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Help to better my prints

Posted by Horse Renoir 
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Horse Renoir
Help to better my prints
February 02, 2014 09:11PM
Hi all,
So i decided to give my prusa i3 a good endurance test and printed the waiting warrior figure (http://www.thingiverse.com/thing:61160). Im running ABS with a 0.35mm jhead at 0.2mm layer height and 30% infill, head temperature was 230 degrees C and the bed temp was set at 100 degrees C. As you can see from the printer there appear to be several issues, the worst of which seems to be overhang (not sure if that is the correct term). Also there are several layers that im guessing it didnt printer properly together or that printed but then warpped as there are afew gaps, any idea what could be causing these issues? if i understand the root cause then i can better understand how to fix it.

Many Thanks
Max
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brnrd
Re: Help to better my prints
February 03, 2014 01:44AM
The quality of the print looks very good. Other than overhang, as you wrote, I don't really see any major issues. To fix those, the standard approach would be to turn on support in the slicer.

In order to print properly, the filament needs to have something to support it. You can print bridges if your printer is properly tuned to span gaps, but if there's nothing on the other side, gravity wins. That chin and the arm regions are good examples of that.
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swoozle
Re: Help to better my prints
February 03, 2014 09:43AM
Thinner layer height with the same or larger extrusion width will help with overhang as there be less of the extrusion width unsupported for each layer.

I agree with the previous responder, in general this print looks very good. Perfection with these hobbyist-grade machines is not a reaslistic expectation. A nice goal, though. Post pics and directions when you get there. smiling smiley
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cnc dick
Re: Help to better my prints
February 03, 2014 01:25PM
I agree it's a very nice print I don't think you going to be able to do much better. The separation you see is from thermal shrinkage you would need a heated built chamber to reduce some of that. For a non-professional machine that is actually very good
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brnrd
Re: Help to better my prints
February 03, 2014 02:26PM
Quote
swoozle
... Perfection with these hobbyist-grade machines is not a reaslistic expectation. ...smiling smiley

I agree with everything except for this statement. There are plenty of examples on the web and based on my own experience to show that this is a realistic expectation.
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cnc dick
Re: Help to better my prints
February 03, 2014 03:17PM
I agree with you some people with Hobby machines spend a lot of time on tuning their machine and get a knack for setting perimeters in their slicers and they can do a pretty good job. But just a guess from seeing everybody's prints that post on the Internet I would guess only about 25% managed this and again this is a rough guess
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Horse Renoir
Re: Help to better my prints
February 03, 2014 07:31PM
Thanks guys for the feedback, i realize that this kind of machine wont ever print 100% perfect prints however im certain that my machine can do better than it is at present, dont get me wrong, this print in very nice, but im sure it can be improved, to address the seperation issue im going to increase the bed temperature. Im not sure what to do about the overhang, i understand that the machine can only print upto a certain angle before needing support however this print is supposed to be able to be printed without supports, i might try increasing extrusion width as suggested earlier
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jpan
Re: Help to better my prints
February 03, 2014 07:53PM
You'll be satisfied with your print after seeing my poor print quanlity....spinning smiley sticking its tongue out
I am running Mendel and experiencing terrible z wobble.

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Horse Renoir
Re: Help to better my prints
February 03, 2014 08:23PM
I previously had z wobble issues, i was able to reduce this problem by switching to a flexable coupler and ensuring that there was afew mm gap between the motor shaft and z threaded rods, perhaps you could try it, maybe it would help
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Ralf
Re: Help to better my prints
February 04, 2014 07:50AM
Raising the bed temperature might give you issues with deformation of the lower part of the print because it doesn't cool down enough before the next layer is put down. 105 degrees for the first layer, and then 95 degrees for the rest works for me.

It may sound counterintuitive, but I would start by raising the extrusion temperature, this makes the ABS flow better, and pulling less on the previous layers as it it is laid down, and also increasing layer adhesion. With ABS hotter is better, of course without burning or discoloration, I print all my ABS on 245 degrees.
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jamesdanielv
Re: Help to better my prints
February 04, 2014 09:32AM
jpan:

if you provide a large clear image of one of your prints someone on this forum will likely help you with your z wobble issue.
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jpan
Re: Help to better my prints
February 04, 2014 01:40PM
Thanks guys, I'm going to try tighten all screws and nuts again tonight and see what will happen. (in my impression there are indeed some nuts that are a little loose) If that won't work the I'll try other means.
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brnrd
Re: Help to better my prints
February 04, 2014 01:56PM
Tightening nuts and screws is not always the best approach to get rid of "z-wobble" artifacts. In Prusa 1 and 2, some play between the z nut and the x-carriage nut trap is enough to get rid of z wobble if the rods are not bent too much. Loosening the z motors or not mounting all of them to give some lateral play to the motor also helps. I think mounting the motors tightly can actually lead to more z wobble.
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