Why is my print crappy?

[dmcmd]

My Rostock Max V2 is having an issue. It seems like sometimes it skips a layer. This causes some structures to fall apart. See pics below: (I'm sorry that the images are rotated. They're not rotated on my computer, and I don't know how to fix them on the forum. )

Also, this print had some pretty significant blobbing as well:

Here's the STL if you're interested:

Vase.STL

(1.12 MiB) Downloaded 327 times

I'm printing Hatchbox ABS at 220C.
Layer height 0.25
Infill 40%
Infill speed 40
Insider perimeter speed 40
Outside perimeter speed 35
Retraction length 6.5
z lift 3mm
Minimum travel requiring retraction 2mm
Minimum extrusion requiring retraction 1.5mm

Printed with MatterControl
Sliced with MatterSlice

Any help would be appreciated! I'm new at this...

Thanks,
Darren

[Polygonhell]

You'd have to watch it print, but more than likely it doesn't skip a layer, but rather it stops extruding for a layer or at least parts of it.
Plastic isn't entirely consistent throughout a roll, and you can end up with parts of the roll requiring slightly higher temperature than the rest. 220 is borderline for ABS, and that might be what you're seeing, I'd retry the print at 235, and see if it does the same thing.

Other inconsistencies in the plastic like wider areas in the filament can cause similar issues, though that usually results in complete failure.

[teoman]

That looks like a crack due to thermal stress.

[dmcmd]

I was thinking along the same lines, that it might be a little cold. I'm going to try it hotter tonight. It's an 8 hour print at these settings...

Darren

[dmcmd]

Here's an update:

I set my hotend to 235C. I only has one area where it did not extrude, as you can see in the picture below:

I'm still getting lots of blobbing. I think this has to do with my z-lift settings being too aggressive. I'll tone those down and see what happens. It seemed while it was printing that it was pausing for a split second at each of those areas that has a blob.

Darren

[KAS]

Here's an update:

I set my hotend to 235C. I only has one area where it did not extrude, as you can see in the picture below:

Darren

Looks like it's the exact same location? maybe a slicer issue

[dmcmd]

Could be. I'm thinking it could also be the extruder/bowden tube. I'm currently working on a suspended extruder design. We'll see if it works out.

Darren

[teoman]

Try moving the printer temporarily in to a cupboard.

By thermal stress i mean onse side of the print cooling faster than the other which causes stress on the part and the layers let go forming a crack.

[DavidF]

Try moving the printer temporarily in to a cupboard.

By thermal stress i mean onse side of the print cooling faster than the other which causes stress on the part and the layers let go forming a crack.

Cupboards must be bigger in your neck of the woods

[dmcmd]

Try moving the printer temporarily in to a cupboard.

By thermal stress i mean onse side of the print cooling faster than the other which causes stress on the part and the layers let go forming a crack.

From the pictures I can see how it may look that way, but I promise there is a line missing. On the latest print, the insider perimeter is ok, but the outside perimeter is missing.

Darren

[KAS]

Usually the missing line theory gets thrown out because the line above it would sag down or ooze out. On the next attempt, maybe rotate the model 45 and see what happens.

I'm not an ABS printer, I stick to PLA for now. Not sure about the heat issues.

[dmcmd]

Good point. I'll try the rotation idea and see what happens. For the next few days, I'm busy designing and building brackets to fly my extruder, though.

Darren

[Khalid Khattak]

Bump the bed temperature and Nozzle (you did) slow down the speed.. I was getting the same with ABS but now it vanishes.. I use Super glue to keep these cracks/opening shut tight...

[teoman]

You have to watch the print to determine if it is a lack of extrusion or a crack. A camera would come in handy here.

Have a look at the gear in the extuder, if it is too full of ground filament then it may cause slipping.

[dmcmd]

More good suggestions. I'll check the gear. It could very well be full of junk.

Darren