[PSUBS-MAILIST] Motor modification

[Sean T. Stevenson via Personal_Submersibles]

Getting rid of every last air bubble isn't strictly necessary (although you should attempt to), provided you have enough compensation volume to account for the bubble volume when they shrink under pressure. If you really are about attention to detail, draw a vacuum on the housing before you begin the oil fill.

I have never been a fan of compensation at ambient with no bias pressure, but if you use a bladder with any elasticity (such as a hot water bottle or soft blocked tubing like surgical tubing), you can effectively accomplish the bias by overfilling the bladder so it is stretched a bit.

Fill at a low point, and vent at a high one.

Sean



On December 5, 2016 11:01:22 AM MST, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>Hi James,
>
>I totally agree on the difficulty of filling up. Well the filling is
>easy,
>it's getting rid of the last bubbles that is the real issue. For a
>thruster
>compensation bladder, the last thing I was testing on Snoopy before her
>sale was little plastic squeeze bottles. Google "plastic accordion
>bottle"
>and you should get some hits. Like this:
>
>https://www.grainger.com/product/5FVF7?gclid=CjwKEAiAvZTCBRDvnoOaoa2j3xISJABxPjN9ekm4clPKgKRoIN07DTRepXFPSkcSB1GAMOTILj3jBRoCcMfw_wcB&cm_mmc=PPC:GOOGLEPLAA-_-Adhesives%2C%20Sealants%20and%20Tape-_-Dispensing%20Guns-_-5FVF7&AL!2966!3!50916782397!!!g!104636426757!&s_kwcid=AL!2966!3!50916782397!!!g!104636426757!&ef_id=VzemaAAAAJR6JHK7:20161205180023:s
>
>
>Best,
>
>Alec
>
>On Mon, Dec 5, 2016 at 7:28 AM, James Frankland via
>Personal_Submersibles <
>personal_submersibles at psubs.org> wrote:
>
>> Hi All
>>
>> I have been talking to Rick about motor compensation which has got me
>> thinking.
>>
>> I originally did my motors like other psubbers have done with the
>rubber
>> tubes around the sides, but have found them a real pain to fill. 
>Problem
>> is the location of the tube, plus the tiny bit of protruding pipe
>nipple on
>> the inside.
>>
>> So, I modified the motors by drilling a hole in the top part of the
>> aluminium endcap and use that now as the vent\final fill.  Its
>better, but
>> still awkward.
>>
>> I have suggested to Rick this idea, which I am tempted to adopt
>myself.
>> Blocking off the existing side mounted pipe nipples and
>> filling\venting\compensating all from the one top hole.  There would
>be a
>> rubber bulb of some sort on the end of the pipe.  2x pictures show
>filling
>> and operation.  Appologies for rubbish drawings, im at work.
>>
>> What does everyone think?
>>
>>
>> ​
>> ​
>>
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>>
>>
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