<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px"><div id="yui_3_16_0_1_1458822019452_3535"><span>Hi Alan,</span></div><div id="yui_3_16_0_1_1458822019452_3488" dir="ltr"><span id="yui_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="yui_3_16_0_1_1458822019452_3488" dir="ltr"><span>Hank</span></div> <div class="qtdSeparateBR"><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: 12px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div dir="ltr"><font size="2" face="Arial"> On Thursday, March 24, 2016 12:27 AM, Alan James via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br></font></div> <br><br> <div class="y_msg_container"><div id="yiv3204014139"><div><div style="color:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"><div id="yiv3204014139yui_3_16_0_ym18_1_1458793494416_4233"> This is my latest brushless thruster design for scrutiny.</div><div id="yiv3204014139yui_3_16_0_ym18_1_1458793494416_4199">The last thruster I made was 2 piece with one seal.</div><div id="yiv3204014139yui_3_16_0_ym18_1_1458793494416_4332">I machined the last version out of aluminum rod, which was expensive & difficult.</div><div id="yiv3204014139yui_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="yiv3204014139yui_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="yiv3204014139yui_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="yiv3204014139yui_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="yiv3204014139yui_3_16_0_ym18_1_1458793494416_4367" dir="ltr">for welding?</div><div id="yiv3204014139yui_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="yiv3204014139yui_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="yiv3204014139yui_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="yiv3204014139yui_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="yiv3204014139yui_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="yiv3204014139yui_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="yiv3204014139yui_3_16_0_ym18_1_1458793494416_5246" dir="ltr">any water out that may get past the outboard seal. </div><div id="yiv3204014139yui_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="yiv3204014139yui_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="yiv3204014139yui_3_16_0_ym18_1_1458793494416_5383" dir="ltr">Any comments welcome.</div><div id="yiv3204014139yui_3_16_0_ym18_1_1458793494416_5384" dir="ltr">Alan</div><div id="yiv3204014139yui_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="yiv3204014139yui_3_16_0_ym18_1_1458793494416_5112" dir="ltr"><div id="yiv3204014139yui_3_16_0_ym18_1_1458793494416_5539"><br></div><div id="yiv3204014139yui_3_16_0_ym18_1_1458793494416_5494" style="display:block;"><div class="yiv3204014139yahoo-compose-assist-image-card yiv3204014139ymail-preserve-class" id="yiv3204014139yui_3_16_0_ym18_1_1458793494416_5541" style="width:100%;"><div id="yiv3204014139yui_3_16_0_ym18_1_1458793494416_5540"><img id="yiv3204014139yui_3_16_0_ym18_1_1458793494416_5551" style="width:100%;vertical-align:middle;max-height:406px;max-width:800px;" alt="motor cut away.jpg" src="cid:ZLxW1HuHGVrkxa5OaO8l" itemprop="contentUrl"></div></div></div><div id="yiv3204014139yui_3_16_0_ym18_1_1458793494416_5542"><br></div></div></div></div></div><br>_______________________________________________<br>Personal_Submersibles mailing list<br><a ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br><a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br><br><br></div> </div> </div> </div></div></body></html>