One method I have seen to produce these types of shapes for speaker use is instead of layering the MDF from the inside out, you layer it from bottom to top.
Essentially you build your self a router or jigsaw template and cut a number of identical rings out of 18mm MDF. You then stack these rings on top of one another, glue and clamp and voila a speaker of just about any shape you could imagine. Innner and outer profiles can be different from one another and you can make the sides as thick as you want. In your case you could then apply the lead on top and then a final layer to protect it ( or you could get really fancy and cut two seperate ring profiles one designed to fit inside the other with a small space in between for the lead).
I know there is a project on the web that uses this technique, but I don't have the link handy.
Essentially you build your self a router or jigsaw template and cut a number of identical rings out of 18mm MDF. You then stack these rings on top of one another, glue and clamp and voila a speaker of just about any shape you could imagine. Innner and outer profiles can be different from one another and you can make the sides as thick as you want. In your case you could then apply the lead on top and then a final layer to protect it ( or you could get really fancy and cut two seperate ring profiles one designed to fit inside the other with a small space in between for the lead).
I know there is a project on the web that uses this technique, but I don't have the link handy.
from an earlier post....
"well there are 2 ways from the way I see it.
1. use 4mm MDF and use multiple layers (6 in my case). I would then bond 5 layers to make 20mm MDF then add the lead (3mm) and then add the last layer.
2. use 18 or 25mm MDF but break it into vertical strips and use toungue and grove joints. This way the sides will be made of many vertical strips (maybe as many as 6) then cover the strips with lead sheet (3mm, cover that with 4mm MDF and lastly cover that with veneer. I am using teh 4mm MDF as a shield so my son (born April 4th 2002) accidently does not get his hands on the lead as he begins to crawl"
I considered this but the tongue and groove joints were proving diffcult in MDF. What is easy in Ply is not so easy in MDF.
Regards
Navin
"well there are 2 ways from the way I see it.
1. use 4mm MDF and use multiple layers (6 in my case). I would then bond 5 layers to make 20mm MDF then add the lead (3mm) and then add the last layer.
2. use 18 or 25mm MDF but break it into vertical strips and use toungue and grove joints. This way the sides will be made of many vertical strips (maybe as many as 6) then cover the strips with lead sheet (3mm, cover that with 4mm MDF and lastly cover that with veneer. I am using teh 4mm MDF as a shield so my son (born April 4th 2002) accidently does not get his hands on the lead as he begins to crawl"
I considered this but the tongue and groove joints were proving diffcult in MDF. What is easy in Ply is not so easy in MDF.
Regards
Navin
laminating -- remember Swans and epoxies?
I think that in one of the 1984 issues of Speaker Builder there was a two part series on the Swans which used a pair of 12" Peerless woofers -- they used West http://www.westsystem.com/ epoxy resin with micro-baloons as the adhesive to lay up a couple veneers. I built the speakers and my one son is now the proud possesor!
The advantage which I can see with an epoxy is that it will not cause the wood to swell (as the water is absorbed into the wood fiber they swell, and contract when the evaporation is done -- important if you are laminating.) It is one heck a lot more expensive than using PVAC glues.
Epoxy resins can be bought by the gallon at good auto-supply houses, but check the above link for a variety of formulations and distributors. You really have to protect your eyes (and other vital parts). Btw, we have a company here in NJ which makes epoxy resins which are used to retrofit carbon fiber panels on the bottoms of F14's -- for the expense of a couple hundred k$ you get a new fighter aircraft.
I think that in one of the 1984 issues of Speaker Builder there was a two part series on the Swans which used a pair of 12" Peerless woofers -- they used West http://www.westsystem.com/ epoxy resin with micro-baloons as the adhesive to lay up a couple veneers. I built the speakers and my one son is now the proud possesor!
The advantage which I can see with an epoxy is that it will not cause the wood to swell (as the water is absorbed into the wood fiber they swell, and contract when the evaporation is done -- important if you are laminating.) It is one heck a lot more expensive than using PVAC glues.
Epoxy resins can be bought by the gallon at good auto-supply houses, but check the above link for a variety of formulations and distributors. You really have to protect your eyes (and other vital parts). Btw, we have a company here in NJ which makes epoxy resins which are used to retrofit carbon fiber panels on the bottoms of F14's -- for the expense of a couple hundred k$ you get a new fighter aircraft.
One other solution would be to do it like the real thing (Sonus Faber). They build it out of maple boards and I believe that material has something to do with the sound of the speakers. You could use maple plank they use for hardwood flooring. It comes in 3/4" thicknes and different widths (3" would be probably still easy to bend). You would have to soak the boards and then bend them on some kind of frame to required shape (that's what Sonus Faber is doing I guess). The boards are tongue and groove so putting them together is not a problem. You might even use 4mm MDF as a base or for even better result put another layer of boards over the first one. In my understanding that would make the ultimate walls for the speaker.
I don't think you'll find maple in Nevin's country
the maple sold down here for flooring (tongue and groove) is about 3/8" -- if you ever see an old house being torn down, grab the flooring! (you might just as well grab whatever other woods are in good shape from old houses -- like hardwood moldings. further, pine was used instead of fir in a lot of applications and you just won't find pine with the density in today's lumber-yards.) Down here in the states, at least in NJ, people gut houses entirely, right to the studs -- if you can believe it, they knock out the plaster walls and replace them with gypsum sheetrock.
many US public libraries have collections of "Fine Woodworking" and the publisher, Taunton Press, has a big series of books on applications, i.e. steam bending, as discussed in this thread.
the maple sold down here for flooring (tongue and groove) is about 3/8" -- if you ever see an old house being torn down, grab the flooring! (you might just as well grab whatever other woods are in good shape from old houses -- like hardwood moldings. further, pine was used instead of fir in a lot of applications and you just won't find pine with the density in today's lumber-yards.) Down here in the states, at least in NJ, people gut houses entirely, right to the studs -- if you can believe it, they knock out the plaster walls and replace them with gypsum sheetrock.
many US public libraries have collections of "Fine Woodworking" and the publisher, Taunton Press, has a big series of books on applications, i.e. steam bending, as discussed in this thread.
Andy_G
My parents recently built a house in Hobart, Tasmania. The floor was done using 3/4" flooring chipboard with 1/2" tongue and groove Tassie Oak overlay, with concealed nailing.
This is the source of the timber I used on the side of the vifa 3-way pyramid.
My parents recently built a house in Hobart, Tasmania. The floor was done using 3/4" flooring chipboard with 1/2" tongue and groove Tassie Oak overlay, with concealed nailing.
This is the source of the timber I used on the side of the vifa 3-way pyramid.
An externally hosted image should be here but it was not working when we last tested it.
1. I live in India. we make houses of brick and mortar not wood. That kills goes the above option.
2. i still have 2 choices. 25mm or 30mm MDF or solid wood slats in tongue and groove configuration or layers of 4mm.
dazed and confused - we got 3 threads on one speaker (4 if u count the one on the series crossover)! other threads are "how to make a dead cabinet" and "lots of questions". It makes some sense to read all 3 just so that we are all on the same page.
I hope I am not hogging the forum! Please Mr. Moderator dont beat me up. Besides I am in India; a long way off for any Moderator to find me
*EWG*
regards
navin
2. i still have 2 choices. 25mm or 30mm MDF or solid wood slats in tongue and groove configuration or layers of 4mm.
dazed and confused - we got 3 threads on one speaker (4 if u count the one on the series crossover)! other threads are "how to make a dead cabinet" and "lots of questions". It makes some sense to read all 3 just so that we are all on the same page.
I hope I am not hogging the forum! Please Mr. Moderator dont beat me up. Besides I am in India; a long way off for any Moderator to find me
*EWG*regards
navin
Hello all,
One solution to bending wood I didn't come across while reading the posts in this forum is using a special type of plywood wich lends itself to bending, but in one direction only. The stuff is kind of wobbly so you probably need to brace and/or use a sandwich construction with sand in the middle. Thickness is about 6mm.
Not sure about the acoustical properties of this stuff, I think I would use the "stack and sand" method instead. Stack a very large number of cross sections on top of eachother so you can make any shape you would like.
Greetings,
Jarno.
One solution to bending wood I didn't come across while reading the posts in this forum is using a special type of plywood wich lends itself to bending, but in one direction only. The stuff is kind of wobbly so you probably need to brace and/or use a sandwich construction with sand in the middle. Thickness is about 6mm.
Not sure about the acoustical properties of this stuff, I think I would use the "stack and sand" method instead. Stack a very large number of cross sections on top of eachother so you can make any shape you would like.
Greetings,
Jarno.
"bending" s/wood
Hi
Better late than never. My carpenter did it differently. Try starting with thicker s/wood and glue it together as per the rounded sections of the hedlund horns. The excess can be machined away until a round section is obtained that is the same thickness as the rest of your project. Not necessarily better than laminating but easier if you can figure out the machining bit.
Inside curves are machined prior to glueing and outside curves are planed by hand after glueing.
Good Luck
Sergio
Hi
Better late than never. My carpenter did it differently. Try starting with thicker s/wood and glue it together as per the rounded sections of the hedlund horns. The excess can be machined away until a round section is obtained that is the same thickness as the rest of your project. Not necessarily better than laminating but easier if you can figure out the machining bit.
Inside curves are machined prior to glueing and outside curves are planed by hand after glueing.
Good Luck
Sergio
Bending solid wood
If you are trying to bend solid wood, the only sensible way to do it is to steam the wood before hand.
When the wood is heated in steam, various chemical bonds in the wood's structure are released, and that allows the wood to become more flexible abd be bent. Once the wood cools, the chemical bonds reinstate and the wood becomes strong and set in the new position, ( just think of bentwood chairs).
If you do not heat the wood, but just moisten it, some of these bonds break, and some stretch,and this leads to a tendency for the wood to split over time.
A homemade steamer is easily built using some plastic drainage pipe and a wallpaper steam stripper, for 3/4 inch timber, you probably want to leave it in there for an hour or so, but this will depend on the porosity of the wood grain, so is open to experiment. If you can mechanically dry the wood after it is bent, so much the better.
If you are trying to bend solid wood, the only sensible way to do it is to steam the wood before hand.
When the wood is heated in steam, various chemical bonds in the wood's structure are released, and that allows the wood to become more flexible abd be bent. Once the wood cools, the chemical bonds reinstate and the wood becomes strong and set in the new position, ( just think of bentwood chairs).
If you do not heat the wood, but just moisten it, some of these bonds break, and some stretch,and this leads to a tendency for the wood to split over time.
A homemade steamer is easily built using some plastic drainage pipe and a wallpaper steam stripper, for 3/4 inch timber, you probably want to leave it in there for an hour or so, but this will depend on the porosity of the wood grain, so is open to experiment. If you can mechanically dry the wood after it is bent, so much the better.
good idea
Hi,
I found a Homepage that might help you. I will try it myself to bend the wood this way, I thinks it´s the easiest way to do it!
http://home.tiscali.de/whoeffchen/Lautsprecher/Nautlantis.html
Greetings form Berlin, Jonas
Hi,
I found a Homepage that might help you. I will try it myself to bend the wood this way, I thinks it´s the easiest way to do it!
http://home.tiscali.de/whoeffchen/Lautsprecher/Nautlantis.html
Greetings form Berlin, Jonas
I'm sorry, I haven't been around for a while but I'm a woodworker and I do make handmade loudspeakers for a living, so here is my suggestion.
1. Use a 4mm MDF board curved to the correct shape.
2. Cut out 12mm MDF strips 18mm to 24mm wide and sand them untill they fit perfectly with eachother (not nessecearly to the curved board).
3. Glue two of these strips onto the curved board one to each end, and let dry. Remove excess glue.
4. Glue the rest of the strips in place with non-hardening glue or tar.
5. Immediately attach another 4mm board only glueing the ends and using tar or non-hardening glue in the middle curving that in the process.
6. Secure with screws in the pieces only.
Result:
The 'deadest' cabinet you will ever get.
1. Use a 4mm MDF board curved to the correct shape.
2. Cut out 12mm MDF strips 18mm to 24mm wide and sand them untill they fit perfectly with eachother (not nessecearly to the curved board).
3. Glue two of these strips onto the curved board one to each end, and let dry. Remove excess glue.
4. Glue the rest of the strips in place with non-hardening glue or tar.
5. Immediately attach another 4mm board only glueing the ends and using tar or non-hardening glue in the middle curving that in the process.
6. Secure with screws in the pieces only.
Result:
The 'deadest' cabinet you will ever get.
If your going to bend wood you should build a gluing or bending jig at around 15 percent tighter radius (or radi?) than the finished speaker has. Bending and gluing to the bracing keeps the wood under pressure permanantly and which gradually decreases over the years. Once the glue has set on your sides bent in the jig the relaxed side will have much the same properties as flat MDF and be much more predictable sonically. If you use solid wood like maple you'll have to steam it. The drainage pipe method works great and you can get screwon end caps for it. You can also use a new steel gas can and LPG burner. Use the filler fitting for the steam supply hose and you can add water through the back breather using a funnel. I have used it very effectively. Norm Abram had a great episode about this.
Kelly MacDonald's recommended method is very versatile and has several advantages absent with bent wood designs... 1. the shape of the interior doesn't have to match the exterior. You can make it any way you want, like peaks to disrupt standing waves or behind the woofers to break up back wall reflections. and 2. unless your really, really good at making laminations, you usually have to have two flat walls. You are not limited to that with the stacked method.
Kelly MacDonald's recommended method is very versatile and has several advantages absent with bent wood designs... 1. the shape of the interior doesn't have to match the exterior. You can make it any way you want, like peaks to disrupt standing waves or behind the woofers to break up back wall reflections. and 2. unless your really, really good at making laminations, you usually have to have two flat walls. You are not limited to that with the stacked method.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.