The reader reads fine when heating up, then keeps changing when the head moves

[wjuniorbr 0]

When I send something to print, it will heat up fine (I even measured with an external thermometer) then when it stabilizes the head will start moving to print, at this point the reader changes the temperature about 20 to 30 degrees down, and of course the controller think it needs to heat more, so it continues printing but it will be actually 20 to 30 degrees higher.

I always had this problem since I bought the printer (about 4 or 5 months ago), but I was able to print, only when I wanted to print something like two cilinder towers apart from each other, when the head has to print one then travel to the other cylinder without printing and print the other, in that case I would have "webs" between them, which I´m guessing now it was because it was getting too hot and melting to fast downwards.

But now it´s changing to much, and to lower, so it heats up too much, I already lost 1 insulator, it melted.

Has anybody gone through something like this and has some experience to share to help me?

thanks in advance

 

[gr5 2,267]

Do you have an Ultimaker Original? This is very common on the UM1. It often starts happening after the printer is many months old. Usually the problem is in the wire on the print head. You can heat the nozzle to say 100C and then push the head around to the 4 corners while watching the temperature and duplicate the problem. Also you can duplicate it by pushing on the wires on the top of the print head. The easier fix is to use the extra cable already installed - the cable hanging loose that isn't used - that is meant for a second nozzle. Unplug the current cable and plug that in at the head. Do the same thing underneath the ultimaker at the PCB.

But this time make sure the wiring goes through the black strain relief shaped like a F so it won't break again.

 

[wjuniorbr 0]

 

I actually have a ultimaker reprap called joysmaker r2, this url will show some pics of it, mine is the wooden one:

http://item.taobao.com/item.htm?id=16857610502

I also added here some pics of my printer head so you could see.

It´s pretty similar to ultimaker original as they went open source, they made some changes in the next release the r2, the same as mine, they added a heated bed, the design a little and some other small modifications that I don´t know.

What you said actually makes sense, as it moves the wire would short circuit or something. But mine doesn´t seem to have an extra set of wires.

I was thinking the wires of the thermometer are to blame? what do you think, maybe the heater wires instead?

And where exactly right on the base of the thermometer/heater or along the way?

and if right on the base, is there a way for me to chage it there? it looks like there´s now way to get inside the heater or the thermometer, and the wires look as though they are going straight inside without any connection to fix it.

 

[gr5 2,267]

The stresses are where the bowden and wires meet the head and so that's almost always where the wire breaks.

Push on the wiring near the top of the head and push the head around. If the temp changes suddenly (more than 5 degrees in 1 second) then it's the sensor path and can't possibly be the heater. If it doesn't change suddenly then it could be lots of things.

Once you get it to mess up push many times in different spots to get it to repeat and eventually you can often find the spot that is bad and replace that wire.

There's a similar but I think different common problem when the fan wires are too close to the other temp wires - before the probe is amplified. The signal is very sensitive to noise from the thermocouple but once it goes through the tiny amplifier board it is not sensitive so keeping the fan wires and the thermocouple wires at least 10mm apart can help a lot.

Do you know what kind of temp probe it is? Is it a thermocouple? Or some other design (thermistor, etc)? The UM Original has a thermocouple. And if thermocouple, where is the amplification board? On the print head like the UM Original?