Extruder motor "chugging"

[analog_banana]

Once more I am trying to get my Rostock Max V1 working. I gave up again for a few months..
Recent repairs in February were a new hot end thermistor, crimp terminals on the wiring and new ptc connectors on the bowden.

So... Now I find that I often get a chugging noise on the extruder motor - which I know is the filament jamming.
I have disassembled the hot end, and it did appear to be suffering fomr a bit of clogging.
I burned out any excess pla with a butane torch and everything is clear.

All the same I often get the clunking, chugging sound when printing,
sometimes I think I am reducing it by slowing the print speed or raising the temp,
but generally the printer seems to intermittently chug or not chug,
It doesen't seem to matter what I tweak - i.e. it's an intermittent fault..

The prints are still pretty bad

Any ideas?

[geneb]

It sounds to me like "typical" extruder skipping due to either low extrusion temperature or being too close to the bed for the first layer.

g.

[analog_banana]

So - I did a few more experiements and I think the temperature seems to be oscillating roughly once minute, anything up to +/- 10 degrees.
It's new... I wonder what's causing that?? BAd thermistor curve I guess, although it was working for a while after I replaced the thermistor and recalibrated

I will recalibrate everything again........

In the meantime if anyone has seen this behaviour let me know if you figured out what causes it!

[analog_banana]

I retuned the pid and it's still chugging, temperatures are still up and down a lot.
As usual my PID values seem wildly different to last time and totally inconsistent.

I don't think it's a low temperature issue.
When I extrude in to free air I am still getting chugging even as I nudge the temperature up.
I tried up to 195 degrees and it is still chugging,
so I guess something is wrong inside the hot end.

I guess all I can do is put in more replacement parts and hope for tha best. Again.

[geneb]

So go higher. Guanu has seen PLA that takes up to 210C to print well. You should also solve the issue with the swinging temperature before you change anything else. Solve for a single problem at a time.

g.

[Polygonhell]

Swinging temp is going to be a bad PID setting, the auto tune IMO doesn't work well for large heaters.
Use the values as a starting point then tweak I as close as you can get it, then increase D to take out any remaining oscillation.
You can tweak the values in the EEPROM live with the heat on, but you'll want to test it by letting it cool and verifying after they are set.

You should be able to tune it to have a swing < 1 degree, but 2 or 3 is fine

[analog_banana]

I totally agree with the "solve one problem at a time" ethos Gene.
I'm unsure about upping my temp too much - for two reasons:
1: sometimes the machine prints ok for about an hour or two at 180 - 190 - this is the manufacturer's temp recommendation, and I am using premium filament.
2: I fear that going to 200+ on PLA can cause heat-creep up the peek section - which is leading to bulges in the filament = clogging. (I have tried going this high, and that was when things started getting even worse / broken

The machine's dead again for the time being as I'm trying to get replacement parts for the hot end. Then I can start PID calibrating.

Polygonhell: when you say "tweak I as close as you can get it" what value are you referring to? (before increasing D)

Thanks as always for your advice.

[geneb]

You should have a fan running on the PEEK section at all times.

Keep in mind that the RAMPS 1.4 board will not allow you to change the stepper current through firmware, so any adjustments you make in Configuration.h will have no effect.

Have you ever compared the reported temperature against a thermocouple?

g.

[analog_banana]

Hi Gene, I always use a peek fan, the machine was not shipped with one though.
I also bought a replacement peek fan from seemecnc just to be sure I am using exactly the right amperage and specification.

I have purchased two different types of thermocouple to test the reported temperature at the hot end.
I have carefully calibrated both thermocouples to ensure they are accurate.
I have tried both the nozzle/hotend sandwich method and the dropping down through the peek method to measure temperature.
Advice and information on which thermistor curve to use in the firmware has always been vague - i.e. different sources advise diferent solutions.
If I recall I used a temperature offset function in firmware to get things accurate - I will repeat the process when I get more repalcement parts.
If anyone really knows the correct thermistor settings for marlin firmaware - let me know!

I have never tried adjusting the stepper current - On the ramps it is done with pots on the pololulu. I don't think stepper current is the main issue at the moment though.

[analog_banana]

P.S. the main problem I had measuring temperature is that the marlin reported temperature and real-world measurements have different curve profiles,
and I have never really known which curve to use in firmware - what tallies at 100deg does not tally at 200deg .

I am of course using all stock seemecnc parts,
My crazy dream is that someone (maye even the people who sold me this thing) has made one of these machines work (rostock max v1 **with ramps** not rambo)
If such a person exists and they can tell me how their setup, I will be really happy.

[geneb]

AFAIK, I've never heard of a Rostock MAX with a RAMPS board other than you. I have no clue why CM sold them like that. I know basically nothing about the RAMPS board, so I really don't know how well the firmware works with that board or how well that board works.

g.

[Eaglezsoar]

What type of cold end extruder are you using, the large Steves extruder or the EZstruder?

[analog_banana]

I'm using the EZstruder, I have a spare steve's extruder that I no longer use.

[Eaglezsoar]

I would be interested in knowing what happens if you start a print job with no filament. Does the extruder motor still chug?
If doing a print without filament it does not chug, that pretty well isolates the problem to the hotend. If it is the hotend causing
the problem you have several options. One is to completely disassemble the hotend and make sure the PTFE tubing is in good
condition, you can also use a j-head hotend but the problem is that you would need to print a mount for it. Please let us know
what you find out.

[analog_banana]

No chugging if i print dry.. Yes, the hotend is definitely bad,
But I think the problem is not as simple as replacing it (which I will have to do)
I think the problem is, that I can't find working settings, so I am probably slowly killing the hardware because there's no known firmware config for the machine I was sold.
This machine is a year and a half old and has been running for hundreds of (non-working) hours. It prints for a day and then fails, time after time...

To be safe I am going to get hold of all new ptfe tubing and a new nozzle.
After that I am going to try with all my might to find or create a thermistor curve for ramps/marlin. THIS IS KEY...

I supect that my machine is always falling over and maybe hurting itself due to wrong PID settings and temperature control.

So far:
Replaced the PSU with the best money can buy,
Replaced the bare wiring with properly crimped connectors,
Replaced the extruder,
Replaced the thermistor,
Bought Full replacement electronics,
tried ABS and PLA from the best suppliers in the world,
checked and checked the belt tension, the column alignment, height calibration etc many many many times,
performed untold tests and calibration procedures on the machine and the test equipment used.
And much more...

I need to find the correct firmware settings for the standard rostock max v1 with ramps as follows:

Seemecnc 6.8 Ohm Heating Resistor / 6.8 Ohm / 3 Watt / Ceramic wirewound / x 2 wired in parallel.
Seemecnc 100k NTC thermistor Manufacturer: semitec Model #: 104-GT2
Ramps 1.4
Repetier 0.91 firmware

As I have mentioned before on the forums, Creative Machines sold a few of these machines in Europe, but are no longer selling or supporting the Max.
There must be a few other Max/Ramps owners, but I have yet to find anyone to talk to or anyone who has posted success.

In an ideal world Seemecnc would send me a rambo board and new hotend to bring the machine up to spec.
I really think the machine they supplied is "not fit for purpose".

[Captain Starfish]

For me, that chugging wasn't the hot end. It was the stepper driver chip overheating on the controller board. Threw a fan over it and the problem stopped completely.

[analog_banana]

Hmm, interesting - as Eaglesoar suggested, the fact that chugging stops when there is no filament suggests more likely a hot end problem.

Anyhow - the board overheating issue is ruled out! - one of the first mods I made was a big 40mm fan over the ramps board though, so I know it's cool!

The only difference between me and you guys is I'm using the wrong electronics I.M.H.O.

[Eaglezsoar]

Hmm, interesting - as Eaglesoar suggested, the fact that chugging stops when there is no filament suggests more likely a hot end problem.

Anyhow - the board overheating issue is ruled out! - one of the first mods I made was a big 40mm fan over the ramps board though, so I know it's cool!

The only difference between me and you guys is I'm using the wrong electronics I.M.H.O.

In your latest configuration file what do you have for motherboard type?
Are all your step jumpers under the driver boards set the same?

[analog_banana]

Thanks Eaglezsoar,
Good advice as always,
but this troubleshooting is going round in circles!

I went through the jumper settings issues back in february:
http://forum.seemecnc.com/viewtopic.php ... 1&start=70" onclick="window.open(this.href);return false;

Motherboard issues were covered here in january thanks to your advice:
http://forum.seemecnc.com/viewtopic.php ... 3&start=30" onclick="window.open(this.href);return false;

I'm done wasting my time and that of the forum community on a sickly Rampsenstein Euro-Chimera device.
Lord knows you guys are patient!

So I am stopping any work with my Rostock max until:

I can get hold of a rambo board and get this machine up to factory spec.
Then I can use normal firmware and settings rather than the wild guesses I have now...

[Captain Starfish]

Sounds like a plan - except are you then going to go "nawwww, all the cool kids are getting Smoothieboards!" ??

You might find one of those guys has a RAMBo surplus to requirements they might let go of cheap...