<html><head></head><body><div style="color:#000; background-color:#fff; font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px"><div><span>Thank's Sean,</span></div><div><span>Well that sucks lol. My motivation with this idea was not just to save money. I thought it was a great way to have a thickened hatch area as if it was a cast part. It likely would cost more because I am sure at least one ring would be replaced from machining screw up.</span></div><div><span>Hank</span></div> <div class="qtdSeparateBR"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 13px;"> <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 Wednesday, July 12, 2017 8:41 PM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br></font></div> <br><br> <div class="y_msg_container"><div id="yiv9391344097"><div><div dir="ltr">I'm pretty sure that head forming would be cheaper. </div>
<div dir="ltr">Sean</div>
<br clear="none"><br clear="none"><div class="yiv9391344097gmail_quote">On July 12, 2017 8:37:10 PM MDT, "Sean T. Stevenson via Personal_Submersibles" <personal_submersibles@psubs.org> wrote:<blockquote class="yiv9391344097gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex;">
<div dir="ltr">Hank, the physics of this doesn't work. Within the shell wall, you have tensile or compressive (hoop) stresses, shear stresses, and bending stresses. Anytime you stress a material in tension or compression, you also induce stresses in the transverse direction. With thin-walled shells, you can make an effective approximation about the stress distribution being evenly distributed across the shell cross section. With thicker shells, this doesn't hold true. Bending and shear stresses are introduced even in a nominal geometry shell. With a sphere cut into slices, only compressive load which is perpendicular to the seams will carry across the gaps unaffected. At any angle of incidence, shear force is introduced which will not be carried through the interface unless sufficiently precompressed, just as when tensioning a bolt joint. These shear forces will not be borne by glue.</div>
<div dir="ltr">The solution is to make the interface surfaces coincident with the center of the sphere, just as when designing a hatch to replace shell material in a hole. Each ring in such a sphere would consequently have a different conical angle on each side. The difficulty would be in maintaining tight machining tolerances for concentricity and mating angle. You would also require some sort of external strapping / structure in order to both keep it all together, and bear any external loading which is not purely compressive. Also, the glue won't work if there is an extrusion path. Plan on metal to metal sealing between each ring, with an elastomeric backup at the outside of each seam.</div>
<div dir="ltr">Sean</div>
<br clear="none"><br clear="none"><div class="yiv9391344097gmail_quote">On July 12, 2017 6:50:44 PM MDT, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="yiv9391344097gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex;">
<div class="yiv9391344097yqt6441680846" id="yiv9391344097yqt97825"><div style="color:#000;background-color:#fff;font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px;"><div id="yiv9391344097yui_3_16_0_ym19_1_1499906747909_2507">Hi all,</div><div dir="ltr" id="yiv9391344097yui_3_16_0_ym19_1_1499906747909_2507">Today I had an idea that would not have been possible before I had a big lathe. I can buy a series of 4 inch thick rings and machine them flat, glue them together to create a sphere. The rings can be machined individually so when glued together I have a sphere. The beauty of this is I can have additional thickness where I need it, like the hatch land. The ring that makes up the hatch land can be thicker.</div><div dir="ltr" id="yiv9391344097yui_3_16_0_ym19_1_1499906747909_2507">Any reason this is a bad idea.</div><div dir="ltr" id="yiv9391344097yui_3_16_0_ym19_1_1499906747909_2507">Hank</div></div></div><div style="margin-top:2.5em;margin-bottom:1em;border-bottom:1px solid #000;"></div><pre class="yiv9391344097k9mail"></pre><hr><br clear="none">Personal_Submersib!
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