Faustian:
I can't speak for Kneadle, but my understanding is that the pipe is 6" outside diameter.
The length of the Line is supposed to be 66", but he wants it to end in a tee where the woofer mounts beautifully. Therefore,the length of line is to be 58". This is measured from the middle of the pipe, since the outside of the spiral and the inside will be two different lengths. The length and circular area of the Line were all worked by Martin J Kings' (DIYAudio member MJK), Transmission Line program.
Kneadle said he wants the base part of the enclosure, but has allowed for the possibility of a mount. I myself am thinking of submitting two plans, one for having the base flat on the floor, one for having the Line entirely spiral. I think the latter would be visually better. But it's his choice.
He wants the Line to be 58" into the Tee, all 6" pipe. To function correctly, the Line must have a free open aperture. If you can figure out some way to deliver a freely open end, but attach more pipe to lengthen the spiral that would be separate from the Line but not inhibit the Line end breathing in any way, maybe that is a possibility.
This is Kneadle's project. I don't want to be presumptuous, but I thought I would just give you the answers as I understand them so far. You seemed rather eager to get going, so I thought this might help.
I can't speak for Kneadle, but my understanding is that the pipe is 6" outside diameter.
The length of the Line is supposed to be 66", but he wants it to end in a tee where the woofer mounts beautifully. Therefore,the length of line is to be 58". This is measured from the middle of the pipe, since the outside of the spiral and the inside will be two different lengths. The length and circular area of the Line were all worked by Martin J Kings' (DIYAudio member MJK), Transmission Line program.
Kneadle said he wants the base part of the enclosure, but has allowed for the possibility of a mount. I myself am thinking of submitting two plans, one for having the base flat on the floor, one for having the Line entirely spiral. I think the latter would be visually better. But it's his choice.
He wants the Line to be 58" into the Tee, all 6" pipe. To function correctly, the Line must have a free open aperture. If you can figure out some way to deliver a freely open end, but attach more pipe to lengthen the spiral that would be separate from the Line but not inhibit the Line end breathing in any way, maybe that is a possibility.
This is Kneadle's project. I don't want to be presumptuous, but I thought I would just give you the answers as I understand them so far. You seemed rather eager to get going, so I thought this might help.
Kelticwizard!
You missed an important post (man did this thing go fast)!
Check page three where I answered some things you asked in detail. There's 2 important variations we have to decide on, and there I changed the final length to 60".
BTW, this is hardly my project, anymore, and happily so. I'm eternally grateful for the help you're providing thus far. Don't feel like you're presuming.
Let's do the spiral method, and I'll devise a mount.
Dave
PS--the post is the one titled "OK, Let's build this baby."
You missed an important post (man did this thing go fast)!
Check page three where I answered some things you asked in detail. There's 2 important variations we have to decide on, and there I changed the final length to 60".
BTW, this is hardly my project, anymore, and happily so. I'm eternally grateful for the help you're providing thus far. Don't feel like you're presuming.
Let's do the spiral method, and I'll devise a mount.
Dave
PS--the post is the one titled "OK, Let's build this baby."
Okay, from Post #36:
"1) The first 180 degree turn (from bottom up) will be a true half circle, in order to provide a solid base.
2) The next 360 degree turn will be a full circle, but spiraling up from the half circle. Let's leave a 6" space between the outer diameter, a slow spiral upward, not very tight at all. "
From later posts, I take it that we have abandoned the half circle on floor concept and adopted the idea that the whole Line will be in the spiral? Personally, I was thinking that the last segment would be flat on the floor, so the mounts can hold up two or three other segments of the structure. Is that ok?
Since the structure will have 14 segments-I think-and we are building an octagon, that means that we will have almost two full turns on the spiral, which I think will be very nice to look at. Have I got this right?
Also, I take it that you want at least 6" of free air between the two "loops" on the spiral. Correct?
"1) The first 180 degree turn (from bottom up) will be a true half circle, in order to provide a solid base.
2) The next 360 degree turn will be a full circle, but spiraling up from the half circle. Let's leave a 6" space between the outer diameter, a slow spiral upward, not very tight at all. "
From later posts, I take it that we have abandoned the half circle on floor concept and adopted the idea that the whole Line will be in the spiral? Personally, I was thinking that the last segment would be flat on the floor, so the mounts can hold up two or three other segments of the structure. Is that ok?
Since the structure will have 14 segments-I think-and we are building an octagon, that means that we will have almost two full turns on the spiral, which I think will be very nice to look at. Have I got this right?
Also, I take it that you want at least 6" of free air between the two "loops" on the spiral. Correct?
post 36, yes. Did you know you can copy and paste the shortcut right to it? The internet is going to catch on.
The way you have described it seems very reasonable, and properly mounted, will be very beautiful.
Did you catch the 2" discrepancy? I'm thinking that I should fire the driver straight down the pipe. If so, the pipe length has to be 60" (12"-6"=6"). If not, i.e., if I fire it from the side hole, then the pipe length will be 2" shorter. Wait. Nevermind. I'll simply seal the pipe at the 3" mark, where the speaker would mount.
I think straight firing is the way to do it, and I think the pipe length has to be 60".
OK.
Dave
The way you have described it seems very reasonable, and properly mounted, will be very beautiful.
Did you catch the 2" discrepancy? I'm thinking that I should fire the driver straight down the pipe. If so, the pipe length has to be 60" (12"-6"=6"). If not, i.e., if I fire it from the side hole, then the pipe length will be 2" shorter. Wait. Nevermind. I'll simply seal the pipe at the 3" mark, where the speaker would mount.
I think straight firing is the way to do it, and I think the pipe length has to be 60".
OK.
Dave
Having the Tee connect to the Line straight up-and-down, in perisope fashion, id doable, but will require a bend likely to be somewhere between 60 degree and 90 degrees. It might look nicer, but we are building this to minimize smoothness in the line, and so far we look like we will be using bends no greater than 45 degrees. It is up to you-the stright on method, with the Tee following the same angle as the rest of the spiral, might not look as good, but will provide a smoother line. How much difference acousitally it makes, I could not say.
Re: MAYBE A LITTLE OFF TOPIC, BUT...
Yes, I don't have the tools to heat enough 6" pipe uniformly to make it work. Smaller diameter pipe bends very easily, and the only challenge is to fill the section you wish to bend with sand so that the pipe holds its volume.
Do a google for "bend PVC" and there's several sites that demonstrate how to do it. I tried 'em all.
Dave
nobody special said:
Yes, I don't have the tools to heat enough 6" pipe uniformly to make it work. Smaller diameter pipe bends very easily, and the only challenge is to fill the section you wish to bend with sand so that the pipe holds its volume.
Do a google for "bend PVC" and there's several sites that demonstrate how to do it. I tried 'em all.
Dave
Re: MAYBE A LITTLE OFF TOPIC, BUT...
Not off topic at all. Was going to bring that up.
Here is the Materials Safety Data Sheet for PVC pipe and fittings. It says this stuff bend at 390 degrees F. the Flash point-I guess that means catching fire- is over 700 degrees F. Lots of room there.
http://www.charlottepipe.com/products/Assets/01-MSDS/PVC_MSDS/PVCPipeFittings_1.htm
I was thinking that maybe you could cut the PVC into 6 inch sections, maybe longer, then make two pieces of pipe or sheetmetal rolled into a pipe to insert into the ends of the heated pipe that function as holders. A form can be set up so the pipe, while hot, is gently bent and the holders fit into the jig at the correct angle.
Sor of make your own elbows. and you would only have to make one jig for all the pipe pieces if the entire length of the Line is in the spiral.
390 degrees F is very doable in the oven. However, I strongly suggest you make sure that poisonous or dangerous fumes are not given off before you do this!! I mean, you don't want to have a big hole in the kitchen wall where the oven used to be.
A torch is another possibility, and it can be done outdoors, preferably on cement, so you can just throw it away and run if anything goes wrong.
Just a suggestion.
nobody special said:
Not off topic at all. Was going to bring that up.
Here is the Materials Safety Data Sheet for PVC pipe and fittings. It says this stuff bend at 390 degrees F. the Flash point-I guess that means catching fire- is over 700 degrees F. Lots of room there.
http://www.charlottepipe.com/products/Assets/01-MSDS/PVC_MSDS/PVCPipeFittings_1.htm
I was thinking that maybe you could cut the PVC into 6 inch sections, maybe longer, then make two pieces of pipe or sheetmetal rolled into a pipe to insert into the ends of the heated pipe that function as holders. A form can be set up so the pipe, while hot, is gently bent and the holders fit into the jig at the correct angle.
Sor of make your own elbows. and you would only have to make one jig for all the pipe pieces if the entire length of the Line is in the spiral.
390 degrees F is very doable in the oven. However, I strongly suggest you make sure that poisonous or dangerous fumes are not given off before you do this!! I mean, you don't want to have a big hole in the kitchen wall where the oven used to be.
A torch is another possibility, and it can be done outdoors, preferably on cement, so you can just throw it away and run if anything goes wrong.
Just a suggestion.
no sweat
In my initial post, I mentioned in parentheses that I almost died trying to bend this pipe. I wasn't exaggerating. When I tried the oven method I could smell the C being separated from the PV, and I began to feel very ill. I'm pretty sure that Chlorine gas was in my house, in however amounts.
So, theoretically, PVC pipe should bend when heated uniformly, but 6" PVC doesn't heat in a uniform enough way to pull it off. I noticed that the ends began to melt and that the middle wasn't soft yet, so that did the oven method in.
I thing pro-plumbers can do it, but I didn't want to pay a guy to bend a pipe. This IS a DIY, after all.
Dave.
Man, I'm getting no work done.
In my initial post, I mentioned in parentheses that I almost died trying to bend this pipe. I wasn't exaggerating. When I tried the oven method I could smell the C being separated from the PV, and I began to feel very ill. I'm pretty sure that Chlorine gas was in my house, in however amounts.
So, theoretically, PVC pipe should bend when heated uniformly, but 6" PVC doesn't heat in a uniform enough way to pull it off. I noticed that the ends began to melt and that the middle wasn't soft yet, so that did the oven method in.
I thing pro-plumbers can do it, but I didn't want to pay a guy to bend a pipe. This IS a DIY, after all.
Dave.
Man, I'm getting no work done.
Just checking in... I think you ought to abandon all thoughts of bending the PVC... It can be bent... but only to a very limited degree.. I believe that 6 inch PVC can be bent to a 48 inch radius for a 90 degree bend.. No way to twist it as you require for this project. My next question.. have you tried to cut ( and glue) even one section of pipe to test the feasibility of your plan? I suspect that you will need a really big band saw to accomplish this. But hey... if it were easy.. everyone would be doing it...
ok here's my first whack at it.
it's made of 14 pieces: (1) 'tee'; (12) wedges cut at 22.5 deg at each end; and (1) end piece squared off at one end.
the pieces are assembled by mating the ends together with a rotation of 11.25 degrees. this can be roughly accomplished by marking off quadrants, then halfing the quadrants (octants???), then halfing the 'octants'. it won't be scientifically accurate.
i wasn't sure what orientation the 'tee' was supposed to be in, so i just plopped it on there.
base is to be developed by builder.
the white line shown on the bottom right image describes the spiral thru the center of the pipe; its length (not including the 'tee') is 60 inches.
i just realized i didn't put an overall dimension on the wedge shapes; but it should end up being 7-1/2" on the long side, and 1-1/2" on the short side.
hope this gives y'all something to look at and talk about.
/andrew - liked doing this better than working today
*** EDIT ***
also, the total height is roughly 3'-1 1/2", and the outside diameter is roughly 1'-7". YMMV.
it's made of 14 pieces: (1) 'tee'; (12) wedges cut at 22.5 deg at each end; and (1) end piece squared off at one end.
the pieces are assembled by mating the ends together with a rotation of 11.25 degrees. this can be roughly accomplished by marking off quadrants, then halfing the quadrants (octants???), then halfing the 'octants'. it won't be scientifically accurate.
i wasn't sure what orientation the 'tee' was supposed to be in, so i just plopped it on there.
base is to be developed by builder.
the white line shown on the bottom right image describes the spiral thru the center of the pipe; its length (not including the 'tee') is 60 inches.
i just realized i didn't put an overall dimension on the wedge shapes; but it should end up being 7-1/2" on the long side, and 1-1/2" on the short side.
hope this gives y'all something to look at and talk about.
/andrew - liked doing this better than working today
*** EDIT ***
also, the total height is roughly 3'-1 1/2", and the outside diameter is roughly 1'-7". YMMV.
Attachments
gorgeous!
It looks good, but I have one question, and it's the one that everyone else will have: Quote:
the pieces are assembled by mating the ends together with a rotation of 11.25 degrees. this can be roughly accomplished by marking off quadrants, then halfing the quadrants (octants???), then halfing the 'octants'. it won't be scientifically accurate.
End Quote
Is that going to work? The walls are 3/8" thick. If I turn identical segments against each other, won't I lose integrity? That is, if I'm understanding this correctly. I could be mis-reading that. I'm wondering if I shouldn't CUT the pieces with an 11.25 offset...
Kelticwizard and a few others have been keen to this problem throughout.
Otherwise, it's a tremendous effort, and I'll cut a prototype tomorrow.
Dave
It looks good, but I have one question, and it's the one that everyone else will have: Quote:
the pieces are assembled by mating the ends together with a rotation of 11.25 degrees. this can be roughly accomplished by marking off quadrants, then halfing the quadrants (octants???), then halfing the 'octants'. it won't be scientifically accurate.
End Quote
Is that going to work? The walls are 3/8" thick. If I turn identical segments against each other, won't I lose integrity? That is, if I'm understanding this correctly. I could be mis-reading that. I'm wondering if I shouldn't CUT the pieces with an 11.25 offset...
Kelticwizard and a few others have been keen to this problem throughout.
Otherwise, it's a tremendous effort, and I'll cut a prototype tomorrow.
Dave
true
well, you're right. and i knew that was the case, but i think my decision was based on making the wedge piece easier to cut.
it certainly would have been just as easy to model it that way though.
however, i think if you're willing to do the 11.25deg turn as a cut, instead of just a rotation of the piece, then by all means go for it. it would definitely be stronger and would look better.
if the rotated cut proves too difficult, however, i think you could try 'my' way. it would definitely not look quite as slick, unless you trimmed off the overlapping edges.
to solve some of the strength problems, be sure you use the right adhesive. for most plastics you would use cyanoacrylate, which melts the plastic together. but for PVC i don't think CA works, and i don't know what to use. probably epoxy...but you should ask you PVC supplier if you don't know already.
/andrew - anxious to see how this turns out...
***EDIT:
--- FYI i think using a rotated cut will result in an assemblage that is generally the same in appearance as my drawings, except that the joints will be rotated and smooth. the overall form stays the same though, if i'm not mistaken.
(also, one more thing - to make the 'tee' work properly you will have to fill in the collar fitting to provide area for adhesion to the top wedge piece. that may require some experimentation.)
well, you're right. and i knew that was the case, but i think my decision was based on making the wedge piece easier to cut.
it certainly would have been just as easy to model it that way though.
however, i think if you're willing to do the 11.25deg turn as a cut, instead of just a rotation of the piece, then by all means go for it. it would definitely be stronger and would look better.
if the rotated cut proves too difficult, however, i think you could try 'my' way. it would definitely not look quite as slick, unless you trimmed off the overlapping edges.
to solve some of the strength problems, be sure you use the right adhesive. for most plastics you would use cyanoacrylate, which melts the plastic together. but for PVC i don't think CA works, and i don't know what to use. probably epoxy...but you should ask you PVC supplier if you don't know already.
/andrew - anxious to see how this turns out...
***EDIT:
--- FYI i think using a rotated cut will result in an assemblage that is generally the same in appearance as my drawings, except that the joints will be rotated and smooth. the overall form stays the same though, if i'm not mistaken.
(also, one more thing - to make the 'tee' work properly you will have to fill in the collar fitting to provide area for adhesion to the top wedge piece. that may require some experimentation.)
There are solvent-welding cements specifically for PVC. You swab on an (often purple) primer to clean the tube end, then apply the cement to bond the deal together.
Thank you, Faustain, for the 3D diagram. It is exactly what I was imagining, though a bit wide on the angle of the spiral.
Yes, rotating each successive cut by n° is what I was getting to, and should work much better than otherwise.
Tim
Thank you, Faustain, for the 3D diagram. It is exactly what I was imagining, though a bit wide on the angle of the spiral.
Yes, rotating each successive cut by n° is what I was getting to, and should work much better than otherwise.
Tim
I've been thinking about your project.. you probably have noted my many nay-saying comments about the difficulty inherent in cutting large pvc pipes.. it is the voice of experience. though I was working with 10 inch pipe, which is a lot more difficult to handle than 6 inch. Anyway.. seems to me that the best tool for the job would be a compound miter saw.. A 12 inch saw could handle 4 inch pipe with a single cut.. 6 inch pipe would require a reverse cut.. but that could be done quite easily. Makita makes a 14 inch miter saw.. but unfortunately it is not a compound saw. If you want to spiral you will have to make a compund cut. The diagnol cut on a cylinder leaves you with an ellipse, so you can't simply twist two sections to make your spiral..
Great job, Faustian!!
Just what the project needed-someone with software and experience with 3-D building!
Looks like I had gotten the angle wrong. I neglected to take into account the cumulative effect of raising the angle of each piece-I just calculated the length of the line and the angle necessary for the line as a whole to end up at a certain height. Sort of like neglecting the effects of compound interest, LOL.
One tiny thing. The last piece, nearest the ground. Kneadle had expressed interest in making that lie flat on the floor. From a practical standpoint, it seems to me if the last piece can lay flat on the floor, making the mounts to support the rest would be a much simplified task.
Any way to calculate how much the last piece can be rotated to lay flat on the floor, and to commence the rise of the spiral with the second piece?
Just what the project needed-someone with software and experience with 3-D building!
Looks like I had gotten the angle wrong. I neglected to take into account the cumulative effect of raising the angle of each piece-I just calculated the length of the line and the angle necessary for the line as a whole to end up at a certain height. Sort of like neglecting the effects of compound interest, LOL.
One tiny thing. The last piece, nearest the ground. Kneadle had expressed interest in making that lie flat on the floor. From a practical standpoint, it seems to me if the last piece can lay flat on the floor, making the mounts to support the rest would be a much simplified task.
Any way to calculate how much the last piece can be rotated to lay flat on the floor, and to commence the rise of the spiral with the second piece?
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