Prusa I3 Temperature Falling

[pgriffy]

Very new to this, so apologize in advance if asking a stupid question.
What I've Tried To Do:
Purchased a HIC Technologies Prusa i3 kit.
Assembled kit.
Print.

What I'm Using:
Repetier
Cura(I tried both just in case)

What Happens:
Hot end heats up to 210
printing starts
hot end immediately starts cooling, like it has been shut off.

I ended up clogging up the nozzle, so I ordered another. It appears as if everything should work (if I manually move any axis or the extruder they all do what they are supposed to and the printer does go through the motions printing something but no filament comes out), but when I tell it to print, the dropping temperature eventually creates a cold extrusion prevented situation. I think.

I also tried removing the shroud to the fan that blows on the nozzle/print area. For one thing it was hanging down lower than the nozzle, for another, I wanted to take the cooling out of the equation. Same issue.

I'm stuck and frustrated. Any help would be appreciated.

[printbus]

...hot end immediately starts cooling, like it has been shut off...

Using either the LCD on the printer (if it has one) or the host software you are using, can you confirm whether the "set temperature" for the hot end stays at 210 when the hot end seems to be cooling off? If the set temp drops off, the printer is doing what the slicer is telling it to do in the gcode. If the set temp stays at 210, it could be something like intermittent connections at the heater or in the wiring, or printing way too fast for the hot end to keep up with.

EDIT: If the set temp drops off, another possibility is that the connection to the thermistor in the hot end either shorts out or opens up. Most if not all firmware will detect this as an overtemp or undertemp error condition and shut off the heater circuit.

[3dkarma]

Repetier should prevent cold extrusion. I'd definitely do what @printbus says and check what's happening with the set and reported temperatures as it's printing.

If the reported temperature is dropping off but the set temperature isn't, it may be that your power supply isn't capable of providing enough power to run the hot end and motors concurrently (although this would be unusual). Can you tell us what it's (the power supply) rated at?

[pgriffy]

Sorry it took so long. x and z endstop switch wires decided to pull loose from switch. So Ive got them soldered back together and reran the test. For some reason, Cura didn't want to connect to the printer, so I saved the print (20mm cube) to SD card and printed from there.

As near as I can tell, it is falling, but if i look at control/temperature/nozzle on the lcd panel, it still says 210. It is coming back up now, so I think that it must be something in the gcode telling it to cool or it doesn't regulate temp very good or it just has some serious bad juju. Or my ignorance (most likely).

Anyway, I've attached some video of it printing. For some strange reason it starts off like a normal cube for the first few layers then starts gradually moving in the y direction (nozzle does also travel in z direction).
https://drive.google.com/open?id=0B6...kNQTkZFVUpHaEU
Power Supply: https://drive.google.com/open?id=0B6...zB1ckFJV2xtTkU
Finished Print: https://drive.google.com/open?id=0B6...TZ4Vl84cl9qdjQ

I'm sure I've missed something simple, I was just wanting to print something regardless of the quality to see if everything was working right before I started dialing things in.

BTW - I did look for a local maker group to draw from their experience, but the closest one is about 50 miles. I appreciate the help you are offering. There is just sooo much on 3d printing out there and some of it contradictory. I don't know what's the "best" place to look and I don't know exactly what everything is called to know what to look for. I've gathered that the kit I bought is a Prusa I3, but sometimes looking at pictures of other Prusa I3's the extruder setup looks nothing like mine.
Very confusing!

[printbus]

Never seen printer with a heated bed and a power supply only rated for 20 amps. Well, unless the HIC powers the heat bed with 120V line voltage or something. If you are printing on a warm/hot bed, try running a print with the heat bed turned off. Like 3dkarma suggested, maybe the power supply is dropping out when the motors are added into the mix. If you have a voltmeter, monitor the 12V output of the power supply and see how stable it is. If the power supply is bogging, it could be affecting the motors too. Also, if the y-axis is belt driven, make sure the belt is tight so that it can't slip on the motor pulley.

I've also never, ever seen a video of a hot end dripping melted drops of filament like that. That suggests to me the hot end is actually a LOT hotter than you think it is. The extruder is supposed to soften the filament, not turn it into a liquid state. Usually when a hot end drifts over time, you end up with a spaghetti pile of filament or what people describe as a nest. Maybe a dumb question, but is there a chance that the connections for the hot end and heated bed temp monitoring thermistors are swapped at the electronics?

[pgriffy]

Anything is possible. I do have a voltmeter, so I'll check that out along with the thermistor. I've got a non contact thermometer, so I can check if the temps match too.

I was already printing with the bed off (read that was better for pla).

This would probably be going better if I wasn't so impatient

Edit: Well that doesn't make any sense. I used the preheat pla setting which does heat the bed up to 70 and the hot end up to 180. The bed measures pretty close temperature wise.

If I point the laser on the nozzle, I get 25.0 C, aluminum block 31.1 C, barrel above the aluminum block 69.1 C. I thought maybe it was F for the hot end for some reason, but that is 155 F at the barrel, nowhere near 180.

I'm assuming it is melting like this because it is too hot, so that doesn't make sense.

The power supply stays pretty constant between 12.01 with nothing going on and 12.09 with everything running.

I don't know what changed, but it is printing sorta now. It printed nothing the first layer or two, now it looks pretty good. I think the cube is supposed to be hollow. it appears to be trying to print the walls next to the base of the cube instead of on top of that. I should be able to tell by looking at the gcode if that is something funky there and not the printer's fault, right?

[printbus]

Measuring the hot end temp with a non-contact (IR) thermometer has fooled many people. Most of the thermometers aren't that accurate or just otherwise struggle in measuring such a small hot spot. The outside temp of the aluminum block is also not the same as the inner chamber temp. I know on mine, if I move the IR thermometer around to find the highest reading I can, I still read about 20 degrees (C) lower than the set temperature. EDIT: The thermistor approach used to measure hot end temperature is also not all that accurate - just another variable to be aware of.

Both hot end and bed are described in celsius temperatures, not F. I'd be curious to hear other opinions on the drops of melted filament. Maybe I've just missed similar issues.

You could post the gcode here for a look see, especially with the temperature commands. They'd be few and far between in the gcode and easy to search for in a text editor. As far as the stackup of the layers, some slicers and host software allow you to view the layers. When I want a truly independent view, I take a look at the file in an standalone viewer like http://gcode.ws/ . With gcode.ws, enable layer view and then move the buttons on the bottom and on the right side of the view area to "walk" through an interpretations of what the gcode is telling the printer to do.

[LambdaFF]

You definitely should try and look at the temp commands in the gcode using the txt text editor.

For the nozzle, you should see something like this :
M109 T0 S200
or like this :
M104 T0 S200

For the bed :
M140 T0 S70
or
M190 T0 S70

TX means extruder/bed X, as you only have one, then it is 0
SX means the target temperature

If there is 4 in the MXXX, it means set temperature but don't wait to reach it.
If there is 9 in the MXXX, it means set temperatire AND wait to reach it.
http://reprap.org/wiki/G-code#M104:_...er_Temperature

I agree with the others, try without heated bed and see what happens. Also, there should be nothing in Farenheit. The nozzle temp can be off a bit from the reading but more than 5% is surprising.

[printbus]

I have another thought, based again on seeing the dripping filament and the smoke in the video that suggests a too-hot temperature. How is the thermistor attached to the hot end? It could be that it isn't quite touching the metal block. That could cause it to read a lower temperature than it should, which would cause the closed loop heater control to raise the hot end temperature higher than it should. Depending on how the thermistor wiring is bundled, starting to print could move the thermistor and further affect how well it is reading temperatures.

With the hot end at a set temperature, you could try tugging around on the hot end wiring and seeing if the measured temperature changes. Ideally the measured temperature would remain steady.

[pgriffy]

Well, there is a small hole in the side of the aluminum block that doesn't look like it serves any other purpose. Is the thermistor supposed to go inside that hole? It is touching the block right next to that hole, just not actually inside it.

I did some more monitoring of the voltage during a print and it did drop below 12. I'm not certain if I may have accidentally shorted something trying to do the measurements or not, but now as soon as I plug it in (before running any commands, no pc connected, etc) the hotend heats up until it reaches maxtemp then keeps going. I am trying to test it with an old atx powersupply with the green and black wire jumpered, but that measures at 12 v, so I don't see how that could cause this problem.

The vendor sent me new firmware, but it is a marlin.hex file, so I can't see what is in it and don't know what to put in the firmware file if I download vanilla marlin and flash that.

At this point I'm about to pull my hair out. I want to contact the vendor, but I don't know if I have a bad power supply, hot end, electronics board or all of the above.