Not even flow of pla

[dwittenberg]

So I finally got most things tweaked and leveled and all that good stuff, but when it's printing, it seems more like hot glue in that it's coming out in globs, so meanwhile the head is running around the shape it's supposed too it's only getting blobs of pla at a time and not an even flow so of course doesn't work so well. Any ideas what would cause something like that? I was also looking for a more advanced guide that maybe had the settings/values for all the controls this appears to have, maybe something is out of whack ?

Any ideas welcome...

Dan

[RetireeJay]

You can post a picture to show us what's happening. Use the "Upload Attachment" tab below the editing screen, then "Browse" to find the photograph on your computer. Attach the file. Then position the editing cursor where you want the picture to show up and click "Display Inline"

But based on your verbal description, you see erratic blobs. Are there fine threads between the blobs? This sounds like the extruder is starving for plastic. You might have a problem with the way the filament is feeding into the extruder. Do you have a geared extruder drive or is it direct drive? The calibration for geared extruders is usually near 600, while for direct drive extruders it's near 100. But you really do need to calibrate the extrusion correctly. It's pretty critical; if you are more than 5% off then your prints won't be very satisfactory. The Getting Started Guides will help you with this.

[dwittenberg]

Sorry I did forget to mention the model was the Printrbot Plus. I scanned through the Getting Started guide again and I don't see that I missed anything in there, but always possible I guess. Here's one pict of it printing, one of the final product and what the setup looks like, maybe you can spot something obvious.

[RetireeJay]

It looks like you have virtually no compression on the springs that tension the idler wheel against the hobbed bolt in your extruder.

I wish that Printrbot HQ would make it more clear that you need to look at BOTH Getting Started Guides. Here's the link to the older guide, which discusses how to calibrate the Extruder: http://printrbot.com/wp-content/uploads ... Guide2.pdf

[dwittenberg]

Ahh will give that a shot. Yeah I had it a lot tighter, but had no clue what it was supposed to be at. Originally I was thinking maybe I had it too tight so it was having a hard time pulling through...

[dwittenberg]

So the hardware calibration was good info, but didn't help much. I did put the digital temp meter on the bed and found it was about 20 degrees cooler with the glass so I upped the bed temp to 80 and now it's sitting at about 60 on the glass itself. Here's a pict of the "square" it was trying to print:
IMAG0042.jpg

I've also got a video of the next square I tried to print:


So as it's starting to print, it's going around in circles, but nothing is coming out, even though the gears are moving and when I grab the filament it feels like it's moving. I did the test of marking the filament, and I ran 30mm through it according to the Repeteir control panel, and it actually pulled through about 33mm (worth worrying about?) So it looks like stuff should be coming out, but it's not, and it keeps going around but for some reason only bubbling out and not that constant flow. Any more thoughts!

Thanks again so far good advice!

[dwittenberg]

On www:dropbox:com/s/c9nj8hxxydj0xp2/VIDEO0005.mp4
Video of failed print

[KDog]

Your filament is not feeding. If you have had lots of jamming then your hobbed bolt could be full of chewed up filament and needs to be cleaned out.

[dwittenberg]

I'll try cleaning it out, but this is has pretty much what it's been doing since it was put together unfortunately.

[dwittenberg]

So things are getting closer! I got this print last night, and you can see in the pict that the solid areas are still rough, you can see each layer, and for some reason in the middle it got really thing, and those were supposed to be arms sticking out but it got really stringy and not solid layers. So seems it's acting more like hot glue, would that be from being too hot? Another config? I've been going through the slic3r docs and that's helped tweak things in closer so hopefully something small to finally get some good prints!

Thanks again!
Dan

IMAG0047.jpg

[PxT]

Break it down to basics. What happens when you try to extrude filament out into free air? Move the print head up from the print bed and try to extrude a few tens of mm. Do you get a nice consistent string of filament with no gaps, bubbles or inconsistencies?

[dwittenberg]

Yes, that's what is weird. When I just run the extrude by itself it seems to run fine. This weekend I tore some of the extruder down and re-built and it seems to be a little better aligned now. I did notice that the gear and the filament hole were offset a bit, maybe 1/16", so I took some super thin aluminum shims and shimmed the bearing to where those line up now. I did some small test parts and they worked well, so I moved on to try some bigger stuff. Now what I'm seeing is after awhile of printing, say about 10 minutes, the filament starts to jam up in the gear:
IMAG0050.jpg
So it's almost like the gear is pushing it down but the filament isn't melting it fast enough...just a guess anyway...thoughts?

Dan

[davec]

I hear a lot about the "straw fix" but this is what I did. It has helped a lot.

01 Circuit Board Spacer.jpg
01 Straw Fix.jpg
02 Straw Fix.jpg

If you need to shorten the spacer take it out and drill it out some more with the 5/16" drill.

03 Straw Fix.jpg
04 Straw Fix.jpg

The following is my first extruder with the hobbed bolt. I had to use 2 spacers on this one.
I left the two spots that hit flat and just filed the bottom one and drilled the top one. I
don't know if they make longer spacers, but already had these ones.

[dwittenberg]

Awesome picts and descriptions, will get on trying that one out!

[dwittenberg]

So I got the new sleeve in place, and working great so far, thanks for that info! So it was able to get through another full print without jamming, but as you can see from the picture something is a little off. This was supposed to be a standard 2x2 lego, but the edges look a little melted, the circles on top aren't nice and round, and the bottom is solid not open. Does that happen from being too hot maybe ? Right now it's at 210 for the extruder and 80 for the bed. I've gone through the slic3r docs, and not sure if I've missed something ?

Thanks again!
Dan

IMAG0056.jpg

[PxT]

210 is pretty hot for PLA unless you know that the brand you are using needs a higher temp. I usually print around 180 with most PLA.