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Jack_Campin
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[*] posted on 6-23-2019 at 01:25 PM
3D-printed rosettes


Anybody tried 3D-printing oud rosettes, or the even more complicated rosettes for baroque guitars?

Dunno anything about the acoustic properties of printing resin but it doesn't seem like a very critical problem.




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jdowning
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[*] posted on 9-4-2019 at 04:05 PM


About 18 months ago I purchased a relatively low cost 3D printer as a tool to learn more about CAD (Computer Aided Design). The Creality Ender 2 printer comes as a kit for self assembly - taking about 30 minutes to assemble. It has a small footprint so does not take up a lot of bench space has a heated bed and a print volume of 150 x150 mm by 200mm height. Having run a number of test prints - some to make parts to improve on the original printer design - other priorities have got in the way so the printer has been put on one side for the present time - perhaps to be further explored as a winter project.
I did have in mind printing out some lute or oud rosettes from first principles using free software to create the files to input the printer. There is an online community of 3D printer enthusiasts that post free developed CAD programs for a whole range of print projects - including this one for an oud rosette!

https://grabcad.com/library/sound-hole-rosette-for-new-project-an-ou...

I have yet to run a test print of this rosette but will do so once I have time to get my printer up and running again.

There is a wide range of plastic filament materials available for 3D printers some impregnated with wood or metallic powder to give the appearance of wood or metal. There is also a filament that will print a model in wax that can then be used for casting solid metals by the 'lost wax 'process. See here for a description of the full range of filament materials. Not every printer can handle all of the materials but there is scope for some interesting possibilities.

https://all3dp.com/1/3d-printer-filament-types-3d-printing-3d-filame...

Note that the rosette does not significantly affect the sound hole acoustics of an oud or lute compared to an open sound hole as the mass resonant airflow across the sound hole is restricted to the outer perimeter of a sound hole. This excellent recent research paper from MIT exploring the acoustic effect of sound holes in violins but also including some related investigation of lute sound holes provides the complete technical analysis but, like all good published research work, summarises the conclusions of all the physics and mathematical proofs in a straightforward manner that can be understood by those (like me) who are not physicists.

https://royalsocietypublishing.org/doi/full/10.1098/rspa.2014.0905

I do not know if a baroque guitar '3D' rosette will have some effect on sound hole acoustics (by modifying the apparent depth of the sound hole and hence the Helmholtz resonance value). Another potentially interesting topic for experimental investigation no doubt!



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Dr. Oud
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[*] posted on 10-14-2019 at 07:34 PM


Just to get your terminology straight, the 3-D printer is a CAM (Computer Aided Manufacturing) system. The design input to the 3-D printer is the CAD system. Two different animals.



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[*] posted on 10-22-2019 at 01:08 AM


I don't like the machined appearance of laser cut roses. They are too perfect. The hand cutting produces irregularities that gives the rose character and is witness to the hours spent sawing out the pattern.



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jdowning
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[*] posted on 10-28-2019 at 03:40 PM


Most affordable 3D printers produce a three dimensional print in thermoplastic others (relatively more costly) print in greater detail in light cured resin. Both types build up a print layer by layer in 'slices' - an additive process.

The cheapest entry level printers currently cost around US$200 but industrial quality printers can cost thousands. My printer is the cheapest I could find at the time (about 18 months ago) that had good reviews and which could handle a variety of thermoplastics (see my previous post). To test the printer I have made a number of prints from .stl (stereolithography) files prepared by others and freely available on line. The input files must be further processed with slicing software (I have used CURA) prepared on a PC and then loaded on to a micro SD card that is inserted into the printer to run the print. It takes some experience to select the optimum parameters for producing the best print from the printer as well as setting up the printer mechanically for best performance.

The Creality Ender-2 printer (sold as a self assembly kit of parts) has some design imperfections that may be overcome thanks to support groups on line. For example one of the decorative plastic strips on the vertical column had to be removed as it fouled a screw on the back of the X axis module disturbing free movement and so adversely affecting print quality.

As an example of the complexity of print that is possible the attached image shows a roller bearing printed in one piece. It is not perfect due to less than optimum mechanical set up (that may be improved upon by trial and error) but it does rotate as designed.

Since the preliminary trials 18 months ago the printer has been set aside due to other work and life priorities so there will be some re-learning of the process to go through. Once I can find the time - hopefully as a winter project - I plan to try printing oud/lute rosettes starting with scanned 2D line drawings and converting these to 3D using free TinkerCAD software just to see what might be possible - good or bad - at lowest cost. This project will be reported as a separate topic on this forum.






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[*] posted on 12-1-2019 at 06:08 AM


Hi John I have been following with interest as you know.
I stumbled on this YouTube video of someone making oud rosettes with a 3d printer I believe.

https://youtu.be/HS8CF4BQUcQ




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[*] posted on 12-1-2019 at 03:20 PM


Thanks Samir

Very interesting and it shows what can be done. The 3d printer in this case is a Dremel product - fully enclosed and ready to go 'out of the box' - very nice printers (and tempting!) but costing in the CAN $900 to $2,000 range. My challenge is to see what can be done with an entry level printer kit - no doubt less precise - costing CAN $250 or less!

The use of 'Auto Desk 123 Design' free CAD design software shown is interesting so I hope to give that a try in future. Also confirmation of my current approach in using B/W 2D images as a successful start point to printing is encouraging.

I also liked the decorative use of the patterns left by intentional filament layering in the printing process.

For an oud it is beneficial to allow the main rosette to be removable to enable small internal repairs through the sound hole wiuthout need for removing the sound board (impossible for a European lute with 'cut in' rosette). I have yet to test if there are thermoplastic rosettes that can be successfully glued in place with hot hide glue. PLA softens at around 70C so might just be a possibility with hide glue at 64C max? We will see! No doubt synthetic non traditional glues might be used if a rosette is to be a permanent fixture.


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