<html><head></head><body><p dir="ltr">Were your heads supplied as perfect hemis, or with a length of flange? Weld prep? How close to the rim is the defect? A photo would help.</p>
<p dir="ltr">Sean<br>
</p>
<br><br><div class="gmail_quote">On October 22, 2015 6:05:19 PM MDT, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<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_1445557973610_2827"><span>Sean,</span></div><div id="yui_3_16_0_1_1445557973610_2827" dir="ltr"><span id="yui_3_16_0_1_1445557973610_3013">This is a new project, and I am exploring this option because of the imperfection in the pressed heads I got for my pod. EE told me they can not press a smooth head without this </span>imperfection. The imperfection does not go away until a thickness of 2 inches. The problem stems from changing the die's. </div><div id="yui_3_16_0_1_1445557973610_2827" dir="ltr">My plan is to have the pieces cut and pressed and will fit over a head that I already have, the head I have will be cut to act as a jig. </div><div id="yui_3_16_0_1_1445557973610_2827" dir="ltr">My preference is to use two semi heads of coarse, but I am concerned over
this wrinkle in the heads. I could overlay weld and grind smooth as the imperfection is quite shallow, maybe 1\16 in. other than this wrinkle, the heads are deadly accurate.</div><div id="yui_3_16_0_1_1445557973610_2827" dir="ltr">I will post a picture of the imperfection, </div> <br /><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, October 22, 2015 5:11 PM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br /> </font> </div> <br /><br /> <div class="y_msg_container"><div id="yiv9103381972"><div><div dir="ltr">For segmented construction, instead of full hemispheres, you
only need dished heads of the same radius as your sphere and sufficient diameter to encompass all of the vertices in the segment.</div>
<div dir="ltr">I would refer to this as a "dished-only" head, and am unaware of other industry terms. Of course, you only really get the benefits out of segmented construction when you have good control over thinning, and pressing is preferable to spinning for that reason, if your press can accommodate your required diameter.</div>
<div dir="ltr">Sean<br clear="none" />
</div>
<br clear="none" /><br clear="none" /><div class="yiv9103381972yqt2142342061" id="yiv9103381972yqtfd55180"><div class="yiv9103381972gmail_quote">On October 22, 2015 5:02:45 PM MDT, "Sean T. Stevenson via Personal_Submersibles" <personal_submersibles@psubs.org> wrote:<blockquote class="yiv9103381972gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex;">
<div dir="ltr">What are you making?</div>
<div dir="ltr">As I mentioned, the DW hulls are segmented according to a cube projection, so a complete sphere would have six segments / sides and eight vertices, and three times the welding (and subsequent 100% NDT inspection) that two hemispheres would require.</div>
<div dir="ltr">You need a template for cutting, and an accurate jig for welding them together.</div>
<div dir="ltr">Did you get hemispheres supplied out of spec? Or is this a new project?</div>
<div dir="ltr">Sean</div>
<br clear="none" /><br clear="none" /><div class="yiv9103381972gmail_quote">On October 22, 2015 4:15:08 PM MDT, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="yiv9103381972gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex;">
<div style="color:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px;"><div><span>Sean,</span></div><div dir="ltr" id="yiv9103381972yui_3_16_0_1_1445551920035_2874"><span id="yiv9103381972yui_3_16_0_1_1445551920035_2873">Do you know how many sections a DW hull has and what is the technical name for what I want to do. I will ask EE if they will make the pieces. I think Dr Nuytten calls them woks? I want to sound like I know what I am talking about :-)</span></div><div dir="ltr" id="yiv9103381972yui_3_16_0_1_1445551920035_2872"><span>Hank</span></div> <br clear="none" /><div class="yiv9103381972qtdSeparateBR"><br clear="none" /><br clear="none" /></div><div class="yiv9103381972yahoo_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="A! rial">
On Thursday, October 22, 2015 12:27 PM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br clear="none" /> </font> </div> <br clear="none" /><br clear="none" /> <div class="yiv9103381972y_msg_container"><div id="yiv9103381972"><div><div dir="ltr">That's just a construction. Any regular polydehron that fits in your sphere can be used as a guide. Nuytco uses a cubic projection, so if you imagine a cube where all of the vertices touch the sphere, the weld lines are the great circle routes between vertices.</div>
<div dir="ltr">If two hemispheres don't work for you, the next lowest part count you can go to is four, corresponding to the tetrahedron projection.</div>
<div dir="ltr">Sean<br clear="none" />
</div>
<br clear="none" /><br clear="none" /><div class="yiv9103381972gmail_quote">On October 22, 2015 11:49:51 AM MDT, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="yiv9103381972gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex;">
<div class="yiv9103381972yqt4325772942" id="yiv9103381972yqt51135"><table cellspacing="0" cellpadding="0" border="0"><tbody><tr><td colspan="1" rowspan="1" valign="top"><div>Sean, do you have a program that will disect a sphere into equal sections like the DW. I am looking for a way to cut hemis into equal sections to create a new sphere. When we buy heads they have full cerumference dent caused from changing the dies. I am thinking about buying three heads to make one perfect sphere.</div></td></tr></tbody></table></div><div style="margin-top:2.5em;margin-bottom:1em;border-bottom:1px solid #000;"></div><pre class="yiv9103381972k9mail"></pre><hr /><br clear="none" />Personal_Submersibles mailing list<br clear="none" />Personal_Submersibles@psubs.org<br clear="none" /><a rel="nofollow" shape="rect" target="_blank" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"
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