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Extruder help

Posted by simono71 
Extruder help
November 18, 2012 08:29PM
Hi, I just finished builder my mendel max from a kit I got from ebay. It uses ramps 1.4, with a wade extruder and J hot end. I have got everything working, but the extruder doesn't seem to work properly.
I did a search on here and see that some people have suffered similar issues. I tried following some of the ideas, but to no avail.
I am using abs, and if my thermistor can be trusted, have tried extruding at 230, 240 and 250 degrees. The abs initially feeds the filament into the extruder, and then the abs stops feeding when it should be coming out, but the gears keep turning though the hobbed bolt just eats into the abs and stops feeding it forward.

As I read in one the posts I removed all the tension and tried just pushing the filament through by hand. I can get it to extrude doing this, but I do have to push fairly hard. I don't know how much pressure is normal, but it seems that it is more than the extruder can do without my help. I have tried tightening up the tension screws, but all that happens is that more abs gets chewed up.

My ideas are
1) I have a clog in the extruder (but as I can force it through, albeit with a lot of force, I am not sure about this.)
2) My hobbed bolt is not very good.
3) My my power level is off, or my thermistor is off, and I am not actually at the required temperature.
4) I have lousy abs.

Any thing else someone might suggest, and any more ideas as to how I might track this down? After spending all this time putting this thing together, it sucks to be stuck at the last hurdle.

Re: Extruder help
November 19, 2012 10:49PM

your temperature reading is off ... i had the same problem and i measured my temperature with another thermocouple attached to my hot end ... it would be good if you can do that.... if not just raising the temperature 10 degrees and retry extruding ... and keep raising till your extrusion is smooth but not burnt and brown....
Re: Extruder help
November 19, 2012 11:42PM
also lower flow rate. flow rates with 3mm will be alot slower if the nozzle size is less than 0.5mm
Re: Extruder help
November 20, 2012 08:53PM
hi, i'm using pla but have had problems with my extruder of late
my problems all ended up being that my hotend was too close to the bed. this prevented the
filament coming out correctly which put pressure on the extruder and then it would start stripping the filament and then stop.
i raised my hotend only 0.1mm (via the Z value in slic3r) and is working 100 times better.
hope this helps,

Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.
Re: Extruder help
November 21, 2012 01:15AM
I don't think this is related to the hot end height, as I have the hotend about 50mm up in Z, and am simply trying to do a manual extrude using Pronterface. I set it to 30mm extrude, and nothing comes out.

I have also read, in addition to temperature, that I might not have enough tension. If I push the filament manually then it comes out. Also if I squeeze the ball bearing as hard as I can, then it also comes out, but this seems like a silly amount of tension.
I am nervous to increase the temp too much, as I don't want to start melting the PEEK, in case it turns out to not be a heat issue. I took it up to 250 (according to my sensor), but no improvement yet.

I took my j-end apart and noticed that the teflon tube seemed to bind when I pused the filament through, so I thought I had found the problem. I reamed it so the filament would slide easily through (when cold of course), and then re-assembled, but no luck sad smiley

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