last update: 1st June 2018 - 1- History, 2- steel caracteristic , 3- nitriding, patent & licence... by Matthieu
A great collective energy binds experienced manufacturers, apprentices and people passionate about sound sculptures. Each in their own way participate in building a community.
The most valuable advise we received from one of our elders was "You have to work in a team !" and this energy has helped our Shellopan project to persist since 2010.
Shellopan is a cooperative enterprise, and is actively exploring an alternative way of exchange than what we have grown used to in our market economies. Following the message of our elders, we decided to open our workshop and share our means of production* in the manner of a fablab** dedicated to the sound sculpture.
(* here is one of our biggest means of production : our tool to make deep drawn handpan shells)
(** fablab = fabulous laboratory or fabrication laboratory... you choose ;) )
1) A Shellopan story...
Our work was born thanks to the work of our precursors and the information they published or communicated with the desire to see the knowledge become shared and more important. Our approach is to honor them and try to share the knowledge we use. For collective "knowledge" to increase, it requires that people using what we make available are also in the same process.
When we started our project in 2010, the main problem for creating handpans was to sink the shell by hand. We had initiated a project to create a deep drawing tool but the costs of such tools were too important for the two apprentices we were (Delphine and I, Matthieu). A few years later, other apprentices started projects all over Europe and we proposed to share a future production of stamped shells to make possible the construction of tools. A group of 5 makers agreed to take the risk of supporting the project (without knowing if the shells would suit them) and we collectively decided dimensions of the future shells. I then built the press tool with an industrial prototyping company and I made my first choice about which steel to use. In 3 years, we have produced 7 batches of shells that have become known as "Shellopan shell" and have been used by different makers around the world. We also welcomed many visitors who wanted to learn the basics of our work in our workshop. The demand for raw material and learning has become very strong but we did not want to increase our production and reception level. We wanted to promote the arrival of new projects and therefore the diversity of instruments manufactured.
Since 2017, other material manufacturing projects offer the sale of pressed, hydroformed or spun shells have arrived in a market in high demand and some have simply copied the Shellopan shell shape and industrialized the production and selling. We are therefore free from pressure and we will continue to develop / share our steel products and research at our own pace and with no desire for commercial development of this activity. Products and services are offered as part of a voluntary sharing process and they will only be accessible after prior agreement and / or by appointment. As should be possible for every human being, we reserve the freedom to choose when and to whose service we devote our energy.
We therefore choose to focus the "fablab" part of our business rather on people wishing to get involved in the Handpan community with a sharing approach that balances their business activity. We are not subcontractors for other manufacturers, so we do not respond to requests that are similar to an activity of this type. Although we do not always find them suitable, we respect traditional forms of business and hope to receive the same respect when we choose not to participate.
Information about the availability of shells: We launch a production every time we find the steel of our choice, it can take several months. We always keep a stock for the activity of the fablab and a stock of each batch for research and development operations. These considerations have priority over the resale activity of our shells. We are still very pleased to see the instruments made with our raw material by other tuners and to allow our research on the links between chemical / physical characteristics / timbre of the sound, we are interested in receiving feedback from the manufacturers using our stamped / deep drawn shells.
2) characteristics of the Shellopan deep drawn Handpan shells
The RAW material
To make our stamped shells, we must use a steel suitable for this purpose. The reference steel "DC04" is well known since the publications of the company PANArt. This reference is not a guarantee of getting a good steel due to the excessive tolerance of the standard. It is quite easy to obtain a bad steel DC04 (a steel marked DC04 can have with mechanical characteristics equivalent to a sheet of the standard DC05). The best parameters favoring the stamping are not better parameters for the management of compressive stress that we induce in sheet metal when we grant it, so we have to find the right "balance" when we choose a new batch of steel .
It is also possible to use other materials such as steels with higher carbon content (structural steel) or stainless steel. The method of forming and tuning should be adapted to the material used. Regardless of the work of the tuner, the sound of the instrument will be affected by the choice of basic material. We therefore think that it is important for a handpan manufacturer to know the physical and chemical characteristics of the sheet he buys.
ps : If you need shells and we have nothing available for you, you can check this page for spun shells. There is some other shell makers but I can share the link only of those who communicate the chemical composition and physical parameters of their steel.
Different methods of forming shells
(in increasing order of personal preference, benefits and defects in brackets):
- manual hammering pneumatic sand rammer (+ cheap / + can control the thickness with experience / - risk to health, dangerous for the muscles and joints)
- manual spinning or CNC (+ cheap / + ease of forming the port on the bottom shell / - problem of inconsistent thickness, sheet metal is refined further away from the center)
- hydroforming (+ easy choice of the depth of the shell - unable to control the thickness distribution, the final shell is thinner at the center up to 25%, we have eliminated this technique for this reason)
- spinning inside rings (see Pantheon Steel process, + possible control of the thickness according tooling / - need a thicker sheet initially as spinning will only refine the material / - marked grooves in the surface)
- Stamping / Deep drawing on hydraulic press (+ control the thickness of the sheet with the possibility of letting go material from the blank holder, - expensive tooling and need a huge press)
Shellopan shells are deep drawn under a 400Tons hydraulic press with a tool that we have co-built with a french industrial prototyping company.
Dimensions and thickness information
size: external 550mm, internal 530mm, high 130mm - starting thickness 1mm
A very important feature is the distribution of thickness after stamping (see photo below). The slippage marks are the consequence of the method we use to control the thickness repartition: steel is coming from the ring to avoid to stretch too much the steel inside the shell. The only way to be able to know the thickness distribution is to be able to mesure it with the good tools (ultrasonic sensor or other tools).
Information about the "raw" steel: the steel that we use has a light corrosion protection applied by the steel manufacturer in the form of a thin layer of oil. Stamping work, laser cutting and the various manipulations needed systematically alter the quality of the surface and more or less visible traces of oxidation can form during transport and storage. Sanding the shells may be requested just before packaging / transportation but this will make them more sensitive to rust, this choice is advisable for those who provide the transport themselves and have a storage with humidity control. Whatever the visual condition of the shells, we recommend to always perform a brushing & degreasing of the shells just before having them nitrided.
Information about the nitrided products: to prevent scratches, stains or rust, shells were sanded and cleaned before nitriding. Despite this, irregular marks, stains or oxidized points can occur during the process of nitriding or transportation. A further cleaning step before the annealing treatment and protection against rust after heating should be applied. These final steps will determine the corrosion resistance and aesthetics of the final product. Shellopan will not be able to provide a guarantee on the result of the work done with the shells.
3) nitriding and patent information
The choice of a low carbon stamping steel (eg DC01 to DC05) requires a treatment to harden the steel.
One possible treatment is nitriding, the principles of which were applied to a metal musical instrument in the year 2000 by PANArt Hangbau AG (Conference on New Developments of the Steelpan – Paris – 20/05/2000). Patents have been filed by this company concerning the manufacture of musical instruments in nitrided sheet. These patents are the subject of much discussion and sometimes misunderstanding in the Handpan community. We recommend everyone to study the contents of European patent EP2443625 and its history in order to form its own opinion and also to appreciate the impact that it can have on a manufacturing project. There is a possibility of using the techniques covered by the patent under license. The PANArt company published at the end of 2017 a document to explain their positioning.
We can distinguish 3 approaches concerning nitriding:
- a very short nitriding (about 1h30 to 5h) creating 3 layers in the material: a surface layer of combinaisaon, a layer of diffusion then a central layer of variable thickness whose characteristics of the matter were not changed. The protection against oxidation is rather weak but it is possible to try to improve it by a post oxidation procedure. In my experience, instruments made with this type of material generally have a very long sustain but may require more annealing to be stabilized.
- a medium nitriding (between 9h and 20h) creating 2 layers in the material as presented in the PANArt publications in the year 2000: this results in a combination layer and then a diffusion layer to the heart of the material. The surface hardness is about 2x greater than the hardness at the core. Compared to a short nitriding, it is a type of nitriding that gives more character to the material and is often considered harder to work for beginners. In my opinion, the longer the nitriding, the more the reaction of the membrane to the touch of the fingers can be worked by the tuner.
- a long nitriding (100h) as presented in the patent of PANArt to obtain a certain density of precipitated nitrides. It is a nitriding that no manufacturer of Handpan seems to use. PANArt would use it since Hang said "integral". I have never been able to test such material and can not comment on its characteristics.
In this period when the PANArt patent issue concerning nitriding is still relevant, I (Matthew - Shellopan) chose to share here my personal and current interpretation of this question:
PANArt's 2000 Nitriding Publications for the World of Steelpan are the most recognized contribution of PANArt to the history of this musical instrument, and these freely shared publications have been the most informative source of information that all Handpan manufacturers have integrated into their research.
The patent on which PANArt has been working since 2009 has given rise to a licensing program offering Handpan manufacturers the use of PANArt-protected know-how. This patent protects an improved version of the nitriding procedure that was freely shared since the year 2000. This patent has been the subject of legal debate in the United States and Europe because it has often been considered a trap for Manufacturers or apprentices manufacturers of Handpan. Its wording made it difficult for everyone to know if what he was doing could infringe the patent, the nitriding companies could not interpret it or its innovative character was questioned because it was based on research work that does not have not been published. Finally, the license program that resulted from the patent was more the commercial advantage derived from the use of the name "PANArt licensed" than the quality advantage of the licensed material.
A patent revision procedure has been requested from the United States and Europe. In Europe, it is a rather light procedure that makes it possible to fight against harmful patent filings (patents being as much tools for securing intellectual property as economic attack weapons ...) and any citizen can ask for this procedure before a certain time has passed. According to PANArt's communications published in late 2017, it appears that they experienced this revision process as an attack against them. The review procedures resulted in a more precise version of the patent. This more accurate version protects a nitriding program leading to complete nitriding throughout the sheet to give a linear density of needle-shaped iron nitride crystals in a range of 40000 m-1 to 80000 m-1. The patent also specifies a method for determining this linear density and PANArt offers again to each manufacturer to have the material he uses tested by an analytical laboratory ... All that seemed simple, until the review procedure was the subject of an appeal procedure initiated by the group Handpan Maker United and a few days later by PANArt. The documents published for the future appeal procedure demonstrate that it is possible to obtain a nitriding under the patent even if it is of average duration (about 12 hours) but the appeal procedure cancels the revision procedure and the original version of the patent becomes legally valid again. This appeal procedure can take many years (it is possible to request an accelerated procedure at European level in case of legal proceedings based on the patent between PANArt and a manufacturer).
For me, the main question posed by this patent is that no one is able to say if a material made under PANArt license would achieve "best" handpans. People who have signed a license in the past use it for their commercial advantage, but actually achieve short or medium nitriding. However, only some proof of achievements by other manufacturers with a material made according to the know-how of PANArt and the publication of some research to reveal the qualitative sense of this licensing program. In the absence of such demonstrations, this program appears as an offer for the development of economic activities. The evolution of the number of manufacturers seeking to differentiate could make such a program attractive, but I hope to better understand the quality aspect of this program.
4) metallurgical concepts and the importance of the scientific approach
It is possible to make musical instruments by simply tunning shells available on the market but it seems to me that starting a real craft project related to the physical characteristics of the metal should be accompanied by a study of these characteristics. I do not have the skill to do a course on this subject but to not be limited to talking about a hard or soft metal, I can still invite to learn about the following concepts:
- Chemical composition
- Yield stress : YS
- Young's modulus and elasticity
- Ultimate tensile stress : UTS
- Fracture elongation : e%
- strain hardening coefficient : n
- anisotropy coefficient : r
- bake hardening and work hardening
- annealing and tempering
- nitriding technology
- compressive stress
- necking phenomenon
- aging phenomenom
- differences between drawing steel, solid solution steel, bake hardening steel, high strength IF steels
Being able to explain the differences in stiffness, strength and hardness is the sign of a good understanding :)
The challenges in our research would be to understand the impact of all these parameters on :
- the timbre of a note and of an instrument as a whole
- each person's style of preparing notes and of tuning
- the durability of an instrument
5) essential tools at every building stage
While some expensive tools can be pooled, some become highly personal such as hammers. Everyone will have their own preferences - this article presents our approach to the subject.
- cleaning of shells: Scotch Brite with grain 180-1000 on edgegrinder, isopropyl alcohol or other degreaser
- nitriding: a rack to space the shells in the oven and avoid distortion
- stamping dimples: male/female press molds + press <20 tonnes. Here we share our tool to help you to calculate the notes and dimples size : shellopan-note-dimples-ratio.xlsx (right click and save as...). Kristof from handpanmold.nl can prepare the molds for you and is selling some other tools for the makers.
- making bottom shells: male/female press mold + press <20 tonnes + hammer
- shaping notes: rings and support stand, pneumatic sand rammer with different heads and/or other air hammer + air compressor.
- annealing/tempering: oven that can hold up to 400 °C. Electronic temperature regulation system.
- hamering: hammers and mallets set (eg jimmyshouseofhammers) or our tuning hammers. Be carefull with low cost hammer, most of the time it's not cast steel or not hard enough... you may quickly have surface scratch on the hammer. You will need to polish the head to correct the (too) quickly made shape. About weight, 70% of the time I work with 750g, 25% with 1kg and maybe 5% with 500g but that's really personal preference and note size dependant. Quite flat and round shape may be usefull too. We need bigger distance than usual between head and handle because we are working in concave shells, it's not easy to find that !
- tuning: audio analysis tool (eg linotune, overtone analyser, peterson mechanical strobe tuners). Tuning rings + stand to be able to work on each side of the shells (see next point)
- gluing: sand paper, isopropyl alcohol or good degreaser, high thrust caulk gun (polymer glue is thick and you need to put the good quantity in a regular way), rotating plate, mastic cutter
6) handpan tuning stand
You will find basic information to be able to build your own tuning stand here. You just need to find a laser cut company and to be able to drill holes and optionally screw thread. For the support, you can use an old desktop or make your own with second hand material. Click on the second picture below to download the .dwg files (right click & save as... if it doesn't work)
7) fablab pricelist and availability
|Shellopan FABLAB - prices list||fablab visitors price with french VAT||
price without VAT only for export or intra-europa**
|no shells or material available at this moment|
|next update should be after 2019/03|
** export = sell outside Europa. Custom fees may apply and we are only able to make genuine and accurate invoices. Intra-europa = you need a valid european VAT number to be able to buy without VAT.
8) Questions & Answers
Excel calc tool : are the note size dependent of the steel thickness ? Yes, thicker steel need bigger note size. Just adjust "C4" to change your starting point. Some technic to make shells create unregular thickness distribution, we are making deep drawn shells with hydraulic press to avoid this effect as much as possible.
Excel calc tool : why do you use note number instead of a clearer "note name" notation in your note size calc tool ? Because I don't know your steel thickness, but not only. Tuner skills are changing in time, most of the time with increasing experiences you will be able to tune the same note with smaller area. The border condition that you're creating during the shaping and the note dimple/ratio have big impact on this note size too. You will find your confort zone only after many try and error. I consider that the first size #0 is the biggest note that is possible to make on a shellopan shell (A2) but of course, even me may find that it's possible to make something lower. Step between 2 note number is 1/2 tone, so you will have 3 full octave in my calc tool.
Excel calc tool : what can I do with the F2 cell ? You can control the progression of the ratio between notes and dimples. For smaller notes, if you have a too big dimple, it may be hard to tune the note because you will not have enough space between the dimple and the note border. The color code in colum "K" give you a visual information on this space.
Excel calc tool : can you give me a warranty that I will be able to make a good handpan without changing the value in your calc tool ? No, I think that you need to adjust all these value. I choose the F2 parameter to gradualy change the note dimple ratio from 4 to 5.. this is only to illustrate how it works. The parameter you will choose will give the personal touch of your creation.
Dimples only or dimples & note border : is it possible to make dimples only with laser cut steel of the dimensions written in the excel file ? No, if you cut your molds with the external size, it will be hard to make the dimple only and you will mark the steel on the note border during the process. Some people like it and some people find that it's not good to create the note membrane or for tuning. Again, this is an important personal choice and if you want to make the dimple only, just cut the steel 1cm around the dimple hole.
Choosing a shop press : do you have any advises if I want to use a press to make the dimples ? You don't need a huge press, few tons are enough to make dimple and 20 tons is enough to press a really marked (too much ?) note border