<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_ym18_1_1458842538155_2681"><span id="yui_3_16_0_ym18_1_1458842538155_2855">Hank,</span></div><div id="yui_3_16_0_ym18_1_1458842538155_2750" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_2749">thanks for the advice.</span></div><div id="yui_3_16_0_ym18_1_1458842538155_2683"><span id="yui_3_16_0_ym18_1_1458842538155_2682">I thought that welding would be quicker & cheaper rather than cutting an o-ring groove</span></div><div id="yui_3_16_0_ym18_1_1458842538155_2685" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_2684">& drilling & taping & recessing for 6 bolt holes. Also a more smoother hydrodynamic</span></div><div id="yui_3_16_0_ym18_1_1458842538155_2734" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_3208">finish. I will be welding on the fins for the kort nozzle attachment so can do it all in</span></div><div id="yui_3_16_0_ym18_1_1458842538155_3217" dir="ltr"><span>one shot.</span></div><div id="yui_3_16_0_ym18_1_1458842538155_2854" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_2853"> I will probably add a fill port in to the top of the seal compartment to aid air</span></div><div id="yui_3_16_0_ym18_1_1458842538155_2869" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_2868">removal. Once there is oil in there the only way you would get air in would be</span></div><div id="yui_3_16_0_ym18_1_1458842538155_2862" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_2861">running it out of water with some sort of reverse pumping action </span><span id="yui_3_16_0_ym18_1_1458842538155_2895">caused by the seal.</span></div><div id="yui_3_16_0_ym18_1_1458842538155_2906" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_2947"> The double seal arrangement I am copying from that military document on</span></div><div id="yui_3_16_0_ym18_1_1458842538155_3081" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_3080">sealing & compensation. However they use face seals. This thruster is so small</span></div><div id="yui_3_16_0_ym18_1_1458842538155_3040" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_3039">that 2 face seals would take up too much space, so have doubled up on 2 low</span></div><div id="yui_3_16_0_ym18_1_1458842538155_3025" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_3024">pressure lip seals. In the pdf it makes a good case for the secondary seal & I</span></div><div id="yui_3_16_0_ym18_1_1458842538155_3055" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_3056">intend to do most of my diving in seawater where it is a more destructive environment.</span></div><div id="yui_3_16_0_ym18_1_1458842538155_3119" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_3118">All the Minnkotas I have seen have 2 seals, I think just lip seals.</span></div><div id="yui_3_16_0_ym18_1_1458842538155_3146" dir="ltr"><span id="yui_3_16_0_ym18_1_1458842538155_3223">Cheers Alan</span></div><div id="yui_3_16_0_ym18_1_1458842538155_3092" dir="ltr"><span></span><br></div><div class="qtdSeparateBR" id="yui_3_16_0_ym18_1_1458842538155_2699"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div dir="ltr"> <font face="Arial" size="2"> <hr size="1"> <b><span style="font-weight: bold;">From:</span></b> hank pronk via Personal_Submersibles <personal_submersibles@psubs.org><br> <b><span style="font-weight: bold;">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Friday, March 25, 2016 1:31 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [PSUBS-MAILIST] MK 2 Brushless Thruster<br> </font> </div> <div class="y_msg_container"><br><div id="yiv9315279386"><div><div style="color: rgb(0, 0, 0); font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255);"><div id="yiv9315279386yui_3_16_0_1_1458822019452_3535"><span>Hi Alan,</span></div><div id="yiv9315279386yui_3_16_0_1_1458822019452_3488" dir="ltr"><span id="yiv9315279386yui_3_16_0_1_1458822019452_3487">It wouldn't hurt to clamp the end cap tight but you do have a nice shoulder for the end cap to sit on. Any time I make a part that can and usually does warp, I make it oversize and machine it true after welding. I am curious why you want to weld it-that big shoulder has room for an o-ring. I would also ditch the second seal-it is an air trap. Great project!</span></div><div id="yiv9315279386yui_3_16_0_1_1458822019452_3488" dir="ltr"><span>Hank</span></div> <div class="yiv9315279386qtdSeparateBR"><br clear="none"><br clear="none"></div><div class="yiv9315279386yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div class="yiv9315279386yqt2648156135" id="yiv9315279386yqt39232"><div dir="ltr"><font face="Arial" size="2"> On Thursday, March 24, 2016 12:27 AM, Alan James via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br clear="none"></font></div> <br clear="none"><br clear="none"> <div class="yiv9315279386y_msg_container"><div id="yiv9315279386"><div><div style="color: rgb(0, 0, 0); font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);"><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4233"> This is my latest brushless thruster design for scrutiny.</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4199">The last thruster I made was 2 piece with one seal.</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4332">I machined the last version out of aluminum rod, which was expensive & difficult.</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4331">The end pieces in this design are from solid rod but the mid section is from a stock tube</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4371" dir="ltr">that I intend to have welded to the propeller end. The back end is bolted on.</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4334" dir="ltr">Am I likely to get distortion when welding the two sections together? There is a sleeve</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4333" dir="ltr">press fitting to help give it some rigidity for welding. Should I make a jig to clamp it in</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4367" dir="ltr">for welding?</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4372" dir="ltr">The thruster is for 500ft depth & is oil filled with a slight over pressure above ambient. </div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4490" dir="ltr">Oil filled mainly for cooling purposes, but also as a secondary defense against any leaks,</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4555" dir="ltr">& for lubrication of bearings & seals. I am using low pressure lip seals & have a double </div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4565" dir="ltr">seal redundant arrangement. The outboard seal is orientated to keep the oil in & with the</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_4612" dir="ltr">internal overpressure should keep the water out. The outboard seal should fail first as it is </div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5135" dir="ltr">exposed to abrasives, especially in sea water. The inboard seal is oriented so that it keeps</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5246" dir="ltr">any water out that may get past the outboard seal. </div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5265" dir="ltr">The tube coming out of the seal cavity is for pressurizing it & for collecting any water that</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5247" dir="ltr">may get through & come out of suspension. I am thinking of putting a water sensor in there.</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5383" dir="ltr">Any comments welcome.</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5384" dir="ltr">Alan</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5281" dir="ltr">p.s. if image isn't big enough keep hitting ctrl & + TO ENLARGE.</div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5112" dir="ltr"><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5539"><br clear="none"></div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5494" style="display: block;"><div class="yiv9315279386yahoo-compose-assist-image-card yiv9315279386ymail-preserve-class" id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5541" style="width: 100%;"><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5540"><img id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5551" style="width: 100%; vertical-align: middle; max-height: 406px; max-width: 800px;" alt="motor cut away.jpg" data-id="ddee6915-270e-a2cb-4f5d-ca03651d5cee" itemprop="contentUrl"></div></div></div><div id="yiv9315279386yui_3_16_0_ym18_1_1458793494416_5542"><br clear="none"></div></div></div></div></div><br clear="none">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a href="mailto:Personal_Submersibles@psubs.org" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"><a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank" rel="nofollow" shape="rect">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"><br clear="none"><br clear="none"></div></div> </div> </div> </div></div></div></div><br><div class="yqt2648156135" id="yqt38260">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a href="mailto:Personal_Submersibles@psubs.org" shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"><a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank" shape="rect">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"></div><br><br></div> </div> </div> </div></div></body></html>