[TRADERXFAN]

Question for you DIY buillders...

So the saw I have only can get to about 24" max to the rip fence.

I wanted to build something a bit wider than that... and was curious if I titebond wood glue 2 square cut mdf panels side by side edge to edge, --  is it that same quality as a solid panel?

For example glue a panel of  24" wide to a panel 12" wide to get a 36" wide panel. I would have a brace on it...  I can't see how the seam would ever see any direct lateral force to it

From what I recall people always said the glue seam is stronger than the mdf itself...

Anyone ever do this and see any difference they notice in rigidity/resonance/stability over time?

[As an alternative, I know I could use a flushmount router bit and cut to what i need with a good straight edge, but that is more work for maybe no gain]

Thanks!

[WGH]

Edge joining MDF will be just as strong. I would use biscuits for alignment and they make the joint stronger. If you plan to use the biscuit joiner for this one project then the $49 Wen should do the job.



Regarding the glue, Titebond Original will work the best. The higher Titebond numbers like 2 & 3 are more water resistant and flex more with higher humidity. The ability to move with the wood adds to the strength but it also means you will get a raised glue line in high humidity. Titebond Original is harder and the glue line will remain flush.

[TRADERXFAN]

Thanks very much.
Always admired your work btw

[planet10]

The technique is mandatory with solid wood enclosures.

Will work for MDF, but you would not catch me using MDF for a speaker box.

Its only advantage is that it is CHEAP.

dave

[Doublej]

The technique is mandatory with solid wood enclosures.

Will work for MDF, but you would not catch me using MDF for a speaker box.

Its only advantage is that it is CHEAP.

dave

Why not? After all you are a self declared frugalphile.

[planet10]

It is false savings. My intent is alwasy to build the best loudspeaker i can.

Andfor the longest time our cost on Baltic Birch was similar to MDF. But quality dropped and the product we switched to was about twice as costly. Still cheap in comparison to all the other inputs, labour in particular, swamps the sheet material cost.

I have a big burn pit for MDF boxes. I’ve burned liertally hundreds of them.

dave

[WGH]

Question for you DIY buillders...

So the saw I have only can get to about 24" max to the rip fence.

I wanted to build something a bit wider than that...

If you want to cut a 27" wide panel from a 4' wide sheet and your saw can only rip 24" max, set the fence to 20-7/8" (assuming the saw blade is 1/8"). The "scrap" will then be 27".

You will probably need a helper to catch the cutoff before it falls to the floor. Usually an inexperienced helper feels the need to do more than help catch, like pull, which is real bad and more than dangerous.

[TRADERXFAN]

Planet 10 or anyone...
is the stuff at lowes "void free" baltic birch? Not sure if there is a difference or some specification that I need to look out for when buying "baltic birch plywood".

I do see it is pretty decent jump in cost over mdf...

Thanks

[Peter J]

I've never seen Baltic Birch at home centers. It will certainly call it such as it's a unique product and most often seen in 5'x5' sheet, although my supplier carries 4x8. What I've seen at home centers is what I call "China Birch" which is sourced from, you guessed it, China. Absolutely not the same product although it looks similar in the plys. Stuff is not fun to work with. Lots of internal tension which releases in all sorts of ways when cut. Delamination of outer veneer common.

To give an idea, I pay well over $6 sg. ft. for Baltic Birch which gets a 4x8 up over $200. This is from a cabinet supply house. Ranger Board Platinum (high density MDF) is over $85 per sheet. I do like the Lowes MDF for one thing and that's a spoil board for my router as it's porous enough to pull vacuum well.

[Digi-G]

I've always been under the impression that MDF was a good material for speaker cabinets, as it's very dense and doesn't ring like real wood does.  Granted, all MDF is not the same quality, but neither is all wood. 

[planet10]

... as it's very dense and doesn't ring like real wood does…

Dense is not an asset. Stiff is. MDF is not stiff.

As to the ringing the ringing in MDF can be worse because it is lower Q and lower frequency of potential resonances more likely to be excited and heard.

Real wood is tricky to build with, different species are different. If you know what you are doing solid wood can be fine, but there are few of those people.

As an example, except for the soft outside surface that, left untreated, will bruise easily, is a fantastic box material. Very stiff, low density.

dave

[S Clark]

I've always been under the impression that MDF was a good material for speaker cabinets, as it's very dense and doesn't ring like real wood does.  Granted, all MDF is not the same quality, but neither is all wood.

MDF is a good material., even though Dave/Planet 10 has always hated it. HDF is even better.   Are there better materials? Yes, but by how much and for what price.  Panzerholz is great stuff... for a $75K Wilson speaker.  But you probably don't want to spend more on exotic plywood than you did for your amplifier.

[TRADERXFAN]

Thanks for the china comment to watch out for...

is there a different quality designation for "voidless/voidfree baltic birch" than just "baltic birch" though?

I rather not have mdf dust... if i can find it.

Thanks

[S Clark]

I rather not have mdf dust... if i can find it.

Thanks

That's perfectly valid.  I usually move my table saw outside, and wear a mask when cutting it.   I have successfully used a biscuit joiner to edge join mdf for some of my physics students.  Seems to be plenty strong. 
I've found maple plywood to be almost void free, but not entirely.  Might be a good alternative and can be finished nicely as is. 

[planet10]

is there a different quality designation for "voidless/voidfree baltic birch" than just "baltic birch" though?

There is. As time went on we found that the BB was coming from Russia or China and was not that good. We switch to MurphyPky out of Oregon, good Baltic cores with maple veneers on the outside. Twice the price, easily money saved vrs cleaning up (or tossing parts) of th echeaper stuff.

dave

[S Clark]

We all agree that ply with zero voids is ideal, but when do diminishing returns set in?  1% voids, 5%, ??  We are all engaged in a hobby where almost all make compromises in price vs. quality- where an interconnect can be had for $10 or $10 000. 
I can't even find Panzerholz for sale, although a search showed an audiophile sold two sheets? for $500 a year back.

[Peter J]

Let's clear the water some. Baltic Birch is nearly void free and has no designator for lack of voids. It will be labeled as "Baltic Birch" or "Russian Birch" although given current political environment, I imagine no one is looking to market under the latter.

Baltic Birch plywood is nearly all made in the same Northern European region by several different mills. The "Baltic States" is where it gets its moniker. It has unique properties, like all same thickness hardwood plys and no thin veneer plys on faces. It's not graded in the same way as North American plywood. Those grades are primarily BB/BB which allows plugging on both faces and B/BB which allows fewer plugs on one side.

"China Birch" is slang for a similar looking plywood manufactured in China. The difference being thin finish plys on outer surfaces much like North American plywood.

Most North American hardwood plywood is made with softwood core plys and thin hardwood outer finish plys. It would probably be fine for your project but edge isn't as cool looking as BB. Slightly different resonant qualities, but I doubt most would hear the difference in finished product. Will you have exposed edges?

Dave, have you actually got a source for Murphy Ply? That and another, Apple Ply, seem to have gone the way of dinosaur, at least around here. I think Murphy offers custom stuff, but I'd imagine a minimum order of significant size to get on that train.

[planet10]

One of the local distributors handled it. We had to buy an entire lift for the first batch of 15mm, 18&12 were readily available.

dave

[TRADERXFAN]

Hey guys thanks for everyone input...

That cleared up about the void thanks

[S Clark]

Thanks, Peter J for that info.