LLT Sonosub with the SI 15HT D4 - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 57 Old 11-19-2014, 08:51 PM - Thread Starter
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LLT Sonosub with the SI 15HT D4

In a nutshell, we're looking at an LLT of 11 ft³ (311.5 liters) tuned to 14 Hz. (Sketches to be added to reserved posts below)


EDIT: As discussed, volume was reduced to 9.5 cu. ft.

I am all but finished with the design aspect. I expect this thread will be followed by a build thread, followed by (or including) a calibration thread. A second sub is planned for, and is expected to be added at a later date.

Room is about 14 x 20 x 8 (2,240 ft³) and open to another room, so about 4,000 ft³ total. This sub is intended for movies.

The sub will be wired at 2 Ohms and powered by one side of a NU3000DSP with a 14 HZ high pass filter, fed from an Audyssey MultEQ XT equipped Onkyo TX-SR805 receiver.

Notes

1. I typically listen 10 to 20 dB below reference,
2. I want low end extension, and
3. I plan on building a twin if this build works out.

Advice and other observations are welcomed.

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post #2 of 57 Old 11-19-2014, 08:51 PM - Thread Starter
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First Port resonance models as 219 Hz



WinISD Charts


600W SPL w/ no equalization (can easily increase this about 200 watts, see 800w charts below)

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600W Port Air Velocity w/ no equalization

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600W SPL w/ low boost +3dB @14 Hz (Used to flatten the low end. Is this even necessary in-room?)

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600W Port Air Velocity w/ low boost +3dB @14 Hz (a bit high, but I am planning 1-1/2" radius flares

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600W Cone Excursion w/ low boost (boost puts it just past xmax)

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800W SPL w/ no equalization

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800W Port Air Velocity w/ no equalization

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800W Cone Excursion w/ no equalization

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post #3 of 57 Old 11-19-2014, 09:19 PM - Thread Starter
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One question: Is the low end boost even necessary for a flat response in-room?
Which brings up the second question: Will it be enough?
People with LLT experience please chime in here.

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post #4 of 57 Old 11-19-2014, 10:07 PM - Thread Starter
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Oh, and I was toying with designing it like this Click image for larger version

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ID:	375482 but I have no need to disguise it.

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post #5 of 57 Old 11-19-2014, 10:10 PM - Thread Starter
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3/4" MDF Cut Sheet


Everything needed is nested, requiring just one 4 x 8 sheet. I envisioned using a CNC router, but will probably do the cutting manually. There are eight nested sections, each with their own center guide for a circle jig. Simply cut all diameters in order, from largest to smallest.




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3/4" MDF Parts

Each nested part is shown outboard of the piece it came from.




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The only really critical cutting step is to ensure that the inner diameter of the Trim Rings (3 and 6) are large enough that the router cut does not impinge on the outer dimension of the Tube Plug (3a and 6a) that is nested inside, as the Tube Plugs need to fit snugly into the Sonotube. A 1/4" bit should work nicely here, but a bit just a tad larger than the Sonotube wall thickness may even allow both edges to be made with the same cut just by setting the jig to cut the O.D. of the Tube Plug!* As the Trim Ring I.D. only needs to clear the Sonotube O.D., it isn't critical as long as the Trim Ring will still be wide enough for its round over. This will be investigated before cutting starts, and the O.D.s of the Trim Rings and Trim Plates will be adjusted for this if necessary.


*EDIT (03/20/17): The Sonotube wall was approx. 3/16" thick, so the 1/4" bit cut the O.D. of the tube plug, and the I.D. of the trim ring in the same pass.

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Top assembly w/ port (minus 3/4" trim Ring, discussed below in post 6)



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Bottom flare detail

Made from two 3/4" rings glued together (A scrap piece of port tube and a flush trim bit will be used to match the I.D. of both flares with the port tube I.D. prior to rounding over).




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Port Tube


Utilizing 6" Poly Pipe made by Advanced Drainage Systems and available shipped to my local Home Depot. The pipe is made with a white, high density polyethylene layer around a black polyethylene core to form a lightweight pipe. Under $15 for 10 ft, very lightweight, and already black inside! (very happy to have found this) EDIT: Home Depot no longer carries this pipe.


EDIT (03/20/17): With the project stalled, I had lots of time to tweak the design, resulting in a change of port diameter. I now needed something in the 7-8" range, and rescued two scrap 7" (6-7/8") post sleeves from the company trash bin that work perfectly.. http://eagle-mfg.com/product/Smooth-...2--Yellow.aspx





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post #6 of 57 Old 11-19-2014, 10:11 PM - Thread Starter
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I designed the port to be removable, much like a speaker, with a Flare Plate that fastens to the Top Plug with a gasket, just as the speaker fastens to the Bottom Plug. This is intended for future tuning/part scavenging, but also allows clearance for a large Bottom Flare on the port tube when inserting it into the enclosure. The only avenues for air leakage will be the glue joints of the Tube Plugs, and the gaskets for the speaker and Flare Plate, none of which should pose a problem.

Flare Plate Detail

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The flare (1-1/2" radius) is shown fabricated from layers of MDF, but...

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...the plate could easily be fabricated with a rabbet edge to accommodate an off-the-shelf flare and tube, as shown here, and the design still allows clearance for a bottom flare.




The Trim Plates shown below surround both the port Flare Plate and speaker driver, and will fasten to the Tube Plug as well, extending about 1" past the outer diameter of the Sonotube. I wanted a look with a thicker edge on these top and bottom plates, but rather than double up the MDF on the Trim Plates, I designed a Trim Ring 3/4" x 3/4" and equal in diameter to the Trim Plates, that will extend over the Sonotube edge like a bottle cap, to give the illusion of a 1-1/2" thickness (shown rounded-over). This saves MDF and weight.

Trim Plate Detail

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Flare and Port Tube Assembly Cross Section

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Shown mounted through a 10" hole to a single layer 20" d. x 3/4" thickness port plug, (actual plug will be 1-1/2" thick). Trim Plate (shown above), will fit on top, surrounding the Flare Plate.


Trim Plate And Port Tube Assembly (shown with both 3/4" sections of Tube Plug, complete except for the Trim Ring)

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Parts List

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The port flare and Port Plate assembly is made from Parts 2a, 3b, and 4a in the Parts List, while the Tube Plugs (Parts 3a, 4, 5, and 6a) are to be ring shaped and constructed out of two layers of 3/4" MDF, the outer diameter corresponding to the Sonotube inner diameter, with an inner cutout for the speaker (about 14") on the bottom plug and clearance for the port tube bottom flare (about 10") on the top plug. The top Flare Plate will be about 12" O.D. to provide a 1" overlap to seal it over the hole in the tube plug.

Trim Plates and Trim Ring assemblies are made from Parts 2 and 3 with a 15.5" hole (speaker side) and Parts 6 and 7 with a 12.25" hole (port side). Parts 1 and 8 are the Floor Plate and Top Plate. I have not yet finalized how I will attach them as I have a few different ideas I am still mulling over, including this one with no Top Plate:
Attached Thumbnails
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post #7 of 57 Old 11-19-2014, 10:11 PM - Thread Starter
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post #8 of 57 Old 11-19-2014, 10:12 PM
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looks good. a high pass might not be a bad idea. there is a thread on how to do that with the inuke below 20hz.


low end eq probably not required. once below the first non-zero mode rolloff won't look quite as bad as the winisd 2 pi space model.

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post #9 of 57 Old 11-19-2014, 10:33 PM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post
looks good. a high pass might not be a bad idea. there is a thread on how to do that with the inuke below 20hz.


low end eq probably not required. once below the first non-zero mode rolloff won't look quite as bad as the winisd 2 pi space model.
Thanks, LTD02. I've followed some of your stuff and I already planned on using your method to high pass @ 14 HZ. I was a bit concerned with low end EQ. Good to know I needn't worry.

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post #10 of 57 Old 11-20-2014, 08:10 AM - Thread Starter
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Added some sketches and descriptions above.

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post #11 of 57 Old 11-20-2014, 08:05 PM - Thread Starter
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I just finished running some numbers on materials cost.

The cost for one sub will come in at around 65-70% of the cost of two subs, because of the up front cost of the 2 channel Amplifier, a full length Sonotube, and some bulk material purchases. I will then only need to spend the remaining 30% to add another sub down the line.

I also have some alternate finishing ideas I'm contemplating that would add about 4-5% to the cost of each sub...

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post #12 of 57 Old 11-20-2014, 08:28 PM
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I love this thread.

ATM I just finished painting the first coat on my plates and rings for my LLT sonosub build. Mine is 480L tuned to 15hz using an 8" port 33" long. I too have made my port removable in near the same way as you! I am using 18" Ultimax speakers. I am also using a NU3000DSP amp (I am told it is too small but ATM it is what I have).

I am excited to follow your build because it is much the same as mine. Please keep posting. I appreciate your level of detail!

Cheers,

Phill

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post #13 of 57 Old 11-21-2014, 01:32 PM - Thread Starter
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Thanks for the compliment. You are way ahead on your project. What a monster. What diameter sono are you using?

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post #14 of 57 Old 11-21-2014, 05:31 PM
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24" diameter Sonotube 6' feet long/high. I hope mine are indeed monsters. Yes I am making two of these. I read threads here and compared to most my subs will pale in comparison.
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post #15 of 57 Old 11-23-2014, 02:17 PM - Thread Starter
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I was originally planning a 20" Sonotube, but with a driver to box top resonance of 102 HZ, I was thinking I better go shorter, with a 22" diameter (122 Hz resonance) tube.

I will be applying damping material to the top plug either way, but does anyone have a recommendation for or against?

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post #16 of 57 Old 11-23-2014, 08:56 PM
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Looks good so far. Going to follow this and hopefully start mine in the next week or so.


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I would wait to see what response you get before any HP filters. A 14hz tune will get you around 12 hz in room so you want to start protecting the drivers below that. IT also depends on the volume and how hard you will pushing these in your room. I had 4 LLT's tuned to 13hz in my 2000 cubic foot room and never needed a HP because they did not work that hard. I used 18's and the sono's were 6 feet tall and 26 inches round.

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Quote:
Originally Posted by MKtheater View Post
I would wait to see what response you get before any HP filters. A 14hz tune will get you around 12 hz in room so you want to start protecting the drivers below that. IT also depends on the volume and how hard you will pushing these in your room. I had 4 LLT's tuned to 13hz in my 2000 cubic foot room and never needed a HP because they did not work that hard. I used 18's and the sono's were 6 feet tall and 26 inches round.

According to WinISD, excursion exceeds xmax at around 12 Hz with only about 200 watts.

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Update

(Going slowly I know, but I have had other irons in the fire)




I have purchased most of the parts I will use, including:

Socket Cap Screws
http://www.amazon.com/gp/product/B005DS8E5W

E-Z Lok Threaded Inserts
http://www.amazon.com/gp/product/B002WC8TUC

Magnets
http://www.amazon.com/gp/product/B000SJ61EC

RCA to XLR Adaptor
http://www.amazon.com/gp/product/B000068O4D

Speakon Plug
http://www.amazon.com/gp/product/B006ZAC2AU

Speakon Plug
http://www.amazon.com/gp/product/B002BERXW6

Speakon Jack
http://www.amazon.com/gp/product/B00067JSFK

I also bought some black tech-flex with a (subwoofer-purple) stripe and an older style speakon plug (with purple bushing) to sex up the cable. I have an amp and mic available for testing, so I will purchase the NU3000DSP last. All other materials have been sourced, I am just waiting on router availability (I have a friend who is contemplating a router purchase, so this build will be delayed accordingly in anticipation of using his router).

The additional time has allowed some tweaking of the original plan.

Latest vision:

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My original plan of 11 cu. ft. left me feeling uncomfortable with both the overall height, and a 102 Hz driver to box top resonance. By reducing volume to 9.5 cu. ft. and increasing diameter to 22" I have shortened the sub and moved the resonance further out of the pass band while only slightly changing the frequency response. Trade offs...

I want an 1-1/2" round over on my port exit, and have been mulling over my options, with the intention of saving the cost of purchasing or fabricating such a large port exit. Buying the flare and pipe seems expensive, and so does the cost (per use) of the proper router bit. Buying the router bit has always been the fall back plan, but I still have time to develop alternatives. Having experimented with heat-shaping the PVC Pipe, I was not happy with the results. With the properly shaped mandrel (again, cost) it would work, however.

I had also considered molding the flare section using 2 part urethane foam. Cost of the foam comes out to about $1.25 for the flare, which is great, except it would cost about $30 in materials to make the mold, and one can only purchase 2 part foam in lots that cost $35 and up. If I had easy access to small quantities of the foam, it might be an option. My latest idea is to recycle some of that MDF dust I've been expecting to produce, and mixing it with glue to mold the flare. Doesn't have to be dense, and may work out as the cheapest option, though I might still have to fabricate a mold. I will experiment with it once the dust starts flying.

In one of my experiments, I fabricated a 3/4" radius inside flare from pipe insulation using a heat gun. a bit ugly to use externally, it is functional, and will work fine internally.


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post #21 of 57 Old 03-23-2015, 03:08 PM
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You could make the port flare with fiberglass. Messiest crap I've ever used but you can make just about any shape.

Or maybe one of those pool noodles. Covered somehow to look better. Or use the pool noodle for your fiberglass mold.

Have you seen this page:

http://www.subwoofer-builder.com/flares-25mm.htm

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post #22 of 57 Old 03-23-2015, 05:51 PM - Thread Starter
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Quote:
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You could make the port flare with fiberglass. Messiest crap I've ever used but you can make just about any shape.

Or maybe one of those pool noodles. Covered somehow to look better. Or use the pool noodle for your fiberglass mold.

Have you seen this page:

http://www.subwoofer-builder.com/flares-25mm.htm
Those are all good ideas, thanks. I might try bondo resin and sawdust, but not fiberglass. If I'd have to build a mold, I think I would lose the cost advantage over buying the router bit.

I've considered shaping a pool noodle, but need to find one in a store to do a hands-on evaluation before spending money on it. As slow as this build is going, I'll probably still be looking into this by the time pool season rolls around. Based on my experience with the pipe insulation though, heat-shaping the noodle will be very tricky.

I spent a lot of time on subwoofer-builder.com when I first started. It's a great source. I may still build a mandrel to shape the pipe, but I think with a separate flare it will be easier to make port changes if I'm not happy with the tune. Right now I'm looking for something I could shape like clay with this homemade extruder, then paint after it hardened.

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post #23 of 57 Old 03-23-2015, 05:54 PM
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I bought a 1.5" round over off ebay for under $50. As long as I can do a couple flares with it, I'll be happy. I considered some of your options as well, but I'm hoping the bit does what I need. I really wanted to use 22" tube as well, but man is it hard to come by up here. It would have to be shipped from the states, but I couldn't justify over $300 for a length.

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Found these styrofoam wreaths. Available at most craft stores or walmart in lots of different sizes.

http://www.joann.com/styrofoam-wreat...n/8200354.html
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I bought a 1.5" round over off ebay for under $50. As long as I can do a couple flares with it, I'll be happy. I considered some of your options as well, but I'm hoping the bit does what I need.
Yeah, buying the bit is always gonna be my fall back option, and is probably the best option anyway. But since I have plenty of time, it doesn't hurt looking for other options. I need to purchase other bits as well, but they only run around $20 each, and will be used for multiple cuts on this project. I also have the option of finding a local woodworking shop to see what they can do for me, but I'd rather do it myself.

What first got me interested in this project was the cost savings in the base design, but when you add tool costs, nicer finishes, and other options, it adds up fast. I don't mind splurging a bit on things that are seen or add value; like the tech-flex cable, tube cover, and paint finish (all appearance options), but I want to shave cost where I can, and I KNOW I'm only gonna use that bit once or twice.

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Found these styrofoam wreaths. Available at most craft stores or walmart in lots of different sizes.

http://www.joann.com/styrofoam-wreat...n/8200354.html
Great minds...

Yep, I looked into those as well. I even contacted some manufacturers to get the proper I.D., but no luck. The torus shaped wreaths are extruded like donuts and allowed to expand freely, with little control of their dimensions, so getting anything close to the size required is a long shot. The one shown is rectangular in profile and would need to be shaped... Hmmm.

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One more! Cooking mould:

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One more! Cooking mould:
Been there as well!

Even considered the eddy-reducing properties of a spiral Bundt pan...


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You could make the port flare with fiberglass. ...Or maybe one of those pool noodles...
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Originally Posted by Augerhandle View Post
...I've considered shaping a pool noodle, but need to find one in a store to do a hands-on evaluation before spending money on it. As slow as this build is going, I'll probably still be looking into this by the time pool season rolls around. Based on my experience with the pipe insulation though, heat-shaping the noodle will be very tricky...

Pool season is here, and I picked up a pool noodle a while back...


(I didn't take many pictures, but I think there are enough to explain my procedure)







That is a battery cable I had lying around that I used to pull the noodle into an arc for thermoforming. One could use anything, such as an old piece of hose or thick rope.


I bent the noodle until it showed distortion (crinkling) at the bend and clamped the cable to hold it there. Then, using a heat gun, I gently brought up the temperature at the bend, softening the foam until the crinkles smoothed out on the inside and the outside relaxed somewhat. I then let it cool and it maintained it's shape. One must be careful not to overheat the foam, or it will shrink and deform, becoming useless.


After it cooled I bent another section and repeated the heating and cooling steps. I could only bend a small section at a time because otherwise the previously bent section would relax and straighten, undoing my previous work. It will only bend a small degree before deforming, so it takes several iterations before the bend radius approaches the size needed. The most difficult part is finding a way of shaping the bend and maintaining the bend until it cools (and having patience, this took hours).


Since the outside finished diameter will be slightly larger than a five gallon bucket, I used one as a jig to reduce the bend radius and further shape the noodle once I got most of the curve formed.







After coiling it into the bucket, I heated the inside radius to smooth out the crinkles, then set the bucket outside in the cool evening breeze to cool. Unfortunately, the bucket sides flattened the outside diameter of the softened noodle. I will only be using the inside portion of the noodle for the flare so this flattening shouldn't be a problem, but I decided to do something about it anyway.


I wrapped the noodle tightly around a scrap section of port tube and carefully reheated the outside of the noodle...





...the flattened sections softened and regained most of their round profile.


Using the port tube as a guide, several sections of the noodle were identified that required either a tightened bend or a straightened bend to match the port. So back in the bucket, with emphasis on those areas. The bucket sides are tapered, so sliding the noodle further down tightened (and crinkled) the inside radius. I then applied heat only at the areas that were found to require tightening. After cooling, those areas held the tighter radius while the unheated areas sprang back to their previously finished shape when removed from the bucket. To straighten a too-tight bend, I simply heated it very slightly in free air to relax the bend


.


Notice that the ends of the noodle are not curved. Curving at the ends is almost impossible, so I measured the noodle longer than what was required to account for this. Once the final shape is achieved, the idea is to cut away the excess length, leaving just enough to create the exact circumference needed when the cut ends are glued together. Unfortunately, I got in a hurry and overheated (deformed) a section of the noodle, so unless I am able to reshape it, I may not have enough length after trimming to make it all the way around the port. If that proves to be the case, I will simply add another, smaller piece and have two glue joints.

I plan on sealing the foam with watered down PVA, then sanding and painting it. This should also make the flare more rigid.

Well that's as far as I've gotten with this experiment, and it will be awhile before I can get back to it. Yet to tackle: slicing the foam horizontally in half, then vertically in a circle to get the final flare profile needed, shown here, in post #22 : LLT Sonosub with the SI 15HT D4





I considered cutting the noodle lengthwise in quarters before shaping, but decided it would be more difficult to hold it in shape while cooling than cutting the full tube afterwards. We shall see.
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post #30 of 57 Old 06-03-2015, 03:56 PM
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Looks good!

If you only need a quarter round section, the outside that gets flattened by the bucket really doesn't matter since that section will get cut off.
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