Very very persistently bad printer... Running out of ideas

Hello reprappers!

Long story short:
At work we got a AXIOM 3D printer of the brand Airwolf. It has been a constant pain in the ass really. It should have been returned immediately, but unfortunately this wasn't an option.

Originally the printer uses the nozzle tip and electrical connection to autolevel. This process involve forcing the nozzle through a brass brush. This means that the printers aluminum nozzle wares out extremely fast.. like after 10 prints. The printer also had extruder problems and the belt tension wasn't sufficient. The printer has been subject to heavy modification. But it still doesn't print good. It looks like the extrusion is simply not consistent at all!. Following prints are the best it can do even after hours and hours of tweaking in slic3r. The filament used is Innofil (which works absolutely amazing on my own prusa at home).

The printer prints perfectly fine at some point and others it under extrude or over extrude. Both over and under extrude often happens in the same prints!


In the beginning the printer would usually fail almost all prints and was completely unreliable. The autolevel bend the buildplate when measuring due to plastic leaking out and all sorts of other problems. After our modifications the current printer configuration is now like this:
*Dyze-end 500 degree version
*Bondtech QR extruder
*Innofil filament
*Inductive proximity sensor
*Control board is a rambo board

Custom printerhead to fit the dyzend and the inductive sensor


The bodentube is bend very little to ease filament movement. Originally the printer was closed and had a very tight bend near the printhead.


The bondtech extruder on the rear.


The autolevel works like a charm now. Very consistent and reliable.
The extruder never skips a beat. It also doesn't grind. In fact it has such a good grip on the filament that it at one point ripped the boden tube right out it's fitting.
But it just doesn't print well no matter what i try..

Does anyone have had good or bad experience with the dyzend?

What can course the inconsistent extrusion?

Looks like some temperature issues. What material? what temperatures and cooling settings are you using? Did you redo the PID settings?
I don't like the spool feed into the extruder but I am not sure why. Can you put the spool lower down and make sure the PTFE tube doesn't touch the spool. That's to ensure there is a straight entry to the extruder and no chance of the spool jamming.
One of you cubes has gaps at the edge of the infill so also check for play in the belts or hot end movement.

Id toss a TRUE E3D V6 lite on there.

The material is 1.75 PLA.
The temperature was set to 220 degree C
The cooling fan is always on 60% and on 100% during bridging and layer times below 10s.
The PID controller is doing a pretty good job at keeping the temperature stable with the values recommended by dyzend.

Hmmm i really doubt there is a problem, i have a feeling the bondtech extruder could lift the spool from the floor if it had to. But i get your point, it wont be smooth. will try to flip the spool so the PTFE tube wont drag on the spool.

The hotend, belts and so on is dead stable. The bed on the other hand i think is what cause the remaining z "wobble".




I also started to suspect temperature issues. so i started playing around with the settings.
These two badboys are printed at what the printer thinks is 255 degrees C. Except for the chimney on the benchy and the legs of marvin both prints actually look pretty okei, not perfect but okei. They certanly doesn't look like they are printed at 255 degrees!

We chose the dyzend 500 degree version, hoping to be able to print Ultem, at least just to some extend. The high temperature is therefore crucial to us. Personally i would always have went with a E3D anytime myself.

So it seems that there is a offset on the temperature somehow. Since the hole hotend is made of steel, both the heaterblock and nozzle i suspect that the temperature at the sensor is in fact fairly high, bot the nozzle tip which is rather far away from the thermistor may be cooled down to much. However the problem seem to be present with cooling fans off as well though..

220C is a bit hot for PLA, let alone 255. Try printing a temperature calibration tower ?

Or get a multimeter with a temperature probe and measure inside your hot-end.

Yes i know that 220 is a bit hot. At home i print at 190-195 actually (might be a bit cold but it doesn't have the best cooling..)

I haven't found a good way to measure the actual temperature of the nozzle tip (any advise appreciated. A multimeter with a temperature probe? something like this: [www.google.dk] ?). However, i have now confirmed the temperature was the issue.. The following part is printed at:
-60 mm/s
-0.2 mm layer height.
-265 degrees (at least that is what the machine thinks)
-Sliced with Cura 2.3.1

And the part:





So finally the printer is producing useful parts!! Still not perfect, but useful!

It seems like i have to adjust the thermistor table (dyze design provide a special table for their specific thermistor)
Any good idea how to do this? I don't want to calibrate to what the sensor reads, but the actual temperature at the tip of the nozzle

Yes, that's the kind of thing. The long probe would probably be more nuisance than value. I don't know if you can just buy a probe to use on any multimeter. , or whether you need to buy both together e.g. [www.eliseparts.com]

Since all you're interested in is the temperature measurement, I'd remove the nozzle from the hot-end and insert the temperature probe into the heater-block if you can do that. Otherwise remove the hot-end from the printer and put the probe in from the top.

What's the firmware on the printer? I think in your situation I'd throw away the thermistor (unless you know exactly what it is, and that it's working properly) and replace it with a known thermistor and the correct thermistor tables.

The other thought I had is that perhaps you need to run a PID tune on the hot-end... does it maintain a nice stable temperature within a degree or two?

I realized we had a digital thermometer similar to the multi-meter-probe combination, so i used that. I measured with 10 degree increments from what the printer think is 100 to 300 degree. Turns out, the heat block is exactly what the printer thinks if i measure at the thermistor -> the thermistor is working just fine, and is well calibrated. However, the nozzle tip is 40-60 degrees colder depending on temperature. I did the measurements without the cooling fans running, so they are not the reason.

I must admit I'm surprised how big of a difference there is, and why i couldn't find anything in a forum about someone who had the same issue..

Is it really just because the whole thing is steel??