tag:blogger.com,1999:blog-23681518.post1965374548959261847..comments2023-10-14T04:05:08.546-07:00Comments on Diary of a Technocratic Anarchist: More printing large objects with HDPEForrest Higgshttp://www.blogger.com/profile/17208965471464716174noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-23681518.post-8155392575837585082009-11-15T17:09:02.885-08:002009-11-15T17:09:02.885-08:00Yup, that's the term. You see the effects whe...Yup, that's the term. You see the effects when you try to cut polypropylene sheet. Cutting releases the residual stress and the cuts can warp into some very weird shapes over a few hours to a few days.Forrest Higgshttps://www.blogger.com/profile/17208965471464716174noreply@blogger.comtag:blogger.com,1999:blog-23681518.post-68197078880509827212009-11-15T16:54:26.269-08:002009-11-15T16:54:26.269-08:00Residual Stess is the proper term as I recall from...Residual Stess is the proper term as I recall from school http://en.wikipedia.org/wiki/Residual_stressMike Fassbindhttps://www.blogger.com/profile/12951169230092598337noreply@blogger.comtag:blogger.com,1999:blog-23681518.post-18826203772335330562009-11-15T13:13:13.598-08:002009-11-15T13:13:13.598-08:00Bogdan, who posts in the forums at BitsFromBytes, ...Bogdan, who posts in the forums at BitsFromBytes, has said much the same thing. It makes sense to me.Forrest Higgshttps://www.blogger.com/profile/17208965471464716174noreply@blogger.comtag:blogger.com,1999:blog-23681518.post-36979141794098364242009-11-15T12:34:27.413-08:002009-11-15T12:34:27.413-08:00The reason I was thinking this route is because th...The reason I was thinking this route is because the guying technique (as far as my understanding goes, and could be wrong) does not actually eliminate warping.<br /><br />As I understand it the forces that create the warping are still embodied in the block. (Perhaps more so) A bit like a compressed spring.<br /><br />You are holding it in place until it has cooled sufficiently to resist the warping forces. Which are still embodied in the material.<br /><br />A bit like pre-stressed concrete the tension is maintained until the concrete sets enough to resist the stresses in the reinforcing elements.<br /><br />Interestingly enough they might actually be greater, as the components warping relieves the stresses that it embodies.<br /><br />To my limited understanding this has two effects.<br /><br />1. under certain circumstances if the component is used in a way that the uses the embodied tension to good effect it will give the part greater strength. But only in that mode.<br /><br />2. failure modes of the part may be other than as expected. IE it may appear to randomly delaminate and spring into it's own preferred warped state at a later time.<br /><br />I have got to admit that pre-stressed concrete is an overly dramatic analogy. Sorry. (Particularly as the failure modes of pre-stressed concrete can be spectacular)<br /><br />Thinking about the above is what prompted the original question. <br /><br />I guess ultimately without knowing what the magnitude of the captured forces are in real terms my thoughts could turn out to be irrelevant.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-23681518.post-45178754633157158982009-11-15T10:24:18.873-08:002009-11-15T10:24:18.873-08:00I tried heat treating HDPE prints with crosshatche...I tried heat treating HDPE prints with crosshatched infill some years ago with poor results. My parts just sort of collapsed in that I was using sparse infills.<br /><br />I think Nophead did some work like that, too. I can't recall what he found out, though.Forrest Higgshttps://www.blogger.com/profile/17208965471464716174noreply@blogger.comtag:blogger.com,1999:blog-23681518.post-21835037754131549572009-11-15T10:15:16.515-08:002009-11-15T10:15:16.515-08:00Out of curiosity.
Do you think it would help any ...Out of curiosity.<br /><br />Do you think it would help any to try and devise a heat treatment strategy (domestic oven) to relieve stress in the object. As a post printing thing.<br /><br />I have been recently reading a book on knife making and the author does a lot of heat treatment of the blanks etc at various stages in the making process to relieve the stresses set up in the material as part and parcel of the making. Not just annealing and hardening.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-23681518.post-2091318206142505762009-11-15T09:14:00.897-08:002009-11-15T09:14:00.897-08:00Yes, I wondered about that, too. I asked Jim Wari...Yes, I wondered about that, too. I asked Jim Waring at New Image plastics, however, and he said that he hadn't added anything, pigments or otherwise after the consignment was delivered.<br /><br />I can say this. It is transparent when it comes out of the extruder head when I am running the filament in before printing. ABS, otoh, stays opaque.Forrest Higgshttps://www.blogger.com/profile/17208965471464716174noreply@blogger.comtag:blogger.com,1999:blog-23681518.post-47789609712087071932009-11-15T09:00:30.329-08:002009-11-15T09:00:30.329-08:00You say HDPE, no additives but on the pics it look...You say HDPE, no additives but on the pics it looks whiter and more opaque than mine.nopheadhttps://www.blogger.com/profile/12801535866788103677noreply@blogger.com