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lazurus

Ultimaker 1 MAXTEMP triggered by cooling fan>

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The fan wire acts as an antenna broadcasting noise. The temp probe wire acts as an antenna receiving that noise. Keep the wires at least 10mm apart (in the lower part of the print head) and you should be good. Once the signal passes through the tiny board on top of the print head it should be immune from these issues.

 

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The fan wire acts as an antenna broadcasting noise. The temp probe wire acts as an antenna receiving that noise. Keep the wires at least 10mm apart (in the lower part of the print head) and you should be good. Once the signal passes through the tiny board on top of the print head it should be immune from these issues.

 

You mean to keep the temp probe wires 10mm apart from the fan wires, right? Not the two wires of the temp probe from each other? That would even increase the sensitivity of the 'antenna'...

 

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Well then, that's not the problem.

I don't know what the problem is then. Are you sure it's related to the fan? Could it be a coincidence? The MAXTEMP error is very common on UM Originals after (very roughly) 100 prints are printed. But in that case it is related to the wiring on top of the print head and has nothing to do with the fan - it will happen when the fan is on or off. You can sometimes duplicate this by pushing on the wiring at the top of the print head.

Does it work okay at 100% fan? at 1% through 99% the PWM circuit is turning the fan on and off many times per second and this can cause possible electrical interference but at 100% (setting 255 on ulticontroller) there is much less interference.

Also consider just swapping to the backup temp cable at the top of the print head (and of course you will have to change the wiring at the other end also on the PCB).

 

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Very interesting. Yesterday I had an almost similar problem. Maxtemp ended two prints after less than 5 minutes. But I don't have a fan on theo printhead, useing a cross flow fan. Thought the reason might have been that I have been working on the hot end and installed a thermal sock, so maybe the a cable has become loose. But it hasn't. The third print worked and all the others too. Hope the problem won't come again.

gr5 can you tell me more about maxtemp problem after 100 prints and how to solve it? I have done roughly 100 now and it can't be the fan. Didn' t find anything with the search function which does not work very well. But interesting though, that the metal mesh around the sensor cable is for blocking radio signals. Thougt it's for thermal issues.

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There's a tiny board on top of the UM Original test head that converts the tiny thermocouple voltage into a voltage from 0V to 5V where 0V is 0C and 5V is 500C (and 20C is 200mv). The wires that leave this board go along the bowden tube and are moved every time the test head moves.

The problem is usually at the connector of that wire bundle. I think the wires are ground, power, and signal. The wires are supposed to be crimped into that connector but UM typically solders them which is bad because some solder wicks along the stranded wire and inside the insulated part and having a partial wick causes a stiff strand which can break when the head moves back and forth. There is a black "F" shaped strain release that is supposed to help this but you (like me) may not have used it.

This commonly causes MINTEMP and MAXTEMP errors. You can usually duplicate the intermittent error by pushing the test head to all 4 corners a vew times or if that doesn't work, push on the cabling (at least 30 times) in every different direction right near the connector at the top of the print head.

The quick and easy fix is to switch to the other cable (for the second extruder). You have to switch at both ends of course (both on the head and on the PCB).

 

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The search ability for this forum kind of sucks - for example it ignores anything 3 characters or shorter even when it is likely to be the most important search term e.g. ABS. The simple solution is to use google. You can tell google to only give results from a particular website like this:

site:umforum.ultimaker.com ABS

 

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Thanks a lot gr5 for both of your answers. That helped a lot. I love to understand problems and how machines work in detail... So the reason is a broken or half broken wire, because of the stiffer wire next to the connector. Took some time to understand what you meant with "F" shaped strain release. Well, I should have installed that one. But I didn´t because I did not see any sense in it...

Okay so the quickfix is to change to the second wire bundle and install the strain release. Does the strain release completely solve the problem or will it occur again in 100 prints? This would mean a new set of wires sooner or later and every now and then. I would love to have a permanent solution and a stable printer. Additional heat shrinkable tubing might help, I think. Crimping the connectors would be perfect, but don´t have the right tool for it. What did you do on your UM original?

Pushing the print head into all four corners, well haven´t moved the printhead with the UM switched on. When switched off, I know its not a problem and done it before, but switched on. Anything to consider for not damaging the machine?

The tip for useing google this way is great. Hope UM or the company programming the forum software will fix the search function sooner or later.

 

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Pushing the print head into all four corners, well haven´t moved the printhead with the UM switched on.

This is fine. You do it with steppers off, but power on. For example when you first turn power on the steppers are all off. After you stop a print or pause a print the steppers turn off within a minute or so.

It's okay to turn the big extruder gear by hand also.

or will it occur again in 100 prints?

Probably not - it was probably because of your lack of strain relief (hopefully we have diagnosed the problem correctly).

Additional heat shrinkable tubing might help, I think.

Sounds good. I added some glue from a hot glue gun on top of the strain relief because that is a very flexible but firm material.

 

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Well then, move steppers move. Printing right now, but will do the test later.

I think the diagnose is right. Sounds logical, and if not well then I will certainly find out. Installing the strain relief won't do any harm.

So I will switch to the second cable, install the strain release and reinforce the new cable with heat shrinkable tubing and maybe a little glue from my glue gun. Hope this was the last time I have seen this error.

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Done. Moved the head and the cable several times, error occured. Your diagnosis seems to be right gr5. Changed cable, installed strain release, fixed with glue gun and isolating tape.

Lazurus, did you find the error and got it fixed? Sorry for hijacking your thread...

P.S.: Got 3 spools of Colorfabb today and 3 more to come. Let´s see how well it prints. Got my boss paying :-P :cool:

 

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Shit! Did a 7 hour print tonight. Stopped right in the middle because of Maxtemp. Did all the stuff to fix it before, like I wrote above.

The printhead stopped next to the Autohome position. Also next to the cross flow fan. Twisting the wire improves the situation, will do that. Anything else I can do.

Is there maybe a software approach to fix this? I don't know exactly how the signals generated by the fan look like, but I think the value change is much faster than the right signal comeing from the temp sensor. So maybe you can use this for an If clause which says that the maxtemp error should not be triggered if the temperature change is bigger than 10 degrees Celsius in 10 seconds sth. like this. Did some programming in Arduino, but I am no programmer. Although this would be a workaround and nit solve the root cause.Possible? What do you think about it?

How did others solve this problem if it is well known to occur on the Um1 after some time.

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I don't know what to do about your particular hardware issue but I can address the 7 hour print...

It's not that hard to continue a long print. Even the next day. As long as you don't remove it from the print bed. Here are some general instructions:

http://umforum.ultimaker.com/index.php?/topic/4213-ideas-for-recovering-failed-prints/

Specific code example for UM2 (UM original has different way of homing and different startup code):

http://umforum.ultimaker.com/index.php?/topic/5269-um%C2%B2-printing-more-than-24-hours-non-stop/?p=46704

 

 

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Thanks gr5. Will try that the next time a print fails.

Found the reason for maxtemp error. Hardware. Was the conector and and the strain release on the print head. By adding glue from the heatgun, I made things worse. Switched back to the original cable, fixed strain release and made sure there can´t be any force on the connector. Since then I did a lot of long prints, maybe 20h together. None failed. Works.

 

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I just had an 18 hour print interrupted at 10 hours with a MAXTEMP error. My thermistor wiring is far (physically) from the fan wires, so I doubt it the two are related. The last time it happened, the yellow wire had obviously come loose from the thermistor. But this time, it appeared locked under the screw in the green housing. So I clipped the yellow wire shorter, and stripped a small portion and reinserted it. This is only the next day, but it has been printing OK for 13 hours now.

You refer, above, to alternate wiring, but I am unclear what exactly you are referring to, or what my options are to avoid another MAXTEMP error (I have a UM1). I also don't really know exactly what you mean I should do to "improve strain release." All I know is that is it is quite frustrating when it is unclear what is causing such a fatal error.

 

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Usually the problem is *not* between the sensor and the top of the print head where the little circuit board is. Usually the problem is at the connector at the top of the print head and the next 50mm of wiring.

There is a spare cable attached along the bowden tube for a second extruder. You can simply unplug the existing cable at the top of the print head and then plug in the spare plug (the other plug that fits and is just hanging there). Also you would of course need to do the same thing underneath your UM at the PCB.

Then you also should do a good job with the strain relief on top of the print head. There is a black plastic (delrin plastic) F shaped strain relief part on top of the print head - make sure the cable uses this.

 

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