Version 2.2 now available
Minor errors fixed (see version release notes below).
Assembly Guide finished!
The assembly guide has now been been completed, containing 38 pages with over 60 diagrams to assist in creating the banjo from start to finish.
Print layouts added
Separate .3mf files now available, with layouts planned by colour and to fit build plate.
G-code files also uploaded.
Newbie Alert
Before I begin – let me say that prior to May this year (2023), I had no experience designing 3D models, using CAD (Fusion 360 in my case), printing anything on a 3D printer or knowing anything about what can be done, or designing and making musical instruments.
(I also can’t play the banjo yet either – but ran out of time for that one ;P ).
My Inspiration
This competition came at just the right time for me – and was my inspiration to learn new things with a goal at the end!
This banjo aint no off-the-shelf cheapie… it is based off a purchased MusicMakers blueprint and instruction kit. It really felt like I was following along the steps in woodworking, but in 3D design instead! (It is so much quicker to split or combine a body, than to glue and clamp or even bandsaw/plane/sand!)
Many many thanks to MusicMakers for their tremendous set of instructions!!! Also for their video of the (irl – not 3D printed) mountain banjo which helped inspire me along the way…
https://www.harpkit.com/banjo-plans.html
https://youtu.be/2yqYszgqVtE
Additional Parts and Hardware
My goal was to make an instrument that would (hopefully?!) sound like the real thing as much as possible. Hence I designed as much as possible to be printed, but still am using real hardware and parts where strength or tone are needed.
- While I have modelled most of the extra items within the CAD software, I am using the following "real" parts (more details and instructions to follow in a few weeks):
- real (small) banjo head
- tone ring
- bridge
- strings
- pegs and tuners, and
- truss rod (double action)
- A small handful of screws, bolts and nuts were built into the design – for strength where needed, and ease of removing the back from the instrument to repair or replace the head.
- Marking dots for the fretboard can either be purchased or printed according to preference.
For details please refer to the attached Bill of Materials.
Still to Do…
I do NOT own a 3D printer, and merely have occasional access to one that is a borrowed one at my son’s house. As such, I was unable to print it (apart from from a few test sub-parts which I used as a sanity and tolerance check) - so no photos of the finished product unfortunately.
As such, I also was also not able to do a sound test :( …
…however I HAVE uploaded a sound file replicating my screams and weeping of frustration - for your listening pleasure?! ;P
Version Release Notes
v2.2 Release Notes
Small errors fixed (6 July 23) as follows:
- Revised the bolt length required for the Neck-angle screw (reflected in BoM)
- New part photos added to the BoM
- Fixed missing joining lug in bottom of nut (affecting .3mf and .gcode files)
- Corrected texture maps on some neck components
- Completed Assembly Guide uploaded
v2.1 Release Notes
Small changes were made in this minor update (end-June 23) to address printability issues and errors:
- Split the flip-lid on the peg-head so that the “B" and the hinge are separate and hence printable.
- Fixed the joining hexagonal lugs between the neck pieces, and associated fixes to the fretboard attachment to the neck.
- Shaved a fraction off the truss-rod cover so the bottom was flat and printable.
- Corrected some loose faces/edges making a couple of the models non-watertight.
- Created print layouts (.3mf) to enable printing by colour and to fit the build plate.
- Uploaded gcode files.
- Partially-completed Assembly Guide uploaded
v2 Release Notes
Many substantial updates and changes were made from V1 (uploaded 31 May 23), until now (end-June 2023).
A summary of the changes is as follows (not an exhaustive list!):
- Fretboard and neck split into sections which will fit on the build plate, and attachment mechanisms provided between all parts.
- Split peghead and tang into 3D-printable sections, incorporating attachment mechanisms.
- Removed fillets on the bottom of parts and replace with chamfers.
- Fixed hex coupler sizes where required, and standardise the size across all components of the model (interchangeable).
- Added fretboard marking dots.
- Engraved part names, joint identification and build-plate-surface ([BP]) onto parts where needed.
- Added grooves in the tailpiece, bridge mockup and nut to ensure the clear routing of strings.
- Added buttons for shoulder strap connectors.
- Improved shape of peghead.
- Added logo to peghead, in conjunction with mechanism to secure the truss rod cover.
- Improved look/realism of tuning peg mockups.
- Added decals to improve realism of render.
- Added mockup of the remaining strings, and added more detail to all string mockups.
- Reworked component appearances and texture mapping.
- Restructured component hierarchy, to enable more efficient identification of printable/non-printing parts, and the grouping of parts by colour.
- Created a Bill of Materials (see attached).
- Created a list of Suppliers (see attached).
- Created a list of References (see attached).
Design Considerations
3D printing considerations
- PLA is a good (and cheap!) choice for this project. My understanding though is the woodfill PLA is not as good for something like this that requires more strength and minimal warping… I coloured my CAD design cos I love the look of timber!
- All the pieces slot together and have locking lugs or hex nuts (printed) to hold pieces in place while glueing.
- Parts will fit on a 22 x22 x25cm build plate.
- No supports are required during printing – however a brim MAY be required to facilitate part removal from the build plate (just ask my son… ;), and to help reduce warping.
- It is highly recommended to increase the number of shells for printing to 3 or even 4, to guard against warping. With this change, infill should be right at around 20% or so (but do more if you prefer).
- Increase the number of top/bottom layers for a better quality surface.
- Ensure that parts are laid out sensibly on the build plate – flat sides down etc. Where not obvious, some parts have engraving to indicate which side should face the build plate [“BP”].
- Considerations such as overhang angles, unsupported holes and ledges, strength in the z-axis etc were researched and considered during the design.
(See attached References for further details on some of the many aspects taken into consideration for this design.)
Musical instrument considerations
- First and foremost – it must sound good!
- Ideally it should be a creation of beauty.
- Should be predominantly 3D printed – yet still incorporate use readily-available hardware and parts where needed for strength or musical tone.
- Comfort of the player is important.
- Design should adhere to established widths, lengths, distances, fret shapes, bridge angles etc.
- Expense is important - It should be cheaper than the real thing to buy, and easier than making one from scratch.
- The ability to alter instrument tone is desirable where possible – for example, altering the tension of the head.
- Maintenance aspects must be taken into account – for example the ability to replace the head, or cater for an adjustable the truss rod to support/adjust the neck.
- There should be enough inherent advantages within the 3D printing process, to offset any possible loss of tonal quality or perceived beauty.
- Consideration should be made to the limitations of 3D printing (eg. smaller pieces to be joined, maximum angles and shapes, weakness between layers, warping etc) – and turn those around into a positive if possible (eg. unique design).
- The final design would ideally be adaptable according to taste (eg. colour).
(See attached References for further details on some of the many aspects taken into consideration for this design.)
Hardware Considerations
- Off-the-shelf parts where possible (eg. hardware store).
- Extra parts should be easily purchased online through lutherie supplies, Amazon/eBay etc. See attached list of suppliers for those I purchased from.
- Standardised sizing where possible (eg. M3, M5)
- Clearance around holes, chamfers/fillets to aid part insertion
- Glue where possible (with positioning lugs to ensure exact match), but screws/bolts/nuts for strength or for more reliable tightening/loosening where needed. (Less chance of stripping the screw or cracking the part).
- Interlocking parts designed to reduce the need for fasteners.
Recommended Suppliers (Australia)
Please see attached list of recommended Suppliers (within Australia).
References
Please see attached list of References (useful reading).
MyHotPL8
