Hot end not heating up fully

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JohnSays
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Hot end not heating up fully

Postby JohnSays » Thu Jun 30, 2016 1:16 am

Using N2 and Raise3D PLA - Firmware 1.1.1:

I thought I had a clogged nozzle because the filament would not flow. However, I checked the temperature of both nozzles using my infrared thermometer ( both were set to 215C and show that on the LED screen). The one I am having trouble with, the left, is 100C cooler than the right nozzle. So what causes that and how do I fix it?
- John

2 Raise3D N2 Duals, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection, Firmware 1.1.9ABH - with Lin_Advance, Palette 2 Pro, Custom E3D hot end and ultra-light carriage and printer head

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Vicky@Raise3D
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Re: Hot end not heating up fully

Postby Vicky@Raise3D » Thu Jun 30, 2016 2:41 am

Mostly a thermal couple problem.
Please remove the right thermal couple from the right heating block. And loosen the left thermal couple. Insert the right thermal couple to the left heating block and keep the left thermal couple inside as well. Please make sure the probes of two thermal couples have been inserted half in to the left heating block. DO make sure the depth is the same. Then heating the left nozzle. When it stop heating , advise the different of temperature showing on screen.

Jetguy
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Re: Hot end not heating up fully

Postby Jetguy » Thu Jun 30, 2016 2:52 am

An infrared non-contact thermometer is not a good tool to measure a hotend. More likely than not, this is a giant red herring, now you are ripping into wiring and thermocouples on the bad assumption you have 100C offset temp.

If you study how thermocouples work, the first conclusion is you should have known you are dead wrong for even thinking it's 100C off.
By the very structure of the system, at most we might ever have a 5-10C offset between any 2 hotends. The thermocouple is guaranteed to be + or - 3C with the AD597 amp. The depth these go into the long heater block makes an offset beyond highly unlikely.

Sorry for being abrupt here but this is a giant problem across forums. Novice user grabs a infrared non-contact and asssumes everything they measure is accurate which is beyond false. This leads down a train of destruction and further bad assumptions.

Either use a real external thermocouple contact probe, or use a piece of filament and touch the nozzle. We could eliminate so many day long troubleshooting issues and red herring events if we followed that simple rule.

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Re: Hot end not heating up fully

Postby Jetguy » Thu Jun 30, 2016 2:55 am

And, the Raise 3D answer is not wrong, but I have issue with it.
You rob Peter to pay Paul. You rip apart a known working operational hotened, to use the probe to measure the other.
Sure it works, but come on, there was no proven issue in the first place. The first test should be take a piece of filament and touch the nozzle.
Cheap, effective, and doesn't require touching anything and certainly not touching a working hotend to test an assumed non-working one.
Last edited by Jetguy on Thu Jun 30, 2016 3:13 am, edited 1 time in total.

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Re: Hot end not heating up fully

Postby Jetguy » Thu Jun 30, 2016 3:00 am

Again, sorry for jumping this but it's driving me crazy to see the new folks hell bent on damaging parts for no good reason out of ignorance.
The less you can mess with wiring and thermocouples, the SAFER and more RELIABLE your printer will be. While they aren't glass fragile parts, the wiring exiting the heater cartridge and the thermocouple should NOT be repeatedly bent at a right angle. And I assure you, it's just a matter of time of repeated abuse of tearing these hotends down and back up that somebody is going to short and blow the electronics sky high and then be crying. Seriously, people ripping the threads out of heater blocks, leaking nozzles, this is a ripe disaster and it's all preventable.

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JohnSays
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Re: Hot end not heating up fully

Postby JohnSays » Thu Jun 30, 2016 3:19 am

Thanks for the answers and the understandings. I will touch the filament first. That's a nice simple test.
As far as infrared thermometers go, I use them to get rough differences in temperature by averaging several spots on each hot end. I'm not looking for 215C -- the set temperature. I'm looking to see if the hot ends are even in the same ballpark. In my case, they are 100C different. I have two infrared thermometers and they each show a different temp, but about a 100C difference between left and right. That much variance should be paid attention to.
- John

2 Raise3D N2 Duals, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection, Firmware 1.1.9ABH - with Lin_Advance, Palette 2 Pro, Custom E3D hot end and ultra-light carriage and printer head

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Re: Hot end not heating up fully

Postby Jetguy » Thu Jun 30, 2016 3:47 am

Let's get back to basics:
#1 infrared thermocometer is based on black body radiation. The heater blocks are silver aluminum, and surrounded by aluminum heastink fins above and plastic fan shrouds to the sides. This makes it nearly impossible to assure proper look angle and spot area- let alone the proper emissivity. Bottom line, it's the absolute wrong tool for the job for any accuracy and far too often leads down a goose chase.
#2 basic thermal rules. Heat always flows from a heat source of higher temp to a lower temp object, not unlike water only flowing downhill. The heater cartridge is hotter than the heater block when on, the thermocouple is heated by the heater block, meaning it will always be cooler than the heater block (by only a few C at most). Knowing that relationship, the heater block is hotter than the thermocouple at all times.
#3 Understand that in order for the controller to stabilize temp and read 215C, that the "system" and all parts has to be working. If there was poor thermal contact between the thermocouple and heater block, then the thermocouple is cooler, much cooler, than the heater block. As such, the controller turns the heater on more in attempt to reach the target temp making the heater block hotter than the set temp and the reported temp. Again, you said you saw it stabilize, that cannot happen in a malfunctioning feedback loop. Even if there was an offset, the answer is it will be HOTTER than setpoint, not 100C cooler.
#4 The firmware is doing bounding on temp measurements and if there is an error in the thermocouple circuit, the heater is disabled.

Knowing all the above, either you have the most unique failure method recorded to date and somehow, beyond all reason, logic, and principle of operation of the very heater control and firmware, your system has a real 100C offset,
OR
As stated, your measurement is bogus and a IR thermometer is not reliable or accurate for measuring hotends

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Re: Hot end not heating up fully

Postby Jetguy » Thu Jun 30, 2016 4:03 am

Again, let's step through failures.
Let's say the thermocouple shorted- that throws the AD597 into an out of range condition, the firmware sees this and shuts the system down
Let's say the thermocouple went open circuit- the AD 597 tests for this and again, throws error, the entire firmware shuts down the front LCD throws a mintemp error
Let's say it's a partial short. The thermocouple works on creating a microvolt signal. The resistance would have to be perfect to result in an in-range temp offset. The likely hood is impossible. I mean you would have to have a perfect not short of several megaohms of resistance, just enough to reduce the produced voltage by the TC wires, and yet still stay in range and still follow the actual temp and track so the heater and controller did stabilize at the set point.
Let's say the mode Vicky suggested is possible, the thermocouple was not making good contact and measuring the real heater block temp. That means it would be lower (thermal rule #2 heat flow high to low) than the real block temp. The block would be 100C hotter, not cooler
Lets say in some insane and mechanically impossible way, the heater cartridge and thermcouple were in contact with each other, but NOT well coupled to the heater block. In other words, the only real way the thermocouple could report 215C is if BOTH the thermocouple and heater were touching each other, yet somehow, beyond the mechanical impossibility of that, the heater block was cooler than the reported temp because it was not making good contact to either the sensor or the heater, but the heater and sensor were making good contact with each other even though they are in separate bores and totally mechanically separated by the heater block. It's so impossible I can't believe I typed it.

So again, by the very nature of what you are saying, somehow, somewhere, there was an offset that allowed the control to still feedback, still stabilize the heater, not go into thermal runaway, and yet the heater block was 100C below (or whatever offset yet cooler) than the reported temp.

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Re: Hot end not heating up fully

Postby Jetguy » Thu Jun 30, 2016 4:08 am

One I left out, lets say the microcontroller ADC (Analog to Digital Converter) is blown. That results in a stuck temp. (typically 170 when we see it happen on the HBP failures of the ADC). If that was the case, that "stuck temp" would have to be 215C. Otherwise, if below or above the set temp, either the heater is stuck on indefinitely, or never turns on because reported temp is higher than target temp. And, you saw the temp change and rise over time.
By far, the most important thing is not just the change in temp, but the fact it stabilized. I cannot stress enough, that indicates a working system because it's so improbable to have any failure or offset and have any reasonable stability in a feedback loop.

firesped
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Re: Hot end not heating up fully

Postby firesped » Thu Jun 30, 2016 12:59 pm

the left is not flowing? the first question is, are you still on the original feeder system or the bondtech feeder system?

option A)
is your feeder motor clicking when you try to feed filament?


option B)
are you running a bondtech firmware?


just to note: we seem to be having major issues with filament loading/unloading that a guide to properly loading and unloading filament should be made so the issues can be stopped in the future.
RL name: Michael Nolen
printers:
raise3D N2 kickstarter Early Bird
Trinus Deluxe (running smoothieware on Azteeg X5 GT board)
Monoprice Maker Select v2

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JohnSays
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Re: Hot end not heating up fully

Postby JohnSays » Fri Jul 01, 2016 1:40 am

So, thanks again Jetguy. Look, the PLA filament did not melt at all on the left nozzle even though the temp on the screen says 215C. It melted on the right -- got gooey and made a small mess at the end of the filament. This is consistent with my observations of temperature. Also, my IR gun has a setting for aluminum -- both polished and oxidized. That is what I used.

Firesped: Yes it was clicking even thought the bore hole was completely open = no plastic in the nozzle or tube or cold end. Verified by looking through it and running a small wire (.35mm) through the nozzle end. I couldn't see through it. Not running Bontech.

So, this morning I turned the machine on and the left extruder began to click again, but filament melted on the nozzle. So I pushed on the filament and it fed! Just went in and fed. Now I did this very thing the night before to no avail.

So today I printed two parts with the left extruder. So the problem is intermittent. I checked the tightness of all connectors on the board by the heads. All were good but I moved them a little and re-tightened.

Going out of town for vacation tomorrow morning. So will revisit when I come back.
Last edited by JohnSays on Fri Jul 01, 2016 4:50 am, edited 1 time in total.
- John

2 Raise3D N2 Duals, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection, Firmware 1.1.9ABH - with Lin_Advance, Palette 2 Pro, Custom E3D hot end and ultra-light carriage and printer head

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Vicky@Raise3D
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Re: Hot end not heating up fully

Postby Vicky@Raise3D » Fri Jul 01, 2016 2:58 am

Since the filament cannot be melt with the left nozzle. I guess it should be the thermal couple problem. You can switch the right and left thermal couple to make a double check.

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Re: Hot end not heating up fully

Postby JohnSays » Fri Jul 01, 2016 4:49 am

Which one is the thermal couple and which the heater?
- John

2 Raise3D N2 Duals, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection, Firmware 1.1.9ABH - with Lin_Advance, Palette 2 Pro, Custom E3D hot end and ultra-light carriage and printer head

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Re: Hot end not heating up fully

Postby Vicky@Raise3D » Fri Jul 01, 2016 5:11 am

The upper thin one is the thermal couple. The below thick one is the heating rod.

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Re: Hot end not heating up fully

Postby JohnSays » Sun Jul 03, 2016 2:13 am

Thanks
- John

2 Raise3D N2 Duals, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection, Firmware 1.1.9ABH - with Lin_Advance, Palette 2 Pro, Custom E3D hot end and ultra-light carriage and printer head

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Re: Hot end not heating up fully

Postby Vicky@Raise3D » Tue Jul 05, 2016 5:22 am

How is your hot end going? Is the problem due to left thermal couple?

Jetguy
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Re: Hot end not heating up fully

Postby Jetguy » Tue Jul 05, 2016 11:53 am

I highly, highly, highly recommend you run the latest "Motion Board Controller Firmware" 1.1.3 firmware before doing any such tests. https://www.raise3d.com/pages/download

This is for your safety. Since you are about to intentionally change thermocouples and extruders, there is a chance that you cross connect.
The firmware 1.1.2 and below does not check for this error and could lead to a runaway glowing red hot melting the aluminum block heater.

I still don't have 100% proof positive since I just saw the new version posted it includes the safety function commit, but timewise, it should since the source contains it before the latest version was released. I suggest editing the release notes to include the safety feature if it is truly in there. https://github.com/Raise3D/Marlin-Raise3D-N-Series

v1.1.3:

Reverted reset function to v1.1.1 implementation.
Add compile option for single extruder. (uncomment #define DUAL to get dual head version.) In case to avoid the damaged second thermocouple on single head machine to generate an error.


This function simply checks for the thermocouple to report a rise in temp when the heater is on within a defined time period. In other words, if the thermocouple is not properly attached then it cannot see the temp rise and will trigger safety.

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Re: Hot end not heating up fully

Postby Jetguy » Tue Jul 05, 2016 11:59 am

Again, what really bothers me here is we are saying the following.
The system heats and stabilizes per the LCD
The motion controller PID loop is working and not oscillating
The reported temp is higher than the actual temp (a physical impossibility) The thermocouple cannot be hotter than the heater block.

Known errors that could happen:
Damaged ADC that reports a fixed non-changing temp value
Thermocouple shorted near breakout board- would read ambient temp, not far end heater block temp (thermocouple wire generates voltage along the length of the very wire itself)


Due to the presumed offset in temp, the theory is updated firmware would catch this as a safety fault, although in this case, if reported temp is higher than actual temp, I would think you would slam into max temp first with an overshoot on the first rise.

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JohnSays
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Re: Hot end not heating up fully

Postby JohnSays » Wed Jul 06, 2016 1:21 am

Thanks again Jetguy. Not sure what this means: "The motion controller PID loop is working and not oscillating" I'm not intentionally reporting something that is not oscillating. Did you infer this from something I wrote?

I've got my Bondtech parts now. Last time I tried to print, everything worked. Jetguy, in your opinion should I go ahead with the Bondtech install/upgrade, or wait for the hot end problem to re-materialize and try to resolve it?
- John

2 Raise3D N2 Duals, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection, Firmware 1.1.9ABH - with Lin_Advance, Palette 2 Pro, Custom E3D hot end and ultra-light carriage and printer head

Jetguy
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Re: Hot end not heating up fully

Postby Jetguy » Wed Jul 06, 2016 3:39 am

By all means, install the bondtech upgrade and remove filament feeder problems from "the list".
Your hotend problem won't matter one way or the other.
Either you fix it, or it shows up, but at least the feeder is good.


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