You guys know I don’t post Kickstarters, especially for 3D printers. But this one has actually got me interested. I laughed SO HARD at the water-cooled E3D they “built” using nothing but a punctured tube through some silicone tubing. The rest of the machine is equally interesting in that it uses a sandwich of aluminium, plastic, and aluminium to make these living hinges that they use all over the machine.
That, along with the little gimbals and stuff - I’m almost more interested in the material they’re using than the machine they built with it.
If the live hinges have a reasonable life-time they might actually have less play than conventional joints.
I am intrigued by the water cooling design, tempted to try it just to see if it’s actually sufficient.
There’s a lot riding on the performance of those living hinges, especially over time. Will that water tube leak at the heat break? I dunno, fingers crossed, hopefully it all works great and he has many happy backers (I don’t need a new printer, so I won’t be one of them). At least it’s nice to see a fresh approach to all the problems of making a delta kit and hotend.
A long time ago ( I think in the deltabot google group ) he posted about this and got a lot of skepticism. He did post long-duration tests of the hinges ( though we only have his word on the data ) that seemed to show it’s ok, however, he was super hostile to any form of inquiry, which seemed to me like a very bad sign.
He’s also pretty spammy.
I backed it because I like all the interesting design ideas in it. Living hinges are a better fit for this than you might think; most delta arm cycles are very small angular displacements that are hard on traditional bearings because they don’t have enough travel to wipe wear debris or build a good lubricant film. Infinite hinge life is entirely possible here.
@Brandon_Satterfield the theory is that all the torque will be at the hinges, not on the aluminum plates themselves, so fatigue should not be an issue.
Yeah, only polypropylene is bending, and it’s well-documented that PP living hinges of appropriate design can last forever. Marc Peltier (Zatsit guy) rigged up a hinge on an electromagnet and flexed it millions of times without failing.
I think you could probably get them to fail if you were milling, or bending them 180 degrees every cycle or something. But Delta 3D printing is a pretty benign application here.
@Ryan_Carlyle I guess that even if they don’t last forever, some year of lasting is still a reasonable time. I’m not sure that chinese bearing last much more before without worsening so much their performance… In my small experience of living hinges I have some PP tablets containers used almost every days since decades and still perfectly working. I know, there is not far same ammount of load on my hinges, but changing few hinges every 2 years I would be still happy in this design.
@Ryan_Carlyle have you seen any reference on fatigue and fracture data for polypropylene? The designer’s flex tests are curious but don’t seem to exactly model the loading. The lightweight hotend is one things, but how will the hinges last if they are holding up something heavy like a water cooled Chimera? I like the concept, and even if the parts have a finite life cycle, the advantages and benefits might be worth it depending on longevity.
@Dennis_P I read a living hinge design manual a while back. If the hinge geometry is reasonable and the PP molecules are oriented in an appropriate direction (ie meaningfully across hinge, not parallel to hinge) it can last forever with no fatigue or cracking. The molecules just slide right over each other.
The milled Hylite composite panel should be biaxially oriented molecules, so that more or less checks out. The other thing that will make a difference is whether the hinge cuts are radiused or sharp notches. I don’t know what the Zatsit is doing here.
@Ryan_Carlyle iirc, live hinge should be radius ed on one side, flat on the other, directionality matters. PP does experience hysteresis depending on strain rate and strain level. Live hinges typically don’t transmit transverse loads to the hinge and it looks like some of these hinges are subjected to a constant tensile force. While these forces may be small, the combined stresses of flexing and tension may lead to eventual failure. I don’t agree with the conclusion that test method shown in the video is accurate and feel that the conclusion is misleading. Cylces to failure might still be well beyond what most 3d printers will ever experience. I still think its inventive and ingenious.
PP living hinges in general SHOULD be capable of doing the job here
The high strain rate bend test rig reached a pretty reasonable number of cycles on an actual milled hinge, so we know milled Hylite is at minimum capable of making functional living hinges
A light-weight Delta FFF printer is a pretty low-severity usage case for drivetrain loads
Marc has been using this design in actual prototype printers for 1-2 years now
Given the novelty and cleverness of the design, and the datapoints above, I’m happy to back it just to get my hands on it
Reasonable people can differ on whether it’s worth the money for them. I think it’s a good concept, and the best way to see how well it works “in the real world” is to back the campaign and get a bunch of people running them.
@Ryan_Carlyle I watched the video and now I understand well how it works. Still may be it worth, I’m not so sure about watercooling system, seems something that will leak easily how it is designed.
