Help, internal size of part(s) too small... November 29, 2013 02:10PM |
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Re: Help, internal size of part(s) too small... November 29, 2013 08:16PM |
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Re: Help, internal size of part(s) too small... November 30, 2013 01:34AM |
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Re: Help, internal size of part(s) too small... November 30, 2013 02:37PM |
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Re: Help, internal size of part(s) too small... November 30, 2013 03:45PM |
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Re: Help, internal size of part(s) too small... November 30, 2013 05:24PM |
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Re: Help, internal size of part(s) too small... November 30, 2013 05:50PM |
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justcurious
well, I think you have by far too big ambitions about accuracy with 3d printers.
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Re: Help, internal size of part(s) too small... November 30, 2013 05:56PM |
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Re: Help, internal size of part(s) too small... November 30, 2013 06:02PM |
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Re: Help, internal size of part(s) too small... November 30, 2013 06:03PM |
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tmorris9
So Sublime, what program do you use now?
I was thinking of switching to Kisslicer but I am just so familiar with Slic3r that I have not yet.
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Re: Help, internal size of part(s) too small... November 30, 2013 06:07PM |
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justcurious
Sublime, you claim that it certainly is possible to get accurate results, but you do not give any directions for this to happen? it is not a good proof that a specific print can be made accurate, that was what I indicated above.
What is the magic to be used to get 0.05 accuracy with every print then?
I did not say that accuracy was impossible but getting to that is some hard work and intuition and for some, selection of best fit tools, but in my opinion there is no easy way getting there.
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Re: Help, internal size of part(s) too small... December 01, 2013 12:39AM |
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Re: Help, internal size of part(s) too small... December 01, 2013 01:16AM |
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Re: Help, internal size of part(s) too small... December 01, 2013 01:27AM |
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justcurious
well, I think you have by far too big ambitions about accuracy with 3d printers. Think about again.
You have a nozzle that can make a line that is 0,40 wide or larger, never smaller. .....
...
You can always try with the specific print to choose small changes of extrusion width and layerheights to find the optimum result for that print, but never expect that there is a standard formula that covers any print with these relative bad nozzle conditions given for accuracy in expectations of 1/10 mm accuracy or whatever very small. Just my point....
Re: Help, internal size of part(s) too small... December 01, 2013 01:31AM |
Registered: 12 years ago Posts: 40 |
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waitaki
I think the problem is with circles, not hex nut holes. .......
A 6 sided nut hole is easy for the extruder just as a square hole would be - it will move in "easier" straight lines so to speak but dragging the filament around a circle seems to cause it to pull towards the center, hence making it smaller.
Re: Help, internal size of part(s) too small... December 01, 2013 01:51AM |
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Re: Help, internal size of part(s) too small... December 01, 2013 01:58AM |
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waitaki
I think the problem is with circles, not hex nut holes. Any part I print which requires hexagonal sockets always come out perfect - the nuts will drop in with total precision. Nophead has some info on this somewhere but basically it seems that the more "edges" in a circle, the tighter it will be.
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waitaki
A 6 sided nut hole is easy for the extruder just as a square hole would be - it will move in "easier" straight lines so to speak but dragging the filament around a circle seems to cause it to pull towards the center, hence making it smaller.
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Re: Help, internal size of part(s) too small... December 01, 2013 01:59AM |
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Qsilver
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Sublime
.......Now my prints are always within 0.05mm of the target size and I now model all holes exactly the size I want them......
Did you try the attached STL file, doesn't take too long to print.
Rich
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Re: Help, internal size of part(s) too small... December 01, 2013 03:04AM |
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Re: Help, internal size of part(s) too small... December 01, 2013 08:59AM |
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Re: Help, internal size of part(s) too small... December 17, 2013 04:12AM |
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Re: Help, internal size of part(s) too small... December 17, 2013 05:51AM |
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Re: Help, internal size of part(s) too small... December 17, 2013 06:23AM |
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Re: Help, internal size of part(s) too small... December 17, 2013 08:38AM |
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Re: Help, internal size of part(s) too small... December 17, 2013 12:49PM |
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tmorris9
I might be mistaken but I believe the calculator is for use with Kisslicer. And the tool path is off in slic3r so no settings will ever make holes the right size.
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Re: Help, internal size of part(s) too small... December 17, 2013 12:55PM |
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QuackingPlums
Sublime, I've tried using your calculator before but it has baffled me. I've taken another look just now and maybe I've learned a lot more since, but the words are starting to have a bit more meaning.
I still am not sure however whether using the figures that it spits out will actually help me;
I have a Mendel90, I print ABS at 0.2mm layer height, 0.4mm nozzle and 0.5mm extrusion width.
My current workflow involves plating up using Repetier and slicing with Slic3r (I have multiple profiles setup already for various filaments) to generate gcode files, which I either upload to Octoprint or copy to the printer via SD.
My external dimensions are usually fine (bar a little excess squish on the first layer that sometimes needs filing/paring off) but internal dimensions, whether they're circular holes or just square cut-outs are often out by half the extrusion width. This means that I have to add 0.5mm to all internal dimensions in order to get them to fit (ok it varies depending on the size of the hole)!
When I plug my figures into the calculator it suggests that extrusion width should be 0.48mm rather than my current setting of 0.5mm - if I make this change in Slic3r then will I really see a dramatic improvement, or do I need to accept that Slic3r will never produce accurate objects such as those you have shown above? Have I even used the calculator correctly?
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Re: Help, internal size of part(s) too small... December 17, 2013 03:03PM |
Registered: 12 years ago Posts: 40 |
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justcurious
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tmorris9
And the tool path is off in slic3r so no settings will ever make holes the right size.
Is it possible that you can give us some documentation on this statement, which i believe untill otherwise proofed is your own experience.
Re: Help, internal size of part(s) too small... December 18, 2013 05:26AM |
Registered: 12 years ago Posts: 369 |
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Sublime
Since you are already manually setting the extrusion width to 0.5 I doubt the 0.02 will make much of a difference. This was more about the auto defaults being completely out to lunch. I read someone that made a chart of Slic3r's auto extrusion widths and they showed it would try and make the extrusions 1.6mm wide with a 0.5mm nozzle at a height of something like 0.1mm which is completely wrong and would cause major issues. Also are you using speeds similar to what my calculator says? If you are running a lot faster then it could be causing to much back pressure which when it slows for the small holes causes over extrusion. Also are the temperatures similar to the ones calculated? The calculator can not get them correct but are a good guide line as to where to start. If the temp is too high the plastic may be to liquid which again results in over extrusion when it slows down.
Re: Help, internal size of part(s) too small... December 18, 2013 11:26AM |
Registered: 14 years ago Posts: 2,947 |
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QuackingPlums
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Sublime
Since you are already manually setting the extrusion width to 0.5 I doubt the 0.02 will make much of a difference. This was more about the auto defaults being completely out to lunch. I read someone that made a chart of Slic3r's auto extrusion widths and they showed it would try and make the extrusions 1.6mm wide with a 0.5mm nozzle at a height of something like 0.1mm which is completely wrong and would cause major issues. Also are you using speeds similar to what my calculator says? If you are running a lot faster then it could be causing to much back pressure which when it slows for the small holes causes over extrusion. Also are the temperatures similar to the ones calculated? The calculator can not get them correct but are a good guide line as to where to start. If the temp is too high the plastic may be to liquid which again results in over extrusion when it slows down.
My extrusion width of 0.5mm is based on a W/H ratio of 2.5 (gleaned from one of nophead's threads here as ideal for ABS) - I have created a lookup table that gives me the extrusion width values for all valid combinations of W/H and H that I am likely to use, and set this value manually for each filament. I have to admit I don't understand how to measure the other influences such as die swell and optimal speed. I have set all my print speeds to 40mm/s (again I think this is a nophead recommendation), which is lower than the 55mm/s suggested by your Basic calculator.
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QuackingPlums
I notice that if I use the Basic calculator with these values then I get a message that says "The current layer height of 0.2mm has a rounding error of 000nm per layer." but if I use the Intermediate calculator then it says my rounding error is 029nm. The additional figures I have plugged into the Intermediate calculator are the target speed (= 40mm/s as currently set) and the E steps per mm (straight from my Marlin firmware = 516.86mm). Z-steps per mm has been left as default and I'm a bit confused why there's nowhere to input my extrusion width.
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QuackingPlums
I also don't understand how the recommended print temperatures work. So far I have been "calibrating" my temps based on cranking it up until it starts oozing, then backing off a bit. This results in an extrusion temperature of 235C which is giving good adhesion on a PET-covered heated bed at 115C (surface temperature) first layer, 105C subsequent layers. The recommended temperatures from the calculator are a bit lower?
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Re: Help, internal size of part(s) too small... December 18, 2013 08:21PM |
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