illuminarti
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Posts posted by illuminarti
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Did you also check that the bed is properly pressed down onto the springs, and slid sideways to hold it in place, with the springs properly compressed? Sometimes the bed can slide sideways so that it pops up around the heads of the screws that are supposed to hold it down.
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For some reason the raw HTML format of your post is getting converted to text. I don't see a way to undo that automatically; it seems like its the forum's editor code not playing nicely with your browser. What browser and OS are you using?
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I think George was wanting to see the other end of the filament - where its been through the extruder drive. :smile:
Here's one I printed a long time ago - not a great print, but it does give you some idea of what is possible - it should look like this or better.
You mention the fan going on/off... it should come on, and stay on for the rest of the print. That's probably what you were indicating, but just in case, i thought I'd point that out.
Can you also show some pictures of the extruder drive, or maybe even a video of it turning and retracting etc - would be useful to be able to see your spring as well, if only to know what the new moulded piece looks like in use. :-)
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There isn't a separate 'fill' speed option on the ulticontroller. You can adjust the overall speed (perimeters, fill, moves) jsut my turning the knob when on the main screen, or adjust the flow rate by going into the 'tune' menu during a print. But you can't adjust the infill speed by itself.
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The gradual shifting in the Y-axis is probably due to one or other of the pulleys for the y-axis not being tightened properly. Check all the grub screws and make sure they are really tight - including the one on the stepper itself. It can be hard to tell which one is shifting - you can use a sharpie to make a mark on the pulley and shaft in order to better see if one of them is slipping.
What OS are you running Cura on?
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The infill is vulnerable to under-extrusion because it's only printing every other layer - the stripes go one way on one layer, and at right angles on the next. As a result the infill is mostly printing into thin air, except at the crossing points. As such, you're going to get poor infill when printing fast and/or with thin layers - again it's a failure to bridge properly, just as with the tops.
The problem with the top - as I've said a bunch of times now - is that the infill is too sparse, and you aren't printing enough solid layers to cover it up well. Make the top and bottoms thicker, or increase the infill percentage.
In general, when you take those things out of the equation, it sounds like you're actually getting fairly good results at slower speed - so again, double checking the alignment and tension of your extruder will probably get you the rest of the way.
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If you're printing at the same 100mm/s linear head speed, then a 0.1mm layer height is extruding half as much plastic per second than a 0.2mm layer height. The fact that reducing the volume seems to be producing better results makes me think that probably the problem, to the extent that there is one, lies in your extruder set up.
Are you locking the extruder pressure plate properly, with the lever on the bolt all the way at the bottom of the slot, and the lever rotated past horizontal? How long is the compressed spring on the back of the extruder?
Why would 0,1mm layer height at 100mm/s have no underextrusion and 0,2mm layer height would, isn't it the same amount of plastic squashed more or less thin ?
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Take a look at your filament when it starts going wrong... and look at the teeth mark spacing (as discussed here...). Are you seeing reduced spacing, or other problems perhaps related to over-aggressive retraction? Whether that is the cause or the effect would still be open to debate, but it might at least give you a way to quantify the effect that you are seeing.
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For initial prints, I'd start at 0.2mm layer height, and get everything dialed in at that layer height before going lower. You can still get *very* nice results at that layer height - only in very specific cases where I think the model will benefit do I go much lower than that.
You need to make sure that you have the fan on, and set a minimum layer time of probably 7 seconds or so, so that the lower layers have time to properly cool and solidify before the next is laid down. Try that, and see how it compares, then post more pictures!
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I've often wondered if there might not be a role for it in the print cooling fan system though... in order to cool and solidify the extrusion as quickly as possible....
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Additionally, I'd invest in some top notch filament from a reputable supplier and see if that makes a difference - the dimensional variability you posted earlier certainly isn't going to help.
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Try printing the same thing at half speed, and see if that helps. If it does, then your under-extrusion is speed/pressure related. Printing at 100mm/s with 0.2mm layers is marginal to begin with. If slower makes it better, take a look at the assembly of the extruder drive, and make sure everything is good. Maybe post some pictures of the teeth marks on your filament (outside of the Bowden).
Looking at the pictures, the bottom surface is much better than the top in general. This is because, as noted above, infilling at 100mm/s over the top of only 5% infill isn't going to work well. You need to have more infill for the surface to rest on and/or print more than 3 layers of solid to get a decent finished surface.
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Oh, eek. That's not good :-( Sorry that happened.
I haven't had that problem, or really heard much about problems with the Bowden attachment on the cold end of the tube... but evidently it does happen. Have a look on thingiverse for possible fixes. For instance, something like this might help... (once you're able to start printing again... perhaps you could clamp the block in place somehow long enough to print a fix? I'd be wary of glue as it might preclude taking it all apart later for other fixes/upgrades.
http://www.thingiverse.com/thing:40544
Oh, btw, I highly recommend getting the v2 extruder clamp upgrade with the spring-loaded pressure plate. It definitely solves a lot of problems, and would probably have helped in this case, by giving some room for the filament to slip back past the drive bolt when running excessively fast, rather than continuing to cram filament into the tube until something had to give.
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Also, looking at your photos, I see some problems with under-extrusion in some spots in the side walls of prints. This could be due to printing at too high of a volume... (if you're using Cura, what is your wall thickness/nozzle size settings, they can sometimes make things even worse).
Also, do you have the Joris and/or 'Skin' (half-height perimeter) settings turned on? Those can both cause defects in walls.
Perhaps it would be helpful for you to attach a sample gcode file here, or email it to me at gcode@fbrc8.com, so we can take a look at the settings, and see if anything unusual is happening.
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Is the 'under-extrusion' happening on the solid bottom layers of your print, or only on the flat tops? If it's on the bottoms, have you made sure your short belts haven't slipped again, causing backlash, as you discussed with George at the start of this thread? If not, then it may be volume-related under-extrusion as discussed below...
If it's mostly on the top surfaces, then I stand by what I said earlier - make your top and bottom skins thicker, and infill a higher percentage. Printing solid plastic over sparse infill never works very well, as there's no plastic underneath for the extrusion to stick to. You need several layers - I typically go for at least 4 or 5 - for all the gaps to fill in and get a smooth surface again. Your photos seem to show exactly this effect on the top - thin cratered spots.
Regarding speed and volume considerations, the fact that the Ultimaker can print at 150mm/s is irrelevant. It certainly can, and it can go a lot faster than that. In the right circumstances it can print at 250 to 300mm/s. What it can't do is fit more plastic through the nozzle than will be allowed by the viscosity of the plastic, the pressure that the extruder can deliver, and the size of the opening in the nozzle. For the stock nozzle, this limit is somewhere in the 8-10mm³/s range. Furthermore as you approach this limit, the pressure in the head builds to the point where the extruder cannot keep up, and under-extrusion occurs. The only way to print the fastest linear speeds is to lower the layer height proportionately, in order to keep the volume of plastic per second below the limit. Printing at 100mm/s and 0.2mm layer height is asking for 8mm³/s - right around that limit, and definitely where I'd expect you to start seeing under-extrusion. See my blog post for more details, and examples of the degradation in feeder engagement pattern that looks a lot like what was posted earlier in the thread. Even when the feeder is making clean marks in the filament, it may not be working as effectively as it should.
If your filament is the proper standard size, and the extruder isn't improperly set up or grinding, so as to deform it badly, then the standard bowden tube should be just fine. You want as little space as possible in the tube in order to keep the filament path as constant and predictable as possible. If you can't push the filament through the tube by hand (before it gets to the hot end) very easily, then there's probably a problem with your filament, not your tube.
Clogging can happen if dust and debris gets dragged into the nozzle, or if molten plastic gets forced under pressure into unheated areas where it can solidify and be unable to move back through the hot end. The former can be general dirt that gets stuck to the filament by static, or impurities melted into the plastic, or occasionally wood fibers and dust from the extruder drive. The latter (molten plastic in bad places) is particularly likely when printing very fast (in terms of volume per second) due to the pressure build up, or very slowly, due to the transmission of heat up the filament causing it to soften in areas where it normally wouldn't. In my experience, using the Ulticontroller or sometimes even a computer interface, to feed the filament when doing filament changes is an excellent way to cause instant blockages, as you can end up feeding at way too high of a rate, leading to very high pressures in the nozzle.
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Welcome to the Forum! I'm sure you'll enjoy your new printer. :-)
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What George said. Plus... it looks like the defects are mostly in areas where you're printing solid over the top of infill? If so, try increasing your bottom/top thickness to add a few more layers, to give you a better chance of filling it in.
Also you could try increasing the infill percentage a bit, so you have smaller gaps to bridge. You could try lowering the bridge speed in Cura (I think that slows down solid fill over sparse infill, as if it is bridging over gaps, but I'm not 100% sure).
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The gcode looks fine... I see that you're slicing with a first layer height of 0.3mm, but in your photos it looks a lot less than that, so I suspect that your z=0 position is wrong. Also, at the start of the skirt, it does an unnecessary 4.5mm de-retract (which is a bug in Cura), and yet I don't see any sign of major blobbing at the start of the skirt either. So I think that the plastic couldn't escape due to the closeness of the nozzle to the bed. And then this excess pressure build up is compounded by the fact that the printer thinks it's printing a 0.3mm first layer... pressure builds up, and then starts to squirt out in blobs.
Therefore I recommend you heat the nozzle, autohome the bed, and then carefully re-level the bed at each corner, and then try again.
Also, I noticed that you included multiple gcodes with different file names that included an 'Exxx' value in the name. Does this reflect you changing the E steps value in Cura before each slice? Because if so, it isn't doing anything. The e-value you specify needs to be included in an M92 Exxx command at the start of the gcode file - but it isn't there. I'm not sure exactly how/when Cura includes it - maybe you have to add placeholder code in the start gcode for it.
To be honest, the gcode of every print isn't the best place for it. It should be set in the firmware ok the printer and saved to EEPROM. If you have an Ulticontroller, it's easy to do (Control -> Motion). If not, then you can use Cura or pronterface etc to connect to the printer and issue the M92 command, followed by M500 to do the save. (Best do this on a freshly power cycled machine, so you don't also save any other temporary settings that got changed in the last gcode you printed).
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Ok yes, makes sense.
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Glad you got it fixed, Sam. Those are some really nice looking prints, btw.
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Does the retraction appear to happen? Do you see the gear wheel turn backwards when those moves are being made? Did you remember to enable retraction on the first tab of Cura?
Secondly, what firmware are you using? Is it one that came with Cura, or something newer you built yourself?
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No problem! It's just that you found the right (or, more to the point, wrong) combination of bed position, lower later texture, acceleration and direction to over-stress the loose pulley.
It happens to all of us at some point :-)
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I think this is also why sparse infill can sometimes be a messy- it's basically all bridging, if its a linear pattern on alternating layers. I get particularly good results in kisslicer when I do infill slower but fatter and for multiple layers at once. (Having a wider nozzle helps hugely with this).
In fact... If you are using linear infill that does lines roughly at right angles from one layer to the next... Shouldn't they be printed twice as fat, to allow for the fact that except at crossover points they're really needing to cover two layers of space? Does The new Cura do that?
I have to say I much prefer hex style infills that lay down the same pattern on each layer, but from different directions.
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I haven't done any testing, but my gut says that bridging is another area where the volume flow rate is the critical variable. Printing thicker layers and/or faster probably make for better bridges as it increases the ability to get the plastic to leave the nozzle cleanly. There's probably capillary and electrostatic/adhesive forces at the tip of the nozzle resisting the movement of plastic; at low flow rates those are able to resist the smooth flow of plastic needed for bridging, when there isn't a solid object below with its counterbalancing forces.
The downside of achieving the necessary flow rate through faster movement is the likelihood of tearing the filament bead before it hardens - leaving thicker layers as generally the best option.
why a dumping ground for all topics ??
in Coffee corner
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I also much prefer a single bucket, although I only ever use the 'View New Content' mode, which gives me that anyway, irrespective of where the items are originally posted. Since most posts/problems end up touching on some mixture of hardware/software/firmware/materials I'm not sure that artificially dividing up posts on the front end is particularly helpful.
The only division I would see as useful is having separate areas for posting in other languages. Since the only non-english language I can even begin to try and speak is French, I like being able to filter out posts from my 'View New Content' feed that I simply can't hope to contribute to.