I think the other benefit to the single stacked belts was the ability to use milled aluminum plates for the bearing blocks instead of just 3d printed parts. The hope is that metal parts would allow for heated chambers for those of us who want to play with higher temp materials.
I think one of the design goals was to try and have most of the parts able to be milled instead of just 3d printed.
Skimmed through previous Printer build topics. Stumbled onto this pic again…
Was so fixated on the impressive cable lacing when I first saw this pic, that I didn’t notice other interesting details…
Didn’t realize how much weight loss can significantly increase accelerations possible.
Had to think on that one for a second…
also found this part very interesting…
Probably not ideal if super high forces are on the upper belt, but if there was only one belt, you could conceivably do this and not need an upper capture plate… but I like the idea of plates above and below. Any other info on how that vertical x rail attaches to that y truck?
That gets all the idlers easily sandwiched between two plates.
Good point.
bingo!
Every little bit. Those H2 extruders, the fancy one uses aluminum hardware and hollowing where ever possible, it brings it down 10% in weight.
I love all the machining that went into those printers the parts are gorgeous from mandala. I do not understand why they did not support the tops of all the pulleys (they are all double stacked with a very long M3). That is my one quip about it.
That X rail is set into the slot and there is an M5 screw coming in from the front to pinch it into place. Brilliant, a lot of machining and tapping I think.
I think I like horizontal here, the main reason being plate thickness is not fixed.
Secondary is less hardware to mount it to the trucks, we can get to the bearing screws and extruders screws at the same time, and I think the belt mounting is stronger.
I think I need to print a couple test parts to see if the split core with the belts in the middle is rigid or not.
something like this,
if it was in a printed part i could see possible issues. But its a steel bolt threaded into aluminum plate and the two belts are pulling opposite each other. I mean there is a difference of leverage but I cant see the steel caring at all about that. The belts are still the weak link for sure.
That being said, I do feel like it was an oversight that could have been dealt with pretty easily.
That is just it, they are not pulling opposite, they combine to pull towards the middle. -y and +y cancel, 45 degree +xy and 45 degree -xy vectors add and together to get 2Y
Even this rough, chunky version is pretty dang small. The two pieces seem to work well. With that lower half braced on the outside and touching the bearing block it is solid, and the top is nearly a straight shot.
I am feeling good about it. If I can get the belts in there, I am going to keep pushing forward. Unless someone sees something I don’t?
We know the Hemera fits, as well as anything with a 34mm (maybe even 28mm) or larger screw pattern height (80mm wide or less). I looked at the H2 as well since it is so tiny. And it will fit just like it did on the V4 screwed into the top and bottom instead of the side…ultra rigid.
Physics! Gotta love a FBD.
I usually get them wrong, ha.
Doing better than me. I don’t even know what FBD is lol
French Bull Dogs
Free body diagrams solve a ton of problems, the problem with them is it is simple to get the initial setup wrong. I school when we tested on them most of the time you did not even need to solve the equations you just need to draw the diagram to prove you knew which way things the forces were acting. I did very poorly in that class.
Ok then. I can see where that’s a tough one for sure.
I aced that class, but that is not always the indicator that matters.
If you can correctly make the free body diagram, and dimensional analysis, you can predict most dynamic interactions to a high level of certainty. Even a 3 body problem, which is notoriously complicated can be simulated with just these techniques (but breaks down after a lot of sim steps).
If you’ve seen me make those long equations to determine the steps per mm, that is dimensional analysis and it works in a lot of places:
16 microsteps / 1 whole step * 200 whole steps / 1 rotation * 1 rotation / 16 teeth * 1 teeth / 2mm = 100 microsteps / mm
It’s easier to see on paper. The units just cancel each other out. I don’t have that memorized. But if I am missing something like rotation/teeth then the units end up weird (microstepsteeth/rotationmm). It also helps to make sure you are dividing or multiplying correctly.
I chose a bachelor’s in Physics because I loved the 1st and 2nd year maths in Physics, which was all Newton and FBDs and Dimensional Analysis. No memorization or complicated terms. You could visualize everything. Once I got into the higher level physics courses, it all changed. It was Laplace this and Fourier that and surface integrals. Nothing was visual, it was all math models. But by then I was stuck. I chose a program where my nonthesis masters in electrical engineering would only be one year after the physics degree. So I kept at it. MS at 23 from Colorado School of Mines was a strong start. Then my first job was software in robotics which was only loosely related to EE and I never looked back
FWIW, my grades were always poor, because I was lazy (and working through college). But I aced the tests because I was interested in it. So I had a solid 2.7 GPA or so. 3.5 in grad school because it had less busy work.
This is still on topic right? Should we add a link to the Physics posts?
Whoo hoo!.. high five for the “underachieved because sick of school” club… (don’t tell my kids I said that)
Don’t tell me kids either. In my experience, it is easier to get lazier than the other way around. So I am starting them with a strong work ethic.
Okay, I had an idea for fixing the belts and keeping things as strong as possible. Not sure how to describe it so I am going to print out a quick visual aid. Instead of printing the center post to wrap the belt around (not ideal in this printing orientation), or using a piece of filament (a little to small), how about we use one of the M3x10 screws at each connection. It fits perfectly and it frees up a ton of room. It will not be screwed into anything but it will be trapped.
I taught my daughter this already. She used it on a math exam and her teacher asked her where she learned it. She’s a very visual learner and it helps her a lot with problems.
Sounds ideal.
