Why am I having to run with an extrusion multiplier of 60%?
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@Nyl0cke:
Are you 100% sure the nozzle diameter in your slicer is correct? I have a J-head that I thought was .5mm but it turns out it was much smaller than that and the first couple layers of the print I did with .5mm settings came out funny (the increased pressure caused the material to wiggle out like a snake causing some funky waviness)
Measured with drill bits (measured the drill bits with calipers). A 0.5mm drill goes in, a 0.6mm doesn't. I guess it could be 0.55 or thereabouts. Tried setting the nozzle diameter to 0.6mm in Slic3R - result just the same. (Thanks for the thought though).
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But what I can't get my head around is that the extruders deliver exactly what is being asked of them - all 3 of them. i.e. I ask for 100mm to be extruded that's exactly what I get (well with a percent or so). That's by doing the "normal" 100mm test both with the hot end disconnected and with the hot end connected but heated. Also, if I mark the filament at 500mm, then print an object which should use 417mm of filament, then measure the filament again, it's within a percent or so of 417mm (but the finish is god awful - covered in blobs, lumps and stringy as hell with the nozzle dragging over the previous layers). Drop the extrusion down to 80% or so and all is sweetness and light.
Just doesn't make any sense…........
Its a slicer setting somewhere
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I have a feeling it's infill that's wrong and I have a feeling it's accumulative, as if each layer adds a bit more to the problem. Just observing with the naked eye, it looks as if the infill is always proud of the perimeter and gets a bit worse with each layer. It's very noticeable on the topmost layer. Strange though that Slic3R default settings do the same thing as S3D default settings. Also strange that I can use the same Slic3R settings that I used to use on my old RRP Mendel which worked well, but don't work on this machine. I have them set to default again at the moment but I'll try setting the same nozzle width and speed for perimeter and infill in Slid3R (but I'm sure I've done that before). Manyana - it's getting late.
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Here's mine.
I'm running a Zortrax M200 converted to DuetWifi and PanelDue. Both are running latest firmware that isn't beta.
The direct extruder in these is extremely reliable, and the hotend is a common aftermarket called Z-temp than runs a Mk8 0.4mm nozzle, also very reliable.
Extruder steps/mm works reliably and consistently at 120 steps/mm @ 600mA. Never a click/jam/skip, always been bulletproof even before the conversion.
Pics below are generic ABS at 235 degC. I initially thought only minor changes would be necessary:
After speaking to Deckingham, I went harder at it:
For my money it seems that lower than 85% shows signs of under extrusion, in that I think I can see the previous layer.
I don't really care what the value is, I just want the best surface and would rather keep the actual steps/mm set at an accurate figure.
Please let me know your thoughts as to which surface looks best to you.
Sorry, should have said that's 0.2mm layer height with width set at manual/0.48mm. Filament was measured in 5 places and averaged to 1.714mm. I hope to use the extrusion setting across all other layer heights without going through all this process for each variation.
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My twopence worth - difficult to compare with the lines being orientated in different directions (also looking at the real thing with the naked eye is better than photo's). If I had to make a choice, my personal favourite is 80% - just they way the infill joins to the perimeters. It does look to me that with higher extrusion multipliers the infill is raised above the perimeters (something that I'm seeing too) but we'd need some close ups looking sideways on, which might be difficult to achieve. I guess you are in the best position to make that judgement (sorry - that wasn't very helpful was it?).
It could be that whatever the reason, it might be different for other filaments or temperatures or speeds (not that I've observed any difference with speed and temperature with respect to this issue) or some other setting that we have not yet tried, so personally I think keeping the steps per mm and changing the extrusion multiplier is the best approach.
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Are these all with 100% infil? I think what you are seeing is what was mentioned previously about filament packing.
For background reading I recommend Nophead's blog post about this here:
http://hydraraptor.blogspot.co.uk/2011/03/spot-on-flow-rate.htmlAlso interesting but for a different but not totally unrelated issue see this:
http://hydraraptor.blogspot.co.uk/2011/02/polyholes.htmlNot that when Chris was writing these the slicer used was skienforce which is now truely prehistoric. It did alow for significant customisation of how the Gcode was generated. Later slicers had abstracted this a bit more.
The potential issue with simply dropping to 80% flow is it affects a wide range of things. Such as hole sizes, layer adhesion etc.
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Are these all with 100% infil? I think what you are seeing is what was mentioned previously about filament packing.
For background reading I recommend Nophead's blog post about this here:
http://hydraraptor.blogspot.co.uk/2011/03/spot-on-flow-rate.htmlAlso interesting but for a different but not totally unrelated issue see this:
http://hydraraptor.blogspot.co.uk/2011/02/polyholes.htmlNot that when Chris was writing these the slicer used was skienforce which is now truely prehistoric. It did alow for significant customisation of how the Gcode was generated. Later slicers had abstracted this a bit more.
The potential issue with simply dropping to 80% flow is it affects a wide range of things. Such as hole sizes, layer adhesion etc.
These are all done the way I was instructed by David.
The multiplier was set to 1.0/100% in the slicer, then I used the extrusion slide bar in the DWC to drop 5% per square until I was happy with the surface, then use that setting in my slicer next time around.
I think 85% leaves plenty of meat there, but meets the level of the sides pretty much smoothly.
I'll read the links, but what do you think of the surfaces in the pictures? Which setting would you use?
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If I read nophead's blog post correctly (I have to say I got a bit lost in all the technicalities) it seems that he concluded that the optimum flow rate for infill was about 5% more than for perimeters. If I instigated that, it would make my situation worse because as near as I can tell, the infill is what is being over extruded. I have to say that I'm about to give up and just accept that it is what it is. The 200 colour vase that was printed at an extrusion factor of 0.70 looks OK finish wise and it survived a drop of about 4 feet onto a wooden floor without any sign of damage so layer adhesion is fine too.
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Corexy
I agree with you about the surfaces of the pictures - What I think it that 100% infill overfills by default because of slicers not taking into account the filament packing issues that Chris talks about in the flow rate post. My solution generally is to use 100% flow rate and not use 100% infill except for top and bottom skins. I am not saying that doing this is better, just trying to narrow in on the root cause.
Ian - Chris had the advantage of being able to specify things like the amount of overlap between different printed lines which I am not sure you can do in S3d or Slic3r - you can't in the version of cura I am using
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Tony,
Slic3r has an Infill/Perimeter overlap setting. Default is 15%. I've played around with it but haven't found a value that works any better.
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Corexy
I agree with you about the surfaces of the pictures - What I think it that 100% infill overfills by default because of slicers not taking into account the filament packing issues that Chris talks about in the flow rate post. My solution generally is to use 100% flow rate and not use 100% infill except for top and bottom skins. I am not saying that doing this is better, just trying to narrow in on the root cause.
Ian - Chris had the advantage of being able to specify things like the amount of overlap between different printed lines which I am not sure you can do in S3d or Slic3r - you can't in the version of cura I am using
Bugger, I should have mentioned that was only 20% infil.
I've now read you are supposed to print a 20mm cube at 100% to set extrusion??
Bloody fickle all this.
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Corexy - no not necessarily - I just assumed you had printed them at 100% infil.
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FYI you can also set the overlap percentage in S3D.
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Bugger, I should have mentioned that was only 20% infil.
I've now read you are supposed to print a 20mm cube at 100% to set extrusion??
Bloody fickle all this.
You don't have to do what anyone else says you are supposed to - many people have their own way of doing things - whatever works best for you.
What makes a good print? To me, it needs to have a good surface finish, be the right size and shape, and have good layer adhesion so it doesn't fall apart. I don't really give a crap about what the infill is like, as long as there is enough of it to do the job and that it doesn't affect the perimeters that go, around and on top of it. That's why I like to evaluate the surface finish and from what I've been doing throughout this thread, it seems to me that the surface finish is improved (in my particular set of circumstances) by reducing the extrusion multiplier far below what most people have to use. I'm leaning towards the theory that the issue is caused by over extrusion of the infill (for reasons as yet unknown) which is affecting the surface finish, perhaps because 2 perimeters and 3 solid layers aren't enough to compensate for the underlying defects in the infill. This is my latest theory but thus far, every other theory I've come up with has been later disproved.
P.S. I've just noticed that, as well as being the oldest member on these forums, I can now claim the title of being the instigator of the first thread to exceed 100 posts. Is there a prize for that?
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Go Get a well deserved Coffee Ian????
But as an aside having taken a closer look at mine I suspect I am also over extruding even tho the Steps/mm are spot on need to do some more testing yet which isn.t to easy as it is time consuming but I will give it a go later.
Mind in S3D I could set up a series ob shallow boxes to print simultaneously but with different Infils and extrusion factors shall give that a try? It will be a learning experience as well lol?
Doug
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Do not underestimate the infill overlap effect. For me, 5% is good, 10% is puffy and 15% is ridiculous overextrusion (with S3D and a 0.4mm line width/extrusion width). An interesting way to dial this in is to use M572 (pressure advance) to reduce extrusion during speed changes, IE where infill meets the sides. You can (and must) run a much higher infill overlap value when using high values of M572 (depending on your actual extrusion hysteresis), or risk infill not touching perimeter. I once "perfected" my top surface finish by balancing acceleration, pressure advance, feedrate and infill overlap. I've since stopped using pressure advance until I can get caught up with the firmware that fixed some bugs, so I use a much lower infill overlap setting than I used when I had pressure advance activated.
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@bot:
Do not underestimate the infill overlap effect. For me, 5% is good, 10% is puffy and 15% is ridiculous overextrusion (with S3D and a 0.4mm line width/extrusion width). An interesting way to dial this in is to use M572 (pressure advance) to reduce extrusion during speed changes, IE where infill meets the sides. You can (and must) run a much higher infill overlap value when using high values of M572 (depending on your actual extrusion hysteresis), or risk infill not touching perimeter. I once "perfected" my top surface finish by balancing acceleration, pressure advance, feedrate and infill overlap. I've since stopped using pressure advance until I can get caught up with the firmware that fixed some bugs, so I use a much lower infill overlap setting than I used when I had pressure advance activated.
I've dropped from the automatic 0.48 nozzle width down to 0.40, and am seeing better results, but I'm still heading down around the 85-90% extrusion multiplier before it gets neater.
Never thought about the overlap, so I'll toy with that as well.
What I am seeing are protruded corners in all extrusion settings, that I suspect my be retraction/acceleration related.
My retraction is set at 1mm@60mm/sec, and I understand that a direct drive extruder should run extraction between 0.5-2.5mm. Any suggestions?
What can be done to find best acceleration settings?
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I don't understand why S3D uses oversize automatic sizing. It's true, that you can vary that size of the extrusion a bit and still get good results, but I like to stick to the default orifice size when possible.
I didn't pit much thought into the overlap originally, either, but I found that even small adjustments to it make a huge difference (when you are as close to dialing it in as you are). Definitely go overboard, too. Exaggerating things is often the best way to understand their effects (thank Don Bailey for that tip :P). When you figure out what happens when you go too far one way or the other, dial it in to where you need it.
If you are seeing protruded corners, then it sounds like pressure advance is needed. M572 0.1 is a good place to start, but probably too much for your setup, since it is direct drive. It is definitely correlated with acceleration and instantaneous speed change values, as the "gentler" you have the acceleration, the more the pressure varies in the nozzle, the more the pressure advance is needed. I had to play with a huge range of values of acceleration, feedrate, "jerk" (instantaneous speed change) on the same print and see what I liked best. I spent probably a week printing I bet nearly 50 little tests that had both straight lines, hard corners, large and small radii and text embossed into flat surfaces. You just have to try all the possible combinations and see which you like best. I find the best results are found by simply slowing down the outer perimeters in S3D and using moderate (not super conservative/slow) acceleration settings.
As for retraction, I personally find that between 0.2 mm and 0.4mm length at 5 mm/s speed is optimal for my setup, which is a nema 11 5:1 reduction direct drive through an e3d v6.
I wouldn't stress too much, your results seem pretty respectable already. Just pick one and roll with it. I tend to avoid "top surfaces" as much as possible by orienting prints at an angle and using support for stabilization. Usually the "top layers" of my prints are one or two perimeter extrusion lines, or even a tiny little point/blob.
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My retraction is set at 1mm@60mm/sec, and I understand that a direct drive extruder should run extraction between 0.5-2.5mm. Any suggestions?
The best way I've found is to use firmware retraction - even if it's just temporarily. DC42's firmware uses G10 to retract and G11 to unretract. The retraction amount and feedrate are set by using M207 Sn.n Fnnnn where S is the amount in mm and F is the feedrate (speed). I believe David has just added extra parameters so that you can change the unretract speed and amount too. Anyway, for example I have M207 S2.0 F3000 in my config.g file but the great thing is that you can set a print going, then play around with the retraction by entering M207 commands through the web interface. Print 2 objects ( I use thin cuboids 3mm in X and 20mm in Y by about 30mm tall) spaced about 50 to 100 mm apart. Start with a low retraction and increase it until you lose all signs of stringing between the two. If you want, you can try it different temperatures and/or different filaments. This'll tell you what to use, even if you go back to "normal" retraction after you've set it up.
To use firmware retraction you need to tell your slicer that's what you want to do. In Slic3r it's easy - just tick the box under "Printer Settings" - "General" and it'll insert G10 and G11 commands instead of "normal" retraction commands. In S3D, you have to jump through a few hoops. I managed to get it working and posted my method here https://www.duet3d.com/forum/thread.php?id=396 before I gave up with S3D and started the process of getting my money back.
What can be done to find best acceleration settings?
My way is a bit unconventional. Basically, I use acceleration to limit speeds on short moves without it having to much of an adverse effect on overall print time. In theory, Slic3r has a setting for what it calls "gap fill" which it defines as being short zigzag moves. What I can't find out is how short a move needs to be and there doesn't see to be a way of setting the threshold. Anyway, imagine printing a largish square, say 100mm or more with infill at 45 degrees to the sides. I can print this quite happily at 90mm/sec or more and it's fine on the longer moves but as it gets into the corner, it appears to go faster and faster. In fact it's not, it's just that the moves are getting shorter. So, if acceleration was infinitely large and the speed is 90mm/sec, when the distance moved is 30mm, the time taken will be 0.33 of a second, at 20mm it's 0.22 of a second and at 10mm it's 0.1 seconds etc and it gets a bit alarming to watch. Also, you may be able to throw the carriages around like that, but the filament is soft a squishy and won't respond to those sort of changes in speed even if the extruder can, so the print quality will suffer. So, if we now limit the acceleration, on short moves, the axes will never get up to 90mm/sec because there isn't time and the shorter the move, the slower the speed will be. I've been playing around with it a bit and am currently using max acceleration of 1200mm/s^2 but I'm throwing around a great big heavy diamond hot end so you might well find a higher setting works better for you.
Anyway, that's just my twopence worth. It works for me, No doubt other people have their own preferred way of doing it.
HTH
Ian -
@bot:
If you are seeing protruded corners, then it sounds like pressure advance is needed. M572 0.1 is a good place to start, but probably too much for your setup, since it is direct drive. It is definitely correlated with acceleration and instantaneous speed change values, as the "gentler" you have the acceleration, the more the pressure varies in the nozzle, the more the pressure advance is needed. I had to play with a huge range of values of acceleration, feedrate, "jerk" (instantaneous speed change) on the same print and see what I liked best. I spent probably a week printing I bet nearly 50 little tests that had both straight lines, hard corners, large and small radii and text embossed into flat surfaces. You just have to try all the possible combinations and see which you like best. I find the best results are found by simply slowing down the outer perimeters in S3D and using moderate (not super conservative/slow) acceleration settings.
As for retraction, I personally find that between 0.2 mm and 0.4mm length at 5 mm/s speed is optimal for my setup, which is a nema 11 5:1 reduction direct drive through an e3d v6.
Where would this "M572 0.1" go? In the config.g file?
I'm a bit confused about retraction, as I read it's more about speed and you should set it as fast as it'll go without shredding the filament.
I've got mine at 60mm/s_1mm, and all seems well enough, but I see yours is a geared extruder of some sort….mine is a nema 17 with a 9mm OD drive wheel/gear.
