At the moment i’m trying to print some parts that need to be accurate in size. Problem is my print are to large on the outside and to small on the inside (holes) about 0.3mm off
If been tinkering with this and so far i know that the extruder multiplier is correct. And the steps per mm on the x and y axis are correct aswell according to steps calculator
[color=#FF0000](EDIT: yeah might be to early on that one testing newly calculated steps as we speak will report results[/color].
Also i read somewhere that this is a problem created by slicer but i’m not sure about that statement.
Any advise/tips i can try
[color=#FF0000]Ok so far i changed the y,x, and z steps per mm and the results are getting better z axis was off as well but is good now with the ideal calculated steps.
the x and y im still working on but its getting there.
so outer diameters looking better.
inner diameters not so much but that might just be that issue with slicer.
also re-calibrated extruder multiplier new test print in progress[/color]
This is something inherent with FDM/FFM, 3d printing parts will be a bit smaller or larger.
You need to adjust the tolerance in your design depending on the printer
That is something that has to be taking into consideration, 3d printers are not a precision instrument yes.
However it is to be expected that in a well build and calibrated machine these tolerances should be smaller that 0.3 to 0.5 mm. Also correct me if wrong but these tolerences should be somewhat uniform. Not like im experiencing right now that the x is perfect the y is slightly off, but holes are off by 0.5mm.
Just to be clear I’m not pointing fingers or anything. Just trying to fix this alone or together and sharing solutuons for other users how might find it helpfull.
So the smaller holes issue, been researcing it a bit more and i think it is caused slicing indeed. Thus is what i found in the slicer manual about it.
[quote] More material is deposited in the inside
When you extrude along a curve, more material per distance unit is deposited in the concave side. Such excessive material makes the internal radius shorter. A compensation algorithm was proposed by Adrian Bowyer, and it was implemented in Slic3r some time ago but many users complained about holes being too large – it was removed thereafter since smaller holes are better than larger holes since they can be drilled. [/quote]
Going to try alternative slicing softwares to see if i can find one that better when it comes to holes.
Some points that influence tolerance from my (limited) experience so far:
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Steps per millimeter for the extruder is (apart from the axes of course) the most important one. Some filaments might also need a different multiplier than other. Most of the time I found that I still had overextrusion when I thought I had it right, but you are already experimenting with this if I read correctly. For different layer heights different settings might be necessary unfortunately.
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Part cooling is also extremly important expecially for holes. If the filament can be pulled around by the nozzle before it adheres to the layer below the hole will be far too small. Having airflow from opposite sides helps a lot and also reduces the risk of deforming straight lines while bridging.
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Hole diameter: Smaller holes are worse than bigger ones. On one recent print I only added 0.1mm to the radius for 15mm holes, but 0.3mm for 2mm ones. It has again to do with the filament being pulled towards the center of the hole by the nozzle. Unfortunately there is now way around, but to testprint and remodel until it’s right. (layer height dependent again)
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Print speed difference. If an outer wall (i.e. the inside wall of a hole) that is printed comes directly after a high speed part like infills or inner perimeters of a wall (if those are printed at higher speed) there might be some leftover pressure in the hotend that squeezes out now that the speed is lower and there actually is air to one side. Slower overall speed with less speed variations has better results for tolerance in my experience.
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Wall thickness in slicer: If this is not a multiple of the nozzle width I have seen over- and underextrusion on the same part.
All this helps to be at least somewhat correct, the rest has to come from the modelling.
EDIT Just saw your last post: If you find a slicer with a customizable diameter-dependent hole correction factor, let me know. The problem is that no two printers are the same here as the deposition of to much material on the concave side is a problem with the printing method itself and just changing the nozzle to a slightly different one with the same hole diameter might already yield different results, or a fan blowing at 50% instead of 100%. That’s why some users experienced too large holes after it was implemented while it worked for others.
So before i can go and try other slicers i first have to fix some issues with my printer. Meanly the fact that my pulleys are very poorly made and useless for preccision printing (bad on my end that i didnt notice this sooner)
Ordered new ones that will hopefully arrive tommorrow.