Extruder Struggling

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Theycallmejohn
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Re: Extruder Struggling

Post by Theycallmejohn » Wed Feb 12, 2014 12:46 pm

Piercet,
1. Can the filament spool move freely, or is it caught on something? Yep.
2. Is the filament feed tube allowing the filament to move through freely with no restriction (spcifically are the zip ties holding the tube in place too tight?) Yep, I was able to pull out more to feed it in when I tried to get it working.
3. Is the filament binding where the idler filament guide contacts the upper extruder body? (If so, sand some material away until it is able to move freely. No it quit working a third of the way thru the print. If it was binding it should have been an issue from the beginning.
4. Is the hobbed bolt grinding chunks out of your filliament? Yes but it it did half way thru the print and I cleaned out the teeth and sprayed with some compressed air to clear the chunks
A. If yes, you have either a temperature or force issue for feeding. Why would the temperature fail part way thru the print though.
B. If no, your small gear on your NEMA motor isn't tightened at the set screw all the way or your main gear is installed on the hobbled bolt incorrectly. I will check but I doubt this is the issue.

I am wondering if the heat sink is over heating that why it is failing part way thru the print. Hench I my idea of putting a fan on it. I do not want to take it apart again as it seems like every time I do I break something.


Can the PTFE tubing where out from all the heat cycles?

I will try dismounting the hot end and running the filament thru. I will also try hooking up a stand alone thermocouple with an alligator clip attachment. Then I will be able to set alarms for high and low temperatures and it can record highs and lows.

I appreciate your help.

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piercet
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Re: Extruder Struggling

Post by piercet » Wed Feb 12, 2014 3:44 pm

If it is stopping mid print, I'd guess that the heater cartridge has a short (or maybe the thermistor) and is losing connectivity at some point in it's range of motion that is causing the extruder temperature to drop below 230. it doesn't take much below 230 to cause the plastic to resolidify to the point where it will not pass through the nozzle at all. That would cause an immediate jam situation. It would only need to be shorted out for a few seconds to cause BAD THINGS to occur.

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Orias
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Re: Extruder Struggling

Post by Orias » Thu Feb 13, 2014 12:27 pm

You'll also want to check for breaks/intermittent connections for the hot end:

With the printer turned off and unplugged disconnect the hot end from the wiring harness and test hot end for the proper resistance. The smaller orange wires are for the thermistor and should read ~100k at room temperature. The larger red wires are connected to the heater resistor and should read between ~4-7 Ohm. Try to see if you detect fluctuation when moving the wires. Make sure that the hot end connector is fully seated and that the pins are fully seated within the connector housing.

You'll also want to turn on the option "Monitor Printer". Look at the temperature graph if the print fails again and note what is displayed if the print fails again.

Feel free to send a message to Support@LulzBot.com if you'd like any help troubleshooting this.

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piercet
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Re: Extruder Struggling

Post by piercet » Thu Feb 13, 2014 1:04 pm

One other thought too, what layer size are you trying to print at? If you are attempting a really really tiny layer, you can encounter situations similar to the first layer "too close to to the bed pressure backup filliament grinding issue"

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Theycallmejohn
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Re: Extruder Struggling

Post by Theycallmejohn » Mon Feb 17, 2014 12:47 pm

So....
I checked the thermistor and it was pretty close to the recommended range of 100k. I did not check the resistor because I switched over to heater cartilage when my resistor broke.

I had to take the extruder off because the filament snapped when it was worn down but the hobbled bolt, as I was trying to pull it out. I heated the nozzle with my heat gun and used that to loosen the filament. On a side note this seam like a much more effective way to pull out a clog because it heats the nozzle from the outside and you don't get the semi liqud state in between the heater block and the nozzle. I checked the the filament could easily pass through the extruder and down through the aluminum extrusion all the way to the nozzle without much friction resistance. I inspected the nozzle and the print head and seem like it was a another clog/partial obstruction.

I also did a test config with the Lulzbot Green. The filament is noticeably smoother than the other stuff I have used. Though does anyone what the diameter is suppoed to be? I measured the end and it was like 2.80mm but then I was geting a lot of over extrusion when I did my first test print. Is there a calibration step for this? Also is there a recommended extrusion temp for the Lulzbot Green?

True to my typical modus operandi. I did manage to break something when i was putting it back together. :oops: I snapped the plastic that holds one of the nuts to tighten down the extruder. So now I guess I get to print a whole new extruder body... yay... Any tips? I was thinking of doing 100% infill with and then do the acetone hardening. Thoughts?
lgreen.jpg
My most successful print in three weeks...

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piercet
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Re: Extruder Struggling

Post by piercet » Mon Feb 17, 2014 2:29 pm

Diameter on a bunch of filliament out there is 2.80 - 2.85mm, not the 3.00mm that would be ideal. There is a setting to adjust for that inside of repetier host, it may be part of slicer as well. check and see if you have a filliament tab and input the diameter of the filliament accordingly. That should ease the overextrusion. If it's still doing it you can repeat the filliament extrusion length calibration steps.

The extruder temperature should be pretty much right on 230 for most forms of ABS.

If you are getting actual debris plugging your nozzle, I would honestly throw that other filliament out and send whoever sent it to you a really nasty letter or something. Debris clogging nozzles is almost unheard of.

As a temporary fix for your extruder, use a zip tie to hold the isler shut while you print another one. Higher density is good. I'd also reccommend grabbing the extruder latch and idler from this: http://www.thingiverse.com/thing:224242 as they are improvements over the AO-100. You will need longer bolts to use the extruder latch, but it really makes opening the idler chamber much easier. No more having to reset the tension once you get it right. The filliament guide in the other idler helps prevent the tube from getting pinched. The belt one itself is also nice, but i'm still testing it and the parts are somewhat difficult to come by still.

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Theycallmejohn
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Re: Extruder Struggling

Post by Theycallmejohn » Mon Feb 17, 2014 3:02 pm

piercet wrote:Diameter on a bunch of filliament out there is 2.80 - 2.85mm, not the 3.00mm that would be ideal. There is a setting to adjust for that inside of repetier host, it may be part of slicer as well. check and see if you have a filliament tab and input the diameter of the filliament accordingly. That should ease the overextrusion. If it's still doing it you can repeat the filliament extrusion length calibration steps.

The extruder temperature should be pretty much right on 230 for most forms of ABS.

If you are getting actual debris plugging your nozzle, I would honestly throw that other filliament out and send whoever sent it to you a really nasty letter or something. Debris clogging nozzles is almost unheard of.

As a temporary fix for your extruder, use a zip tie to hold the isler shut while you print another one. Higher density is good. I'd also reccommend grabbing the extruder latch and idler from this: http://www.thingiverse.com/thing:224242 as they are improvements over the AO-100. You will need longer bolts to use the extruder latch, but it really makes opening the idler chamber much easier. No more having to reset the tension once you get it right. The filliament guide in the other idler helps prevent the tube from getting pinched. The belt one itself is also nice, but i'm still testing it and the parts are somewhat difficult to come by still.
Tim,
I rand the original with 2.80 and got a lot of over extrusion. Trying to remember what the original default was... :? .

The link you sent is to the one with belt. Are you saying that I can use that one with the standard gears?

Also what is your opinion on using acetone to harden the parts?

Thanks for the help.

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piercet
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Re: Extruder Struggling

Post by piercet » Mon Feb 17, 2014 3:25 pm

No, That belted extruder body as designed is for belts only. it's also a quickfit mount. But the idler and the latch will work with a standard wades extruder. You want the budaschnozzle compatable Johnaskhuling's Wade reloaded extruder from the lulzbot download section (probably the one from the Taz 3 folder) for the extruder body itself.

I've never tried the Acetone hardening. It should work, especially if you get the vapor bath setup. Might make your dimensions off too though for getting a good flat 0 degree extruder nozzle position.

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Theycallmejohn
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Re: Extruder Struggling

Post by Theycallmejohn » Tue Feb 18, 2014 2:30 pm

I think figured out what the issue was it is the over extrusion setting for the first layer. I think it just wasn't as noticeable with the black plastic.

Still fine tuning the filament diameter though. I only had time for two prints because some how my slice config file got corrupted and tried push the nozzle through the board.... not fun.

How do you know when you have the right calibration. I included an image but it is hard to see. the 2.87 is slightly smoother and the bumps where it changes layer are smaller.
Calibration.JPG
50mm Calibration cubes
Also Piercet do you know what size heat set nuts are need for the ext ruder?

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piercet
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Re: Extruder Struggling

Post by piercet » Tue Feb 18, 2014 3:56 pm

For the extruder body itself, unless you are making a flexystruder or my belted one, you don't need any heat set nuts. The Johnaskuling's style greg wade extruder here: http://download.lulzbot.com/TAZ/3.1/pro ... 3.7.11.stl uses a couple drop in nuts and a couple press fit nuts, but that's it.

Calibration is the art of trying to get your extruder to reproduce exactly what you told it to reproduce. On a belt drive machine there isn't much you can do on the X and Y aspect if they are set correctly from the factory. If you parts measure correctly with the calipers after they print in the X and Y direction (a 50mm cube is 50mm wide, a 2.14mm wall is 214mm thick, etc. You know that aspect is probably ok.. Z height calibration mainly consists of ensuring that your layer height is going up the amount it should be, which usually means making sure your couplers are intact and not flexing too much or too little, and starting layer issues. You can spend hours perfecting your Z height, but for overall part quality it's not nearly as important as extruder calibration. Extruder calibration at it's simplest is ensuring that when you tell the extruder to extrude 10mm worth of filliament, the filliament moves exactly 10mm, that the filliament measures exactly 2.80145mm in diameter (or whatever) and that setting is in Slicer exactly. A perfectly aligned and calibrated extrusion would exactly line up with the layer below it, and will not have any extra lunps or voids. The calibration steps for the filliament are here:

http://richrap.blogspot.com/2012/01/sli ... s-and.html
http://richrap.blogspot.com/2012/01/sli ... t-and.html

Looking at your pictures, I can see that you have some minimal Z axis banding occurring. If you look at the corners and you see that there is a bit of a wavey pattern, that height matches up exactly with the thickness of your threaded rod threads, and occurs as the threaded rod shifts from side to side inside the acme nut. There isn't much you can do about it in the stock configuration short of upgrading things, though I can tell you yours look better than my AO-100 started out looking like so you probably don't have a bent rod like I do so you shouldn't need to compensate for it as much in your hardware. Under or over extreusion will tend to magnify the layer change banding. It's still present the same amount either way, the material over or under extrusion just makes it look worse.

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