Nozzle temperature fluctuation and pause

[sangjoo @sangjoo seoul]

I found a problem in the firmware.
after googling, another user already know it.
this problem is not 24v connector. because i fixed connector.

recently, i checked nozzle’s heater and temperature sensor using by oscilloscope.

nozzle’s heater do not heating during work in temporary.
and do not get a signal from firmware to heating.
also as i know it’s problem is always occured in same XYZ position.

anyone try and see it by use attached two 3d modeling file.
test1 & test2 has a temperature drop and paused always at around hole in the r731 version.
but test1 are not paused even during nozzle heating in r747 version in my memory.

additionaly, sometimes firmware r747 has drop nozzle temperature to 150’c in work.
i was stop the work by push stop button.

Fortunately, r731 drop to around 188’c.
so i was downgrade to r731.
i wish update the firmware in the nozzle temperature controller ASAP.

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[William Ha @williamha My Robox is a Blue Commercial Version Hong Kong]

Noticed this problem since 2.00.01/r741. Someone else also complained about it. Can’t say 1.03/r731 never does that but much less frequently even if it does. Hopefully your great troubleshooting helps solve this problem.

[Johnathan Garrett @jgarrett My Robox is a Blue Commercial Version]

I have been seeing this problem as well whenever I print small details. It doesn’t seem to matter where the object is placed, if there is a small hole or pillar, the heater turns off.

[BHudson @bhudson I have several Robox units Kickstarter and Commercial Arizona, USA]

@sangjoo @williamha This issue is evidence of a head that is not making proper connection and therefor cannot pull enough current to run the head heater and the stepper motor at the same time. You need to get your head carrier and head updated or if you have already done that, you need to check your head retaining screw to make sure it is tight.

In some prints, a model or slicing error may replicate this behavior, but the most probable issue is poor connection between the print head and head carrier.

I operate two Betas and one Production Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben

[William Ha @williamha My Robox is a Blue Commercial Version Hong Kong]

@bhudson, you could be right. A poor connection might have caused it. However, although I can’t show you data, it seems to me that there were much fewer pauses and temp fluctuation when I was using AM 1v03 / r731.

And I should have everything updated after my machine comes back after service. I will then try the test files by @sangjoo to see if I can replicate the problem. Perhaps you or other Robox staff may try the test prints as well.

@sangjoo, I can’t see anything in test2.stl. Please check. In addition, would you mind sharing detailed measurement data (e.g. scope traces)?

rgds William

[sangjoo @sangjoo seoul]

I make sure that 24V connector already using by glue-gun after open in the case..

Unfortunaetly, i found the firmware not make a signal to heating before that problem in several seconds.
I have seen the control signal of heater by oscilloscope.
I think no problem in power-supply.

[sangjoo @sangjoo seoul]

I attached a picture that normal state.
I don’t captured in that problem.
when occured that problem, duty of the control signal are 100%.
this means the firmware not make a signal before that time.

ch1 is a temperature sensor signal.
ch2 is a control signal to FET for heater.

refer the youtube.

• This reply was modified 2 weeks, 3 days ago by  sangjoo.
• This reply was modified 2 weeks, 3 days ago by  sangjoo.

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[pelgrim @pelgrim My Robox is a Green Kickstarter Early Bird Belgium, Flanders]

All I want to say about this problem:
I got this behaviour only a few versions of AutoMaker ago,
after the next update it was gone, and until now it happens very rare that the printer stops to heat up the nozzle.

java (EE), JavaFX, HTML, GIS) programmer, database wizard, framework inventor, looking for a job ! http://roboxing.com/wizards

[Terry Taylor @n6mon My Robox is a Green Kickstarter Early Bird San Lorenzo, Ca, USA]

The basic problem with the types of connectors used for the 24V power to the print head carrier is that the metal part is stamped, rolled metal. They are meant to be connected and forgot and NOT for continuous motion and flexion. What happens over time is that the female connector begins to spread and loose contact. Since this is a relatively low voltage, low current connection, it also corrodes easily when there is any air gap. There are other type of connectors that are made that would be better suited to this application, but we have what we have. I SUSPECT that a liberal application of the paste version De-OxIt MIGHT mitigate this.

 

All of the nylon, round terminal connector types (think Molex) exhibit this problem to some degree. Something LIKE Anderson Power Poles would have been a better answer for this power cable.

Terry Taylor

[BHudson @bhudson I have several Robox units Kickstarter and Commercial Arizona, USA]

@sangjoo @n6mon @williamha The connection in question is the POGO pins between the head carrier and the head. There are a few printers out with bad pins - if you remove the head, the pins may not slide in and out smoothly or they may wobble side to side. If this is the case, they need to be replaced.

There may also be an issue where the head cannot fit tight enough against the head carrier to keep the pins in good connection while the head is moving, especially short, fast motions. This causes the printer to go into safe mode which you see by the pausing.

Look at the clips on your head power cable. If the release lever on the cable end is smooth, it needs to be replaced. If it has a step in it, it is up to date and is fully capable of taking the motion.

I operate two Betas and one Production Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben

[sangjoo @sangjoo seoul]

1. that problem is occured in print the small modeling file.
2. problem is always occured in same XYZ position in same modeling file.
so that this problem is firmware bug.

24V connector & POGO pins are another issue.

is there a hardware engineer?
you’ll try check it i mentioned above.
if you want i try again to get a picture at that problem.

[Terry Taylor @n6mon My Robox is a Green Kickstarter Early Bird San Lorenzo, Ca, USA]

@bhudson, Ben ALL of the problems that I saw with printer pausing to reheat were related to the 2 pin 24V “molex” type connector working loose on the back of the print head carrier. All I need to do was to push it back tight and it would be happy for a few prints.

Terry Taylor

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