Hot end problems

[dylantep]

I recently put together a Rostock Max V1. The hot end was working fine at first. I was working through some other problems when I noticed that the hot end was taking quite a while to heat up. I redid the PID autotune (set to 200C) and when it got to the upper range a bunch of white smoke started coming out of the hotend. I immediately shut it off. I've done some more test and it seems when I get up to 180 or so I get the white smoke (though there is very little now) I checked to make sure the connections for the resistors and thermocouples are ok and they looked fine. The onlything I noticed was that the nozzle was a little loose and it looked like some filament had been oozing out of the crack. So other symptoms are that it seems to stop extruding after about 15 mins of a print and the printed part has some dark blackish looking stuff smeared into it. Also when I heat up my hot end there is now a strange metallic smell. Any thoughts on this would be greatly appreciated.

[gestalt73]

Hey dylantep,

not sure about the smokey part, generally that's bad, but I can't remember if my hot end smoked a bit the first couple of times it was powered up.
I'd be interested in knowing *where* the smoke was coming from. Some places are worse than others.
A few puffs of smoke coming out of the nozzle end may not be so bad.
Smoke pouring out of your heating element would be a bit more worrisome.

Also make sure you pay attention to geneb's instructions about the hot end. I'm pretty sure there's a step where you tighten the nozzle at temperature, but it seems youv'e already figured that out.

I'm assuming you're trying prints using PLA, right?

Either way, make sure that you have the PEEK cooling fan installed. PLA is jam-city without it.

Oh, and welcome to the Rostock Max V1 Owners Club!

[dylantep]

I've tried to identify the origin of the smoke. Its definately not the nozzle. I think it might be one of the resistors. Kinda hard to tell though.

Yes i'm using pla, I have a 25mm fan installed (it's not PEEK but i didn't think that would matter)

Thanks

[mvansomeren]

On the V2 the hotend smokes the first couple of times you heat it up. It also smokes a bit sometimes when the filament extrudes out of the hotend.

[Earthbound]

Probably burned up one of the resistors. It could have been the source of the smoke, and only having one remaining functional resistor would explain why the hot end now is slow to heat up.

[dylantep]

Probably burned up one of the resistors. It could have been the source of the smoke, and only having one remaining functional resistor would explain why the hot end now is slow to heat up.

This would make sense. I tried to test if one wasnt working by putting a finger by either resister, heated up and tried to see if I could feel a difference (hardly a legitimate test) and I couldn't feel a difference. I still think you may be right though. anyways, what would cause a resistor to burn up?

[DanHall]

Too much current, a bad resistor, damage either before or during installation... could be many things. Grab your trusty multimeter and check resistances across both.

[Earthbound]

what would cause a resistor to burn up?

Air pockets around the resistor body. The resistors need to have good heat transfer to the aluminum hot end body.

Or bad/damaged resistor before it went in...