Wooden Hut
  • Dylan Crismani

How to build a Cristal Baschet

If you want to build a Cristal Baschet of your very own, you have arrived in the right place. This post describes the process of building a cristal baschet, with links to materials and tools so that you can build your own exciting instrument made mostly from things you can pick up from your local hardware store, or if online purchasing is more your thing, I have you covered.

Before we delve into the fine details of putting the instrument together, allow me to provide you with some back story on how my own cristal baschets came about. Late in 2019, shortly before we found ourselves in the grips of the COVID-19 pandemic, Gabriella Smart (concert pianist) approached me to write a piece of piano music for her that she could tour nationally and internationally with. I was on board, but I wanted to avoid writing music in 12-TET, so the solution I devised was to build her an instrument that she could travel with. I came across the Cristal Baschet in a book called Musical Instrument Design by Bart Hopkin and decided to build an adapted version that could fit into a suitcase.

Early in 2020 funding came through from Arts SA and then I actually had to figure out how to construct the instrument using little more than photographs from the internet, and the information contained in Hopkin's book. Initially I had an instrument maker working with me on the project, but as international lock-downs started taking place, I was unable to rely upon anyone but myself. So I set about making some prototype instruments, ironed out some critical flaws in my design, and then set to work building two cristal baschets capable of producing a 30-pitch (unequal) division of the octave. Enough on the background of my own cristals, let's look at how you can put your own instruments together.

Main Components

There are five main components that any Cristal Baschet is made up of, these are:

  1. The pitch producing mechanism.

  2. The resonator cone.

  3. The base plate.

  4. The support bar.

  5. The stand.

The pitch producing mechanism

This mechanism is made up of six main components: a glass rod, two threaded bolts, a tuning plate, a cable lug, and a number of nuts. The first component is the borosilicate glass rod that the cristalist rubs with wet fingers to produce a sound. The main thing you need to consider when purchasing the glass rods is that their diameter matches the diameter of the cable lugs, 6-8mm diameter is a good size. The option I went with here was finding a local glass worker who purchases borosilicate rods in metre lengths, and asking them to cut the rods to a specific size for me, but purchasing them online or from a laboratory supplies shop is also an option.

The second and third parts of the mechanism are the threaded bolts; one mechanism contains two threaded bolts. One threaded bolt is directly attached to the glass rod and energy is transferred from your fingers, through the glass rod into this bolt. For this first threaded bolt, I decided to use an M6 size rod. The second threaded bolt is designed to stabilize the vibrations of the first bolt, for the second threaded bolt I chose to use an M8 size rod. The length of the bolts affects tuning, longer rods create lower pitches while shorter rods create higher pitches. To cut the threaded bolts to size you will need either an angle grinder or a high tension hacksaw in addition to a good G clamp to hold your work pieces in place. I would caution against using an angle grinder to do this, angle grinders are extremely dangerous tools if being used by an inexperienced user. Although using a hacksaw is more labour intensive, it's much safer than an angle grinder and you can feel that you've earned that knock off beer instead of ending up in the ED of your local hospital. If you've been trained how to use an angle grinder safely, however, then by all means go ahead.

Once you cut the threaded bolts to length using either tool, you will need to file the jagged ends down so that you can easily thread nuts onto the bolts, and so that the instrument is safe to handle. Finally, there are a few options to choose from in terms of what material the threaded bolts are made from, the best options are galvanised, or stainless steel, remember the instrument relies on water to make sound so you want prevent corrosion.

The fourth part of the mechanism is the cable lug. The cable lug is the small piece of metal that attaches the borosilicate glass rod to the threaded bolt. The critical element of the cable lug is that the eye of the lug will slide easily onto your threaded bolt, and that the glass rod will slide neatly into the other end. Silicon sealant can be used to avoid excessive amounts of buzzing and general unwanted noise, simply apply a small amount of the silicon sealant to the inside of the cable lug and to the tip of the glass rod, then allow to cure for around 12 hours.

The fifth part of the mechanism is the aluminium tuning plate. You purchase these in long flat bars of aluminium, alternatively a local steel works or hardware store usually stocks this item. The aluminium bars need to be cut to the desired length, then drill on M6 size hole and one M8 size hole on each tuning plate for the bolts to slot through. Once these tasks are completed, the tuning plates can be filed and sanded to avoid jagged edges.

The sixth part of the mechanism is the hex nuts. The nuts should not be an oversight, you will require around twenty nuts per mechanism, if you have 88 mechanisms like a piano keyboard, then you'll need 1,760 nuts. In the case of my cristal baschets, I used 9 x M6 hex nuts for the M6 rod, and 9 x M8 hex nuts for the supporting M8 rod, then to attach each rod to the base plate I used a single M6 lock nut and M8 lock nut.

As you can see in the image, three M6 nuts lock the tuning plate in place, four nuts hold the cable lug in place, and two nuts hold the M6 bolt onto the base plate (with the lock nut on the bottom side of the base plate). The M8 nuts are distributed in the same way across the M8 bolt, but in place of a cable lug is the stabilizing support bar.

The resonator cone

Most cristal baschets rely on a large metal, fiberglass or wood resonator cone to push the vibrations of the instrument through the air. These cones look incredible and actually play a critical role in the amplitude of the instrument. For my instruments, I opted to amplify the sound using a number of contact microphones as ease of transportation was a key factor affecting my build. You can pick up a cheap contact microphone for as little as $8AU, but if you plan to be attaching and removing the microphone often, you will thank yourself for buying a slightly more expensive one with a clip, instead of one that uses adhesives. Using contact microphones instead of resonator cones gives the instrument some very interesting timbres you can work with, these will be covered in another post.

The base plate

The base plate is the part of the instrument that all of the mechanisms are attached to, preparing this is reasonably straight forward. For my instruments I used a fairly thin base plate to avoid excessive weight, but using a thicker one is advisable. The base plates I used were around 50mm x 3mm. Because this bar of aluminium was so thin and flexible, I needed to reinforce it using a small 10mm x 10mm aluminium tube in the same way that a luthier reinforces the soundboard of a violin with a bass bar. To eliminate unwanted vibrations, I attached this tube to the base plate using silicon and a number of very small bolts. If I were to start again, I would try to find a base plate that was around 10mm thick and did not require bracing. Once you have selected your base plate, determine how far apart you want your mechanisms to be, and the spacing you want between the M6 and M8 bolts. Mark up the base plate using a ruler and a sharpie. Prepare the piece for drilling using a sharp centre punch and hammer. Drilling these holes out will ideally be done on a drill press. Using an electric hand drill is also possible if you want to do it on the cheap, but it is well worth the investment to use a drill press, you will achieve neater and straighter holes. Alternatively, a local community workshop such as Sane Maker Space will let you use their workshop and tools for very reasonable rates saving you the expense of purchasing many tools you may not want to buy to build a single instrument.

The support bar

The support bar is another flat aluminium plate which you need to prepare in the same way as the base plate, but this plate only slots over the M8 bolts, and can be seen in the cristal baschets pictured in this post. The support bar serves to keep all of the bolts neatly spaced in a straight line, and to decrease how much the M8 bolt can move about as it vibrates. Initially I didn't think this bar was necessary, so I omitted it. After pulling my instruments apart and putting them back together a number of times to trouble shoot various issues, I would advise simply factoring this bar into your build to avoid pulling your instrument apart more than necessary.

The stand

The stands that I made for my instruments will likely not suit everyone, so I won't go too in depth with how to build them. They were build specifically to be small and to fold up, so that they could fit into the suitcase with the cristal baschets.

The stands are made of rectangular aluminium tubes which can be purchased from your local hardware store or steel works. The tubes are held together using M6 bolts, with the fixed joints being held together with metal screws (these are screws that are designed to hold two pieces of metal together). I textured the metal using a cheap handheld electric sander. This is shown in the picture below.

Finally, if you choose to build your own cristal baschet, you will want to stock up on rubber strips. I have used rubber in a number of the joints in the stand and also in the gap where the cristal baschet slots into the stand. Rubber is essential for troubleshooting unwanted vibrations.

Thank you for tuning in, and if you would like to hear how my cristal baschet sound, check out my portfolio here.


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(C) Dylan Crismani

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