An attempt to investigate pressure in the extrusion system



  • For anyone who is interested, I've just completed an attempt to investigate the pressure in the extrusion system of a Diamond hot end and published my findings on my blog which you can find here https://somei3deas.wordpress.com/2018/01/15/an-attempt-to-investigate-pressure-in-the-extrusion-system-with-a-diamond-hot-end/

    Note that there is an accompanying video on YouTube. Neither the blog nor the video will make much sense on their own so they should be used in conjunction with each other.

    Note also that this work was carried out using 3 extruders concurrently and that the Diamond hot end is a mixing hot end and therefore quite different from other designs.

    There is one other thing I'd like to mention. Firstly, these tests prove to me that my hunch that asymmetric pressure advance might be a good thing to have is ill founded. My hunch was wrong at least according to the tests that I ran.

    Even if you have no interest in how pressure builds up, the blog and video in particular are worth viewing if you want to see a print head mass of around 4kg being thrown around at print speeds of up to 300mm\sec whilst producing what are are in my opinion, respectable results considering the speeds attained.

    Hope some of you find some of this of some interest.



  • Very nicely done! I appreciate you sharing the research. I was really surprised to see that 40 watts was enough to melt all that material that fast.



  • Great, detailed testing. Thanks for sharing that.

    John



  • @BDubs:

    Very nicely done! I appreciate you sharing the research. I was really surprised to see that 40 watts was enough to melt all that material that fast.

    Thanks.

    I think I read somewhere that the theoretical energy to melt the filament is low single digit watts, given enough time and good contact between the filament and the heated surface. Obviously time is limited when we are pushing the filament through continuously. The filament itself is a poor conductor of heat so it takes time for the heat to transfer from the outer surface to the inner core. This is why a mixing hot end is so good for high speed printing. Because we have (in this case) 3 melt chambers so the contact area between heated surface and filament is very much greater, and also because each filament moves at 1/3rd of the speed of a single melt chamber hot end, so the time in contact with the heated surface is 3 times greater.

    I've been shouting this from the rooftops for quite some time, but nobody listens so I've given up. One day, I'll put the 5 Colour Diamond on and see just how fast I can print with 5 melt chambers.

    Ian


  • administrators

    Hi Ian, regarding your comment "this free version of WordPress doesn’t allow me to embed Videos into posts (at least, I haven’t found a way of being able to do it)", I have a video embedded in mine. Just put the YouTube link on a line by itself. In HTML editing mode, mine looks like this:

    https://www.youtube.com/watch?v=xVrRGaeOiKA

    Note, no tags around it.

    HTH David



  • @dc42:

    Hi Ian, regarding your comment "this free version of WordPress doesn’t allow me to embed Videos into posts (at least, I haven’t found a way of being able to do it)", I have a video embedded in mine. Just put the YouTube link on a line by itself. In HTML editing mode, mine looks like this:

    https://www.youtube.com/watch?v=xVrRGaeOiKA

    Note, no tags around it.

    HTH David

    Hi David,

    Thanks for that but what I meant was that I can't put the actual video clip into the post like I can with still images. For sure I can put links to YouTube videos (which is what I have done) but it means that readers need to switch between browser windows (one for the post and another for the video).

    Edit. To upload videos directly to the site I get this message "To upload video files to your site, upgrade your plan".

    Ian



  • Yes, you can embed videos; I do it for the web site of a photoclub, running wordpress. I will retreive the needed extension.



  • @fma:

    Yes, you can embed videos; I do it for the web site of a photoclub, running wordpress. I will retreive the needed extension.

    Not on the free plan that I have. As above, if I try I get this message "To upload video files to your site, upgrade your plan".



  • Well, you don't really need to upload videos, just to link them. I'm not sure what they don't forbid you to do…

    Can you freely install extensions?


  • administrators

    @deckingman:

    @dc42:

    Hi Ian, regarding your comment "this free version of WordPress doesn’t allow me to embed Videos into posts (at least, I haven’t found a way of being able to do it)", I have a video embedded in mine. Just put the YouTube link on a line by itself. In HTML editing mode, mine looks like this:

    https://www.youtube.com/watch?v=xVrRGaeOiKA

    Note, no tags around it.

    HTH David

    Hi David,

    Thanks for that but what I meant was that I can't put the actual video clip into the post like I can with still images. For sure I can put links to YouTube videos (which is what I have done) but it means that readers need to switch between browser windows (one for the post and another for the video).

    Edit. To upload videos directly to the site I get this message "To upload video files to your site, upgrade your plan".

    Ian

    If you do what I suggested then it will embed them. See the one at the end of https://miscsolutions.wordpress.com/mini-height-sensor-board/ (before the Appendix and comments).



  • @fma:

    Well, you don't really need to upload videos, just to link them. I'm not sure what they don't forbid you to do…

    Can you freely install extensions?

    Yes, adding links to the videos that's is exactly what I do, because as I have said, the free version of WordPress does not allow me to upload them directly to my site. The link tool that WordPress supply is quite good in that you can add a link to the URL but then give that link a meaningful name. So instead of having https://www.youtube.com/channel/UCEMXNdKKMLIVwEqPvohKsng in the post, I can have something like "Click here to access the Linked Video". I can also change the behaviour, such as whether clicking the link opens a new browser window or not.

    No, I can't add extension either - just a limited number of themes, each with a limited number of options.

    For info, I use a paid version of WordPress for my main business web site, so I do know the difference. As my blog is purely for other people's benefit and I get nothing out of it, I'm not going to pay money for it. It's bad enough putting in the time. Of course, if someone else wants to cough up the annual fees for a paid site then I'll gladly upgrade 🙂



  • As said, you don't need to upload the videos on your blog ; recent wordpress releases allow you to embed videos just by putting the link (as David said), but previous ones need an extension. If you can't install it, then it is a problem.


  • administrators

    @fma:

    As said, you don't need to upload the videos on your blog ; recent wordpress releases allow you to embed videos just by putting the link (as David said), but previous ones need an extension. If you can't install it, then it is a problem.

    I have had that video link working for 2-3 years. So support for this feature in Wordpress can't be all that recent.



  • @dc42:

    If you do what I suggested then it will embed them. See the one at the end of https://miscsolutions.wordpress.com/mini-height-sensor-board/ (before the Appendix and comments).

    Hi David,

    Just tried it again and it doesn't work for me. All I get is the link words but not the window with a play button like you have.

    I think it must depend on the theme. If you recall we had a similar discussion about how my posts were indexed (or not in my case) and your suggestion didn't work on my theme. Changing the theme to something else, did however work.

    Ian



  • @fma
    It also depends on whether you are using WordPress.com or WordPress.org. WordPress.org means that you host the site so you can do pretty much anything you like. That's what I use for my decking web site. WordPress.com is hosted by Wordpress so they limit what you can do (or charge you money for the features you want). That's probably why the features available to me are limited - so that they can induce me to pay them money.

    @All. Can we leave this discussion for another time or someone start another post please. The pros and cons and what you can\can't do with various WordPress plans have nothing to do with pressure in the extrusion system.

    Thanks



  • @BDubs:

    Very nicely done! I appreciate you sharing the research. I was really surprised to see that 40 watts was enough to melt all that material that fast.

    Hi Ian, I was thinking the same thing about getting back on topic.

    I sell 50w heaters and they get you up to temp quicker but the wattage whilst maintaining temperature is 8-9w and will be the same whether you use a 50,40,30 or 23w cartridge. It's getting the heat into the filament that is difficult. Circumferential heaters might do this better than larger heater blocks.

    I'm sure a very long melt chamber would improve maximum volumetric throughput but would it decrease accuracy of extrusion? How differently does molten filament behave to solid? I don't know.



  • Ian,
    Thank you for all of your work to improve printing quality and speed. I found this blog and video very informative and clearly shows that pressure advance works really well for straight lines.
    Is pressure advance needed for circles, after all circles are made up of very small straight lines so I can't see how pressure advance could work and be effective in such a short time and distance.
    I wonder if it would be possible to only apply pressure advance for lines over a certain length?

    anyway, great work, thank you
    Paul
    PS I left this comment on the blog.



  • Ian, As always, I like the research you do to advance printing. Excellent work.

    I hope this isn't too far off the subject,

    So far my brief take on pressure advance (minimum user experience) is that it would be more accurate if it were applied by the slicing software instead of the controller board. The slicer software would be better suited to determine segment lengths and apply pressure advance as needed. Small round shapes would be recognized and adjustments made at the time of processing the gcode file.

    Just my opinion,



  • @timcurtis67:

    Ian, As always, I like the research you do to advance printing. Excellent work.

    I hope this isn't too far off the subject,

    So far my brief take on pressure advance (minimum user experience) is that it would be more accurate if it were applied by the slicing software instead of the controller board. The slicer software would be better suited to determine segment lengths and apply pressure advance as needed. Small round shapes would be recognized and adjustments made at the time of processing the gcode file.

    Just my opinion,

    And the Only Slicer I know that has this feature is Kiss 1.6.x although I believe they call it it Preload but it does work extremely well.

    Doug



  • @DjDemonD:

    Circumferential heaters might do this better than larger heater blocks.

    I just visualized a toroid shaped heater…that would be interesting and way more consistent than a lop-sided cylinder somewhere in the block. Aside from coiled induction heaters I haven't seen one suitable for our needs yet.

    This is interesting if you haven't seen it yet: https://3dplatform.com/extruders/ note that some models use 6mm filament. I was thinking about this while thinking of the diamond sucking in 3 filaments at the same time. I am wondering how they deal with enough melting and throughput. I am assuming they run higher wattage heaters.

    6mm filament is 4.5 times larger (surface area and volume) compared to 2.85mm filament. So there's 4.5x more to melt in the chamber.


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