New to 3D printing - first print results

Hello,

I just finished the assembly of my Mendel90 kit, which I received last week from Nophead.
Thanks to the well designed and prepared kit it took only about 20 hours without real problems.
(one of the screws of the extruder motor, which have to be removed to mount the connector clamp, was so tight, that I damaged the crossed slots. I had to remove another screw and turn the motor by 90 degrees, which is no problem)

Enclosed you will find my first print results. Regarding the still not perfect calibration I'm satisfied with them.
Where I'm looking for improvement are the incoherent filaments inside of the gauge clamp and on top of the Lego Duplo brick (the bottom fits very well onto a standard Lego brick!).

The G code was sliced with Skeinforge, using the standard settings delivered by Nophead. I assume, that I have to look at this settings for further improvements.

Cheers, Gerd

You'll never forget your first android!

I attached the wrong pictures. Here are the clamp pictures

Gerd

Yes I got the same thing on a new machine I built myself today. I am not sure what causes is. It seems to squirt out far too much filament occasionally while doing the outline. Maybe the extruder stalls whilst reversing. I wondered if I had made the gears mesh a bit too tight. After printing a few things the problem seemed to go away.

I have only ever seen it do this with PLA.

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[www.hydraraptor.blogspot.com]

Yes this is definitely due to tight spots on the gears when the extruder is brand new. Once run in for a while problem goes away.

The problem is the gears get closer together when the filament is pressing on the hobbed bolt because M8 bolts are about 0.2mm smaller than an 8mm bearing. They have prime numbers of teeth so you have to go through a lot of turns before you find the worst case tight spot but you can't do that when the hot end is fitted. I might change the instructions to set the motor position before fitting the hot end.

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[www.hydraraptor.blogspot.com]

Hello Chris,

thank you for the information.

Does it make sense to readjust the extruder motor position a little bit or running the extruder some time without filament?
Or have I to wait simply until the problem clears itself?

Without filament in place the gears have an extra 0.2mm clearance. To fix it you would need to unscrew the hot end so you can feed enough filament to feel the tight spot.

Have you put grease on the gears?

You could also try reducing the extruder acceleration as it must be a bit borderline.

Edited 1 time(s). Last edit at 08/13/2013 05:26AM by nophead.

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[www.hydraraptor.blogspot.com]

My own experience was the first two prints I did had this problem (both androids) and then it went away.

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[www.hydraraptor.blogspot.com]

Yes, i have put lithium grease to the gears and now I have also printed several parts.

The problem with the incoherent filament seems to be away, as you can see in the photo of the clamp, which I have reprinted. But I don't know what was the real reason for the problem, because in between I have reduced the extruder acceleration to 4000 and I have disassembled and readjusted/recalibrated the extruder also.

Only at the left edge of the clamp I can see some dissolved filament near to the horizontal hole (red arrow). I assume that this is caused by local overheating.

To examine this, I printed a test piece. In the left printout in the photo you can see, that the hollow cylinder on top was dissolved, apparently by overheating, while an equal cylinder left on the base is printed perfectly. Therefore I looked for a way for cooling and first I enabled the orbiting feature in the cool tab of Skeinforge. This was obviously not a good idea (center printout in the photo). Then I tried to activate the extruder fan by checking the related box in the cool tab (right printout) and the top cylinder was printed good. Only at the location of the red arrow there is an artifact which I can't explain.

With the fan switched on from the beginning I had some problems that the first layer filament sticks not so good onto the glass plate. So I added the M106 manually into the G code at the end of the first layer. But at parts with a larger base area this led to warping of the part and detachment from the plate.

Is there any recommendation, how this local overheating can be resolved?

Cheers, Gerd

Yes orbit is useless. You can increase the minimum layer time to slow down more on small layers.

Fan on after the first layer is the right approach. There is a plug in for Skeinforge somewhere to do that. Try increasing the bed temperature 10C to stop it lifting,

Your last picture does not look like it has any overheating. The area circled are blobs at line starts. Perhaps made worse by reducing the extruder acceleration. You can reduce those by making the infill the same speed as the outline.

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[www.hydraraptor.blogspot.com]

If you don't have a fan, what then? :-) Increasing minimum layer time means the head moves slower, and if the layer is small, it's so slow that it basically just sits there heating and ruining the print. Having the head orbit would at least avoid that problem...

Gerv

gerv Wrote:
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> ...and if the layer is small, it's so slow that it
> basically just sits there heating and ruining the
> print. Having the head orbit would at least avoid
> that problem...

The answer to the problem of printing layers which have small areas is simply,,. dont't!
If I want small things, I either add them to another file or else print several of them in one go in order to avoid having GCode with very short layer print times.

Alan

@Gerv,
The heat transferred to the object through adding molten plastic is far more than that radiated to it by the nozzle, or conducted to it along the molten stream of plastic.

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[www.hydraraptor.blogspot.com]