skjbTHI
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Posts posted by skjbTHI
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Hello Ulitmaker community,
After taking apart the feeder for cleaning, putting it back together, and re-attaching it to the UM2E (a process I typically do once a month or so), I noticed that filament is being ground/stripped in the feeder, preventing any material from being extruded once the print starts - the printer will motion over the print area without printing anything. This seems to happen regardless of how tight the tension in the feeder is set. I've had it at max tension, min, and most stops in between, all with the same result.
Manually moving filament using the 'move material' command is no problem, as long as I'm not attempting to feed an already-stripped portion of the filament. Similarly, loading filament is no issue; the feeder will grab the material and advance it no problem, up to and including extrusion of said material from the nozzle.Prior to a print starting, as the machine is heating up, material will extrude from the nozzle before the print begins, as normal, up to the point where the print begins. At this point, the material promptly ceases extruding and won't start again. For reference, I print with PLA and Ultimaker tough PLA.
I've cleaned the nozzle using the atomic method (cold pull looked great), and the bowden tube is clean, leading me to believe this must be a feeder issue, but since no modification to the tension screw seems to make a difference, I'm scratching my head as to the cause of this problem. Any help would be appreciated.
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Hello,
I've noticed on a number of prints from our UMS3 that the first layer seems to be a bit uneven. When this happens on the corner of prints, I'm usually able to solve it with the typical anti-warping tips and tricks (adding chamfers to the 3D file, putting glue on the build plate, etc). But I've noticed more recently that it seems to be happening away from the print edges in some cases. In the attached photos, I think it's most clear in the blue print - tough to get a good image of this with the lighting in my office, but even in the gray prints (paused after first layer went down) I can see a few features which look to be uneven, not flush with the build plate. I've hypothesized that it could be due to uneven layers of glue on the build plate, but I have noticed this even after thoroughly cleaning the pate. For typical prints this isn't an issue—the blue part functioned fine—but there are other times when it seems this uneven-ness propagates through subsequent layers, or else times when we need the smooth bottom layer for the functionality of the print.
Since I have experienced significant warping issues when printing PLA on this UMS3, I typically make the following alterations to my initial layers:
Increase initial layer height (by roughly 20%)Increase initial layer flow (Cura default is 120% for initial layer, I up to 130%)
Initial layer temp +10 degrees from normal print temp
Initial layer build plate temp +5 degrees from normal
Initial fan speed of 0, regular fan speed at 0.65mm
Initial layer print speed roughly 25% normal print speed
Brim (with brim size increasing with print size)
These alterations have positively affected the warping isseus, but could these or other factors affect the "flush"-ness of the initial layer with the bed?
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On 10/6/2020 at 10:14 PM, gr5 said:
To save time, maybe also you could check the part for errors.
Cura has an amazing plugin to test your model to see if something is wrong with it and can repair a very few of the many potential problems:
In the upper right corner of Cura click "marketplace" and make sure you are on the "plugins" tab and install "Mesh Tools". Then restart Cura. Now right click on your model, choose "mesh tools" and first choose
"check mesh", then "fix model normals" and "fix simple holes" to see if that helps.When I attempt to select "fix simple holes", it tells me it cannot as it must slice first, even after the model is sliced. The "check mesh" tool indicates that the part is watertight.
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On 10/6/2020 at 10:10 PM, gr5 said:
Okay so I feel like you aren't showing us something. Please show in cura layer view what's going on? Is the second layer covering the hole in the first layer?
Actually if you could save your project and upload the project file here? In cura do "file" "save...". This will save your stl and rotation, position, settings, printer settings, overrides... everything such that one of us can duplicate what you are seeing.
I can't tell if the second layer is infill or support but it surely seems to be printing something on the second layer. I thought you were describing a problem on the first layer but now it seems it is a second layer issue? Or is it a 3rd layer issue?
Attached is the sliced file — I've replicated the settings to the best of my memory but as I'm out of office today I can't upload it from the USB directly.
From looking at the part as it's printing, it indeed seems to be a 2nd (or maybe 3rd) layer issue. The initial hole prints (and prints wider than designed, presumably due to the horizontal expansion settings), but it seems in the next few layers the nozzle extrudes directly over the hole. This seems to be happening on the 2nd and 3rd layers, and possibly further, but at some point the whole does extrude as designed. I've broken the part in half and it's apparent that at some point up the cylindrical base, there is a hole of ~1mm in the center.
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Just now, gr5 said:
I think you got it exactly. This is on purpose. If you don't squish the first layer extra hard, the part won't stick well which can be a disaster (e.g. head flood).
So the solution (for me) is to always set the "initial layer horizontal expansion" to around -0.3 for a 0.4mm nozzle. Typically you want it about half the nozzle width. But negative.
Now there are cases (e.g. gears in one case) where setting this to -0.3mm causes problems. But for me these problems tend to be rare. It depends on the model.
This was my first thought as well, and I went as far as setting initial layer horizontal expansion to -1 mm, which was the lowest Cura would let me. I would also note that on the previous print in which the hole printed faithfully, I didn't use any of the advanced settings in Cura.
I've attached two more photos of a recent attempt in which it's clear the hole is printing on the bottom layer (extra wide, presumably thanks to the initial layer horizontal expansion setting), but there appears to still be filament printing over it in subsequent layers. (the print looks extra messy because I had reduced material flow on the initial layer and forgot to return it to 100% later).
12 minutes ago, gr5 said:Another solution that I use a lot is to drill out vertical holes of critical diameter. The existing
hole in the 3d printed part makes for a good guide to get perfect holes every time. This solution is for vertical holes in general (not just first layer issues). Also I usually make hole diameters in CAD about 0.4mm larger than desired (for all sizes e.g. from 1mm to 100mm).
This is probably the best long-term solution, but I don't have a 1mm drill bit on hand at the moment :/.
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14 hours ago, Smithy said:
I think this could be the reason. If you really need such small things or holes that are in the neigborhood then you should consider to buy the AA 0.25 core for the S3 as well.
But give it a try and print the same model on the UM2 with the 0,4 nozzle.
Thanks for this. I'll look into purchasing a 0.25 mm core, but looking through old prints I found a print of this same model (which failed for other reasons) which printed this hole successfully, which leads me to believe the nozzle isn't really the issue.
What we've noticed is that it seems that the printer is explicitly filling in this hole in the first few layers. By manually reducing the material flow on the printer itself and pausing mid-print, we're able to see that the hole is printed initially, but that the printer keeps going over the hole after outlining it initially. It's unclear if the code is actually telling the nozzle to extrude material over the hole or if there's just a large blob that's falling out over it, but it doesn't seem that smearing is the main problem. I'm now of the mindset that this could be a G-code issue, though I can't figure out what exactly. Printing with lowered material flow is obviously not desirable as a long-term solution.
I've attached photos of the successfully-printed hole from a previous print, a photo of the first layer as it's being printed now, as well as a few images from the slicer.
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Hello,
Our office recently purchased an Ultimaker S3 to accompany our UM2E, and overall it's been great. One problem I've noticed though, is that when printing parts with small holes (in the neighborhood of 1 mm), the nozzle will smear the filament on the initial layer such that the hole is completely occluded. This effect seems to take place up the next few layers as well. It seems to be an issue with the nozzle being too close to the build plate, from what I can tell. I understand this is a desirable setup in terms of build plate adhesion, but I'm wondering if there's an adjustment to be made to allow for the printing of small holes.
I've adjusted some settings in cura in effort to fix this, but to no avail:
- Initial layer horizontal expansion has been minimized to -1 mm
- I've tried reducing initial layer flow
- Horizontal expansion (beyond initial layer) has been minimized to 0
It looks to be slicing correctly, and it seems that the issue comes when printing only on the S3. I'm able to print quite small holes on the UM2E, though there I'm using the 0.25mm nozzle rather than the stock 0.4mm AA nozzle that came with the S3.
Any suggestions would be greatly appreciated.
UM2E Feeder Stripping Filament Regardless of Tension Setting
in Improve your 3D prints
Posted
Quick update in case anyone else is searching for this issue. Turns out the feeder was functioning fine, but the bed leveling was off—the nozzle was far too close to the build plate and material couldn't be extruded, causing a backup in the feeder which resulted in the grinding. Problem was solved by re-leveling the bed. How the bed got pushed so close to the nozzle without me adjusting the level is a different problem but one for another day!