-cone shapes for testing the difference in tone and note and started printing two more.  The four that have been completed so far definitely have different sounds, and the effort to play the different harmonics on each depends on the shape.  

Also laser cut a few more of the “box” ukulele and finished the large djembe.  Getting the djembe head tight enough required a couple of rounds of zip ties and after one of the strings snapped further work was required to get the tension needed.  The sound is much deeper than the other two drums.

 

 

Session 29

Got second of clarinet-sax – cylinder-cone test pieces off 3D printer. Also started printing two more parts of the set up.  The cone and cylinder with a tiny cone at the end had a different tone and note when played.  Once the remaining 6 parts are completed they will be recorded and analyzed to compare the fundamental frequency and harmonic present.

The top of each piece of the printer has had excess plastic on them when coming off the printer so we may need to shorten the pieces slightly if we print a new set since the printer seems to be running out of room while printing.

Continued working on large djembe.  Taped up the two rings for the drum head and put string on top ring.  Also sanded lip of top of drum to round off the outer edge.

Modified “box” ukulele to make neck stronger and laser cut 4 copies to allow others to make simple ukuleles to test out getting others down into the idea lab to build instruments.

Session 28

Started 3D printing the cylinder/cone test files.  The mouth piece works like a sax mouthpiece with a little extra vibration while playing.  The long cylinder with a short cone was still printing at the end of the day.  Next up will be the pure cone for comparison.

Finished up second ukulele with bent plywood sides.  Tried to adjust neck position to keep distance between strings and fret board more constant.  Didn’t use professionally made fret boards since the dimensions seemed different.  Seem like they are made for a longer neck and instrument.

 

Finished cutting wood for and assembling body of large djembe.  Used thinner wood for bottom to complete the drum.  Have two large rings saved for the drum head.

Session 27

August 3

Worked on CADing up files to 3D print to test out the concept of how the cylindrical vs. conical percentages of a tube change the harmonics present.  This is to test out the differences that we saw as we made our wooden “clarinet” longer without changing the conical length at the beginning of the summer.  We got changes in the note and ease of playing the note that we didn’t expect.  

These will be 3D printed and tested.  The saxophone like mouthpiece is designed to slide onto each of these shapes.  This also will be a nice way to show students how the shape changes the sound of an instrument if it works well.

Here is an image from a book on the physics of music that relates the relative length of the conical divided by the overall length to the harmonic frequencies produced.

(page from The Physics of Musical Instruments by Neville Fletcher and Thomas Rossing)

Session 26

Worked on second ukulele more to perfect some of the details and to get more detailed photos for the Instructable building instructions.

The burned wood from the 1/2″ pine plywood made it more difficult to get the front and back plate to attach since the glue did not hold to the charred regions as well.   Etched physics of sound related images into the front and back panels for this ukulele.

Also created template for form for body of classical guitar based on ukulele design and cut a number of pieces for it and put together part of another ukulele form.  We will need more 1/2″ wood to complete the forms.

Also created files and started cutting out circles to make a 20+” djembe since this will be helpful to have for presentations about the project.  Still haven’t done the casting part of the project, but hopefully can do this towards the end of August.

Spent time cleaning up everything in the Idea Lab and getting stuff put away on shelves to get ready for the fall.

Session 25

August 1

Got new trombone bell off the 3D printer and tested it.  It seems to work well.

 

Also worked on building a second tenor ukulele to improve the design files and process of putting together to be able to have students and others be able to do the project more efficiently.  Also spent time improving the Instructable to be used by students and others.  Bought 1/2″ pine plywood instead of Baltic birch plywood this time.  It doesn’t work on the laser cutter nearly as well so won’t do that again.

The new shape for the outer form for shaping the side panels works much better.  Also found pre-made fret boards for ~$7.50 which seems like a better option than doing this part from scratch.  Also ordered a different size of tuning pegs which will hopefully work even better.