Strang Banding issue

[Jassper]

Anyone seen these bands before in your print?
Any Idea what might be causing them.
On this print they are aprox 2mm apart, on other prints they are 4 and 5 mm apart.
[img]http://www.themakerhive.com/FTP/jassper/bands.jpg[/img]

The bands in that pic look very predominant, but they really aren't. If I turn the part into the light they disappear, but they can be felt by sliding your fingers up the print.
Also note the bands are even less on the inside of the print and the inside is very smooth to the touch. Not sure if it is related, but this part was printed with it printing the inside perimeter first. If I check that in slicer and print the outside perimeter first then the out side becomes very even and smooth, and the inside is then bumpy, but the bands are there in either case.

I should mention that this is a Delta Rostock MAX

Thanks

[mhackney]

I have not seen anything quite like that. Has the printer been performing well in the past? For instance, have you printed this part properly before? Which slicer are you using?

[Jassper]

I have not seen anything quite like that. Has the printer been performing well in the past? For instance, have you printed this part properly before? Which slicer are you using?

The latest version of slic3r.

I think it has just recently shown up. I noticed it while printing a rabbit for Easter. However the bands are very faint on it. They also seem to be most visible on the purple. Other colors are harder to see. As for this part, no I have not printed it before, but the 1" square below has printed fine until now. This band is 4mm
[img]http://www.themakerhive.com/FTP/jassper/bands2.jpg[/img]

The only thing I can think of before this was noticed, I changed my Z to a whole number. It was something like 460.35 or some such and I set it to 461.00 even and adjusted my endstops. I changed my Z again today just to see if that made a different and it didn't.

[Jassper]

Could it possibly be an extruder issue?

[mhackney]

Did you upgrade Slic3r recently? It has been having a host of issues and this could be one of them. It could be an extruder issue, hard to tell but maybe filament starving. Is this the stock hot end?

[Jassper]

Did you upgrade Slic3r recently? It has been having a host of issues and this could be one of them. It could be an extruder issue, hard to tell but maybe filament starving. Is this the stock hot end?

It is the latest, Version 1.0.0RC3.
It is a stock hot end, 0.5mm nozzle. Not sure what would cause it to starve at regular intervals, and those intervals are different from print to print. - although the bands do seem to be closer together the larger the part is. - hummm

I'll keep hunting

[mhackney]

Very odd! I suspect Slic3r just based on my recent not so pleasant experiences with it. Hopefully we'll see. Do you have any gcode for things that printed well before that you could just print that oils gcode and see what happens? That would eliminate the gcode as the culprit.

[mhackney]

I had another debugging thought: how about moving the part on your platter in Slic3r and see if you get the banding there. I'd suggest moving it towards one of the towers - anything to take the part off center. I debugged a carriage problem that way last year. I notice all my parts had a little wave in them and I suspected a bump or debris on the Y carriage. Even cleaning did not fix it so I moved the part as closet to Y as possible - that way movement of that carriage would be at a minimum. That made the problem go away. Long story short, there was a little burr on the inside of the tower track that just happened to be aligned with where a first layer at X=Y=0 would be.

[Jassper]

Yes I have some older code I will try printing tomorrow.
I would be inclined to think it is a layer shift, but the band is indented on both sides, not shifted. The wider band in between are actually bulged out just a bit - depending on which side the perimeter is printed first. Those areas are bonded well also so don't think it is skipping a layer. I'm going to take a close look at my extruder as well.

I'll play with colors too, as I mentioned the color seems to make it more or less noticeable. The Orange rabbit I printed had bands but not nearly as bad as this.

[Jassper]

Thought I was onto something here.
I noticed that when I printed with infill, I didn't have any banding, so I set up a small test shape and printed one with just perimeters - no top no bottom. And then I printed one with 5 bottom and 5 top layers with 30% infill. The one whit infill didn't appear to have any banding so I thought I found the issue - but after taking the picture - and as you can see - the banding is apparent.
[img]http://www.themakerhive.com/FTP/jassper/shape.jpg[/img]

As I mentioned before color seems to have an affect on it. Although the bands are apparent in the photo, you really can't see them on the solid print just looking at it and you can barely notice them on the perimeter print.

[JonAdkins]

Is that PLA and are you using a layer fan? I had something similar once upon a time when getting my slicer to automatically manage my fan, it turned out that with every x layers it was turning the fan down from 90% to 50% and that was enough to cause the surface to look similar to what you've posted.

I just turned off the fan control on the slicing side all together and just manually turned it on myself in Repetier and that issue went away.

-jon

[Jassper]

Is that PLA and are you using a layer fan? I had something similar once upon a time when getting my slicer to automatically manage my fan, it turned out that with every x layers it was turning the fan down from 90% to 50% and that was enough to cause the surface to look similar to what you've posted.

I just turned off the fan control on the slicing side all together and just manually turned it on myself in Repetier and that issue went away.

-jon

I suspect that might be the issue as well. I haven't had a chance to test it yet but I was thinking just the other day that this issue started after setting the fan to run 100% all the time.
This is ABS.

Thanks

[bvandiepenbos]

I think it could be temperature swinging up/down.

have you done a PID auto-tune?

I you run from PC instead of SD Repetier keeps a log of temps, you could look at that to see if temperate is constant.

You could put your J-Head on and see if it changes.

Wrapping the SeeMe hot end heater block with silicone tape makes it more stable and less sensitive to air movements.