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Posts posted by msurunner

  1. /edit: Oh, one thing: It could be a feeding problem if your extruder is pulling on the filament but the spool doesn't move on the holder until the force is high enough, making the spool "pop" and unwind a little. Then the tension starts building up again until the static friction is overcome again -> "pop"...

    It could be that you get some underextrusion every time before the spool pops.

    This should be easy to observe. I've got that phenomenon with the "popping" spool all the time, but until now I've not been able to make a definitive connection to sporadic underextrusion.

    I guess my case is more related to uneven diameters of the filament, but that shouldn't lead to completely empty lines...


    That would be my guess. I see that from time to time on my prints. Usually seems to be a by product of either being slightly off on filament settings (either too cold or slightly over extruding, generating pressure on the extruder eventually) or too tight of a coil on the filament generating too much friction in the bowden. Try cleaning the drive bolt and check to make sure there aren't any straggler dust/grind particles or filament threads in the bowden tube and bump the temp up a bit if you notice it mid-print.


  2. Here's my opinion on the matter, FWIW. If you are planning on a multiple hotend setup, a 1.75mm filament is better for the fact that the smaller diameter filament/bowden acts as less of a spring force against the positioning system. For a single hotend setup, I would prefer a 3mm setup for the following reasons. There is less surface area to volume on a 3mm, meaning that for x volume of plastic you will receive slightly less friction force to overcome in the bowden tube. It also acts as a slightly larger plunger/ram in the semi-hydraulic system that we essentially create. While I don't have the numbers to back it up, my gut says this would be beneficial with retractions in a properly setup hotend. Third, a 3mm setup offers more surface area for a drive system and acts more like a rod, giving a bit more "control" to the extrusion. Now, I think you can get away with a 3mm dual extruder setup on an UM because the drive system is actually quite stout, but some other systems, such as a Rostock, are not conducive to 3mm multi-extruder setups.


  3. Perhaps the biggest question is what is leading you towards attempting to produce your UM versus some of the various other designs out there? Are you a fan of the highly touted precision or the highly touted speed? To increase one kinda decreases the other unless you want to spend more... If you are looking to build as precise of a machine as possible, then yes, go ahead and buy the .9* step motors, alter the firmware (x/y steps/mm and lower the max acceleration and jerk settings) and print slowly enough to realize some benefit (FWIW, I think it's going to be minimal). If you want to be able to produce fairly high precision parts and at a higher speed than most printers, use the 1.8* steppers and just make sure your belts are tight.


  4. Fundamentally speaking, yes, .9* steppers are more precise by a factor of two. Now, are you going to realize the added precision in actually prints? Most likely not a whole lot, especially if you want to print with speed. Microstepping 1.8* steppers still provides a very precise movement that is actually more likely limited by belts/belt tension than the stepping.


  5. Cable stretch introduces backlash, and backlash contributes to a number of problems including fills not properly filling, and dimensions not correctly printing. Honestly, the best means of "simplifying" for the sake of accuracy that I've been able to uncover is SG's direct drive conversion. The other option you would have would be to modify the gear ratios of the pulleys, but that has consequences on speed. For what it provides, the UM is a highly accurate FDM printer. If you need more accuracy than what a well built and calibrate UM provides, you likely need to consider some sort of SLS or SLA printer.


  6. I have been thinking that one of those camping mattress inflatable pumps would be a decent means of moving a lot of air quickly and it's already designed to work with some sort of tubing setup. I'm assuming that's similar to what you have running on your's foehnsturm? BTW, I'm getting our budget numbers shortly and then I think I can order up a set of those pulleys if you're doing another order...


  7. Yeah, the Eiffel Tower requires your retraction to be dialed in well. Print a couple hollow pyramid calibration cubes/pyramids to get your retraction where you want it before attempting unless you are extremely confident and ambitious! Yoda is a fun one to print that doesn't require a lot of work to print well aside from getting your temp settings close (important for retraction as well) and it can be printed without infill and 3 perimeters.


  8. 9/10 it is the pulley on the stepper motor the small belts are connected to. You could test that by making an index mark on the pulley and stepper motor shaft with a pen and seeing if it has slipped after a print (obviously just do a small one to see so you aren't wasting plastic).


  9. I simply look at the skirt, that's why I was critical of those two areas in the skirt. Making the skirt further from the part and multiple lines give you a bit more time and distance to eyeball it. As the skirt is printing I adjust the screws as needed. This tends to work very well as I'm usually within a half turn on at most two screws from part to part. Plus, going all crazy with a dial or feeler gauge is faaaaar too time consuming in my opinion for what I'm doing because the only way it would be relevant would be to do it before EVERY part as every time you take one off the build platform, the platform is going to change. Slightly, yes, but it will change a bit. Most times you can print again without an adjustment, but if doesn't immediately pop off, you would want to re-calibrate. I have found that just adjusting it as the skirt is printing gives me more than adequate results, and quick enough to understand that I can teach a student within two or three prints how to get it close enough to print that I don't have to babysit them the entire time. There's no way I'm having them mess with a dial gauge or feeler gauge and having it be as easily understood as quickly as it is. Like I said, just look for a consistent line on the skirt and you are golden, with the top right of the photo being the part that I would strive to achieve all the way around (if it is indeed different). If the photo slightly misrepresents what the skirt looks like, then you are good to go. If you do want to go after the dial/feeler gauge, Amazon is your best friend.


  10. Reflashing the firmware will reset the memory AFIK, so you don't have to delete anything. It's been a couple months since I was super active (school teacher enjoying summer break) but when I left, Daid's Marlin-builder was down temporarily as he was working on dual extrusion and Cura upgrades. It may be back online and someone can link to it here, or the old link (search "Marlin builder") may still be the active download location. If not, you could search for an older version of Cura (version 12 is still available in the older/testing downloads section) and seeing if it's a package thing, though I'm doubtful any changes have been made in the actual firmware from 12 to 13. All the same, you may be at a frustration level where trying anything is an option.

    Also, not that it will probably make any difference, but how are you asking the UM to read g-code? Via USB or SD on the Ulticontroller? I know there were some issues users discovered when trying to manipulate things with the Ulticontroller while USB printing that I don't know were resolved as the Ulticontroller's primary function is to remove the necessity for the USB tether...


  11. Like I said, you really are very close, I was just nitpicking! If I was to suggest something more substantial I would say try to limit the stringing (that stuff inside the holes) by turning your speed up a notch and seeing how that affects things. There are a couple more things that you can try with regards to retraction, but on such a small spread, speed would be my first move.


  12. Thanks :) Looking at the inconsistency of the skirt line, I would say you have some slight bed level issues. Bottom right looks too low (looks like the extrusion slid across the tape) while the top left looks too high (extrusion color change indicating the layer is slightly thinner there). Obviously the part printed and stuck to the bed so you are very close on that and any issues after the first two layers are going to be something you are going to want to adjust in the slicer, with either speed or jumping into the advanced settings.


  13. (Cure? Cura? Ha ha?) :)


    That's actually kind of the thought process behind how Daid named the program.

    Okay Martin,

    So you confirmed that the switch IS actually interrupting/connecting current flow? I would think that the simple solution to get you up and running immediately would be to swap limit switches from the bottom limiter to the one in question and see if that "solves" the problem. If it doesn't, then there is likely an issue somewhere in the cable/board as the software SHOULD be good. Be sure the cable wires are twisted to avoid interference. Then outside of that, the board would be my only guess, however, UM has been quality checking them (correct me if this is no longer the case Sander) before they leave the door. That's not to say shipping could have damaged it, but that seems more unlikely than a switch getting jostled or developing a case of infant mortality.


  14. I've been doing as Nick suggests for a long time. It just takes a bit of a trained eye to notice what the proper line width should be as it's printing, but it is easy enough to pick up. Basically, unless my first layer is really having trouble sticking, I am just checking to make sure the fill looks like this - - - - - , not -^-^-^-^- (bed being too close and pushing excess PLA into the line next to it then upward) or -v-v-v- (bed being too far away, causing a line that is too tall and not pushing the PLA out to the width expected for the volume). Of course, that requires that your steps per E is pretty dang close to the value it needs to be. If you think it is, just give yourself a couple of one/two layer prints with some fill in them and a skirt to start picking up on what the proper line width should be. Also, a darker color is easier to pick up on the tape/platform as it can look more opaque if the layer is too thin...


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