Vikash said:
I rang them up Vik and the price of that stuff is immense. They also said that regular tooling isn't effective and heavy duty machinery is needed for best results. They said to think of it more as a metal and treat the machinery needed to work it as such
Its really only made for smaller pieces rather than large baffles but after roughly explaining what I wanted they estimated that something could be fabricated for a cost of £400-500 and thats for each baffle including all machining done by them (which they strongly recommended). So between £1600-2000 for 4 finished mid/bass baffles!
Forget that!
Tweaked the cabinet a little more without causing a major rework. MTM spacing now 5cm closer plus the mids and tweeter are time aligned on tweeter axis at 2.75m.
An externally hosted image should be here but it was not working when we last tested it.
Firstly let me say, your projects are awe inspiring.
Now, regarding the finishing, I'm just wondering if maybe giving the baffles a coat of fibreglass resin might help seal and lock everything in place ?
Or even just a single coat of fibreglass.
Would basicly give a single solid surface to work with and any joint creep would be behind a 'wall' so to speak.
I've no idea if this would work, just throwing it out there....
Maybe marine grade paint could help.
Isn't that some sort of epoxy resin ?????
Maybe even the stuff they use for 'refurbished' kitchens.
Granit speakers, now thats a different look..
Now, regarding the finishing, I'm just wondering if maybe giving the baffles a coat of fibreglass resin might help seal and lock everything in place ?
Or even just a single coat of fibreglass.
Would basicly give a single solid surface to work with and any joint creep would be behind a 'wall' so to speak.
I've no idea if this would work, just throwing it out there....
Maybe marine grade paint could help.
Isn't that some sort of epoxy resin ?????
Maybe even the stuff they use for 'refurbished' kitchens.
Granit speakers, now thats a different look..
Shin,
The veneer won't eliminate it. I've tried it several times using various application methods.
It will slow the appearance somewhat. But moisture will get through eventually and cause the telegraphing.
The best results I've had were using 2-3 coats of clear epoxy as a primer. It is formulated for coating wood. It's much thinner and has better wetting/penetrating properties than automotive epoxy primers and is inherently much better at blocking moisture than the 2K automotive primers.
It can be topcoated without any sanding required with automotive primers/colors if done within the recoat window, usualy 12-24 hours.
After that you'll need to scuff sand for adhesion.
If you can get aluminum powder pigmented epoxy that is even better than the clear. It approaches 100% effectiveness at blocking moisture vapor.
The veneer won't eliminate it. I've tried it several times using various application methods.
It will slow the appearance somewhat. But moisture will get through eventually and cause the telegraphing.
The best results I've had were using 2-3 coats of clear epoxy as a primer. It is formulated for coating wood. It's much thinner and has better wetting/penetrating properties than automotive epoxy primers and is inherently much better at blocking moisture than the 2K automotive primers.
It can be topcoated without any sanding required with automotive primers/colors if done within the recoat window, usualy 12-24 hours.
After that you'll need to scuff sand for adhesion.
If you can get aluminum powder pigmented epoxy that is even better than the clear. It approaches 100% effectiveness at blocking moisture vapor.
ShinOBIWAN said:
Bob Barkto said:
I found a local shop that have something like these in stock.
I was told that they are grey in color, lighter than regular mdf, but with same strength as regular mdf. $96 for a 8x4 sheet of 1-1/2" thickness
Is this price OK, almost 2x the price of two 3/4" sheet?
What is this grey, lighter mdf that the guy is selling me?
Probably LDF (Low Density Fiberboard).
It's lighter because it is less dense and there is a lessening of the physical properties compared to MDF. But probably not much of a concern for a speaker cabinet.
Color is not a good guide and can be practically discounted. Any variable in the production of a panel can account for changes in color. It does not inherently indicate the material properties of the panel, unless the manufacturer claims so.
It's lighter because it is less dense and there is a lessening of the physical properties compared to MDF. But probably not much of a concern for a speaker cabinet.
Color is not a good guide and can be practically discounted. Any variable in the production of a panel can account for changes in color. It does not inherently indicate the material properties of the panel, unless the manufacturer claims so.
Thanks for the suggestions chaps.
Bob, I do agree with you but also thought it prudent to point out that the expansion is really only a problem where the MDF has been put together on differing planes such as a joint where you've got the face of the MDF meeting up with the thickness - they expand at different rates.
The baffles have slices where all the joints roughly expand at the same rate because they're in the same plane and the only problem is the glue in the seam doesn't follow suit. The veneer will mostly eliminate that along with other treatments such as the high build primer.
Its good that you also mention the resins etc. because I treat most parts of the MDF with this:
http://www.decoratingdirect.co.uk/viewprod/b/BONWH/
Which I said this about sometime ago:
Bob, I do agree with you but also thought it prudent to point out that the expansion is really only a problem where the MDF has been put together on differing planes such as a joint where you've got the face of the MDF meeting up with the thickness - they expand at different rates.
The baffles have slices where all the joints roughly expand at the same rate because they're in the same plane and the only problem is the glue in the seam doesn't follow suit. The veneer will mostly eliminate that along with other treatments such as the high build primer.
Its good that you also mention the resins etc. because I treat most parts of the MDF with this:
http://www.decoratingdirect.co.uk/viewprod/b/BONWH/
Which I said this about sometime ago:
I must be missing something.
The glue line is telegraphing. This means moisture is leaving and/or entering the substrate, right?
Get the moisture low and keep it that way and you eliminate the problem. Regardless where it occurs or how it manifests visually.
Your thinking is sound about the various surface applications and your wood hardener. But none of the products/methods is of the highest effectiveness at stopping moisture vapor entering your substrate.
Bonda is a polyester resin. Polyester rates comapratively low on a permeabilty scale (it lets moisture vapor pass). Polyesters also are comparatively highly absorbant.
Same for the high build urethane auto primers in general. It depends on the pigment and filler used to some extent. Quartz fillers are the best but the grey pigments are usually hydrophylic and disrupt the continuity of the urethane film.. so.
A thin layer of wood veneer will slow the rate of transfer even more and possibly disguise some of the effects of differential expansion. But I fear not as much as you'd hope for. At least that's been my experience.
Combine all the above and you've slowed the rate of moisture induced movement significantly. But not as much as is needed it seems. Maybe the veneer will be just enough extra, but you're doing a lot of work for what I fear might not be much gain.
I hadn't mentioned this before... It's really an amazing design, Shin. First rate. One of the best I've seen. Kudos!
The glue line is telegraphing. This means moisture is leaving and/or entering the substrate, right?
Get the moisture low and keep it that way and you eliminate the problem. Regardless where it occurs or how it manifests visually.
Your thinking is sound about the various surface applications and your wood hardener. But none of the products/methods is of the highest effectiveness at stopping moisture vapor entering your substrate.
Bonda is a polyester resin. Polyester rates comapratively low on a permeabilty scale (it lets moisture vapor pass). Polyesters also are comparatively highly absorbant.
Same for the high build urethane auto primers in general. It depends on the pigment and filler used to some extent. Quartz fillers are the best but the grey pigments are usually hydrophylic and disrupt the continuity of the urethane film.. so.
A thin layer of wood veneer will slow the rate of transfer even more and possibly disguise some of the effects of differential expansion. But I fear not as much as you'd hope for. At least that's been my experience.
Combine all the above and you've slowed the rate of moisture induced movement significantly. But not as much as is needed it seems. Maybe the veneer will be just enough extra, but you're doing a lot of work for what I fear might not be much gain.
I hadn't mentioned this before... It's really an amazing design, Shin. First rate. One of the best I've seen. Kudos!
Lamiantes (2 sheets bonded) are actually quite a bit stiffer than a single sheet of MDF, but the benefits vs hassles are debateable. IF the machining is easier, that might be seen as a benefit. (single 2" or 4") For ultimate design, I'd go with the laminate, personally. Considerably more hassle to make, yes. Then, proper settling time must be considered, and good bonding is another issue. But, still better than the single 2" or 4" piece. Spraying the glue on is a way to be sure the gluing is correct (layering density of the glue-weldbond thinned with water works incredibly well), and then the issue of imperfect bonds (Air pockets, etc) rears it's head. But..still..properly done, far more stiffness for the mass involved is the end result.
So don't feel to bad about using the laminates, you ended up with a better speaker. Time and effort was certainly not wasted.
BTW, Shin, very nice work, great looking speaker.
So don't feel to bad about using the laminates, you ended up with a better speaker. Time and effort was certainly not wasted.
BTW, Shin, very nice work, great looking speaker.
Design
The current vision of your project reminds me of the Sonics Passion.
http://www.sonicsonline.de/produkte.php
I must say that it is a fantastic undertaking.
Congrats,
C
The current vision of your project reminds me of the Sonics Passion.
http://www.sonicsonline.de/produkte.php
I must say that it is a fantastic undertaking.
Congrats,
C
Attachments
Thanks Bob and KBK. I'm going to stick with the laminated approach with veneer plus the usual products I use because its something I feel comfortable doing and also that it will likely work. If I'm wrong then no doubt I'll be back for your help though!
Applied the veneer to one section and it turned out OK:
Also for those interested, some driver pics:
Applied the veneer to one section and it turned out OK:
An externally hosted image should be here but it was not working when we last tested it.
Also for those interested, some driver pics:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
m0tion said:
EDIT: The veneer is a plain Beech which has little figuring or grain pattern - perfect for spraying over.
I used a straight edge and veneer saw to cut roughly to size:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Then trimmed with straight edge and craft knife once stuck down:
An externally hosted image should be here but it was not working when we last tested it.
And finally light sanding to remove the excess.
pinkmouse said:
Pearl Glue:
An externally hosted image should be here but it was not working when we last tested it.
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