Bamboom Series Acoustic Drum Set (swappable skins)

The Bamboom Series is an acoustic drum set with exchangeable drumskins that can be tuned.

The drumskins can be printed in a variety of different material combinations - each with their own distinct spectrum of sound - and tensioned onto the body with adjustable strength to produce the desired tone.

The Body consists of 2 shells that are connected only at the bottom to enhance the reverb and isolate the main body of resonance from the outer shell that is held. The inner shell is higher than the outer shell to force the drumskin against it when tightened and transmit most of its energy to the inner shell.

The outer body features 8 mounting points for quick M3 self tapping screws or machine screws (optional nuts) to fasten the skins. 

There are 3 different body types you can print:

• “Bamboom” has the biggest volume and is definitely the loudest of them all(very!). It's inside diameter is equally big so it allows for lower frequencies to be amplified as well. The body is versatile and can be very powerfull in a TPU - bass setup with long reverb but also surprisingly snappy - alomst like a snare-drum - with ASA or ABS skins. Sadly, it prints using 850g of filament and is a true investment. That's why i would encourage you to start with one of the two smaller models to get familiar with the concept and maybe try out some drumskin variations first.

   

• “Bambing” is a smaller version of the body, fitting a 180x180 buildplate and prints with 330g. It has a much smaller inner diameter and will lean more towards high-pitched sounds and fast fade-outs this way. The drumskins are mounted with the same 8x M3 16mm screws but come in a different size for this and the other version.

   

• “Bambong” shares it's inner body geometry with "Bamboom" and has a medium sized diameter at this scale. This allows for a nice kick-bass when used with TPU and is as versatile as it's bigger version in high tension applications with a medium reverb.
   

A body printed in basic PLA shows a balanced resonance. Using materials with increased stiffness (PLA+, CF - filaments, PC..) would increase this frequency (sound higher) while using more flexible materials like PETG will set it lower. Because of the way the shape distributes forces, i would not recomment filaments with weak layer bonding (like Silk PLA) for high tension applications.
 

The Drumskins:

The drumskins consist of a frame with 8 mounting holes and a membrane that is typically just 0.4mm thick. These 2 parts can be adjusted individually in the slicer but will print together as one piece. They are designed to interlock 2 different materials that don't like to stick to each other by “stitching” them together to form a strong bond.

There are print profiles containing various setups for the 2 drumskin sizes (Bamboom and Bambing/bong) in different thicknesses (0.2 - 0.6mm). These settings in the print profiles worked for me but are merely there as a rough guideline. Feel free to make your own favourite settings and apply the tweaks you know work best for your filament. 

 

To create a better bond and eliminate air gaps, the material for the membrane should be overextruded by a few percent and in most cases it makes sense to use ironing on one or both layers of the membrane. This unifies the layers and enhances the strength for very thin skins or can be used just to smooth the finish of the second layer that is pressed against the inner body. In this case, use the settings you know work best for the filament you are using. An ironing test will be made available here shortly.

 

Generally, the drumskins print best on a smooth buildplate but it is important to note that the bond between the drumskin and the buildplate should not be too strong, as this can lead to decolorations - and worst case deformation - of the drumskin when pealing it off. Glues or any type of adherent are usually not very beneficial unless they act as a layer of releasing agent when cooled.

Filament considerations for skins:

About any filament can be used to create a membrane and all sound distinctively different. I have tried a few combinations and merely scraped the possibilities so far, so feel free to experiment with every exotic material you feel comfortable with. Just as a corner stone, here are some thoughts about materials i tested so far:

PLA can be used as a membrane but will not be as sturdy as others and can easily get dented and deformed. Good as a temporary solution and can quickly be printed in single material but is too stiff and brittle to make for a good drumskin. But, depending on the material fused to, it could be used for printing the tensioning rings around other skins - if temperatures allow it.

PETG/PCTG seem to work well in a kick-drum area with medium thickness (0.4 - 0.6 mm) but should be ironed to increase the layer bonding and help prevent a tearing of the skin, especially with thinner makes. The material is sturdy enough by itself to create a strong tensioning ring, so it can be printed easily with a single material.

ASA and ABS skins have shown to be very durable and are perfect to produce high pitched  to mid range frequencies when printed thin (0.2 - 0.4 mm) and tightened well. These 2 materials tend to shrink when printed over a large surface (typically 3.5% ABS and 4% for ASA) so it is quite difficult to get them fully adhered to the plate and not lift up the corners while printing. However, you can print the tensioning ring in a material that does not shrink and prints at similar temperatures, like PETG, PCTG or even fibre infused ABS/ASA itself. The ASA/ABS membrane will be held in place by the other material during the print but will still shrink afterwards and gets pre-tensioned inside a sturdy frame this way (it will be shaped like a Pringles probably).

TPU is the best material to make drumskins for deep, loud bass waves but is also the most difficult to print well. TPU sticks to buildplates way too strong to be printed on directly in a thin layer by itself. The common solution is to stick masking-tape onto the buildplate but this method leaves those gaps along the edges of 2 connecting stripes as marks on the top surface of the membrane. (I experimented a bit and found hairspray can work wonders as a film of releasing agent in between but only dared to try that carefully on an old buildplate)

Furthermore, a TPU frame (95A shore hardness) will stretch too much it self in the tightening process and does not allow for high tension to be distributed equally. Because of this, printing the frame from a sturdy material (like PLA, PETG,..) and only the skin in TPU is a good idea.

As this is a project very open for experiments, please consider leaving a comment with simple instructions on what combination of filaments and settings worked good for you, so we can all benefit of each others experiences.

 

Mounting the skin and tuning the drum:

It is important to equaly tension the drumskin on the body. To do so, you will need 8 x M3 screws of at least 16mm length to mount a drumskin. You can use self tapping screws to change the skin more quickly (need less turns) but machine screws can be used as well and there are coutouts in the body to insert a nut, should the hole get too worn out at some point.

 

Insert all 8 M3 screws into the drumskin-frame and push or screw them in all the way. They will break loose any left debris in their holes and can rotate in their mounting points with some resistance. (left and middle picture)

Place the drumskin on the drum body and start to tighten the screws, one by one in an alternating pattern (front - back - left - right -…).

Do this until there is an equal visual gap between the drum body and the skin of about 1 mm from all angles (left picture).
Now, start tensioning the skin slowly. The best way i found is starting with 1 random screw and tightening it by halve a turn - and continue with the next one in counter-/ or clockwise direction until you gave all 8 of them about halve a turn.
Hit the drumskin a few times to center the inner shell with the vibrations - should it come misaligned - and listen to the change in sound. Continue these last steps until you are happy with the produced tone.

Be careful not to overtighten skins made from brittle materials like PLA too much, as they will stay deformed at a certain point.
 

There is a row of hooks along the lower part that can be used together with the upper mounting points to mechanically tighten the drum with a small rope. This can help to apply slightly more pressure to the skin but mostly enhance the drums stability in high tension setups - or also just look nice.

 

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