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Extruder flow issue when printing

Posted: Thu Apr 04, 2013 2:28 am
by bplemmons
My Rostock will flow fine when I load the filament but when I go to print it acts like the extruder isn't hot enough and I have to turn the heat way up and even then it doesn't flow evenly.
If I get a nice even flow when loading PLA at 180 and ABS at 230, doesn't that mean the extruder is getting hot enough? I have the first layer height set at .3 mm and I have checked and rechecked my slicer setting, I even tried kisslicer. It just doesn't want to flow when I got to print.....
Any suggestions?

Bill

Re: Extruder flow issue when printing

Posted: Thu Apr 04, 2013 8:08 am
by MorbidSlowBurn
It could be a couple of things.

1) check your tension on the extruder. It should advance the filament wihout slipping if you put a little tension in the filament going into the extruder

2) at the start of prints the nozzle needs to be primed. That is why most slicers have an option to do a skirt to ensure proper flow of the material before actually printing the part.

3) if the nozzle is too low it can block the filament from coming out of the nozzle. Need to check z height.

4) if it is temp related, check the nozzle temp with a thermocouple. If you don't have one, a digital oven thermometer can be used. Locations of fans can impact the hot end temp.

Do you have any pictures of what your parts look like?

Re: Extruder flow issue when printing

Posted: Thu Apr 04, 2013 6:16 pm
by bplemmons
I just bought a mutimeter with temp. reading and I first checked it on my Replicator amd it wad dead on, then I checked the Rostock on the body of the extruder just above where the resistors are and it was 20c lower than the setting in Repetier. I wondering if this could be from not having quite enough foil on the resistors? What should the ohms read on the resistors?

Thanks for the help!!

Bill

Re: Extruder flow issue when printing

Posted: Thu Apr 04, 2013 6:23 pm
by bplemmons
I just noticed something else, I shut the extruder off and checked the temp as it was cooling and i'm still off 20c as it is cooling, ( checking the main body ) would this indicate the themister being off?

Bill

Re: Extruder flow issue when printing

Posted: Thu Apr 04, 2013 7:22 pm
by cassetti
I personally haven't used an external thermocoupler to test the temps against what my thermistors are 'reading', but if plastic is extruding out the tip - temps might not be the issue. Did you remember to double your steps per MM for the extruder as well as X, Y, and Z?

My very first print (the cube) on the rostock went ok, but it still wasn't extruding enough plastic - turned out my extruder was only running at half the steps per mm! Once I've fixed that, my print quality has been great (though I'm still calibrating).

Re: Extruder flow issue when printing

Posted: Thu Apr 04, 2013 7:28 pm
by Polygonhell
bplemmons wrote:I just noticed something else, I shut the extruder off and checked the temp as it was cooling and i'm still off 20c as it is cooling, ( checking the main body ) would this indicate the themister being off?

Bill
Ideally you want to measure the temperature inside the nozzle, but practically the best place to do it without disassembling the hotend is the interface between the brass and the AL block.
I found mine read more accurately after I insulated the outside of the heater block, so I suspect there is just a significant thermal gradient in the AL block.

Re: Extruder flow issue when printing

Posted: Thu Apr 04, 2013 7:58 pm
by bplemmons
My tower steppers are set at 106.67 and the extruder is set to 584.... I have tried the Marlin and your repetier firmware....

Thanks again!

bILL

Re: Extruder flow issue when printing

Posted: Thu Apr 04, 2013 11:19 pm
by bplemmons
Would someone measure their extruder and tell me what they get? I am checking it at the top of the body right above where the resistors are located and I read 30c less that what repetier reports, this would explain my extruding problems but I don't know how to fix it... what should the resistor read? I'm getting 4.5 ohms reading across both of them...

Bill

Re: Extruder flow issue when printing

Posted: Fri Apr 05, 2013 12:26 am
by cambo3d
bill i have a chart with all my readings in my build log. this is how I know what temperatures i'm actually using in general. though your numbers will be different.

hotend cal and bed temp cal http://forum.seemecnc.com/viewtopic.php ... &start=150

Re: Extruder flow issue when printing

Posted: Sat Apr 06, 2013 12:42 am
by bplemmons
Checking my nozzle temp with my gauge, I was actually a little higher than your reading (182 set at 230) So it must not be the extruder, With the fitting off the extruder I was able to easily push filament through the nozzle. I even checked the resistors and they are reading 3.4 ohms which I have read is right, it must be a software setting, What should I have the flow rate set at? I'm at 100...

Bill

Re: Extruder flow issue when printing

Posted: Tue Apr 09, 2013 1:02 am
by cambo3d
I had a thought, have you checked your filament size, to make sure you are using the correct filament slot in your extruder.

Re: Extruder flow issue when printing

Posted: Tue Apr 09, 2013 1:32 am
by bplemmons
You nailed it, I discovered this last night, I had reloaded Repetier and all of my settings were saved but the filament size.

Thanks everyone!!

I'm finally printing on this awesome machine!!

Bill

Re: Extruder flow issue when printing

Posted: Tue Apr 09, 2013 1:39 am
by cambo3d
well i was thinking the extruder, but looks like it was the software setting. glad its workin