Wood Cabinets


thanks Peter - the link explains it all.

However, my current DIY project (which happens to be my first one ever) will probably see some sort of wood on the outside for the effect but the majority thickness from the MDF.

Furthermore, Im toying with the idea of having the top and bottom real wood with thick layer of speaker grille material round the middle part. Back will just be plain so as to expose the binding posts.

... so much to consider... :)

 
You'll want to be careful about mixing the solid wood top and bottom with MDF sides. You could have issues with the top and bottoms splitting later on down the line. They want to move and the sides don't, this could be a problem. I would suggest you do one or the other, but not both. If you want to make it out of solid wood, do it that way. Otherwise, make it out of MDF and then laminate it.

If you're going to mix, you'll want to do it in such a way as to have the wood movement perpendicular to the non-moving woods. Wood tends to expand across the grain, so if you want to do something where you build the sides and top/bottoms out of solid wood, and then the front baffle and rear panel out of MDF, this would be better than your suggestion. (Make sure the grain in all of the panels run parallel to each other)

Of course, all of this depends on what wood you're using and how its cut. (Quarter-sawn wood has considerably less movement than standard flat sawn wood)

Hope this helps you out!
 
If you are going to use real wood, it needs to be well aged. I have seen a couple projects using wood from an old barn (aged for over 100 years) that are given good points for sound and seem to be very stable.

When building speakers i am moving from HDF (i never used MDF) to void-free plywood -- either new or recycled from old speaker cabinets.

And i have found cardboard & gaff tape quite useful for that quick & dirty (that last a figure of speech) cabinets.

dave
 
wanna know a secret....
I have been using HDF too only because I am not sure of the quality I assume it is MDF. It is quite heavy but I like to be sure. the local manufacturers call it HDF but I really dont know if they have any standards.

BTW, Mr. Pass, What is the notation u used. MDF = double ++ ungood? You mean layers of MDF are not good.

i dont mind usign solid wood only I am afraid of expansion/contraction due to change in humidity and heat in India. Our solid doors and window frames jam all the time and they are aged Burma Teak. Atlteast from 1961 when they were made.
 
GeniX said:

so, guys - the net result of all this is that I shouldnt use real wood outter with MDF inner due to expansion/contraction of the real wood?

SO either all in MDF with some veneer, or all in real wood?


Sort of. If you decide to mix the two, you should just be careful how you do it. Making just one or two panels of solid wood COULD cause you troubles down the road. (I say could, because you might not see any problems whatsoever, there are too many variables to say for sure, you're just safer not doing it)

It's also looking like MDF may be falling out of favor?!?!? If you use plywood, you don't have to worry about the outside, if you buy the right plywood. (We're starting to talk pretty expensive here though!!)

Personally, I'm planning an MDF subwoofer cabinet with either a veneer finish of some sort (might not even be wood!) or some type of paint finish, it depends on what the wife and I think would be more interesting and blend better with the room. (Yes, I do take the room into account when designing speakers! It adds an additional, fun, challenge!)

One final note, if you do decide to go the MDF/veneer route and would like the look of solid wood, look for veneer that was FLAT SAWN. This will give you "planks" in the veneer that will make the cabinet look like it was made from solid wood.
 

Thanks for the tips! Plain MDF it is - if the real wood is likely to cause me problems, Id rather leave it alone (besides it works out cheaper if I do too!)

This is only my first DIY. If I make another after this, Ill look for nicer cabinetry, better components and the like. Maybe even a solid real-wood cabinet... (hopefully a solid real wood cabinet! I reckon if you gonna try make a good speaker, it should be good in other areas, not just sonics!)


 
GeniX said:
a solid real wood cabinet

Reminds me of something we have talked about trying and haven't yet. Around here we have a bit of red cedar, so it is pretty easy o get some big chunks.

An example of a smaller chunk:

cedar-slab.jpg


The idea is to machine a couple big chunks into 2 halves of a clamshell, to make a speaker, then the (very dry) cedar is used as a substrate to hold a lot of liquid plastic/epoxy. Also thinking about using it similarily for baffles. And given it's ease of working also for cheeks on the speakers with big half-rounds.

dave
 

Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
double ++ ungood is a reference to Orwell's 1984, and is
part of Newspeak.

Worried about expansion and all that stuff? Baltic Birch.
It has many more plies (plys?) and is void free. It doesn't
doesn't seem to be affected by humidity much. It's quite
heavy.

Most importantly, it sounds good. I don't mean dead like
MDF, I mean good like musical instrument wood.

:)
 
As a construction material, MDF has consistency going for it, and apart from producing copious amounts of sawdust, it is easy to machine. It is rather porous, and while this can be a problem in humid climates, this characteristic allows one to clamp and glue veneers to the MDF surface by applying a vacuum to the other side of the MDF (the vacuum goes right through the MDF and sucks the veneer in place).

However, MDF isn't very strong. Natural wood gains much of its strength from the wood fibers, but these fibers are chopped into tiny pieces during the MDF manufacturing process. If MDF were made of compressed wood fibers, it would be quite strong, but in actuality it is more appropriate to consider it as compressed sawdust.

There are wood-based materials that are similar to MDF but contain a much greater percentage of long wood fibers, but I don't recall the product or manufacturer names.

One rather interesting wood-based material that I have been using in production is comprised of very thin wood layers (thinner than for normal plywoods) that are impregnated with plastic-based resins, and compressed at high pressures and moderately high temperatures. This stuff is really, really strong.

Back to stuff that is commonly available, if you don't have access to better-grade plywood and you have to use MDF, as corrective measures you can sandwich the MDF between epoxied layers of glass fibre cloth or graphite cloth. This will increase the strength tremendously, and the sound will improve as well. OTOH, with this sort of construction, there is no need to stick with MDF as the core material.

Note. Trimming glass fiber or carbon cloth that has been solidified in epoxy is a major ordeal, especially if you try to do it by hand (but it can be done! ;-))

regards, jonathan carr
 
Bill Fitzpatrick said:
Are you suggesting that the enclosure material should impart a character to the reproduced sound?

I would suggest that almost every enclosure imparts a character to the reproduced sound. How you try to deal with this has a role in how the speaker sounds. MDF is certainly not immune.

dave
 
jcarr said:
One rather interesting wood-based material that I have been using in production is comprised of very thin wood layers (thinner than for normal plywoods) that are impregnated with plastic-based resins, and compressed at high pressures and moderately high temperatures. This stuff is really, really strong.

Is this similar to the material you end up with when you do a West System epoxy/cedar structure (used heavily in boat building)

Back to stuff that is commonly available, if you don't have access to better-grade plywood and you have to use MDF, as corrective measures you can sandwich the MDF between epoxied layers of glass fibre cloth or graphite cloth. This will increase the strength tremendously, and the sound will improve as well. OTOH, with this sort of construction, there is no need to stick with MDF as the core material.

This would be similar in concept to gluing a plastic laminate to both sides of the MDF and then making it into a cabinet.

dave
 
Dave:

>Is this similar to the material you end up with when you do a West System epoxy/cedar structure (used heavily in boat building).<

The basic wood is not cedar. I believe it is beech. Although the stuff that I use is made by a Japanese company that does not have a Web site, similar materials are made in Germany as "tank wood" or "panzer wood". Among other applications, the ride-height planks for current F1 cars are made from panzer wood. the material can be machined to similar levels of complexity and precision as aluminum.

>This would be similar in concept to gluing a plastic laminate to both sides of the MDF and then making it into a cabinet.<

Similar in concept, yes, but for maximum total stiffness, you really want high tensile strength from the laminate and a good amount of distance (cross-section) between the laminate layers. Still, plastic laminate is probably better than nothing.

regards, jonathan carr
 
GeniX,
If it's your first go at making speaker cabinets, I'd use MDF and real wood veneer.

Here's a few tips from my experiences with MDF & Veneer:

Scott Panels &Hardware (they're nationwide) has a good variety of veneer at reasonable prices. It cost me about $30 for enough Rimu veneer to do a pair of standmount speakers. Price varies with the type of veneer.

Unless you have a good bench saw yourself, I'd recomend getting a joiner to cut the MDF to get nice square cuts (the joiner will should be able to supply MDF as cheap/cheaper than Placemakers). I believe Scott Panels &Hardware only supply trade and not retail, so I simply ordered my veneer through the joiner who cut my MDF.

Do some practise veneering on some scrap blocks of wood before starting out on your speakers. And use a good contact adhesive, eg. Ados F2 (available at most hardware stores). Its more expensive than PVA, but worth it. Take extra care to completely cover the edges and corners of the boxes with adhesive - the veneer can (will) most easily/annoyingly de-laminate at these edges. I cut the veneer too large the cabinet and then trim it back with a sharp craft knife afterwards.

I found with a good contact adhesive, it was sufficient just to cover one surface and not bothering to cover both the mdf and veneer. Consider making a frame or getting another piece of thick MDF the same size (or larger) than the biggest side of the speakers. When the veneer is in place, put this frame over the top of it and weigh it down with books, televisions etc.

When you are sanding your newly veneered boxes, only sand the edges/corners by hand with a block. An orbital sander is fine on the flat surfaces but can irreperably damage the edges.

Hope this helps