Extruder Heat Fluctuating

My printer has been working fine, but in the last few prints I've tried (the same pieces it was printing just fine earlier) the extruder temperature fluctuates up and down. It will get up to around 190 and then drop down to 140 or 120, then head back up.

Sometimes it will do this before a print, and sometimes it will start printing fine and then at some point the temperature will drop and it will stop extruding (the printer continues to follow the pattern to print the part).

Also sometimes after killing the print the heat will cycle up and down.

It's all very random, sometimes it drops to 140 and goes back up, sometimes drops to 70, and it can max at 190 or 180 or wherever.

I don't seem to have manual control of the extruder either. I can control the heat bed and extruder fan, but the extruder temp. It will say Heating Extruder at the top, but the temp won't rise.

Any idea what could be wrong?

 

I wish I could answer for you. This is a most frustrating issue for me. I've never had the fluctuation problem. I usually preheat both the extruder and bed. This is when I see the extruder not do anything. Sometimes I would go back the next day and it would suddenly work, other times, I'd go back every day for 4 or 5 days with no luck and then it just like that it works like a champ. I am fortunate enough to live in San Diego and Jerry at Robo has been gracious enough to help me with a issues I have. I've take the printer down to the shop 3 times. We adjusted things, played with the software, did some test prints in an effort to get it to print successfully for me. EVERY time I've brought it home and fired it up, the extruder wouldn't heat. Everytime! It just so happens that today I took it in for a microswitch problem, we did a test, everything was fine. Brought it home-no heat. I guess the printer just doesn't like to travel. You might say something is loose and maybe bumps off while traveling and it would make sense. But it sits very quietly on the seat next to me, and doesn't have any problems going to the shop. I always check the connections and there is nothing visual to indicate a problem. Tomorrow I will keep my fingers crossed and hope it decides to behave. More than likely, both our problems is in the hot end. As soon as Robo gets more of the new hot ends in stock, I'm going to get one installed. Until then, I'll hope the printer gods give me a break. Good luck with yours.

 

If you can't get the manual control working in matter control could you try repetier host?

 

I should have mentioned, I'm using Repetier.

 

I had that with a wire to the heater cartridge. It was broken inside the heat wrap and worked fine until it got moved during a print...no heat....wait! Back again. Replaced the heater and all is well.

 

What firmware are you running? If you recently upgraded it to V4 of the firmware from Mattercontrol, it limits the heated bed to 85deg. Not that you would be using 85deg on PLA, but still I have to mention this. If you go beyond that it will hit the safety switch and shut both the extruder and bed off. If you leave it long enough it sometimes starts heating back up again after the fuse is reset but it will repeat the action.

If you are on V4 firmware, Revert the firmware and see if that helps.

 

Thank for the suggestions, found it.

View attachment 3848 View attachment 3849

 

I'm going to tear mine apart tomorrow. I hope I have the same luck. My fear is, I'm really good at taking things apart-it's putting them back together where I run into trouble. Luckily, I know where Jerry works!

 

Can those of you who have removed your hot end for whatever reason tell me how hard it was to remove the two screws that hold it in place? I found the head of both screws were stripped and one of them wasn't even screwed in all the way. It's like the builder stripped it and gave up. I got a mini vice grip to try to remove it and even with it gripped so tight I hurt my hand tying to lock it, it won't turn the screw. Another trip to Robo headquarters as soon as Jerry responds to my email. It's been a week and no reply, but Brayden is coming to the library Friday and I will talk to him directly. I can't wait to see how they fix this one.


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Like I said, I used a vice grip and you can't grip anything tighter than that! I would surely use hex heads to replace them, but first, getting them out is going to be difficult.


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I used vice grips as well (a new set of long nose with sharp teeth, my old ones were too rounded). They are very tight.