1 Topic by rrssll

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Topic: Extruder not extruding. Jamming, shredding or clogging?

My Solidoodle Press isn't printing again. Imagine that. So first I'll describe what happens and next I'll give my guess about the cause.

Filament feeds in the extruder and the the gear turns without any problem. The hot end is at 245ºC. Plastic starts to come out the nozzle looking fine. About an inch comes out then the filament stops moving. The gear continues turning and digs in. No more plastic is pulled in. Pushing by hand doesn't help. I can retract, pull the filament out, cut off a couple inches and start over. The process is completely repeatable. This is using ABS that shipped with the solidoodle though I've tried others.

The extruder trimpot is at 1.5V. I've tried raising the temperature to 255ºC. I replaced the JST connector on the motor side of the extrude cable. I've replaced the brass nozzle on the hotend. I've cleaned the extruder barrel by soaking it in acetone overnight.

So now I have a guess. Somehow there's backpressure that's building up inside the nozzle and eventually it's great enough that the gear can't push hard enough. Once the hobbed gear digs in, it's all over.

Instead of backpressure it could be some number of other things. I've read about filament sticking to a scratched barrel. It's also possible that somehow when I screwed the barrel and nozzle back into the aluminium block that they're not perfectly aligned or sunk in. Or maybe I could reduce the number of steps/mm so that the extruder gear turns slower. The scenario I described happens when I extrude manually.

2 Reply by android78

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Re: Extruder not extruding. Jamming, shredding or clogging?

Check the alignment of the extruder wheel and the bearing that guides the filament. I've got the extruder wheel face almost flush with the shift of the stepper motor and it seems to work ok like that.

3 Reply by rrssll

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Re: Extruder not extruding. Jamming, shredding or clogging?

Right, in my case the groove in the gear is positioned such that the idler wheel pushes right into the middle of it. It feels like that's not quite flush with the end of the shaft. Maybe I'll try nudging it forward a little bit.

4 Reply by rrssll (edited by rrssll 2015-04-12 19:12:36)

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Re: Extruder not extruding. Jamming, shredding or clogging?

Moving the wheel didn't help for me. Still haven't found a solution for this. I also tried turning the extruder fan around (mentioned on another thread here) since it looks like there's a fat spot on the filament after I retract from a jam.

I wonder if I made it worse tying to clean out the nozzle last month though. I bought these 0.4mm drill bits off amazon http://www.amazon.com/gp/product/B00MQKW230 and these brass nozzles http://www.amazon.com/gp/product/B00PHEKFHM (EDIT: these nozzles are not a good match, see below). The nozzle I'm using now is one of these but I was having the problem before replacing it.

This evening I found that I can manually extrude about 5mm of filament then it stops moving. If I push the drill bit up to clear out the nozzle I can extrude another 5mm. I can repeat this a few times. So it seems like something is gumming up in there.

Tomorrow I think I'll take the nozzle and barrel out of the aluminum block again. I doubt I'll find anything but I'm out of ideas.

5 Reply by Goshdarnit

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Re: Extruder not extruding. Jamming, shredding or clogging?

Is it possible your filament has absorbed moisture? I was having a similar problem. Stuck my filament in the oven for an hour at 95 degrees C and it worked fine after that. I now store all my filament in a sealed container with some desiccant.

6 Reply by madfalcon81

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Re: Extruder not extruding. Jamming, shredding or clogging?

Goshdarnit wrote:

Is it possible your filament has absorbed moisture? I was having a similar problem. Stuck my filament in the oven for an hour at 95 degrees C and it worked fine after that. I now store all my filament in a sealed container with some desiccant.

Has anyone tried blowdryer? I mean at least the few centimeters who enters the extruder a time ?

Fat kids are harder to kidnap!

7 Reply by rrssll

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Re: Extruder not extruding. Jamming, shredding or clogging?

I have five rolls of ABS including the first one that came with the printer. I remember having this problem with all of them but I've only been trying with the original Solidoodle roll lately. I should do a more methodical test to be certain.

8 Reply by kmartin (edited by kmartin 2015-04-08 22:16:17)

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Re: Extruder not extruding. Jamming, shredding or clogging?

I have exactly the same problem and I didn't find a solution actually.

I have try with the original ABS Solidoodle roll and with a roll of PLA.

9 Reply by Goshdarnit

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Re: Extruder not extruding. Jamming, shredding or clogging?

kmartin wrote:

I have exactly the same problem and I didn't find a solution actually.

I have try with the original ABS Solidoodle roll and with a roll of PLA.

Did you try drying it out in the oven?

10 Reply by rrssll

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Re: Extruder not extruding. Jamming, shredding or clogging?

tl;dr those brass nozzles I linked earlier don't work with the Solidoodle Press stock hotend.

Here's how I removed the hot end (of course if you follow my lead and mess up your printer that's your problem). The nozzle is brass, the block is aluminum. These are soft metals, softer than your tools. I had to use a couple large adjustable wrenches and heat the block up a bit to 50ºC since I'd baked it in there with plastic. I put one wrench on the nozzle and the other on the throat to break it loose. If the block is hot it can melt the black plastic on the rest of the extruder, be careful not to let it touch.

After taking them out I realized that there are two tiny set screws the same size as the the one that holds in the extruder gear. You can see they're holding the block on in this photo http://soliforum.com/i/?h6p6kQ0.jpg. In retrospect it would have been smarter to take those out first, as long as I didn't need to heat the block to unscrew the nozzle & throat.

So here's the aluminum block from my hot end http://soliforum.com/i/?wgxxyIj.jpg. You can see in the middle of the hole the problem is just what I was afraid of. The melted ABS squeezed out between the the nozzle and the throat.

Here you can see http://soliforum.com/i/?NpmiHMX.jpg the original nozzle on the left and my replacement on the left. Notice that there's an angle on the hole in the original nozzle that matches up with the end of the silver threaded tube. Notice that the replacement nozzle is flat across the top. So they don't mate properly and that leads to the leak I had which causes the repeatable clogging after about 15mm of extrusion.

Oh, and here's what the heating element (the cylinder) http://soliforum.com/i/?lGuFaHl.jpg and thermistor http://soliforum.com/i/?iowC5em.jpg look like after removing the block.

So I had trouble before replacing the nozzle but it looks like I brought this one on myself. I should be able to put the old nozzle back on and I'll see how that goes.

Anyone know where to get spare parts for these things?

11 Reply by trayracing

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Re: Extruder not extruding. Jamming, shredding or clogging?

Nice photos! How does the leak cause the clog?

12 Reply by rrssll

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Re: Extruder not extruding. Jamming, shredding or clogging?

Based on the little ring of hardened ABS between the two I think there's some uneven heating in the middle or something. Maybe the middle of the filament doesn't melt? I don't believe that ring of ABS was there in the aluminum block last time I disassembled it though (before replacing the nozzle).