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David    6

Hi to all,

It's been a while since I've posted on the forum. Lots of work to do for 3D Hubs customers.

I had a slot free so I tried to print ColorFabb HT with dissolvable supports (FormFutura Atlas) for myself. To minimize the oozing, I am using a change tool script in Simplify 3D to cool the previous extruder to a waiting temp and heat the new one to the working temp. So the printer printer has to heat the main extruder to 260°C, the second one to 210°C and the bed to 90°C (I'm printing on PEI sheet).

After the printer is hot, let's say 20 min, the power supply is constantly cooling, and them temps get unstable, and it's pretty difficult for the PID to compensate and hit the target temp.

The whole print ends up in a mess due to unexpected oozing, degraded plastic, .... And I noticed some layer shifting, but I'm not sure the head hasn't bumped into the part. The whole thing happened twice.

So I've been into some testing to realize that when loaded, even with only one single extruder @260°C, the PSU is getting hot, creating instability in the temps reading, even the non used extruder and heated bed. See screenshot. The oscillation is to fast to be linked to an hardware issue and affects every temp reading. Since the PSU is cold, no problem at all, the issue is that it's getting hot only after 15min of moderate usage. And at the moment, weather in France is getting a bit hot.

I've checked the wirings, the mainboard for any short or burn mark. The board is pretty clean. BTW I already have a 40mm case fan blowing on the driver side of the board.

I'm going to replace the PSU after a bit more than 1 year. I've read on reprap forum that 360W is the minimum if you have to heat the bed + extruders. So I've ordered a 500W industrial grade PSU from local suppliers (TDK-Lambda-GWS-500-24 has nearly the same size).

It will need a bit of drilling and wiring to put in place, but should be easily done.

Anyone had the same type of issue ?

David

Capture d’écran 2017-05-25 à 12.58.15.png

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David    6

I forgot to mention that I've replaced the thermistor on my E3D V6 by a brand new one before getting that temperature plot. It's a cartridge type, so easy to install.

It was exactly the same pattern with the previous thermistor.

David

 

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David    6

Hi

Some news about this issue

I have replaced my PSU with a TDK-Lambda-GWS-500-24, 500W under 24V. Quite easy to do, but I had to do some wiring as the inputs and outputs are reversed.

Since things are a bit better, but I still have temperature stability issues on all temperature sensors, even after some PID autotune.

I have cleaned all my contacts, checked the board for any color change or cold solder. I ran the printer without any bottom cover to allow more cooling.

I have ran some tests, first with no heating at all and of course no steppers motors, then disconnecting one by one temp sensors. There is some contamination on every signal for temp sensors.

Then I started heating the heaters 1 and 2 without the bed. There is some temperature oscillation, +/- 2 °C.
Then I heated the bed to 55°C and the oscillations continued for the extruders and smaller but correlated oscillations on the bed temp.
Increasing the bed temp to 90°C has increased the temperatures oscillations went to +/-5°C.
 
I need to mention that I had two strange events aprox two weeks ago :
- the printer stopped mid print without explanation though I’m having a UPS.
- during a print, the flow rate has increased by itself from 100% to more than 200%, doing nothing.
 
I suspect now the board to be faulty when’s hot, impacting the ADC.
 
While preparing my temporary wiring, I had a closer look at the board. Previously I’ve had a look at the connectors and mosfets, but not on the controller.
Clearly the ATMega 2650 shows signs of overheating and the ATMega16U2 too. See pics.
On my previous check, I've concentrated on the connectors and missed the controllers due to insufficient lightning.
 
After discussion with Savans, the technical support, I have created a temporary separate thermistor line for heater 1, to avoid any electro magnetic interferences.
And ran another test. I have followed the below protocol for the test :
  1. Turn on the printer
  2. Printer idle, just powered on to check connectivity and stability
  3. Heater 1 @210°C no bed
  4. Heater 1 @210°C Bed @55°C
  5. Heater 1 @260°C Bed @55°C
  6. Heater 1 @260°C Bed @90°C
  7. Heater 1 & 2 @260°C Bed @90°C
  8. Heater 1 & 2 @260°C no bed
  9. Heater 1 @260°C Bed @90°C
  10. Printer turned off
Even in phase 2, the temps are not stable and suffers a general interference.
In phase 3 and 4 some interferences, but temperature is stable +/- 1°C. Though I don’t know in the long term, as yesterday I was not able to print PLA with these settings.
Increasing the load on the board generates the instability and it’s correlated (see phases 7 & 8 screenshot)
Reducing the load to only 1 heater is not getting back the printer to normal operations.

Now with the last tests I can confirm that the problem is on the board, the ADC (part of the ATMega2560) is faulty, due to overheating. Maybe the previous PSU has provided too high voltage.

I am awaiting a feedback from the Mankati Support to find the best option for the board replacement.

David

IMG_1313.jpg

IMG_1312.jpg

Printer iddle.png

Heater 1 & 2 @260°C no Bed.png

Heater 1 & 2 @260°C Bed @90°C.png

Heater 1 @260°C no Bed.png

Heater 1 @260°C Bed @90°C.png

Heater 1 @260°C Bed @55°C.png

Heater 1 @210°C Bed @55°C.png

Heater 1 @210°C.png

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David    6

Hi

I had the feedback from Mankati Support, my board is faulty and needs replacing.

Based on their feedback it seems that my board is discontinued, so they kindly offer me to ship me an used board. I'll have to pay for the shipping.

So I will upgrade (again) my printer with an up to date board as I don't want to be in the same situation in a couple of months.

I'm looking at the Duet Ethernet with a full color touchscreen at the moment.

David

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David    6

Hi

Some update about this issue.

I've received my Duet Ethernet board with a 5'' color touchscreen + PT 100 board and thermistors.

I have to implement a 24V DC - 12V DC converter to keep my fans, led and probe. I am also implementing a SSR (Crydom D1D40) for the bed, even if the board can manage 15A current, I don't want to overload it.

I have to do lots of wiring as the board is much more smaller and terminals layout is different with Molex connectors.

I will take the opportunity to use shielded wires for the steppers, thermistors and heaters to reduce EMI, as PT100 are somehow sensitive to that.

I will also put Molex micro fit 3.0 connectors close to the printhead for fans, heater cartridges and thermistor, to avoid any future rewiring when exchanging one of these parts.

Lots of work for the next two days...

I'll keep you updated with some pics.

David

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David    6

Hi

I have finished installing the new board and screen with a brand new wiring. My Mankati is now powered by a Duet 3D Ethernet.

All the tuning has been done. It's pretty easy coming from Marlin, but still tedious.

I'm now printing some parts to finalize the assembly of the case's fan.

The print quality has improved due to the new drivers with 256x interpolation, but the main points are :

  • nearly silent prints (covered by my PSU fans)
  • connected printer, so I can managed it and upload file directly from my computer.
  • touchscreen with direct access to all the functions.
  • yet to come, a IP camera to follow the print when away, using the same interface as the printer web control.

So now, the only part left from the original Mankati is the chassis and the printed including its bearings and lead screw. I hope they will last a bit more longer than the other parts.

Given that, I'll be less present on the forum.

Best

David

IMG_1338.jpg

IMG_1342.jpg

IMG_1341.jpg

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ToliyK    0

David,

Nice write up! Im afraid im having the same issue (Mankati XT) as you were. Im on my second circuit board for my printer looks like im replacing them every 1.5 years. Have you considered other options when changing your mother board? Im currently looking at Rambo 24V board. Is this something relatively decent to use for this printer? Right now the printer is 1660 hours deep and components starting to fail on it. 1) screen died at 1300 hours, replaced with a rep-rap one 2)1580 hours, Main extruder PTFE tube clogged, possible tear in the PTFE tubing, extruder removed completely. Ordered XT plus extruder unit 3)1660 hours Temperature fluctuation +/- 10 degrees. Never happened before, my guess its the main board just cooking itself. On the side note i found a good method to prolong the life of the main board. Instead of heating everything at once i heat the bed first than once the bed is up to temperature, i heat both of the nozzles. This eases the amp draw on the board. High amp draw causes the connectors between the power supply and the + terminal on the board to basically melt.

 

So going back to the issue. Any advice on replacement main board?

Thank you.

 

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David    6

HI Toliyk

My Mankati is running fine for now 3 months with a Duet3D Ethernet board instead of the stock one.

It is a 32bit board running with ReprapFirmware instead of Marlin. It is now connected over Ethernet and I can manage the printer from a web interface.

It has Trinamic stepper drivers: no more noise, 256 micro stepping interpolation and I took the option of PT100 thermistors which are much more accurate.

I recommend !

There is a Wifi version of the board also. A bit expensive, but now the printer is quiet.

Best

David

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Gareth    0

Hi guys,

I believe I am having the same issue. My printer nozzles will no longer meet it's heat temperatures. For example, when I set it to preheat to 210, it will reach 195 drop to 182, rise again to 195, drop and repeat the process. I have changed the thermister the thermostat and tried re flashing the firmware. No luck. 

Does this could like a board issue?

I cannot afford the $400 replacement that mankati want me to buy. Would you be able to reccomend a solution? I have no idea where to even start with changing such a big part of the printer.

Thanks,

Gareth.

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ToliyK    0

Hello. It sounds like a thermocouple issue but, given that you have replaced yours with a Mankati replacement; I would double check connections. I recently did have the same issue as you were describing. I ended up replacing the whole extruder assembly, I needed to replace the whole thing anyway. That solved the issue for me. I wanna post the steps I did in a new topic sometime soon.

My motherboard (Mb) is not in great shape either but, it's working. I found that you can prolong the life of it Mb: you follow those steps. Preheat components separately. I preheat the bed first, than one or both of the extruders.

Found an interesting article regarding the temperature fluctuation in extruder. That may give you more info. https://hackaday.com/2017/12/15/thermistors-and-3d-printing/

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