tag:blogger.com,1999:blog-4339813531032979196.post3354117551751824512..comments2024-02-28T07:32:59.864+00:00Comments on HydraRaptor: Thermal gradientsnopheadhttp://www.blogger.com/profile/12801535866788103677noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-4339813531032979196.post-5639787214184989862009-01-24T00:27:00.000+00:002009-01-24T00:27:00.000+00:00Looking very nice.A thought on the funny measureme...Looking very nice.<BR/><BR/>A thought on the funny measurements: the thermal probe is probably just a stainless tube into which a thermocouple is potted. The 5mm offset might just be how far the thermocouple element is from the end of the tube...Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4339813531032979196.post-17588441990115126642009-01-13T20:30:00.000+00:002009-01-13T20:30:00.000+00:00Thanks those resistors look just right. Not sure i...Thanks those resistors look just right. Not sure if I can get them in the UK though.<BR/><BR/>I am also experimenting with some vitreous enamel ones that can handle 450C. I intend to drill a hole through an AL block and cement them in.nopheadhttps://www.blogger.com/profile/12801535866788103677noreply@blogger.comtag:blogger.com,1999:blog-4339813531032979196.post-55443716251984291832009-01-13T16:08:00.000+00:002009-01-13T16:08:00.000+00:00Thanks for that info Nop. I have compiled some of ...Thanks for that info Nop. I have compiled some of the results of the thermal model I built on my blog. I think that this design could work well, But I think that your previous design will have much better extrusion performance. I put an idea of how to insulate the screws on my blog.<BR/><BR/>I like the idea of using power resistors as the heater. I really prefer the use of cartridge heaters, but they are more expensive and generally are built to run of AC mains. You may look into the power resistors that have ceramic potting instead of silicone. The ceramic potted resistors seam to have higher operating temperatures. I can't find the one I was looking at the other day, but there are definitely resistors with higher temperature ratings. Like these http://www.heiresistors.com/PDF/TMC%20Spec.pdfgeo01005https://www.blogger.com/profile/05207244129346213313noreply@blogger.comtag:blogger.com,1999:blog-4339813531032979196.post-56714785064556783202009-01-13T09:34:00.000+00:002009-01-13T09:34:00.000+00:00Its a stainless steel 1/4" pipe with an ID of 3.6m...Its a stainless steel 1/4" pipe with an ID of 3.6mm. Threaded 1/4" UNF and screwed into the AL block.<BR/><BR/>I have to say that I tried pushing filament through it by hand and it was very hard work. I don't know why. It seems to jam where the stainless pipe enters the heater block.<BR/><BR/>I am refining my previous design at the moment as that at least works well. I am replacing the big aluminium flange with a stainless steel washer isolated with a PTFE washer.nopheadhttps://www.blogger.com/profile/12801535866788103677noreply@blogger.comtag:blogger.com,1999:blog-4339813531032979196.post-25095256414494631672009-01-13T00:26:00.000+00:002009-01-13T00:26:00.000+00:00Wait I'm confused, if the tube from the heater up ...Wait I'm confused, if the tube from the heater up stainless steel or aluminum? I can't quite tell from the picture, but you used the thermal conductivity for stainless in your heat loss equation. I'm trying to duplicate your results with a 1D lumped mass thermal model. I would like to verify my results with your data.geo01005https://www.blogger.com/profile/05207244129346213313noreply@blogger.comtag:blogger.com,1999:blog-4339813531032979196.post-37733977787428602722009-01-12T14:44:00.000+00:002009-01-12T14:44:00.000+00:00Nop,Very nice, *quantitative* results; thanks for ...Nop,<BR/><BR/>Very nice, *quantitative* results; thanks for putting this info up. <BR/><BR/>I had planned to put a substantial heat sink above the constriction in my stainless stem, but I have an interference issue with one of my insulated standoffs for my nichrome. It seems reasonable to me that (without a heat sink to load the constriction's thermal impedance), eventually heat would travel up my stem. I probably didn't run it long enough to fully test that. <BR/><BR/>-- LarryLarry_Phttps://www.blogger.com/profile/17543327228811365805noreply@blogger.comtag:blogger.com,1999:blog-4339813531032979196.post-17377930657234163892009-01-11T16:13:00.000+00:002009-01-11T16:13:00.000+00:00I looked around for high temp spacers but didn't f...I looked around for high temp spacers but didn't find any. I didn't know PTFE ones existed. They don't seem to be available in the UK and McMaster-Carr don't ship here.<BR/><BR/>I could make some though, or some PEEK ones, which would be stronger.nopheadhttps://www.blogger.com/profile/12801535866788103677noreply@blogger.comtag:blogger.com,1999:blog-4339813531032979196.post-32008185729055408082009-01-11T15:53:00.000+00:002009-01-11T15:53:00.000+00:00Just a thought here on your last extruder design: ...Just a thought here on your last extruder design: Why not include a PTFE bushing/washer between the stainless screws and the mounting flange? Something like McMaster-Carr part number 93835A330. Either that or some other highly insulating washer/bushing?geo01005https://www.blogger.com/profile/05207244129346213313noreply@blogger.com