Music Box Advice

[naumanmp]

G'day all,
I was wondering if anyone has had any experience in making timber music boxes?
I intend to make two matching music boxes for my daughters and have already obtained two musical movements (Sankyo 50 note).
I am looking for some advice on the following:
* Design - I am leaning towards a standard box design using the golden ratio but any suggestions are welcome.
* Material - must be an Australian timber. From what I can glean from the web, King Billy Pine is about the only acoustically suitable Australian timber for instruments, but weather this applies to music boxes is debatable, what do you all think? The inclusion of some glass is OK. I really want to make both boxes from a single piece but this could be an issue.
* Finish - I love shellac but perhaps nitrocellulose lacquer would be more appropriate? Longevity and moisture resistance is important here, and probably rules out any of the oil based finishes?
* Construction - I want to go with solid wood, however the overseas websites recommend veneering over MDF or good Ply. I believe that if the timber is of good quality and the right moisture content before any finish is applied, that I should be OK for the small sizes involved. This is a worry however as the movements are quite delicate and are easily affected by changes in their mounting and moisture. I have thought about a raised platform that sits inside the box on loose tenons (like a little table) to try to overcome any movement issues and also to enable easy cleaning ETC. This approach may even improve the sound reflection from the box? My first choice for the overall joinery is box joints, any agreement/disagreement? Apparently the thickness of timber (or MDF) is important with thicknesses over 6mm being detrimental to the tone of the final sound, any comments?
* References - I believe that I have all of the websites that offer info and plans for music boxes but any further suggestions would be most welcome, also any other information sources and/or timber supplier recommendations (must be able to deliver to central Queensland).
Cheers and the best of 2007 to all,
Matt

[Dan]

G'day Matt,

I've never made a music box so take whatever I say with a grain of salt.



Design - I am leaning towards a standard box design using the golden ratio but any suggestions are welcome.


Is it to be a box for the music movement only or will it have a bit of space in there for a bit of jewellery as well? I'd be inclined to include a bit of storage space with a compartment at the back (possibly glass topped) for the movement.


Material - must be an Australian timber. From what I can glean from the web, King Billy Pine is about the only acoustically suitable Australian timber for instruments,

From what I've just read about the movements, the most important area is the panel that the movement is screwed to. So you might consider making the base of the box from 3-6mm KB pine and the rest is up to you. The movements are quite expensive by the looks so a test box might be a good idea.


Finish - I love shellac but perhaps nitrocellulose lacquer would be more appropriate? Longevity and moisture resistance is important here, and probably rules out any of the oil based finishes?

I wouldn't rule out oils, go with what you like using the most.


Construction - I want to go with solid wood, however the overseas websites recommend veneering over MDF or good Ply. I believe that if the timber is of good quality and the right moisture content before any finish is applied, that I should be OK for the small sizes involved. This is a worry however as the movements are quite delicate and are easily affected by changes in their mounting and moisture. I have thought about a raised platform that sits inside the box on loose tenons (like a little table) to try to overcome any movement issues and also to enable easy cleaning ETC. This approach may even improve the sound reflection from the box? My first choice for the overall joinery is box joints, any agreement/disagreement? Apparently the thickness of timber (or MDF) is important with thicknesses over 6mm being detrimental to the tone of the final sound, any comments?


I prefer mitred corners on small boxes (but that's just me) so the grain continues around the box. A bit of reinforcing can be had with a couple of keys. As long as the base of the box is housed in a groove that allows for a bit of movement I can't see much of a problem with warping, but you will need to make sure it can't rattle or buzz.

Make sure to post pictures when you're done.:)

[zenwood]

I would provide a strong link somewhere between the movement and some point on the box, rather than mounting the movement on loose tenons. The aim would be to transfer the vibration of the tines to a vibration of some part of the box, thus amplifying the sound (like the bridge of a violin or guitar connects the vibration of the string to a point on the soundbox.

Come to think of it, if you make the wall thin enough, you should be able to firmly join all edges: after all no part of a guitar or violin deals with movement issues by loose joinery.

Note: I have never made a music box, violin, or guitar, so here are two grains of salt:

:)

[naumanmp]

Thanks Dan and Zenwood, below is an extract from an American website concerning materials. They seem comfortable with Cherry and Walnut (American I assume) so that greatly expands my choices for an Australian wood.

Box Material
Do not use extremely hard (e.g., Ebony) or extremely soft material (e.g., Balsa) because the acoustical amplification properties of these types of wood are not good. Walnut and Cherry are good choices. Generally, more dense woods amplify bass resonance while lighter weight woods are stronger on the treble end of the range.
Choose a wood that is sound, stable and dry (around 4-5% humidity). You don't want wood that will warp or that has hidden cracks.

Box Bottom or "Resonator Strip" Material (the most important element to the acoustics of the box)
Thickness - 3mm - 10mm (nominal 1/8" to 3/8"). The thickness of the box bottom affects the volume and timbre. 1/8" (3mm) to 1/4" (6mm) seems to resonate best in most woods. Most older, quality music boxes have a full bottom about 1/8" (3mm) thick, with 1/8" (3mm) wood strips added on top of that bottom at the front and back, leaving a "trough" down the middle (running from left end to right end). These resonate very well.

Glass:
Use thin glass: 1/16" (1mm - 2mm) is good. It enhances the bass notes as well as protecting the movement. The movement is 1 1/4" (31mm) high, so your dado for the glass should be perhaps 1/4" (6mm) above that.

Rattling or Buzzing
All four feet need to sit solidly on the table. Thin felt pads on the feet will eliminate most rattling and buzzing. Note: most tables are not perfectly flat, so even if your box is perfect, felt pads are still a good idea.
Use a cushion to prevent glass from rattling or humming inside the box. A short piece of rubber band works well. Small scraps of dried silicone caulk work even better.

Regards to all,
Matt.

[silentC]

I made one (http://www.woodworkforums.ubeaut.com.au/showthread.php?t=18765) from River Redgum and it sounds OK to me. I think you are concerning yourself too much about it. Any bit of wood will amplify the sound. If you're a musical purist, then I'm sure some timbers sound better than others but for a music box, which let's face it is not a top end bit of musical gear, I'm sure you'll be happy with the results from any nice bit of Aussie hardwood.

[naumanmp]

Cheers mate, probably good advice as I am known for worrying something to death before I do it (hey, works for me!). the more I look into it, the more I think you are right. I just want them to be special for the girls and remain so for many many years.

Cheers,
Matt.

[silentC]

Yep, my point is that if you build a nice looking box from a bit of hardwood and firmly attach the movement to it, you should be pleased with the results. I screwed the movement to the box bottom. It's a 5mm thick bit of redgum and it floats in a groove. It sounds loud and clear and quite pleasant.

You can test the different sounds by holding the movement down firmly on an off-cut about the size of your base. Of course the shape of the box etc will play a part in the sound but it's hard to imagine that anything you fix it to will make it sound considerably worse than anything else.