particle wood/mdf

[nef]

I went to Sutherlands today to buy a few things and looked at the wood prices before I left. I don't think I saw MDF but I did see particle wood. Costs was about 13$ compared to the 23$ cost of MDF. How is particle for boxes? It wasn't the cheap stuff that you can peal off a chunk(the kind we used to build car speaker boxes out of a long time ago) It was MDF looking material but not as fine as MDF. Maybe the wood used to make shelves and such sold at walmart type stores.

The boxes I will be making are the D8 MTM/DBP/Triune

[disturbed3rdgen]

> I went to Sutherlands today to buy a few
> things and looked at the wood prices before
> I left. I don't think I saw MDF but I did
> see particle wood. Costs was about 13$
> compared to the 23$ cost of MDF. How is
> particle for boxes? It wasn't the cheap
> stuff that you can peal off a chunk(the kind
> we used to build car speaker boxes out of a
> long time ago) It was MDF looking material
> but not as fine as MDF. Maybe the wood used
> to make shelves and such sold at walmart
> type stores.

> The boxes I will be making are the D8
> MTM/DBP/Triune

Try and stick with using MDF if you can. Do you have a Home Depot where you live?...they sell MDF. Particle board isn't as dense as MDF and it tends to crumble easier plus it swells up/warps if it gets damp.

[severius]

Even the high density stuff, which is hard to find, resonates more than mdf.

The particle board that seems to be common these days is low desity stuff that resonates like crazy.

I've made boxes with 2-1/4" of particle board, glued together. It still had a nasty resonance.

[unknownuser]

> I went to Sutherlands today to buy a few
> things and looked at the wood prices before
> I left. I don't think I saw MDF but I did
> see particle wood. Costs was about 13$
> compared to the 23$ cost of MDF. How is
> particle for boxes? It wasn't the cheap
> stuff that you can peal off a chunk(the kind
> we used to build car speaker boxes out of a
> long time ago) It was MDF looking material
> but not as fine as MDF. Maybe the wood used
> to make shelves and such sold at walmart
> type stores.

> The boxes I will be making are the D8
> MTM/DBP/Triune
MDF, MDF, twice as heavy and half as strong, MDF...

Industrial grade particle board with a sheet of 5.5mm plywood glued on top is stronger than a sheet of MDF with veneer, less resonant, and easier to work with.

The 5.5mm (1/4" nominal) plywood only has veneer on one side, but it is twice as thick as typical veneered plywood/MDF, so it cuts and sands better.

It's cheaper too ($15 for the particle board, and another $15 for the Oak ply). Be sure and use T-nuts though.

I like to use solid wood pieces in the corners, held in with a spline or biscuits.


(Originally posted by: djk)

[aricaudio]

> MDF, MDF, twice as heavy and half as strong,
> MDF...

> Industrial grade particle board with a sheet
> of 5.5mm plywood glued on top is stronger
> than a sheet of MDF with veneer, less
> resonant, and easier to work with.

> The 5.5mm (1/4" nominal) plywood only
> has veneer on one side, but it is twice as
> thick as typical veneered plywood/MDF, so it
> cuts and sands better.

> It's cheaper too ($15 for the particle
> board, and another $15 for the Oak ply). Be
> sure and use T-nuts though.

> I like to use solid wood pieces in the
> corners, held in with a spline or biscuits.

The other thing that sucks about MDF is that it will start to get moldy after about 2 weeks in a damp cellar(or garage). Particle board does also, but not as bad and I've never seen it happen with plywood.

Aric

[unknownuser]

> The other thing that sucks about MDF is that
> it will start to get moldy after about 2
> weeks in a damp cellar(or garage). Particle
> board does also, but not as bad and I've
> never seen it happen with plywood.

> Aric
Mold and mildew feed on the starch in the adhesives on the surface. Paint and/or sanding sealer sprayed on exposed surfaces seems to stop it from growing.


(Originally posted by: djk)

[aricaudio]

> Mold and mildew feed on the starch in the
> adhesives on the surface. Paint and/or
> sanding sealer sprayed on exposed surfaces
> seems to stop it from growing.

Very cool. It definitely seemed dependant on what the finish was. Most of the strictly latex-based products have molded up on me over time. I should probably check out coating them with Zinser "Perma-white".

Aric

[madrok]

> Industrial grade particle board with a sheet
> of 5.5mm plywood glued on top is stronger
> than a sheet of MDF with veneer, less
> resonant, and easier to work with.

But for a single layer, mdf is the best. Particle board is very crumbly. Laminating is not easy.

[jmb]

MDF is more dense, in general, than particle board even with a plywood applied. As such, it is better in the mid to lower high frequencies at inhibiting sound transmission. At lower frequencies, the mass law is no longer as much of an issue so sandwich panels with different densities may actually provide some advantage, though best with some form of non stiff glue to attach them. At lower frequencies, stiffness is a more important feature. Here MDF has an advantage over particle board but some plywoods will have an advantage over MDF.

> But for a single layer, mdf is the best.
> Particle board is very crumbly. Laminating
> is not easy.

[dancarroll]

These were built with a combination of 3/4" and 5/8" particle board. I braced well and had no problems. But they were budget speakers that I wanted to look good, so the greatest amount of money in them is the veneer. I applied the veneer with the yellow-glue iron on method and had no problem. They were a gift and I have not heard any complaints from the recipients, nor did I notice any particular resonances when I was listening to them.

Having said that, I would not use PB for the D8TMs. I would not hesitate to use 3/4" PB for the DBs. BTW, I used PB because I had it around from other uses, and because I picked up some sheets for a buck apiece at HD from the cut out rack, intending to use them for grills and internal braces.

HTH

[Chris Roemer]

> These were built with a combination of
> 3/4" and 5/8" particle board. I
> braced well and had no problems. But they
> were budget speakers that I wanted to look
> good, so the greatest amount of money in
> them is the veneer. I applied the veneer
> with the yellow-glue iron on method and had
> no problem. They were a gift and I have not
> heard any complaints from the recipients,
> nor did I notice any particular resonances
> when I was listening to them.

> Having said that, I would not use PB for the
> D8TMs. I would not hesitate to use 3/4"
> PB for the DBs. BTW, I used PB because I had
> it around from other uses, and because I
> picked up some sheets for a buck apiece at
> HD from the cut out rack, intending to use
> them for grills and internal braces.

> HTH

I use PB all the time. I prep lap joints (3/8") with a router, and they turn out very clean. It glues up well (I clamp and don't use screws in assembly). I just paint most of my cabs, but veneer bonds very well with contact cement. I cross-brace all larger panels with 3/4" hardwood or 7/8" dowels. Over at Madisound all their cabs are PB, just like all of PE's are MDF. To each his own.