[PSUBS-MAILIST] Light Experiments

Mon Apr 17 19:42:00 EDT 2017

Cliff,if I remember rightly you had a gasket on top of the lens between the lens & the top retaining ring. That would give you a bit of tolerance when bolting the ringdown if the lens is slightly below the ring / housing mating surface. Perhaps a thicker gasket & deeper lens seat will give more room for error!   Just had a look at one of my commercial pool lights & the lens is proud ofthe housing with a gasket on top & underneath the lens; so the glass is seeing all the force of the screw down retaining ring. In this case the the ring,being screwed on like a jam jar lid, is not exerting anywhere near the forceyou would get with the cap screws.Alan

      From: Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Tuesday, April 18, 2017 11:15 AM
 Subject: Re: [PSUBS-MAILIST] Light Experiments

Alec, not sure what is going on with the borsilicate glass lens.  the version I use is the McAMster carr part number 8477k48.  I have installed two of these in my first set of lights and have never had one break.  I have two more of these lights being machined as we speak.  Again no breakage issue.  Were the failures when the lights were turned on or during assembly?  IF you look at the fabrication tolerance for these annealed glass disk, its +/- 0.015" for a 2" disk so if you got one that was on the high side of this tolerance such that the fit became tight, could be a thermal expansion issue as the lens could get hotter than the aluminum case.
Cliff
On Mon, Apr 17, 2017 at 1:19 PM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Hi Alan,
The borosilicate lenses in these parts are $17 each if that is a useful reference. I would recommend several spares, because while resistant to temperature they are VERY easy to break during installation or if you just look at them unkindly. On one light I'm on the first one, but the other light took three of them before I learned just how gentle I had to be.
Best,
Alec
On Sun, Apr 16, 2017 at 8:04 PM, Alan via Personal_Submersibles <personal_submersibles at psubs. org> wrote:

Rick,I should mention that I have now gone with a 36V system &have some pwm dimming controlled buck boost LED drivers beingmade for me. These could drive Cliff & Alecs light. So waiting for these & a reply on the borosilicate lens enquiry before I go any further.Alan
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On 17/04/2017, at 11:39 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

High Rick,to insert the male subconn fitting it has to be turned 15 times as itwinds down fully in to the thread; so the wire would be twisted 15 times ifyou went this way.Yes the bolts go right the way through. This avoids tapping threads & boltsseizing. It also has the advantage that I can have longer bolts out the backthat an attachment bracket can be bolted to.The back section in the photo, has the led attached to it & an o-ring grooveto seal against the bore of the middle section. The base of the middle sectionhas an o-ring groove & the back section compresses this when the boltsare tightened up. So two o-rings on this section. The top ring that clampsthe lens down on to an o-ring (also o-ring around the side of the lens) canbe made a larger diameter with a second set of bolt holes so the light canbe mounted in a recess.As the back section is the main heat sink & mount for the LED I don't haveroom for a bunch of twisted wires. The nozzle out back is designed so I can pour resin in to it, let it set, then coat the wiring about an inch up & the nozzle with silicone. Then I intend to mold a rubberised supportingsection over the silicon. It should work!Pictures attached. Cheers Alan<image1.JPG>

<image2.JPG>
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On 17/04/2017, at 10:08 AM, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

Hi Alan,
Thanks for the picture. The size housing you are using is kinda what I wanted to go with as well. Not sure what you mean about screwing something in 15 times. From the top view picture you sent, looks like the front head/lens is held on against a sealing surface with 6 Allan head bolts that go all the way threw the back plate so I assume that the back plate is threaded and screws on against an 0 ring or something? If that's the case, can't you drill and tap the back and put a sub-Conn or strain relief fitting in and allow just enough length of wires to protrude inside just enough to connect the LED wires to it before attaching the lens? Do you have any pictures of everything inside the housing by them self's?
Rick
On Sun, Apr 16, 2017 at 10:39 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

Hi Rick,The light in the photos is mk 1 or 2. It didn't have oil in in those photos.Funny but the oil bubble & the temperature sensor had no effect onthe light coming out.  The latest version has a conical lens machined in it & hides the attachment bolts for the LED.Still a work in progress as I have just made enquiries regarding pressurerated borosilicate glass lenses. This light is 85mm D x 54mm long. (excludingwiring nozzle) In the attached photo I have just temporarily siliconed aroundthe wires for the test. I do have 8 subconn male & female connectors & wasthinking of tapping a hole for the male connector to fit. The only problem ishow do I connect the wires? My two LED wires are either side of the LED & comedown two separate angled holes & meet in a central 8mm hole. I would needto fit the LED then attach the LED wires to the subconn wires & twist them 15times to thread in the subconn fitting. The subconn wires are very stiff & itjust wasn't going to work without a large amount of room for twisted wires.   I have some ideas for potting the wires that I will try & test.The housing diameter was dictated by stock material sizes but works out well.I have machined the cooling fin slots in to the bolt holes to give the fins a bitmore depth. Alan<image1.JPG>

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On 17/04/2017, at 5:43 AM, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

Alan,
Do these pictures have the silicone oil in them? Do you have any side and back shots of the housing and other data regarding the housing like wall thickness and what fitting did you use to get the power out of the back and such?
Rick
On Sat, Apr 15, 2017 at 6:33 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

I put a temperature probe inside the housing of my 80W LED light.
The probe was up against the acrylic lens, as I was concerned about
what temperature the lens was seeing on the inside. The lens is 10mm
away from the LED.
The LED manufacturer told me that on normal LEDs the temperature
out the front of the LED can be 338F (170C) but my flip chips should
run cooler.
Briefly; when run at 30W in water they stabilised at 257F after 5 minutes.
At 45W they stabilised at 280F after 5 minutes. I stopped upping the amps
at this stage.
Next experiment, I filled the housing with silicone oil.
At 45W it hit 116F in 4 minutes & temperature stabilised.
At 76W it hit 139F in 6 minutes & stabilised.
So oil has massive advantages in lessening temperature on the lens,
maybe because it is a buffer from the radiant heat & also transfers the heat
out through the housing quicker.
Greg your thoughts would be appreciated on this; I am thinking that without the
oil the acrylic lens would see temperatures at which it is formed especially
if I went up to 80W. Although the outside of the lens was cold there would be a
temperature transition across the thickness of the lens & it would be considerably
weakened. I am building to 500ft, so it would potentially see 250 psi in operation.
   At this stage I haven't made up my mind whether to go with a borosilicate lens
or oil fill with an acrylic lens. I had a large bubble & it would be hard to eliminate
all bubbles in the oil filling process.
Will try & attach photos.
Alan

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