Extruder heater shutting down during build

Hi All,

I have finally finished my RepRap Mendel including a heated bed which is working very well when printing the first couple of layers. (see [pdf417.blogspot.com] for further details on the heated bed).

The problem occurs around the 8th to 10th layer where the extruder heater simply switches off. Everything keeps working.... all axis keep following the correct path, the extruder motor keeps turning back and forth accordingly and it would seem that the build is progressing, but since the extruder cools down as its not being supplied any current, no ABS is being extruded.

The LED on the extruder controller that indicates that the heater is on or off is also off. If I stop the build and turn on the heated manually, it all works fine. I even restarted the build twice and it all works ok, however at some random point around the 8th to 10th layer (that's how far I managed to get) the heater is powered off again. To be honest the build is quite big and covers over half of the print bed.

I set the extruder temperature at 240C since I'm using ABS and using Techzone electronics with Extruder board version 2.2 running firmware that came with reprap-mendel-20100719.zip This is my 3rd extruder board as I blew the first, the second had a number of dry joints on the processor which couldn't be fixed manually and now this.

Can anyone offer some guidance as to what might be happening or what could I do to diagnose the issue further.

Regards

P

First I would check the gcode to make sure that it is not turning off the heater before I looked for a HW/FW problem.

---

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Also check that the MOSFET is not getting too hot to touch.

---

[www.hydraraptor.blogspot.com]

Thanks for your replies,
The MOSFET is just slightly warm, so not even hot.
I'll check the GCode tonight.... what should I be looking out for?
As I said, its quite a big build and the file is 8Mb in size so it will take me all night to check every line, one by one.

Thanks again

Regards

P

Had a quick look at the GCode and can't see anything wrong there. It all looks looks the following in between layers from the beginning till around layer 15 ( I didn't go any further than that and the print stopped at layer 8 and 10 in my print runs)..... Is this code correct? Should T0 be at every layer?

G1 X69.4 Y64.3 E8343.1 F1500.0 ;horizontal move (This is the last command of the previous layer)
G1 F18000.0; feed for start of next move
G1 E8303.1; extruder retraction
G1 F1500.0; feed for start of next move
M106 ;cooler on
G28 X0 ;set x 0
G28 Y0 ;set y 0
G92 E0 ;zero the extruded length
;#!LAYER: 10/140
G4 P9 ;delay
M107 ;cooler off
G4 P20 ;delay
G1 F5.0; feed for start of next move
G1 Z2.55 F30.4 ;z move
G1 Z2.7 F5.0 ;z move
T0; select new extruder
M113; set extruder to use pot for PWM
G1 F1500.0; feed for start of next move (This is the first command of the next layer)

M109: Set Extruder Temperature

Example: M109 S190

Look for any lines containing "M109 S0".

---

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

There is actually only 1 mention of M109 and it goes like this "M109 S240.0 ;set temperature and wait"

Should this be in other locations as well.... I mean in between layers for example?

Thanks again

Regards

P

No. It should only be at the beginning to set the temperature (and wait) and then at the end to turn it off.
If you are using skeinforge there may be an additional command after the first layer since you can print the first layer at a different (usually higher) temperature to get it to stick better to the bed.

---

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

I'm using the Java software that's available for download from [sourceforge.net] to generate the GCode. The STL files where created in OpenSCAD then converted to a Binary STL using NetFabb Studio (free version)

Will be trying out a smaller build today to test if the same happens around the same layer or at a later stage.

Thanks again

Regards

P

The RepRap Host generated gcode should only set the temperature at the beginning if I remember correctly.

---

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

I gave it another go using the same GCode as before and it worked we and got past the 10 layers. However it still failed! This time at layer 39 (one third through the build.
No clue what's going on but I'm suspecting its an issue with the extruder controller board from Techzone. I'm on my 3rd board and its still failing to complete a print. Very frustrating! I'm thinking of swiching to a different extruder controller. Anyone can suggest a good one that works with Techzone main controller?

Regards

P

I can definitely get way past 10->39 layers on a print, and mine is really slow print... I have a print going right now that's 6 hours in. I also lent my techzone extruder board to a hackerspace and they probably put 100+ hours of printing on it. I'm just saying I don;t think it's the design of the board as the most likely suspect...

the best way to tell is to connect it to someone elses printer. it will work on a makerbot even, if it works for them then it's not the board.

I'd be happy to test it for you.

-Anthong

I'm sure others have a working techzone board and I don't believe its the design of the board that's faulty. But I do believe the particular board I own is faulty. Possibly a dry joint or something due to the erratic behaviour.

Anyone willing to swap a good Techzone extruder board for my faulty one

Regards

P

I feel obligated to get back to you on this, my heater stopped after about 10 hours of printing last night. Once the heater stopped the filament stripped... everything else was working great after that still but no extrusion. If I figure it out I'll get back to you.

As to you other question about which board works with the techzone mainboard I don;t think it matters at all. I've been buying makerbot stuff to replace parts as needed only becuase I assume they are the most widely used, but I know the future of reprap electronics is moving towards arduino mega shields like the pololu electronics.

here's a guy that sells the components:
[ultimachine.com]

Thanks Anthong Redbeard,

I'll be looking forward to your comments. I gave it another go this morning, but this time the heater simply stayed on all the time charring the heater wires at contact point with Nichrome wire. This erratic behaviour must be a dry joint on the board but I can't identify where.

Regards

P

Edited 1 time(s). Last edit at 09/24/2010 10:14AM by pdf417.

Techzone replied to my e-mail, but they said I have to wait till mid next week cos the guy that can help me is at an exhibition. I can wait till then. Its not a matter of life or death, but I'm eager to get this printer working.

I decided to take matters into my own hands and build a heater controller that is independent of Techzone electronics. See blog for build details (http://pdf417.blogspot.com)

However I still had other problems. This time the extruder motor stops working for no reason. A quick reset in between layers solves the problem temporarily so now I can at least still print and be able to wait till Mid next week.

Regards

P

Has anyone else ever had this problem and solved it? I'm having it now myself. I've gotten through several multi-hour builds, but now I've had two failed builds in a row with this problem. This is the third time total this has happened. Nothing in the GCode is set to turn off the heat. I also have the Tech Zone boards.

I just happened to be near the machine when I think it failed this last time. The head paused for a moment then started printing again. About a minute later I could tell something was wrong.

hey all
i also have the techzone boards and have had this problem a few times.
most of the time i found it to be a power problem. sometimes my power connector is a little hard to get on, and if anything moves it(vibration, filiment etc) it can disconect for less than a second resetting the extruder board. if this isnt the problem check your temp as the techzone software seems to occasionally reset to 2000 so the heater is shut off. problem im having at the moment with the same boards is the printer seems to shift about 1cm to the side occasionally and try to continue building over thin air. think again this will be a wiring problem as the supplied cable heads were poor.
hope this helps

Brian

Thanks Brian. I'll definitely check for power problems causing a reset. I read somewhere that the TechZone boards should be tied together to a common ground - have you done this as well? Doesn't the motherboard firmware continually monitor the temperature given by the extruder board? I'm not sure what you mean by "reset to 2000..." Whenever I check the temperature of the nozzle post-failure, it's cooled itself down to room temperature by the time I notice it. Whatever the root cause, the heat has definitely been turned off.

Thanks again!

hi
i hav not changed the boards in any ay and have had many successfull(if small and not perfectly tweaked) prints.
what i mean by "reset to 2000" is the firmware is set up so if t does not recieve a temp reading rather than choose 0 and let the heater burn your extruder, it goes to 2000 and shuts the heat ff ill it getsa reading again. will be trying to tidy up my cables tonight and will report back if it improves anything. but i deffo recomend checking all your connections and keeping the filiment away from the power cable. if you have the techzone power supply, add a switch beween the female connector and your chock block(r however you distrobute power)

cheers
brian

Thanks Brian, that makes sense now. I went ahead and tied the ground of my motherboard to the ground of the extruder board as described in this thread: [forums.reprap.org]

I had 3 - 4 failed prints in a row but, as soon as I ran that single ground connection, I managed to get off two successful prints in a row (both just under 2 hours worth of printing). I'd say it's probably too early to tell if this is the final solution, but it sure seems reasonable. I can't explain why I suddenly had a ground problem after about two months of no problems of that sort, but I suppose ground problems like that aren't exactly predictable.

I'm a newbie - so I don't feel in the least bit qualified to even suggest this - but I am as I was having the exact same problem - although my heater was turning off very quickly - not even completing first layer!!!

I had reduced the #define MAXTEMP to 240 in the sprinter configuration.h. As long as the heater temp NEVER went near 240 everything was fine.

However, once I needed to increase the temp to 240 - thinking I would be OK as the max temp was set to 240 - the heater started to effectively disable itself, and not just back off from 240 a little. It would just turn off until it went below the point at which the ABS would extrude.

Here's what I THINK is happening: as the heater heats up it sometimes overshoots by a degree or two. As soon as it hits the MAXTEMP, the heater is disabled, turning it off completely.

My "fix" was to set the MAXTEMP to 250, and still have the heater set to 240. Now, it heats up to 240, sometimes overruns to 242, cools a little then bounces around 240 which is what I wanted.

Morale of this story - check the temp your trying for and the MAXTEMP if its the same or very near, then that may be the problem.

It depends on your firmware, but check to see if you have thermistor temperature smoothing set on. I was getting interference from my thermistor readings and occasionally getting a spike temperature which switched off the hot end. Switching on smoothing stopped this as it averages out the thermistor readings so they can only rise and fall slowly.

The MAXTEMP setting is to stop the hot end damaging itself, so setting it at 250 is too low. I run my hot end at 255 when printing and this does no damage. The max setting in my firmware is 275.