Printer skips after first layer [video]

I am using ABS with all the default Repetier settings, but I am having a strange issue where after the first layer of a print, the extruder begins... skipping?

That is, the filament is definitely being extruded but for whatever reason it isn't being laid down correctly.

I have attached a zipped .MOV file showing my printer in action. Apologies for the low-res video, but you can definitely see the issue at about 20 seconds in.

If you have any trouble downloading and viewing the file, let me know and I will try to host it somewhere else and post a link.

 

What are your temperatures?

It looks like you're jamming or not flowing evenly. What's your extruder speed set to? [mm/min]

Try removing the filament, trimming it, and reinserting. When you do that push a significant amount through until it's flowing out at a consistent rate.

 

Apologies for the slow reply; work has been really busy lately.

Anyway, temperatures are as follows:
Extruder is 220 deg C for first layer and 210 for all other layers; heat bed is 100 and 90 in the same fashion.

We have tried the following extruder speeds (but see below for more details):
99, 75, and 60 mm/min.

Here's the steps we've taken for some additional context:

• A few days ago, we noticed the printer just stopped extruding during a job so we took the extruder head apart.
• On Sunday, we finally got around to cleaning the extruder head. Because we had been noticing a lot of crud on the hobbed bolt, we also installed a new one at the same time.
• After reassembling everything, we did some test runs and discovered the skipping issue detailed in my original post. Since we had just cleaned it and manual extruding worked just fine, I made this thread to try to get some answers.
• On Monday, seeing the replies in this thread, we tried lowering the extruder speed from 99 to 75 mm/min. We also may have raised the temperature by 5 deg but we can't recall for sure.
• Regardless, the skipping issue seemed to improve a bit. We then tried 60 mm/min, but during the resulting test runs, the printer threw its nuts.
• On Tuesday, we spent some time trying to resolve the nuts problem, including adjusting the position of the z-stop and making sure the bed was level. I think the nuts are back in order, so that's a non-issue at the moment.
• Today, we tried some additional test runs at 60 mm/min and the normal temperature, but the skipping issue is as bad as ever.
• Furthermore, manual extruding the filament no longer works correctly; it definitely does not extrude the length you tell it to and it extrudes very slowly.

So, possible questions that come to mind for me are:

Is it possible that we missed something during the cleaning?
Are there possibly contaminants in the ABS?
Has all the heating and re-heating of our test runs made the ABS pool again, thereby requiring another cleaning?
Is the new hobbed bolt bogus?

Here is the link to the actual bolt since I am not sure if it is an "improved" one or not:
http://www.ebay.com/itm/131012353183?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Thanks in advance for your replies.

 

XenoZergie, Did you get this figured out? What fixed it? Thanks.

 

I found the default robo settings to be way to fast for me to get a good print.

Sent from my GT-I9505 using Tapatalk

 

Mark, Do you have a picture or link to the new hobbed bolt? I'm not sure if mine is new or old. Thanks!

 

By pointing out the recess in the hob section, you cleared things up. I have the improved one. Thanks!