jewilson said:
Pinblock maple is a laminate of very thin clear maple boards not a species of maple.
The cause of deformation in wood is its differential response to moisture in its radial and tangential directions. The point of drying is to bring it to a moisture content close to the annual average target ambient moisture--the woods equilibrium moisture content. Obviously this varies depending on your location. Drying in no way improves the dimensional stability of wood. Proper finishing and sealing helps and is essential for unstable woods such as maple--high T/R ratio. Quarter sawn boards from the widest part of the quarter are your best choice--those that are radially sawn. This is the most stable relation of the T R dimensions within a board. If your supplier will let you pick through the stack you can find the occasional radial sawn boards that can occur in the modern sawing process. Have patience, you can just keep going back till you have enough.
BTW I prefer MDF for speakers 🙂
eStatic
One more thing:
To split hairs about it, deformation in wood can also be due to "tension" in the wood. This problem will show up during dimensioning of a board. Ya know whose boards that get a curve _while_ you are cutting or even jointing them. Thery're hopelless. Send um to the chipper.
Both simple movement and (non "tension") deformation can be fairly well quantified and should be for any piece of fine cabinetry--not that I've ever made any.
eStatic
To split hairs about it, deformation in wood can also be due to "tension" in the wood. This problem will show up during dimensioning of a board. Ya know whose boards that get a curve _while_ you are cutting or even jointing them. Thery're hopelless. Send um to the chipper.
Both simple movement and (non "tension") deformation can be fairly well quantified and should be for any piece of fine cabinetry--not that I've ever made any.
eStatic
eStatic said:
Oh poo! I should have said that movement needs to be quantified and deformation accounted for. Hope this slip didn't needlessly ruffle any feathers.
eStatic
I appreciate and enjoy you posts, eStatic, but I disagree with this statement. Proper drying or seasoning is the only way to begin a project with wood that will remain stable. The wood will shrink as it initially dries, as well as expand and contract as the surrounding humidity changes... but the important thing is to get it uniformly dry initially.
This takes time, because both the moisture that is contained _in_ the xylem and phloem and in the cells that _make up_ the xylem and phloem must be brought down to a low level and equalized.
This is why coarse and open grain woods like oak are dried more quickly than maples, and appear to be more stable, but actually maple is far less susceptible to movement after the initial drying.
And after completion of the project, ALL sides should be sealed to keep one side from absorbing more moisture than the other.
It's not that complicated, really. Just use well dried lumber for your projects, plan for some movement, seal them well, or use the old techniques: Linseed based penetrating finish > Once a day for a week, once a week for a month, once a month for the rest of your life.
About the use of 11 to 17 lam pinblock maple for cabs...I dunno whether it's an appropriate use of materials, unless it's for those $150,000 "king of the world speakers"....but I don't believe in them either. (unless you want me to build someone a pair)
eStatic
I was pointing out that there was no species as pin block. Also, I was pointing out with out going into some elaborate details that hardwoods are is not the best thing to build your speakers from. I do appreciate your detailed explanation, however I am aware of these infomation on woods.
I prefer to build speaker cabinets out of stable material like MDF and internally brace it with Baltic Birch. Now building the front baffle out of another material is something that is interesting to me, may a Delran, Aluminum or even some type of very dense hardwood like a Lignum Vitae, Wenge, Bubinga.
I was pointing out that there was no species as pin block. Also, I was pointing out with out going into some elaborate details that hardwoods are is not the best thing to build your speakers from. I do appreciate your detailed explanation, however I am aware of these infomation on woods.
I prefer to build speaker cabinets out of stable material like MDF and internally brace it with Baltic Birch. Now building the front baffle out of another material is something that is interesting to me, may a Delran, Aluminum or even some type of very dense hardwood like a Lignum Vitae, Wenge, Bubinga.
x. onasis said:
Thanks for the kind words x.onasis Let me clarify: What I meant by that statement was that "drying" does not change the T/R ratio. It is essentially constantfor a given species. Regardless of the moisture content of the wood (assuming that is uniform through out the wood) it's quantitative response to changes of moisture remain the same. A board dimensioned of green wood can be placed in water for a 100 years and it will not crack split or warp, bring it out of the water and that process begins in a few hours. Dry wood till it has zero moisture content, place it in the desert and it will not change for 100 years. Take that board to Miami and stand back!
As I tried to say but not as clearly as I should, when you begin a project with real wood you do not want it dry, you want it at equilibrium moisture content for its target environment. That's an easy calculation if target environment is a building air-conditioned in the summer and heated in the winter and has a humidifier. For the average home in a particular geographic area one has to make some informed guesses. The challenge is to construct the piece so that it can cope with the substantial changes that can occur in the home environment. That's the utility of sealing, it slows the response curve of the wood.
x. onasis said:
Regarding maple, the T/Rs for its various species is limited, 2.0 +- .1 For the oaks the range is much wider, 2.5 to 1.4. Thus some oaks are substantially more stable than maple, most are not. But besides the T/R ratio is the matter of absolute movement and maple has the edge there in general except for live oak which is 9.5/6.6 = 1.4 and is superior to maple in every aspect of dimentional stbility.
x. onasis said:
Id'nknow. I never begin a project without actually calculating the movement and laying out how I want to rings to lie in each board. With out the latter your glue joints will likely experience more stress than is desirable or necessary.
eStatic (who apologizes for being so disagreeable this time.)
As to moisture in wood, i once set up an ISO9000 system in a place that made balsa sections for boats. One of the tests was a moisture content more or less based on electrical conductivity.The blocks arrived in approx. 1 meter^3 size , laminated.The outside layers would always show a much lower moisture content than the inner.It would take months for the sectioned layers to reach a balance of moisture content.
And remember that balsa is a very light wood.
ron
And remember that balsa is a very light wood.
ron
Hi Ron;
interesting.
Here in the mountains we have an equilibrium moisture content of about 12.5% The mills around here figure an inch a year to equilibrium, i.e. a three inch board takes 3 years. I do not know how that figure varies geographically. Anyone?
eStatic
interesting.
Here in the mountains we have an equilibrium moisture content of about 12.5% The mills around here figure an inch a year to equilibrium, i.e. a three inch board takes 3 years. I do not know how that figure varies geographically. Anyone?
eStatic
jewilson said:
I'm sure no expert but I feel the same way, MDF for speaker cabinets.
These very dense woods are interesting, I guess you know that Lignum Vitae is almost impossible to glue? I know that the wood needs some special treatment in order to make it suited to gluing but I haven't a clue as to what that is. I would be interested in finding out.
I always had a fantasy of doing a ferro cement cabinet. 🙂
eStatic
has anyone here ever heard of LVL, it is an engineered product for house construction, we are using some for a house being built at the moment and it is extremely strong, it is about 1" thick and it like ply but with about 12 layers, it is very rigid, the difference between this and ply is that all its fibres go in a single direction creating enourmous strength. and being so many layers any knots or imperfections are reduced to one layer in 12.
i know that speaker cabinets need strength in many different directions but in some situation im sure it could not hurt to have single direction strength.
my first thought was that it would make some extreme bracing as it expands much less than normal woods and it is far stronger where it needs to be for bracing...
any thoughts....?
i know that speaker cabinets need strength in many different directions but in some situation im sure it could not hurt to have single direction strength.
my first thought was that it would make some extreme bracing as it expands much less than normal woods and it is far stronger where it needs to be for bracing...
any thoughts....?
comprimise
I've found that on a tower speaker if you use solid wood for the front and top panels and MDF with a real wood veneer (fibercore)for the sides. no one can tell by looking at it that it isn't all solid wood and you have the ease of working and nonresonant qualities of the mdf on the sides and it can make for a very beautiful cabinet.
I've found that on a tower speaker if you use solid wood for the front and top panels and MDF with a real wood veneer (fibercore)for the sides. no one can tell by looking at it that it isn't all solid wood and you have the ease of working and nonresonant qualities of the mdf on the sides and it can make for a very beautiful cabinet.
Combining wood and MDF is tricky because wood moves and MDF doesn't. If anyone expresses and interest in what techniques can be used to minimize the problems of combining these materials I will do some drawings and post them and relevant text to the thread I started titled "Purchasing wood and water."
eStatic
eStatic
brsanko -
Thanks for posting the most appropriate suggestion for this thread.
How wide have you made the baffles without any movement problems?
Michael-
As an engineered product, LVL will be expensive to design around, unless you can find lots of decent scraps, but it might be worth a "stop and ask" at a project near you. It's pretty coarse material that might present it's own specific problems with joining and finishing, but strong it is.
In the States, there are engineered sheet products, one brand name is AdvanTech, that are designed to be single-sheet, flooring substrates to span larger joist centers than 16". But even the 3/4" is far stronger than regular plywood. I haven't seen as many voids in it as you'd find in typical plywoods either. It might be worth a look at your local lumberyard, to see what they're carrying. If they sell a lot of LVLs and truss floor joists,(these are usually made to spec.) they might have thicker grades of engineered floor sheathing in stock. I've built tool and wood boxes out of jobsite scraps and can tell you they're very strong and heavy.
I understand that baffles are (and why) typically built thicker to reduce resonance, but ideas like this (and the ferro cement one) have me wondering how heavy and strong cabinets should really be, and how we might qualify driver size and cabinet strength.
The "seat of the pants" rules of thumb, suggest "the knock" test is good enough, and that seems fine for me. But i've built TL's that could be broken up by stomping on them. Afterall, 3/4 MDF isn't really that strong, certainly nothing like the AdvanTech boxes mention earlier.... but they sound great, and I wonder if there isn't a resonant frequency of the cabinet coming into play here. What might the resonant frequency of a 14' x 48" sheet of MDF be?
Does the ultimate, non-resonant cabinet need to survive the unstoppable force?
Thanks for posting the most appropriate suggestion for this thread.
How wide have you made the baffles without any movement problems?
Michael-
As an engineered product, LVL will be expensive to design around, unless you can find lots of decent scraps, but it might be worth a "stop and ask" at a project near you. It's pretty coarse material that might present it's own specific problems with joining and finishing, but strong it is.
In the States, there are engineered sheet products, one brand name is AdvanTech, that are designed to be single-sheet, flooring substrates to span larger joist centers than 16". But even the 3/4" is far stronger than regular plywood. I haven't seen as many voids in it as you'd find in typical plywoods either. It might be worth a look at your local lumberyard, to see what they're carrying. If they sell a lot of LVLs and truss floor joists,(these are usually made to spec.) they might have thicker grades of engineered floor sheathing in stock. I've built tool and wood boxes out of jobsite scraps and can tell you they're very strong and heavy.
I understand that baffles are (and why) typically built thicker to reduce resonance, but ideas like this (and the ferro cement one) have me wondering how heavy and strong cabinets should really be, and how we might qualify driver size and cabinet strength.
The "seat of the pants" rules of thumb, suggest "the knock" test is good enough, and that seems fine for me. But i've built TL's that could be broken up by stomping on them. Afterall, 3/4 MDF isn't really that strong, certainly nothing like the AdvanTech boxes mention earlier.... but they sound great, and I wonder if there isn't a resonant frequency of the cabinet coming into play here. What might the resonant frequency of a 14' x 48" sheet of MDF be?
Does the ultimate, non-resonant cabinet need to survive the unstoppable force?
8"d X 9"w X 40"h
my speakers are 8"w X 9"d X 40"h and the fronts and tops are solid cherry while the sides and back are MDF. I've had them for four years now and all the edges are still perfectly flush. The top half contains the mids and tweeters while the bottom holds the side firing 6 1/2" woofer with a divider between them I have very little problems with resonance.😎
my speakers are 8"w X 9"d X 40"h and the fronts and tops are solid cherry while the sides and back are MDF. I've had them for four years now and all the edges are still perfectly flush. The top half contains the mids and tweeters while the bottom holds the side firing 6 1/2" woofer with a divider between them I have very little problems with resonance.😎
brsanko said:
They sound very nice. I suspect that using the design you describe you're close to the upper limit on width and depth in regard to gluing wood to MDF. The longitudinal dimension in wood is, of course quite stable, so the 40" still has leeway. I'm curious as to the lie of the rings in the cherry--plane sawn/quarter sawn. Also as to the type of glue you used.
I don't intend this to be "preaching" to you. But I fear that an inexperienced woodworker might get the false impression that there really is no problem in joining wood and MDF and I just want to instill some appropriate caution.
Thanks
eStatic
well actually
actually I designed the speakers and had my brother build them in a professional woodshop. He is also a very experienced woodworker. I believe he used stadard wood glue and also air nailed them together. I wouldn't recomend necessarily that an inexperienced woodworker build this design.
actually I designed the speakers and had my brother build them in a professional woodshop. He is also a very experienced woodworker. I believe he used stadard wood glue and also air nailed them together. I wouldn't recomend necessarily that an inexperienced woodworker build this design.
I would.
An 8" wide front panel might easily be found or planed flat. This seems to me, to be the hardest part of working with real wood. Wrestling with panels to get them flat and square when assembling boxes, is not as easy as when working with MDF.
I built my kitchen out of white oak, and on the free-standing TAL, pantry cabinet, the carcass is oak too. The 14" x 84" side panels are showing no signs of movement at the flush joints, either at the center, (spline jointed) or at the face-frame stiles (biscuits). The base and wall cabs' end panels were left slightly proud (maybe 3/32") so I can't really tell, but the kitchen was built in '89, has 39 raised panel doors, and the only movement I ever see, is in the moving fit of the doors themselves.
This may or may not translate to confidence in the stability of mixing wood and MDF, as I believe white oak is one of the most stable hardwoods, but it is an accurate description of some of my experience. I live in high quality oak country, the largest sawmill in the NE is just down the road, and I've done a lot of cabinet work for the owners of a very large and hightech hardwood drying facility.
This may give me an advantage in the quality of dried hardwoods that I can use in my projects, but I'd like to point out that the local Home Depot and Lowes also buy their hardwood boards from that same drying facility (through a related distributor.) Seek out the local hardwood dealers for better prices than L or HD and as I've said before, ask your local cabinet makers where they buy their hardwood.
Hi x.onasis
White oak is my favorite hard wood. It's such a pleasure to work with! And really, I don't mean to be disagreeable but the fact is its T/R numbers are 10.5/5.6 = 1.8. The ratio is good among the more common hardwoods. However, its high tangential shrinkage figure of 10.5% is why I generally prefer to work with quarter-sawn white oak.
And I do not at all doubt your good results. I am probably fussier than need be for speaker cabinets. My study of woodworking centered on the practices of organ builders whose works are expected to last hundreds of years. They take a more mechanical engineering approach to wood (even on the small scale components). And on practices established by hundreds of years of in use testing. Still, I think this approach is not entirely inappropriate in this context given the great care and effort I see applied here by many DIYs.
Best wishes,
eStatic
White oak is my favorite hard wood. It's such a pleasure to work with! And really, I don't mean to be disagreeable but the fact is its T/R numbers are 10.5/5.6 = 1.8. The ratio is good among the more common hardwoods. However, its high tangential shrinkage figure of 10.5% is why I generally prefer to work with quarter-sawn white oak.
And I do not at all doubt your good results. I am probably fussier than need be for speaker cabinets. My study of woodworking centered on the practices of organ builders whose works are expected to last hundreds of years. They take a more mechanical engineering approach to wood (even on the small scale components). And on practices established by hundreds of years of in use testing. Still, I think this approach is not entirely inappropriate in this context given the great care and effort I see applied here by many DIYs.
Best wishes,
eStatic
Happy New Year eStatic
Yes, piano and organ builders have taken the level of woodworking to high quality levels. Have you done any research into the life story of Edwin Link? One of the unsung geniuses of the 20th century who started out as a piano builder and can take credit for saving the lives and lifestyles of millions.
A good rule in learning the mechanic trades, and I put woodworkers in that category, is to not try too quickly, to re-invent construction, but understand why we do things the way we do. There's a long, rich history behind most building practices, and not only will you better understand how to do the task at hand, but also you'll make better choices in adapting new tools and solutions as the inevitable problems arise.
As DIY'ers many of our problems have already been solved by someone else. And isn't it wonderful this forum exists?
It might be a good time to thank Mr. Pass and all the members of this site for making it happen.😀
Yes, piano and organ builders have taken the level of woodworking to high quality levels. Have you done any research into the life story of Edwin Link? One of the unsung geniuses of the 20th century who started out as a piano builder and can take credit for saving the lives and lifestyles of millions.
A good rule in learning the mechanic trades, and I put woodworkers in that category, is to not try too quickly, to re-invent construction, but understand why we do things the way we do. There's a long, rich history behind most building practices, and not only will you better understand how to do the task at hand, but also you'll make better choices in adapting new tools and solutions as the inevitable problems arise.
As DIY'ers many of our problems have already been solved by someone else. And isn't it wonderful this forum exists?
It might be a good time to thank Mr. Pass and all the members of this site for making it happen.😀
Hi
I have traditionally used MDF but unless it is well damped and at least two layers thick, I have been slightly disappointed due to the MDF signature.
My last pair of speakers were made using 42mm thick oak with a lead lining. Of all the speakers I have built these had the least cabinet signature and are really fast. This was probably helped by the fact that they are quite small and an active design.
I do however fully support the need to use seasoned wood, as real wood will deform with moisture/temperature change.
Also the comparison with past speakers is not scientific, as they were not identical.
I have traditionally used MDF but unless it is well damped and at least two layers thick, I have been slightly disappointed due to the MDF signature.
My last pair of speakers were made using 42mm thick oak with a lead lining. Of all the speakers I have built these had the least cabinet signature and are really fast. This was probably helped by the fact that they are quite small and an active design.
I do however fully support the need to use seasoned wood, as real wood will deform with moisture/temperature change.
Also the comparison with past speakers is not scientific, as they were not identical.
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