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aviphysics

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  1. aviphysics
    So, any idea about finding ~30 mN*m or greater Nema 8 motors in the USA? Just about everything I am finding is like this or worse. http://www.robotdigg.com/product/278/Nema8-High-Torque-Stepper-Motor I wonder if I could get away with putting 0.8 A on that motor.
  2. aviphysics
    Who do those guys think they are specifying holding torque in g cm? Sort of defeats the whole purpose of the metric system.
  3. aviphysics
    You probably don't want to allow the extruder motors to slip, which pretty much means they would need to remain energized. Thus the necessity multiple drivers. However, you could still potentially get away with multiplexing several stepper drivers to a single pair of step and direction lines. That would allow you to control 4 drivers with just 4 lines or 8 with 5 lines (and writing some code for merlin to handle that.)
  4. aviphysics
    With sufficient effort, it could be done on a UM2, but it would be greatly complicated by the fact that the UM2 does not have sockets for swapping out the stepper motor drivers.
  5. aviphysics
    You could use a temperature controlled soldering iron at a low setting to melt a bit of plastic on at either end, as a sort of retaining ring. The axial forces should be pretty small, so you just need a little bit of something to stop them from slipping.
  6. aviphysics
    It should not become deformed. It sounds like you should open a ticket to UM and get them to send you a replacement.
  7. aviphysics
    Is it possible your glass plate is not flat? If you put it on a smooth granite counter top (or other very flat surface), does it lay entirely flat?
  8. aviphysics
    Alternatively, can't you take a usb cable and cut the power wires?
  9. aviphysics
    Just decoupling the feeder from the chassis makes a huge difference. IME, the silentstep stick did not make a huge difference in the sound of retractions, but decoupling the feeder from the chassis did.
  10. aviphysics
    I imagine that in time, the design might start to include inserts for the mating surface. Maybe something sort of like the thorlabs design on their KB1X1 part (I hope that their design isn't patented.) I think the advantage of slightly over defining the coupling is that you have a little more insurance against wear. What I have found in practice, is that PLA will tend to work itself into a perfect fit over time. edit: Just thinking. For the inserts, on one side you could have a plate to trap the ball bearings and on the other side you could have a precision plate with slots cut for the ball bearing to mate with. Both plates could probably be relatively thin and fit on top of a 3d printed structure.
  11. aviphysics
    Could the difference just be the color? For example, this gizmodorks dark gray PLA filament I haven't been able to do much at all to stop it from stringing. On the other side of things, their clear PLA had almost not stringing at all.
  12. aviphysics
    What layer height do you typically print the hot end mounts at?
  13. aviphysics
    Interesting, but I think imperfections in the mesh might cause problems with retractions, as the secondary drive gear will suffer a small change in phase relative to the primary drive gear when the drive is reversed. This could cause too much destruction to the filament when the print requires many retraction along the same piece of filament.
  14. aviphysics
    I don't know. Robotdigg just often gets recommended as a source for cheap parts. No idea how good their linear bearings are.
  15. aviphysics
    Were the ones you bought from robotdigg?
  16. aviphysics
    That little drill is so adorable. Is it just for show or does it have any utility?
  17. aviphysics
    Very nice. I really need to get off my rear and build one of those direct drive extruders. Retractions are giving me such a hard time on my current project. Especially with Gizmo Dorks dark grey PLA. For some reason it is much more rubbery than their clear filament. I also wish that the person that made those would have designed them so each color could be printed standing by itself. Would just be cool to have them apart and together. Might make a good magic prop.
  18. aviphysics
    For the ulticontroller, is it possible the cables are switched? IIRC, plugging the wrong cable into the wrong slot will cause the ulticontroller to display strange symbols.
  19. aviphysics
    When something like that happened on my UMO board, all I had to do was replace the transistor; though that doesn't do anything about how much current the fan draws.
  20. aviphysics
    I wonder what the repeatability of a capacitive sensor would be. Might change depending on humidity or dust.
  21. aviphysics
    I missed that they are copper. You don't want copper bushing. Copper oxidizes in a messy way. That is why it is normally plated when used in connectors. However, I bet they are actually bronze. Copper bushings just doesn't make sense. Would still print your own blocks. Edit: it especially wouldn't make sense for sintered bearings, as the pores that hold the oil (the whole point of sintered bushings) would just clog with copper oxide
  22. aviphysics
    I believe so. IIRC, the UM2 design makes it difficult to remove the XY carriage without breaking the XY blocks. Also, they are designed to put tension on the belt, which isn't needed for a correctly sized GT2 belt. The Reptar blocks are the ones I use. They are lightweight and the GT2 version doesn't put tension on the belts. A lot of people like the Chopmeister Twister blocks, which make it possible to remove the XY carriage without disconnecting the XY blocks from the belts. IMO, they are both good choices. They are also a lot cheaper, if you can print them yourself. Printing them in ABS should be fine.
  23. aviphysics
    I don't know how to change it. I just measured it with an oscilloscope a while back. I do however have my doubts that changing the pwm freq will resolve the issue. I was thinking you could at least test an external power supply. If that resolves the issue, than we can put more effort into electrically isolating the pump, while still controlling through Marlin.
  24. aviphysics
    What area are you from? Maybe you can get someone to print some Reptar XY blocks for you. Also, if you are building from scratch, you might as well use 303 tooth GT2 belts for long belts, which don't require tentioning.
  25. aviphysics
    I know the default UMO hot end fan PWM frequency is 30 kHz. Could you try using a separate power supply?
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