Originally Posted by Samps
You could make the port flare with fiberglass. ...Or maybe one of those pool noodles...
Originally Posted by Augerhandle
...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.