Hey Cal,
I just read about alot of people going nuts with recurring glue lines, grain swell etc. This is all about solvents becoming entrapped in the wood and swelling things up. Paint dries bpth ways, to the air, and into the wood. It takes weeks for the entrapped solvents to escape.
When we were young punks... the talk on the street was that you let your new laquer paint job dry for a month or two before sanding and polishing. With the new low solvent paints (epoxy has zero solvent) and catalytic formulas (part A / part B). You can wait 4 hours and get the same result.
Mind you, I'm NOT advocating FINISHING with epoxy. It's no fun to sand. Rather just using it as a non swelling glue; PVA is the pits for swelling; and epoxy is a nearly solvent proof sealer for your wood. It puts all the shrink-swell problems to an end. AND... you can still go for real wood grain with it; one coat and then use your favorite urethanes (the new stuff is quite clear).
I can tell you where to buy it for $80/ gallon (minus the Canadian factor) and this type doesn't have that amine-blush (that WEST SYSTEMS EPOXY still maintains is more fun). Try it ONE time... you won't go back.
BTW, I did your mussels... NAILED the sauce the first time as your decription of it all was flawless... EXCELLENT!
I just read about alot of people going nuts with recurring glue lines, grain swell etc. This is all about solvents becoming entrapped in the wood and swelling things up. Paint dries bpth ways, to the air, and into the wood. It takes weeks for the entrapped solvents to escape.
When we were young punks... the talk on the street was that you let your new laquer paint job dry for a month or two before sanding and polishing. With the new low solvent paints (epoxy has zero solvent) and catalytic formulas (part A / part B). You can wait 4 hours and get the same result.
Mind you, I'm NOT advocating FINISHING with epoxy. It's no fun to sand. Rather just using it as a non swelling glue; PVA is the pits for swelling; and epoxy is a nearly solvent proof sealer for your wood. It puts all the shrink-swell problems to an end. AND... you can still go for real wood grain with it; one coat and then use your favorite urethanes (the new stuff is quite clear).
I can tell you where to buy it for $80/ gallon (minus the Canadian factor) and this type doesn't have that amine-blush (that WEST SYSTEMS EPOXY still maintains is more fun). Try it ONE time... you won't go back.
BTW, I did your mussels... NAILED the sauce the first time as your decription of it all was flawless... EXCELLENT!
I'm really hoping the edges don't telegraph through but we'll see as I am getting impatient and starting to rush things. I really hope that all the painting and sanding pays off. As of this morning, the texture coats look good, no edges to be seen but it takes a bit to dry so we'll see. After I get them reassembled, I'll run them for a day or two before tweeking the XO.
With the grilles on, Sonia thinks they look like little aliens. Aliens? oh well it's better than some of the other names she calls my speakers when I'm out in the shop ignoring her in the house.
Great to hear about the mussels. That sauce is important and it sounds like you got it right. Mmmm...
With the grilles on, Sonia thinks they look like little aliens. Aliens? oh well it's better than some of the other names she calls my speakers when I'm out in the shop ignoring her in the house.
Great to hear about the mussels. That sauce is important and it sounds like you got it right. Mmmm...
Banned
Joined 2002
Absolutely.
Additionally, sanding is a form of forced erosion. Softer material will be removed at a faster rate than harder, pulp wood more quickly than epoxy, glue line in ply, or endgrain. This is part of the reason our best efforts to fill ply endgrain are subverted by our following effort to sand it smooth. Solvent swelling bites us later with shrinkage.
I restored an oak lam tabletop that had been sitting outside for years by filling all the splits and viods with epoxy. The following sanding was digging into the wood around the epoxy at a faster rate than the epoxy was removed. Switching to planes and scrapers was the answer there, but these aren't useful on most shaped objects.
The trick seems to be creating a smooth layer of like material to lay the finish onto, much like the primercoat in auto finishing. Bondo and epoxy seem like naturals here. Bondo is engineered to adhere, sand and form, epoxy is clear and allows a clear coat finish but doesn't always stay where you want it. I'm still going to try paper with lots of binder... but I'm a luddite by nature.
Poobah, can you tell us more about this crystal clear epoxy? I've worked with west systems before and your right, the only knock is clarity.
Cal, if your close enough to see the grain in that lovely finish, your not hearing it in stereo...
Oh Andy, I agree. I wouldn't have begun this project if a gloss was in order. I knew the cover-up would be the only way. I think on the next one I will use a cover piece of wood with a ployester resin and talc mixture for any filling I do.
I will assmble today and get them broken in ASAP.
Will keep you updated.
I will assmble today and get them broken in ASAP.
Will keep you updated.
ToE,
No problem re the Epoxy and where I get it.
Re the rates of sanding and teletgraphing lines etc... Generally when this happens, 3 things are at play:
1) You are using a rubber sanding block or a block with a pad. This encourages the block to dig deeper into softer materials (I like your scraper technique by the way... they used to be called burnishers and were the tool of choice before sandpaper existed). Unless you are sanding compound curves... rubber sanding blocks are EVIL. Always use the hardest, flatest thing you can find.
2) You are sanding too much with one grit and not moving up to the next finest soon enough. OR, you are sanding with a fine grit for too long in the first place. I'll leave it you to get feel for this and the logic behind it as I have not expressed it well enough (don't quite know how).
3) You are using dull sandpaper... you are scrubbbing the wood rather than cutting it. I owned a auto restoration shop for many years... as many times as I tried lessor priced sandpaper, it never worked out costwise. 3M or Norton period... FORGET the rest. Use fresh paper... sand only enough to remove the scratches from the previous grit... and move on.
You will find the Epoxies I'm talking about here
Now... the "thin" is what you would use for sealing. "Thin" could be used used for pre-wetting joints in thirsty wood while following with "thick" for the actual gluing.
Be mindfull in selecting the hardeners. Some hardeners "blush", meaning they leave a nasty coating of some "amine" junk on the surface you have to scrub off... sucks... avoid it.
You can put new epoxy over tacky epoxy... but you have have to sand "dry" epoxy before you can recoat it. So, think before you start throwing glue all over the place.
For joints... just use little brushes. For sealing... most people use a very short nap roller and then "tip" with a brush. Hell... I use hard plastic squeegies.
This stuff is not perfectly clear but neither is varnish... urethane... whatever. You will only use on coat to seal anyway.
Say goodbye to shrinking, swelling, and other stuff that upsets you... a bit more work & money up-front... lot less work and "even" money in the long haul.
Edit: The people at U.S. composites are nice folks and have aggressive pricing. Well packed shipments and good phonework.
No problem re the Epoxy and where I get it.
Re the rates of sanding and teletgraphing lines etc... Generally when this happens, 3 things are at play:
1) You are using a rubber sanding block or a block with a pad. This encourages the block to dig deeper into softer materials (I like your scraper technique by the way... they used to be called burnishers and were the tool of choice before sandpaper existed). Unless you are sanding compound curves... rubber sanding blocks are EVIL. Always use the hardest, flatest thing you can find.
2) You are sanding too much with one grit and not moving up to the next finest soon enough. OR, you are sanding with a fine grit for too long in the first place. I'll leave it you to get feel for this and the logic behind it as I have not expressed it well enough (don't quite know how).
3) You are using dull sandpaper... you are scrubbbing the wood rather than cutting it. I owned a auto restoration shop for many years... as many times as I tried lessor priced sandpaper, it never worked out costwise. 3M or Norton period... FORGET the rest. Use fresh paper... sand only enough to remove the scratches from the previous grit... and move on.
You will find the Epoxies I'm talking about here
Now... the "thin" is what you would use for sealing. "Thin" could be used used for pre-wetting joints in thirsty wood while following with "thick" for the actual gluing.
Be mindfull in selecting the hardeners. Some hardeners "blush", meaning they leave a nasty coating of some "amine" junk on the surface you have to scrub off... sucks... avoid it.
You can put new epoxy over tacky epoxy... but you have have to sand "dry" epoxy before you can recoat it. So, think before you start throwing glue all over the place.
For joints... just use little brushes. For sealing... most people use a very short nap roller and then "tip" with a brush. Hell... I use hard plastic squeegies.
This stuff is not perfectly clear but neither is varnish... urethane... whatever. You will only use on coat to seal anyway.
Say goodbye to shrinking, swelling, and other stuff that upsets you... a bit more work & money up-front... lot less work and "even" money in the long haul.
Edit: The people at U.S. composites are nice folks and have aggressive pricing. Well packed shipments and good phonework.
This is the product I used on my latest project.
http://www.letsdoit.com.au/?e=24&p=primer
"MDF primer" - water based, drys in 2 hours, sands well, and 1 coat was all that was needed. It's great stuff. ''
http://www.letsdoit.com.au/?e=24&p=primer
"MDF primer" - water based, drys in 2 hours, sands well, and 1 coat was all that was needed. It's great stuff. '
'Thank you Poobah,
Yes, mastering sandpaper is an art, and I am no master.
I am working up the nerve to build some single driver speakers and epoxy would be crucial to my half baked scheme.
Besides, it would do me good to get away from my recent finish of choice. Rubbermaid shelf paper. Self stick, fast, looks great. Comes in polka dots too...
Yes, mastering sandpaper is an art, and I am no master.
I am working up the nerve to build some single driver speakers and epoxy would be crucial to my half baked scheme.
Besides, it would do me good to get away from my recent finish of choice. Rubbermaid shelf paper. Self stick, fast, looks great. Comes in polka dots too...
Very cool design and good work on the build Cal!
Poobah, I was wondering if you could give a little clarification on your use of resin. So you use it in place of wood glue for joining? And then you also can use it when the design is done to seel the wood and provide a clear coat?
I'm thinking of doing an MDF/fibreflass composite baffle when I build my next set of speakers to explore different building techniques. The fibreglass portion will be used where there are complex curves. Being able to use the same resin for the fibreglass layup as well as sealing and joining would simplify things greatly. Are there any good existing threads about building speakers using resin as a joiner and sealant? If not, have you thought about writing one Poobah? (maybe petition to make it a sticky??)
-Scott
Poobah, I was wondering if you could give a little clarification on your use of resin. So you use it in place of wood glue for joining? And then you also can use it when the design is done to seel the wood and provide a clear coat?
I'm thinking of doing an MDF/fibreflass composite baffle when I build my next set of speakers to explore different building techniques. The fibreglass portion will be used where there are complex curves. Being able to use the same resin for the fibreglass layup as well as sealing and joining would simplify things greatly. Are there any good existing threads about building speakers using resin as a joiner and sealant? If not, have you thought about writing one Poobah? (maybe petition to make it a sticky??)
-Scott
adolphe,
I am using epoxy right now to build a boat. Epoxy doesn't like sunlight at all... almost its only enemy. But I am only using the epoxy and a glue and a sealer. It is then covered with marine urethane... and even the clear stuff blocks the UV from the sun.
As far as a thread is concerned... dunno. People are pretty adamant around here about their PVA. The'll be buried in coffins made with it... I only harp on epoxy because it solves so many problems for fanatics trying get mirror finishes etc...
Yes, epoxy will work very well for an MDF/glass composite. You can use polystyrene foam to carve your molds.
I have done lots of epoxy/woodwork/composite stuff. Happy to help you with any specific questions.
West Marine or West System Epoxy has an excellent tutorial on their site. I don't use their stuff because of amine blush and cost, but still a good read.
P.S. If you're thinking about an epoxy project... start saving your cottage cheese and sour cream tubs now!
I am using epoxy right now to build a boat. Epoxy doesn't like sunlight at all... almost its only enemy. But I am only using the epoxy and a glue and a sealer. It is then covered with marine urethane... and even the clear stuff blocks the UV from the sun.
As far as a thread is concerned... dunno. People are pretty adamant around here about their PVA. The'll be buried in coffins made with it... I only harp on epoxy because it solves so many problems for fanatics trying get mirror finishes etc...
Yes, epoxy will work very well for an MDF/glass composite. You can use polystyrene foam to carve your molds.
I have done lots of epoxy/woodwork/composite stuff. Happy to help you with any specific questions.
West Marine or West System Epoxy has an excellent tutorial on their site. I don't use their stuff because of amine blush and cost, but still a good read.
P.S. If you're thinking about an epoxy project... start saving your cottage cheese and sour cream tubs now!
Thanks for the info poobah. My main reason for suggesting a thread on it is to help promote the creation and exploration of new ideas.
I'm in the early early design stages of my design. Researching different baffle materials at the moment. Once I get to a point of coming up with a few different design ideas, I'll likely start a thread on it to dicuss building techniques. Often times my ideas are too complex for someone like me to build (limited skill and tools at the moment).
I'm in the early early design stages of my design. Researching different baffle materials at the moment. Once I get to a point of coming up with a few different design ideas, I'll likely start a thread on it to dicuss building techniques. Often times my ideas are too complex for someone like me to build (limited skill and tools at the moment).
adolphe,
Thanks for the compliment.
Well, nothing telegraphing through yet but it's only two days on the texture coat so I'll keep the fingers crossed.
A very valuable lesson was re-learned on these things. The higher the frequency, the harder it is to integrate multiple drivers. There was nothing I could do to get rid of that "fuzzy, sort of blurry, mixed up, multiple drivers kind of sound"
Until I threw a big ol' choke on one of the woofers and voila, nasty sounds gone away. So unless something really changes over the next little while, these will forever be a 2.5 way. Just couldn't do anything else.
Thanks for the compliment.
Well, nothing telegraphing through yet but it's only two days on the texture coat so I'll keep the fingers crossed.
A very valuable lesson was re-learned on these things. The higher the frequency, the harder it is to integrate multiple drivers. There was nothing I could do to get rid of that "fuzzy, sort of blurry, mixed up, multiple drivers kind of sound"
Until I threw a big ol' choke on one of the woofers and voila, nasty sounds gone away. So unless something really changes over the next little while, these will forever be a 2.5 way. Just couldn't do anything else.
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