tag:blogger.com,1999:blog-4339813531032979196.post690694052996842903..comments2024-02-28T07:32:59.864+00:00Comments on HydraRaptor: Die swell revisitednopheadhttp://www.blogger.com/profile/12801535866788103677noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-4339813531032979196.post-3805963805229890572007-10-03T14:45:00.000+01:002007-10-03T14:45:00.000+01:00That's what seems to be implied. I'm not sure, th...That's what seems to be implied. I'm not sure, though. As you said some time ago, die swell seems to be a pretty complicated phenomena.Forrest Higgshttps://www.blogger.com/profile/17208965471464716174noreply@blogger.comtag:blogger.com,1999:blog-4339813531032979196.post-18683239175494221192007-10-03T10:00:00.000+01:002007-10-03T10:00:00.000+01:00The thermal expansion during warmup gives about 0....The thermal expansion during warmup gives about 0.9mm filament on my system.<BR/><BR/>I think I understand this now. The deeper the hole and / or the faster the feed, the more pressure required, the more die swell. <BR/><BR/>When the hole is as short as yours, i.e. shorter than its diameter, the die swell becomes insignificant compared to the hole size.nopheadhttps://www.blogger.com/profile/12801535866788103677noreply@blogger.comtag:blogger.com,1999:blog-4339813531032979196.post-75441724763886987132007-10-03T03:41:00.000+01:002007-10-03T03:41:00.000+01:00Okay, let's compare notes. I was getting pretty c...Okay, let's compare notes. I was getting pretty consistently 0.8 mm with the last extruder barrel. <BR/><BR/>With the new one I did a direct drill without pecking and I'm pretty sure that I've got a 0.5 mm orifice. It's been drilled through a dimple in a 0.127 mm copper sheet (0.005 inches).<BR/><BR/>I let the extruder barrel heat up and the HDPE extrude by thermal expansion only and got a HDPE thread without stretching of about 0.635 mm.<BR/><BR/>I also ran the system at several mm/sec extrusion rate and got 0.584 mm. I'm assuming that the smaller diameter is due to gravity driven stretching of the filament near the extruder before it had a chance to cool.<BR/><BR/>As best as I can conjure the difference between our respective systems lies in the fact that your extrusion hole, at ~1 mm is just a shade under 8 times deeper than mine.<BR/><BR/>Mind, this doesn't set aside the potential for differences between the feedstock HDPEs that we are using.Forrest Higgshttps://www.blogger.com/profile/17208965471464716174noreply@blogger.com