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Good Quality Prints

Posted: Wed Jul 02, 2014 4:31 pm
by Pavel
Hello all,

I have been printing a few parts for a project of mine, but it seems that M2 has trouble making a good finish on the part (see attached pictures - sorry for the photo quality). I have printed 5 similar parts, and each of them had bad finish in the same exact places. There are so many little protrusions on the right side that I have to shave them off for the part to fit into the groove it designed to go into. Since the left and right side of the part is almost identical, I wonder why M2 messes up so much on the right side. Is it a Slic3r issue? Is it temperature issue? Any other issue?

I can live with some small imperfections in finish, but I would like my parts to be as smooth as possible. Can someone help me figure this out?

Thanks!

Re: Good Quality Prints

Posted: Wed Jul 02, 2014 8:59 pm
by jimc
its all in your settings really. its hard to tell but it does look like your over-extruding just a little bit. im not familiar with slic3r and its settings but you need a little more ooze control and possibly more time to cool the layer. the ooze usually happens at the start of each line. wish i could help more but but unfortunately i use s3d as well as many other here so i dont even know what kind of ooze control settings are in slic3r.

Re: Good Quality Prints

Posted: Wed Jul 02, 2014 9:09 pm
by Pavel
jimc,
jimc wrote:its all in your settings really. its hard to tell but it does look like your over-extruding just a little bit. im not familiar with slic3r and its settings but you need a little more ooze control and possibly more time to cool the layer. the ooze usually happens at the start of each line. wish i could help more but but unfortunately i use s3d as well as many other here so i dont even know what kind of ooze control settings are in slic3r.
Is it worth purchasing s3d?

Re: Good Quality Prints

Posted: Wed Jul 02, 2014 9:26 pm
by jimc
s3d is great and i think you'll get the same response from most everyone here. not all but most of the m2 community uses it so its much easier for most people here to help you. we share profiles all the time which can give you a real jump start. is it worth it.......well thats up to you but for me i think its worth every penny. imo the $140 they charge is small for a piece of software like that. im sure you can do what you need to do with slic3r. its free, it works but for the most part your on your own as far as tuning. i only know of a couple few of the guys here who use it.

Re: Good Quality Prints

Posted: Wed Jul 02, 2014 10:38 pm
by jsc
Post your settings and your model, and someone may be able to spot something.

Re: Good Quality Prints

Posted: Sat Jul 05, 2014 5:46 pm
by ednisley
Pavel wrote:why M2 messes up so much on the right side
It looks like the object has a bit too much plastic, which suggests that the filament diameter & extrusion multiplier aren't set quite right. In particular, the top fill looks slightly overstuffed.

The default value for Infill -> Solid Infill Threshold Area is, IMO, way too high and has probably turned that small column completely solid. I run with 5 mm^2 and that seems to work for the stuff I build; if you do lots of tiny spires, it's probably still too high.

Set Infill -> Solid Infill Every x Layers to zero, which will prevent Slic3r from generating horizontal bulkheads inside the object. Sometimes you want that, most of the time you don't, because it produces effects that can be seen from the outside.

If you aren't already using http://gcode.ws/ to preview the G-Code before printing, now's the time to start: you can examine exactly how the printer produces that column, tweak Slic3r settings, adjust the model, and iterate until the right answer pops out.

Other than that, though, it looks pretty good.

Re: Good Quality Prints

Posted: Mon Jul 07, 2014 10:28 pm
by Pavel
ednisley wrote: It looks like the object has a bit too much plastic, which suggests that the filament diameter & extrusion multiplier aren't set quite right. In particular, the top fill looks slightly overstuffed.

The default value for Infill -> Solid Infill Threshold Area is, IMO, way too high and has probably turned that small column completely solid. I run with 5 mm^2 and that seems to work for the stuff I build; if you do lots of tiny spires, it's probably still too high.
Thanks ednisley for the help. I did have a very high Solid Infill Threshold Area (70), so I changed that. I also made sure that the outside perimeters are printed last. What is the extrusion multiplier?

I also bought the s3d. I have only installed it, and I am planning to play around with it. I'll let you guys know if I miserably fail at it.

Re: Good Quality Prints

Posted: Tue Jul 08, 2014 5:41 pm
by ednisley
Pavel wrote:What is the extrusion multiplier?
That's the fudge factor intended to make the extrusion volume come out right.

Given the extrusion width and height (aka thickness), the slicer knows the volume of plastic it must produce per millimeter of nozzle movement. Given the filament diameter and the extruder motor's steps/mm, it also knows how much filament it will consume to produce that volume. In a perfect world, that would be the end of the story.

But the volumes generally don't match, so you adjust the extrusion multiplier to fix that situation. In Slic3r, that's in the Filament settings section, directly below the filament diameter field.

Some folks fake the diameter and leave the extrusion multiplier at 1.0, but the intent of the multiplier is that it should let you input the actual measured filament diameter and produce the correct volume without further ado. Opinions differ as to whether that works or not.