Skipping layers?

[vtswordfish]

Hey all! I have been printing on the CTC for a bit now, really love it, the print quality is great once you dial it in, but I have been having a strange issue on mostly taller prints, it seems that it 'skips' a layer every now and again, any ideas on what may cause that? I have tried slowing it down, but have seen this behavior as low as 30mm/s, have messed with temp settings and no luck either. Most of what I've read is it could be a filament tangle, speed, temperature, or z axis related, any thoughts? (the small jittery layers is what i mean)
IMG_5379.jpg

[bigo93]

It's not skipping, that is due to shrinkage due to parts cooling faster than others I believe.

[vtswordfish]

No it's definitely skipping, I've watched it on those layers and it's like it's not putting them down, I can't decide if it's the z axis having an issue or if it's not extruding well in those areas though.

[EagleSeven]

No it's definitely skipping, I've watched it on those layers and it's like it's not putting them down, I can't decide if it's the z axis having an issue or if it's not extruding well in those areas though.

Have you checked the filament-extruder drive-Gear,
to see if it needs cleaning ?
(teeth of gear can get filled with plastic,
causing filament not to feed properly)

I use an Xacto-knife and small wire-brush to clean it.

Here's a video about how to do that:
(CTC is similar to FF, your extruder may not have the Arm type assembly)
http://www.bing.com/videos/search?q=...390&FORM=VIRE7

Note: we upgraded to the spring-loaded Arm type,
since it seems a little more reliable,
even though it is a little more difficult to assemble

[vtswordfish]

Just checked the gear on the extruder, seemed to be fine/clean. Did some other checks on it and still am kind of at a loss on it. I thought about upgrading to the spring loaded extruder block, which one did you use for yours?

Also it has randomly started randomly showing a bunch of jumbled mess on the LCD screen, not sure what's causing it, bad sailfish flash maybe? Its weird because I've printed on it probably a couple hundred hours now and it just started that!

[EagleSeven]

Just checked the gear on the extruder, seemed to be fine/clean. Did some other checks on it and still am kind of at a loss on it. I thought about upgrading to the spring loaded extruder block, which one did you use for yours?

Also it has randomly started randomly showing a bunch of jumbled mess on the LCD screen, not sure what's causing it, bad sailfish flash maybe? Its weird because I've printed on it probably a couple hundred hours now and it just started that!

I found a Set of Arm type extruders on eBay, at low cost,
from a place in UK.
I can look for details of that order if you need them ?

Spikes on AC power line to printer can cause the display jumble problem.
Can be caused by an AC type Fan or other device with motors.
Moving power-cords, going to printer's power-supply or to other devices, away from printer Mobo, can help also.

[bigo93]

You can also print them out, couple of prints out there

http://www.thingiverse.com/thing:231310
http://www.thingiverse.com/thing:42250
http://www.thingiverse.com/thing:53125

[vtswordfish]

I went ahead and grabbed one of the arm extruders off the bay, hopefully that'll help with feeding (which I suspect may partially be the issue). I went ahead and cleaned everything out while I had it apart earlier, going to do some oiling of the bars and all that and will give it a go tomorrow sometime!

[EagleSeven]

You can also print them out, couple of prints out there

http://www.thingiverse.com/thing:231310
http://www.thingiverse.com/thing:42250
http://www.thingiverse.com/thing:53125

Yes, if you print them you still have to locate the correct springs, bearings, screws and bushings,
which seemed difficult when I tried to find them, mainly the proper type spring.

But if one ever gets damaged or broken I will certainly try printing a new one !

[EagleSeven]

Yes, I think putting a drop of oil on bars, often, really helps,
as long as you clean away the dust that collects at ends of bars, in the oil.