On one or two occasions there have been amazing pictures of people who have done amazing things with their speaker enclosures by covering the front with some sort of stretchy material and applying fibreglass. The result is a contoured, perfectly shaped front to their speakers. Examples can be found in the permanent post, "System pictures and description" on pages 11 (or thereabouts) and 20.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=23208&perpage=15&pagenumber=20
However, every time these pictures appear, questions to how this is done are not answered. I have searched the forum a few times and cannot find any threads or posts discussing this either. As I don't know what is being done, searches on google are hard and don't yield much. Therefore, is there anyone out there who knows how to do this to their speakers? Thanks for your help,
Philip
http://www.diyaudio.com/forums/showthread.php?s=&threadid=23208&perpage=15&pagenumber=20
However, every time these pictures appear, questions to how this is done are not answered. I have searched the forum a few times and cannot find any threads or posts discussing this either. As I don't know what is being done, searches on google are hard and don't yield much. Therefore, is there anyone out there who knows how to do this to their speakers? Thanks for your help,
Philip
Some information
This might be bargain basement stuff for those who already know how to work with fibreglass, but I was checking out the internet and found a few sites that provide some help:
http://forums.skylinesdownunder.co.nz/archive/topic/31322-1.html
http://www.geocities.com/MotorCity/Speedway/5051/gpod.htm
http://www.talkaudio.co.uk/vbb/showthread.php?p=615802#post615802
So, you begin by covering your surface with some sort of stretchy material: what material seems unclear. One guy uses pantyhose, and a couple others use "stretchy material" from a fabric store. Is there a best one?
The next step is a bit up in the air, and it seems it has been done three ways. First, cover the material with some sort of resin which hardens. Secondly, you could cover with resin, and then fibreglass. I think the resin hardens the material so when you apply the fibreglass the material doesn't sag. Third, although I'm not sure if this is an option, but it wasn't chronicled on the diyaudio thread (above), is lay fibreglass directly over the stretchy material.
It seems that whenever you apply fibreglass, to get a smooth surface, it's necessary to cover with some sort of spray filler to fill in all the cracks. Then, when this hardens, you can sand it and get a really smooth finish. In fact, even if I don't use fibreglass I'm going to look into using this stuff for the outside of my enclosures instead of wood filler! It seems so much easier and would provide a surface so much smoother.
Any information from those who know more would be welcome.
Philip
This might be bargain basement stuff for those who already know how to work with fibreglass, but I was checking out the internet and found a few sites that provide some help:
http://forums.skylinesdownunder.co.nz/archive/topic/31322-1.html
http://www.geocities.com/MotorCity/Speedway/5051/gpod.htm
http://www.talkaudio.co.uk/vbb/showthread.php?p=615802#post615802
So, you begin by covering your surface with some sort of stretchy material: what material seems unclear. One guy uses pantyhose, and a couple others use "stretchy material" from a fabric store. Is there a best one?
The next step is a bit up in the air, and it seems it has been done three ways. First, cover the material with some sort of resin which hardens. Secondly, you could cover with resin, and then fibreglass. I think the resin hardens the material so when you apply the fibreglass the material doesn't sag. Third, although I'm not sure if this is an option, but it wasn't chronicled on the diyaudio thread (above), is lay fibreglass directly over the stretchy material.
It seems that whenever you apply fibreglass, to get a smooth surface, it's necessary to cover with some sort of spray filler to fill in all the cracks. Then, when this hardens, you can sand it and get a really smooth finish. In fact, even if I don't use fibreglass I'm going to look into using this stuff for the outside of my enclosures instead of wood filler! It seems so much easier and would provide a surface so much smoother.
Any information from those who know more would be welcome.
Philip
there are a few different materials they use.....and I believe the best is fleece (like sweatshirt material).....another good one is speaker grill cloth. Either way you need to re-enforce it with fiberglass mat/cloth.
Ive been using this method for a long time for car audio use...and the best place I have found for learning is Glassman's custom forum on yahoo......but you have to get an account...which is like 2 bucks USD...
Ive been using this method for a long time for car audio use...and the best place I have found for learning is Glassman's custom forum on yahoo......but you have to get an account...which is like 2 bucks USD...
also...the spray filler used is usually feather fill....good stuff. It is like spray bondo. You can also use duraglass...for areas you need to fill in...and need some strength....and to fill in some smaller areas...use a light weight filler...like slick sand..or rage gold.
The feather fill can actually be sprayed on pretty thick.....so it is very easy to work with..
The feather fill can actually be sprayed on pretty thick.....so it is very easy to work with..
Cal: I actually tried to contact Raami but to no avail. I didn't post because it was already a page or two old and didn't want to disrupt the way the conversation was going - also, I think this is a subject that should have its own post anyways.
Hey BBKSV, thanks for all the info. When you say "Either way you need to re-enforce it with fiberglass mat/cloth," do you apply resin first, so as the cloth won't sag when you put it on - that's what resin does, hardens the cloth, right?
As for the filler, I don't actually know a lot of the terminology involved. What is feather fill, bondo, and duraglass? What spray filler do you think Raami used, or did he use both?
Thanks for your help guys,
Philip
Hey BBKSV, thanks for all the info. When you say "Either way you need to re-enforce it with fiberglass mat/cloth," do you apply resin first, so as the cloth won't sag when you put it on - that's what resin does, hardens the cloth, right?
As for the filler, I don't actually know a lot of the terminology involved. What is feather fill, bondo, and duraglass? What spray filler do you think Raami used, or did he use both?
Thanks for your help guys,
Philip
Well...basically here is how it works....you might need a little imagination to understand what I am talking about. First you need to cut out an MDF circle....about an inch and a half larger than the speaker you are using. You can also cut another ring to flush mount the speaker....like the sub in the picture you saw.
Then you take the ring and suspend it over the back of the enclosure (could be out of MDF or more fiberglass)....with a piece of 2x4.
Wrap the fleece over the enclosure...and either staple or spray glue it to the back of the enclosure. It has to be AS TIGHT AS POSSIBLE.....or you will get sags...
Once it is all wrapped....apply fiberglass resin to the fleece...and wait for that to harden. Be sure to not get resin on the part that you glues...because the resin will make the glue release...and you project is pretty much ruined.
When that is hard...then apply fiberglass MAT. I really prefer mat because the resin actually melts it a bit....allowing you to not get wrinkles in the project. You can get all the mat and resin from uscomposites.com......and I highly recomment 1.5 oz fiberglass mat...and the premium polyester resin.
when that is all set up...you need to cover everything with the duraglass or Bondo (this is just a paste that, once catalized, hardens like rock........then sand..sand...sand...and re-fill as needed.
Finally cut out the circle that your speaker will actually go it...and remove the 2x4 that was used to support it.
Some people actually like to also do a "bondo milkshake" inside the box...which is a mixture of resin and bondo. You drill a hole in the enclosure and pour in the milkshake...and roll it around inside the box....this gives you a little more thickness...and seals the corners of the enclosure.
Here is a link to my website...that has a few pix of the build process of a fiberglass enclosure
Then you take the ring and suspend it over the back of the enclosure (could be out of MDF or more fiberglass)....with a piece of 2x4.
Wrap the fleece over the enclosure...and either staple or spray glue it to the back of the enclosure. It has to be AS TIGHT AS POSSIBLE.....or you will get sags...
Once it is all wrapped....apply fiberglass resin to the fleece...and wait for that to harden. Be sure to not get resin on the part that you glues...because the resin will make the glue release...and you project is pretty much ruined.
When that is hard...then apply fiberglass MAT. I really prefer mat because the resin actually melts it a bit....allowing you to not get wrinkles in the project. You can get all the mat and resin from uscomposites.com......and I highly recomment 1.5 oz fiberglass mat...and the premium polyester resin.
when that is all set up...you need to cover everything with the duraglass or Bondo (this is just a paste that, once catalized, hardens like rock........then sand..sand...sand...and re-fill as needed.
Finally cut out the circle that your speaker will actually go it...and remove the 2x4 that was used to support it.
Some people actually like to also do a "bondo milkshake" inside the box...which is a mixture of resin and bondo. You drill a hole in the enclosure and pour in the milkshake...and roll it around inside the box....this gives you a little more thickness...and seals the corners of the enclosure.
Here is a link to my website...that has a few pix of the build process of a fiberglass enclosure
An externally hosted image should be here but it was not working when we last tested it.
bbksv said:
I am surprized that you are only using 1.5 oz mat. This is typical of what a sundeck gets done with. I would have thought you would need a layer of roving first and then a 1 or 2 oz over that to smooth it a bit and achieve the desired stiffness.
Also while you're at it, wouldn't the epoxy resin be better suited for the application? Much more expensive but a much stronger resin as well.
Cal
Epoxy resin doesnt melt the mat like polyester....and you HAVE to melt the mat when doing very curved surfaces like this....or you will have wrinkels...which will be hard to fix. Another alternative to polyester....is vinyl ester...which is almost as strong as epoxy...but easier to work with. As for the 1.5 oz mat....you will have to use multiple layers. It is harder to laminate heavier mat to a surface....but then again...there is always more then one way to skin a cat
None of this is set in stone....this is just how I have made over 200 boxes.....so it is a pretty proven method.....not saying there isnt a better way to do it though.....best thing is to get out there and experiment...
None of this is set in stone....this is just how I have made over 200 boxes.....so it is a pretty proven method.....not saying there isnt a better way to do it though.....best thing is to get out there and experiment...
Excellent insight. 200 boxes tells me are doing well. My experience with multi- layered composites is with heavier stuff, done with molds
I realize now you couldn't use roving, it would be to much to work with. You are using non- woven (random strand) matting?
Is it glass mat or polyester mat, because I'm not sure I follow you on the "melting" part.
The idea of stretching the cloth and putting a little resin on it to stiffen sure does make sense for your substrate.
And what a great looking finished box!
Cheers
Cal
I realize now you couldn't use roving, it would be to much to work with. You are using non- woven (random strand) matting?
Is it glass mat or polyester mat, because I'm not sure I follow you on the "melting" part.
The idea of stretching the cloth and putting a little resin on it to stiffen sure does make sense for your substrate.
And what a great looking finished box!
Cheers
Cal
Ive never heard of a difference between polyester and glass mat...but here is basically what I meant by "melting"
When you use cloth (roving)....then if you have an air pocket...or a wrinkle in the cloth....then it is very hard to work out....where with mat....you just get it nice and wet with resin...and give it a few min to work...and wrinkles or air pockets can very easily be worked out.
The thing to remember is resin in itself is very brittle...so just the mold material is very weak structuraly....so you have to re-enforce that with some sory of glass. Now...I ocasionally use a light weight roving...but it has to be the very flexable stuff..and you have to be carefull not to overlap the stuff because that will give you high spots.
When you use cloth (roving)....then if you have an air pocket...or a wrinkle in the cloth....then it is very hard to work out....where with mat....you just get it nice and wet with resin...and give it a few min to work...and wrinkles or air pockets can very easily be worked out.
The thing to remember is resin in itself is very brittle...so just the mold material is very weak structuraly....so you have to re-enforce that with some sory of glass. Now...I ocasionally use a light weight roving...but it has to be the very flexable stuff..and you have to be carefull not to overlap the stuff because that will give you high spots.
bbksv said:
Polyester mat is made from polyester. Often used in built-up roofing in combination with asphalt. Might actually melt if used with poly resin?
Fiberglass mat is made from silica. Standard fiberglass non-woven mat.
[/B][/QUOTE]When you use cloth (roving)....then if you have an air pocket...or a wrinkle in the cloth....then it is very hard to work out....where with mat....you just get it nice and wet with resin...and give it a few min to work...and wrinkles or air pockets can very easily be worked out. [/B][/QUOTE]
I agree
I call that "working out the bubbles"
[/B][/QUOTE]The thing to remember is resin in itself is very brittle...so just the mold material is very weak structuraly....so you have to re-enforce that with some sory of glass. Now...I ocasionally use a light weight roving...but it has to be the very flexable stuff..and you have to be carefull not to overlap the stuff because that will give you high spots. [/B][/QUOTE]
Now I see some of the differences in our experience. In a mold, you put down the gel coat first to create your finished surface and layer in from there. I wouldn't have to worry about slight uneveness, because that's on the inside. You on the other hand have to layer and then finish that side. You must be a very patient person. I think that would drive me batty. I admire your diligence.
The roving I have used is about 20 oz. and not suited for compound curves.
Cheers
Cal
I don't think there will be any resonance of the fibreglass to worry about, because there is a big mdf wall right behind it, protecting it from any pressure changes. This is what Raami found (see link on page 1).
And oh yeah, if you do this "bondo milkshake," how much would you put inside your average subwoofer enclosure? Do you want it to coat the walls as well, or just the junctions?
Talk to you later,
Philip
And oh yeah, if you do this "bondo milkshake," how much would you put inside your average subwoofer enclosure? Do you want it to coat the walls as well, or just the junctions?
Talk to you later,
Philip
An alternative to a chopped strand mat would be a harness-satin (or crow's feet) weave. More continuous fibers, thus higher stiffness, than chopped strand mats but still very flexible and suitable for compound curves of fairly small radius (at least in the lightweight varieties... a few osy or so).
I'd recommend a mixture of resin and microballoon to speed the exterior filling and finishing process. Better than bondo IMO when working with a composite structure of the same resin chemistry. Tends to be more durable as the secondary bond between the resins is very strong relative to dissimilar materials like high-build primers or bondo. Save the primers for the last step or two in the finishing process.
I'd recommend a mixture of resin and microballoon to speed the exterior filling and finishing process. Better than bondo IMO when working with a composite structure of the same resin chemistry. Tends to be more durable as the secondary bond between the resins is very strong relative to dissimilar materials like high-build primers or bondo. Save the primers for the last step or two in the finishing process.
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