Cabinet Construction
 

I am NO cabinet Guru,but why are most cabinets made of Ply material? Would not soild wood be better? Can someone please explain why this is such? Thank you.

Plywood?
 

I would suspect resonance and cost are both factors; and not just any plywood will do, however........

Check out the following interview with David Nordschow of David Eden. He touches on this topic (among others) in this intervew. By the way, the whole article is worth reading.

http://www.musiciansfriend.com/document?doc_id=101761

Several reasons why ply is better in this application. :

- Stability and differential movement. Solid wood moves A LOT along its width and thickness, very little along its length. Also is more likely to warp/twist/crack. Hence double bass tops/backs cracking when glued to long-grain ribs/blocking. The tops/backs shrink, the ribs don't move the same way. The dimensional instability of solid wood requires specific joinery methods for longevity. These tend to be more time consuming/expensive.

Also, when hit, (speaker cabs at work) solid wood may crack along its grain. Plywood just won't, because there is no grain to follow. A chunk of plywood wont break off when hit, like could happen with solid.

Also, because of the great movement of large widths of solid wood (averaging maybe 1/8" per foot), the fronts and backs of cabs would have to be plywood anyway. Otherwise, fabricators would have to use some ridiculously time-consuming engineering/joinery to keep them from ripping the boxes apart as they moved - the fronts and backs would have to "float" independent of the case sides.

- Joinery ease for the cases. In solid wood, the only meaningful joinery is long-grain to long-grain. To build a solid case side, the best joint is the dovetail (glue surface plus mechanical hold) or the box/finger joint (tons of glue surface). Both joints are relatively expensive to produce, compared to ply joinery options, with glue blocks in the corners.

In ply construction, even a butt joint provides some long-grain-to-long-grain glue surface. Add a dado, tongue and groove, glue blocks and staples and you are bomb-proof. Ply is inexpensive to join strongly.

It can also be joined to itself at any angle without thinking about movement. Backs/fronts can be slammed onto sides regardless of grain direction. Plywood has virtually no "grain direction" as far as movement goes, so parts can be glued together any old way.

- Economy. Material processing speed/number of steps, storage, purchasing, etc. Solid wood processing takes lots of toys and room. Ply processing is relatively simple/inexpensive.

Ply can be stacked in lifts, moved around by fork truck, and a ply sheet is ready to be made in parts. Solid wood needs to be milled, the dust/chips/rippings/off-cuts need disposal, and then you can mill your parts.

Sure, you can buy all the toys needed for a rough mill, but that's a lot of expensive stuff. You can buy milled stock, or have others custom mill, but that's an additional cost, compared to ply, per square foot of cab side.

Ply has great yield, especially for speaker companies nesting parts on a CNC router. Plus, if they are using solid and ply, they have to stock a bunch more types of material. If they are just using ply, everything comes from the same sheet.

Bottom line:
"Solid wood" is not always better, depending on the use. Folks think "solid is better." Not for heavy-duty boxes. It might sound better, but there would be a bunch more work involved. I can't talk about acoustics, but I can speak to box construction. Ply offers superior stability, fabrication ease, and economy.

Well, you sure sound like you know what you're talking about. Thanks. :)

Plywood?
 

Thx Eric. Great post!

Looks like I found the Guru! I often wondered why that was and why Plywood was used vs soild woods, makes sense now and Thank you for that information!! It was most helpfull!! Great post!!

Happy to help where I can. I know a little bit about a little bit.

I have been a professional woodworker since I was a teenager, and amateur before that (family business). I did both music and woodworking full time (sic - what can I say...youth) until I was 25, now I am just an amateur player.

Did a union apprenticeship in NY. Worked as a journeyman wood machinist in NY, Boston, and all over CA, working my way up to floor foreman in a union shop. Started my own company and ran it (with much help) successfully for 10 years. Lost our production space, now am Plant Manager for a former competitor. All to say that I have thought about wood movement a bit.

Maybe you folks can help me a bit with my bass playing...

Regarding the movement issue, think about how many door panels you have seen that were cracked. This is usually because at some point the panel got stuck in place (usually with paint or finish) and could no longer expand and contract along its' width. Wood cannot be stopped, so the panel cracks so that the pieces can continue moving.

The issue is magnified by increasing the width of material glued or fixed to an adjacent long-grain component. Here is one place where size does matter. Double basses crack/split more than 'cellos, violins, violas because the tops/backs are simply wider. The whole construction method doesn't account for movement very well. A person can sort of get away with a few inches of width glued to length without much drama, but when you start gluing something as large as a 'cello or especially a bass top to a long-grain rib, it is a recipe for trouble. Because the ribs are curved/angled in relation to the tops' grain direction, it is not quite so dire as if they were glued at right angles. The hide glue luthiers use will often fail before the wood fails, by design.

In other words, DB construction makes very little sense in terms of wood movement, which is why we need good luthiers so badly! Thanks to Arnold Schnitzer et al for being there for us. These brave surgeons keep stitching the patients back together, again and again...

Age doesn't change or stop the movement. Wood recovered from the Pyramids of Egypt is still expanding and contracting with changes in temperature and humidity. "Cut" of lumber has some effect. Quarter sawn or rift cut wood moves less than plain-sawn lumber. This has to do with the number of denser "summer wood" growth rings per inch in the wood. Google will educate anyone interested in the movement properties of differing cuts of lumber. Here's one off the top of a quick search:

http://www.inthewoodshop.org/methods/wwc05c.shtml

The moral is try to moderate temperature and humidity in a DB's environment (or the home of any cherished solid wood object). Use a hygrometer and humidifier. Bless our luthiers, especially we double bassists!