Hi
I’m working on a project that requires me to laminate a glue-up of Maple, Purple Heart and Bloodwood to a MDF sub base. The glue up is 10″ wide x 1″ x 50 long ” the mdf is the same only .75″ thick. I need to allow for expansion seasonally. How should this lamination be done? I have a vac bag and experience with West System epoxy. The final product will be similar to the pic in the link below. It MUST not crack. Thanks in advance for any input
Chris
http://www.meadowlarkaudio.com/pow/bh2Swimsuit2.htm
Replies
Christof,
Those are attractive speakers. The combination of the "high tech" components with the traditional cabinetry is interesting.
What is the thickness of the wood that you want to laminate to the MDF? Are you working with veneer, or substantially thicker stock?
"Laminating" in woodworking is generally referred to as veneering whether the veneer is a micro thin product or resawn wood up to about 3/16" thickness. Veneered construction does not suffer from seasonal movement because the thin veneer is anchored to the substrate. The veneer does impart warping stresses as it tries to move, so a veneered piece usually (but not always) has similar veneers applied to both sides of the substrate (balanced construction).
If you are planning on laminating thicker woods to the MDF, there is going to be a problem with movement.
VL
Venicia
I need to fasten a 1" thick glue-up to .75 mdf. In essence I'm creating a large sealed box from MDF. I'll press veneer onto all sides but the front. I need to fasten the 1" thick baffle to this box somehow. I know it can be done as the picture in the link demonstrates. I believe there is some bit of a gap between the solid wood panel and the actual mdf box. If you look close you can see what appears to be an extruded rubber "T" gasket b/t the face and box?
thx for the help
Chris
Pics I'm refering to are at:
http://www.meadowlarkaudio.com
Christof,
OK. I think I understand. The MDF is not going to move with changes in humidity. The solid wood glue up is. You can use any of a number of methods to allow for the movement, but you can't attach the face glue up to the MDF with any kind of unyielding method.
I wouldn't have come up with velcro, but that sounds like it would work, especially as it would allow the fascia to come off like a front baffle assembly.
I was going to suggest slotted screw holes with a keyhole slot in the back of the face wood.
But I think you have answered your own question and a pretty interesting idea in the velcro.
BTW, you have an interesting web site.
VL
from the photos I can tell that the faces are a glue up and the stringing is layerd in the slices of the front face, you can tell by the carving around the speaker it shows how the 'stringing' undulates from the face plane..
But that is not the problem, you are attempting to glue this slab to a backing of mdf..umm, no velcro please..wont work..you want the mass of the front to be solid..no rattles. A lot of these high end sound enclosures are filled with sand..believe me I build guitars and organs and have a lot of experiance as well with custom sound boxes..
OK, ready?..go ahead and glue the front to the mdf backer..yup, you heard me..use yellow, white, whatever just glue it. NOW, what you are going to do is SEAL the mdf..and the face (after the carving, and sanding..) I mean seal the bugger with alot the finish you are using...the width of the solid wood, and the fact that it has been ripped to create the "inlay" will not give you a problem..unless the wood is sopping wet and you drag it into a hot dry house.
I would start with an oil that allows the grain to shine, and then a goodly layer of cat. lac. all over. If cat. lac is beyond your equipment means then by all means use a multi coat varnish finish..it will work just fine.
Sphere,
Your concern about the solid wood vibrating and rattling is well-taken. However, gluing the solid wood to the MDF is a recipe for splitting and warping. The wood will move. The MDF will not. Finish will not prevent that. Over time, the glue-up will fail. and cracks will appear - not pretty in a high-end product.
The face wood can be firmly anchored by pins or glue along its centerline vertically, but the sides, somehow, must be free to move. It might be possible to deal with the movement and the vibration by using silcon seal or similar for the adhesive, at least at the outer edges.
VL
I appreciate your views very much, however in this instance I would build it as I had described AND warrant it against splitting for life. Thats how much I am willing to stand behind my work. If the moisture content at fabrication is acceptable and the home's heating and cooling systems are up to snuff..there will be NO problems. The amount of expansion/contraction in a modern home (one that can afford that kind of enclosure , must be modern in at least it has some heat or air conditioning, or is in a climate where there are not extreme swings of temp, or humidity) is negligable..in a lamination as shown..we could go to the source and ask the WEB PAGE Company who DOES manufacture them WHAT THEY DO..this person, from what I can gather is COPYING THIER PRODUCT..If he were doing that to one of my products that I had SECURED a copyright on , and he was SELLING that product I would NOT HESITATE to seek legal RECOURSE..
Other than that tid bit..I stand behind my method, I have seen the results in many so called not acceptable practices , mostly in the instrument making trade..some examples have survived 150 yrs. on Pipe Organs. Explore the windchest constuction of a tracker organ from that (1833) era, cross grain glue ups abound, and the wind chest is still air tight, these can be MONSTEROUSLY large, not a 10'' wide laminated blank.
Are not the back braces cross grain glued in a guitar?, The sound board bracing?..C'mon, it can work, if done properly.
Sphere,
This thread seems to have taken on all the flavor of one of those giant truck demolition derbys, with the loudest, most garish, most persistent entry winning by just wearing down the competition. And you seem to be the announcer.
One of the aspects I enjoy about woodworking and craftsmanship is a quiet tradition of experience and gentle appreciation of the material, resulting in quality and endurance. The field has an old world charm of patience and understanding about it.
I don't mean to offend you or anyone else. But you can scream all you want about standing behind your extreme techniques and over-engineered design. You can slather on 3 inches of plastic coating if you like and insist that atmospheric variation doesn't occur in the homes of connoisseurs of "high end" (sic) audio. Sorry to disappoint you. It does, no matter how fancy their homes or air conditioning systems. BTW, what happens when the boxes sit in the warehouse, or are sent shipping?
The basic priciples of wood movement don't change just because you have devised a temporary brute force method. Every once in a while someone comes along to insist that "modern" methods, including epoxies, laminates, metal connectors and sheer mass of construction can force natural materials into submission. It's so tiring to listen to such rantings.
Somehow the fact that this discussion also includes loudspeakers (emphasis on the word loud) with all the ear-splitting noise that they can produce seems fitting. There I go offending an additional contingent of forum participants.
The laws of physics don't change inside the walls of your shop. Solid wood is going to move and no gluing technique is going to stop it. If your method uses a flexible bond between wood and MDF, you are only proving the point.
I know of no unusual construction practices in the making of a guitar (at least an acoustic guitar). I have no knowledge of the pipe organ you allude to. However, if it has withstood even several years of existence, I assure you its makers understood the properties of wood and constructed it according to the simple laws woodworkers have always used.
I wish you luck with your construction methods and proprietary designs. My work just doesn't need 3 inch thick MDF and sand-filled cabinets. and Extreme Finishing.
VL
ahhh..somethin about heat and kitchens...right?
if the purpleheart and bloodwood are accents and the maple the main wood. Be most concerned with the maple's expansion and contraction versus the expansion of the MDF.
Those exotics will probably always be moving as they are slow to react whereas maple will probably react quicker to changes.
If the charts show maple and MDF fairly close to the expansion tables (im not up to exact numbers) you might be able to mirror the finish coat on the inside. Youre if the nubmers are way off you probably should line the MDF inside with a "b" grade lamination of maple. Doing that you might be able to go down to 1/2inch MDF and still maintain some sound characteristics of the MDF.
This is my 2cents it may not work at all.
Has anyone ever heard of velcro used to fasten solid wood to sub-base?
chris
Gluing solid wood to MDF is NOT a god idea at all. If you were to totally encase it in an epoxy finish it would work, otherwise it will not make it for the long haul. Believing so would go against everything craftsmen and wood technologists have learned and know about wood. I wouldn't try this with quartersawn mahogany or catalpa (very stable woods), let alone maple.
I have seen thin veneers successfully wrapped around curved edges with a vacuum press, and that is what I would consider if I were you. I have not done it myself.
how do you think these guys are doing it?
http://www.meadowlarkaudio.com
thx for the input
Chris
Some of those speakers look as though they are veneered on the front. The face grain wraps around the roundover. Not an easy thing to do but it is possible. There was an article on it in FWW a couple of years ago.Tom
Douglasville, GA
look again..at the how we make them part. Thanks.
sorry its not shrunk..
Oops, my bad. Didn't mean to strike a nerve.Tom
Douglasville, GA
No problemeo...just gettin to the bottom of things, no one can respond accuratly with out the proper information..no nerve struck, just pointing out the facts as they are ..
So, if I am reading this correctly, this keldamp stuff will allow some movement between the mdf and the solid wood. It is not a rigid glue line. Correct????Tom
Douglasville, GA
Tom, you got it. Picture real big double sided tape..but it is 'kinetic' it is not a single purpose material..isolation and adhesion and energy absorbsion..the energy dissapates as heat.
I have to add the purpose I have for reading these posts is not only for my entertainment, if I can learn some more..Great, if I can open some doors for inquiring minds...greater. But the whole set of facts needs to be present..a little research on the guy is a good read..I am sure he has patent on this..
Everyone, thanks for all the great info. For the record I am not trying to copy the Meadowlark system. Among diy speaker builders there is great controversy over the solid wood baffle issue. A majority of the people say it simply cannot be done and give numerous arguments as to why. A few others, including myself, say it can and Meadowlark obviously proves it can. While I agree that the folks at Meadowlark should have a design patent for their system and probably do, it is not an ethical infringment to put solid wood baffles on MDF boxes :-) I can name a long list of commercial companies who do this using one method or another.
Christof
That is correct..no infringement, but when the propietary word comes up watch yer kester...I'll take a set of BMW's..not as pretty but sound awesome..I know a very serious speaker builder, and he is way crazy on that weight/mass stuff his weigh a ton..3'' of mdf...and sand..aaarrgghhh. I did his final finishes for him..cuz I have the booth for shooting them killed me to move them.
Problem solved Bro...the pictures of manufacturing them SHOW they are NOT affixed to the cabinet with an attached (by glue) MDF back..fronts waiting for cabs pic...And for chrissake THEY ARE NOT VENEERED..laid up outta solid stock..
They very well could be gluing solid wood to their MDF, that doesn't mean they're doing it the way anyone that knows anything at all about the way wood moves would do it with the hopes that it would stay together for the next 20 years. Add the way that a speaker box can heat up and cool down to the fray and it is a recipe for failure. I don't know speakers, but I know wood.
There are many examples of furniture from history where the maker didn't allow for wood movement. The best do however, and the rest are mostly warped and wobbly.
Those speakers are pretty though!
Here..
Cabinet construction is one inch thick, type II MDF that is intensely braced and internally lined with thick acoustic felt. In addition, the speaker’s top is further thickened and stiffened by a sculpted slab of solid hardwood. The baffle is a five layer sandwich that, starting from the outside, is made from 0.82 inches of solid hardwood adhered by a 1/16 inch layer of Keldamp to 0.75 inches of type II MDF adhered by a 1/16 inch layer of Keldamp to a 1 inch layer of type II MDF, for a total baffle thickness of nearly three inches!
and here...
Excellent Transmission Can Be A Bad If The Wrong Things Are Being Transmitted
While McGinty is all gung-ho on transmitting superior bass, he’s heavily opposed to allowing his drivers, cabinet or crucial network parts to contaminate our listening pleasure with mechanical vibrations. Every trademark sloped Meadowlark baffle is decoupled from its main enclosure via a 1/16th layer of Keldamp, a hi-tech material that converts kinetic energy into heat. A blob of this stuff dropped from on high onto the floor won’t bounce even once. It’ll just crash like a broken egg, fully absorbing all mechanical energy injected into it from the fall. Meadowlark employs the same Keldamp compound for driver gaskets. They decouple the transducers from the baffle. This twin-decoupling scheme undermines mechanical intermodulation between cabinet and drivers. The drivers can’t talk to the cabinet, and the cabinet can’t talk back to them – the perfect dialogue vacuum of a failed marriage. But then, divorcing signal and distortion from each other is a good kind of terminal separation. McGinty even mounts his capacitors on a bed of Keldamp so they can sleep – ahem, perform -- tightly.
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