Yeah...I see this on some of my models, especially tapered cylinders. Not sure its exactly at 30% but it gets to a point where the extruder is doing its thing but no ABS coming out. At first I canceled the prints but then decided to let it continue and after messing up a few layers it finished the rest of the build. My thinking is it is one of these:

1. Faulty STL (I am playing with netfabb today to see if this makes a difference)
2. Memory issue or some other interuption between PC and Replicator over USB (will try sending to SD and see if that makes a diff)
3. Settings - maybe extruder speeds need to be set lower?

Thoughts?I is really frustrating I know. I dont think it's a filament feed issue.

Ok I tried to document what I'm seeing. Hopefully its what youre seeing too. See attached file. Cannot fathom why it stops extruding ABS at certain points and why the scaling of this part is so badly off? Help us here Makerbot people! I am also attaching my STL. I think we can eliminate memory issues and reducing extruder speeds hasn't helped either. Is the STL Ok? Netfabb thinks so.

Mine was doing this too. In my case it’s that the setscrew in the feed wheel is not engaging the indent in the stepper shaft. So when the motor is cool it’s tight enough to print, but as it warms up and expands during a print the wheel expands just enough to slip. You can check this by removing motor and checking to see if your setscrew is still lined up with the indent. Mine was not. The problem is that the indent in the shaft doesn’t go all the way to the base of the motor where the set screw is so even tightened it’s not in the indent, just tight on the shaft. If you re-line it back up with the shaft and remove the setscrew and look through the hole you may see that the indent doesn’t go all the way past it.

Michael Aboltins on another thread suggests dremeling the indent a little further down to solve the problem. I haven’t done this yet am waiting to hear back from support first. But this sure sounds like it may be your problem too.

I had considered the ABS feed but disocunted it when I found that the problem was occuring at exactly the same place in each build, irrespecitve of nozzle used. But this is an interesting and valuable comment. Is it possible to post some pics of what you mean ie setscrew/indent lining up? I wish Support was more active with feedback on comments posted. If they could try the STL file I posted and verify whether this is the issue or not would help a lot of us I feel.

Hey everybody,

I'm sorry we don't get in here more often; we do prioritize ticket requests and that doesn't leave us as much time as we'd like to go through the forums -- we'll often let a thread be if it seems like the community is having a useful discussion.

John: if you're still dealing with this issue, please start up a ticket with us for individual help.

There are a few things to try: you can up the temperature to 230 C, which can be helpful.  Checking that drive gear is always a good idea, but I doubt that's it if you're making it that far.  A print consistently failing at a certain point definitely makes me think it's an issue with the specific .stl you're using.

It might also be worthwhile to try printing with the new 5.5 firmware and ReplicatorG 0037 -- have a look here for details.  This update changes to Skeinforge 50 and also has some changes to the profiles that should hopefully help with the dropouts.

Hi Ethan

I have tried all of the above to no avail. Today I tried to print someone else's STL (here: http://www.thingiverse.com/thing:26143) and the result is the same ie at about 5mm height the dropouts start for a couple of layers before it prints normally again. See pic attached.

I'm kind of treating my experience with Replicator as a bit of a waste of time and money to be honest. Barely using it now since I cannot get the things I need to print properly. And I documented this issue carefully, together with STLs etc attached above. How difficult would it be to try the file on a known good Replicator??????!!!!!!

Rgds

I am still a fan of the thermal expansion of the feed wheel causing drop outs at close to the same time on each build ;) But that is not the problem with that design. I tried to print that with a known working extruder and it looks exactly like yours. So in this case, something is goofy with that design or the way that replicatorG slices it.

Hey John,

That's not good -- I'm going to start up an individual ticket with you about your experience.  There are a few things you've described that aren't making sense to me, and I think they could be problems with your individual bot or software setup.  I see you've just opened a ticket about communication issues, and I'm going to hop on there with you.

-Ethan

ok, but maybe something else is going on as mine did it again printing nothing but the calibration cube that came with the makerbot just a moment ago...

I have a theory that this aberation in printing happens with circular objects only. I can print other straight and curved objects all day long without seeing dropout. But the minute I try cylindrical shapes it drops out in places. I posted a tapered nozzle file above and as shown have checked in in netfabb. it will not print on my Rep without dropout. So the STL looks fine and everytime I print it it fails in the exact same place ie dont think this can be a thermal effect on the filament feed. Slicing procedure?

ok...so Replicator calls me a liar. I tried printing the extrusion I'm designing twice. Same file, same conditions. First time it printed 100%. Second time there was dropout at about 5mm height (see attached image). So this is happening on more than just cylindrical shapes. Interesting thing is that on the second run the bot paused and stuttered a good deal in places. On the first run it was smooth. Could this be the transfer of data to the bot? Perhaps this is the same issue as others have reported on the forum under different headings?

I'm seeing this too, I can get absolutely fantastic prints one minute, and the next time from the same file I get these dropouts. I've taken to turning the AC off here in the evening to make sure no cool breeze sweeps into the platform. My extruders are as tightened up and cleaned up as possible. I've leveled the build plate with the magnetic mount dial caliper while at 110C and sometimes I can get a 2mm slice model to print so lovely that youd think it was injection molded, and other times this happens. Something is goofy.

I have noticed that sometimes if I turn the replicator on and go immediately to unload filament after it heats up I just get ticking and nothing comes out. I can't pull it or push it. It's hot so if it's just running backwards I should see it coming out but it isn't. It's not exactly slipping it seems to be changing direction or just skipping a step or something. If I cancel that, switch to load filament then it will run forward, and reselect unload and it will run perfectly again. This has happened to me dozens of times, but not every time I go to unload the filament. I am running the 5.5 firmware and I wonder if there isn't something actually wrong with the stepper logic at some point? Has anybody else seen that? I'm going to take the extruder apart and watch the wheel spin until I can catch it in what it's doing...

I caught the stepper malfunctioning. I have no idea if this is related to the other problem. I tried to print the axel file for the makerbotmobile last night, and you can see the exact same dropouts as the other folks here are having. i'm including a picture of that. The gear was almost totally hollow due to this and just broke right in 2 when I pulled on it. So we know that is a good file. So it's either the slicing or something in the makerbot firmware. Which I suspect because mine is doing it with some of the calibration cubes which came on the memory card with it and were created prior to the most recent release of the replicatorG software. I can't remember if I had this problem before the firmware update. I'm on 5.5 now, will check for another shortly. But here's the dropouts in the axel file and also a link to the movie of my stepstruder just ticking and not turning.

The movie is interesting. I drew a line on the motor shaft so you can see it's not just ticking due to the filament being stuck or the plunger being loose. The shaft isn't turning at all. I get this if I go right to unload filament after turning on the machine. The fix is to switch to load, then back to unload and then it works. The movie was still processing when I sent this, but should be there shortly.

http://www.youtube.com/watch?v=1NP3M3VSvkk

Oops, uploaded the wrong video, here is the link:

http://www.youtube.com/watch?v=PVmlk4HgbW0

PG...tx for the contribution

I'm getting this freezing regularly now too. We're on our fifth month of using the Replicator and I only started experiencing this problem two weeks ago. We keep our machine rods regularly oiled (by which I mean greased), and I clean out the gears and the nozzles once every two weeks. At first the Replicator was freezing on faulty STLs, but now I'm experiencing this on other STL files I've printed with no problems for months. This problem seems to happen more often on larger prints, with ReplicatorG freezing on a certain build line while the printer head stops moving and the extruder retains its temperature, spewing out plastic over of the side of the model--sometimes burning it--until somebody catches it and shuts the machine off. As mentioned above, the freezes always occur around 30% or 60%.

Sorry, I meant that I'm noticing these dropouts at the 30% and 60% points in large prints, especially circular ones, which will also occasionally coincide with the freezing I mentioned.

Here's a pic of two prints of the same part (the long m8 nut from http://www.thingiverse.com/thing:27769). The one on the right was printed with 90% infill, 0.1mm layer thickness and no acceleration. The one on the left failed - as you can see I have broken it off where the dropout layer occured. This is near the end of the build in this case ie beyong 30% or 60%. This one was 100% infill - that's the only difference in the gCode. Why?

yes, exactly what I am seeing too. And yet other things it will print perfectly. I have several of the more detailed cat renderings printed perfectly with all their curves and circles and 10% infill without any problems whatsoever. But I can duplicate those dropouts with other parts exactly as we've already posted picts of. 

I haven't done enough testing yet to say for sure this is the problem, but it's worth a try as so far things are working really well here. Please check the plastic tab of the gcode generator settings and adjust the diameter of your filament. The default is 1.86 or something and when I put the filament I was using into the calipers I read out at 1.67. After placing that number into there and rebuilding the gCode I've been able to, for the first time, print that M6 coupler file. I've also printed the axel file without those drop outs too. And when i put the default back in I get the dropouts again. even testing with the accelerated settings I get a print without dropouts (but with less precision, probably need to dig up those articles on tuning acceleration) so take a caliper to your filament and put in the proper value vs the default, which is actually wrong for all my filament from makerbot or elsewhere. I'll be very curious what people find out!

I measured our PLA filament with a caliper and got a diameter of 1.72mm. Our default on ReplicatorG was 1.82, so I dropped it down to 1.72mm. I did a few test prints on objects that were having dropouts before and they seem to have went away. I've been printing for about 38 hours now and haven't seen any dropouts yet. I'm keeping my fingers crossed, but this looks like it might have done the trick.