quality issues with Ender 3 and Duet Wifi

fcwilt

@jay_s_uk said in quality issues with Ender 3 and Duet Wifi:

It's the best way to ensure back pressure doesn't affect the calculation. Otherwise you'd have to extrude really slowly which would take forever.

You didn't really answer my question.

I checked on a number of different sites and haven't found one (yet) that says to remove the hotend.

All of them said that is was necessary to test calibration under normal operating conditions since those are the conditions that would exist during printing.

Thanks.

Frederick

deckingman

@fcwilt My take on it is that in any system which comprises several objects, one should always calibrate each individual object on a stand alone basis. That gives a baseline against which adjustments to the system as a whole can be made to obtain the desired result or effect. So in the case of our extrusion system, we have several objects which come together to make up the whole. What we commonly refer to as the extruder is one object and what we commonly refer to as the hot end is another (so too is the thermistor). The problem with calibrating the extruder and changing the steps per mm to obtain a certain amount of filament movement with the hot end fitted, is that we are then making adjustments to one object within a system in order to obtain a certain result for the system as whole. And we know that things like hot end temperature will affect the viscosity of the filament which will affect the resistance that is imparted on the extruder. As will the speed at which we try to push through the filament and as will the nozzle diameter too. So if one used the steps per for the extruder, at a certain temperature, with certain size nozzle, to calibrate the system as whole, then that calibration will not be accurate for other hot end temperatures, filament speeds, or nozzle sizes. But if we calibrate the steps per mm for the extruder without the hot end, then we eliminate the other variables. If then we find that the system as whole is either over or under extruding, we can simply use the extrusion multiplier or use non-linear extrusion to change the characteristics of the system as whole, to compensate for differences which might be due to nozzle size, temperature, flow rate etc...

fcwilt

@deckingman said in quality issues with Ender 3 and Duet Wifi:

@fcwilt My take on it is that in any system...

I see no point in checking the extruder without the hotend. It doesn't matter if the extruder works perfectly on it's on, it has to work with the hotend in place and under actual working conditions.

If calibration should be done without the hotend then all of those sites describing the procedure are wrong and I find that unlikely.

My experience is that the suggested steps/mm value provided by the manufacture has been correct and I have merely verified that the system is working as designed.

Frederick

bartolomeus

@fcwilt @deckingman described exactly what the point is. If you calibrate the extruder with the hotend, your esteps are only valid for that particular combination of filament-temp-speed-nozzle. If you change any of those, your estep calibration, might (slightly) be off. The slight difference might not be noticeable, but a precise setup requires calibration of e-steps without the hotend attached. Flow calibration can then be used to adjust for different filaments and print settings.

dc42

My take on this:

I use the E steps/mm given by the manufacturer when the manufacturer is able to state it with confidence, otherwise I measure E steps/mm either with the hot end disconnected or at a slow filament feed rate e.g. 1mm/sec for 1.75mm filament.
In practice, different filaments seem to swell by different amounts, so I often find I need to adjust the extrusion multiplier to get best results. I use top solid infill to judge it.

fcwilt

@bartolomeus said in quality issues with Ender 3 and Duet Wifi:

@fcwilt @deckingman described exactly what the point is. If you calibrate the extruder with the hotend, your esteps are only valid for that particular combination of filament-temp-speed-nozzle.

My experience says otherwise, at least in relation to real world changes. I have found no significant differences with a given type of filament over the typical range of temperatures one might use.

Naturally I need to set the extrusion multiplier at times for different materials.

But you have to verify that your extruder and hotend work together. It matters not if the steps/mm is spot on with no hotend attached. You need to know how it performs with different materials at different temps, thus the need to check calibration with the hotend attached.

But I guess all those sites could be wrong.

Frederick

deckingman

@fcwilt But if you calibrate the extruder on it's own, then you take away any variables that having a hot end connected might introduce. If you then find that you get under extrusion with the hot end connected, then the difference is caused by something to do with the hot end, not the extruder. Changing what is a known and good calibration of the extruder on it's own, to compensate for errors introduced by the hot end, is simply using two "wrongs" to make one "right". We have a number of tools to make that compensation for hot end vagaries as I explained - extrusion multiplier, non linear extrusion, etc.

.......and yes, IMO "all those sites" probably are wrong - that wouldn't be anything new as far as internet based "information" is concerned.

A Former User

my take on it.

what is the purpose of an extruder and hot end?

To push a controlled amount of molten plastic at a specific speed so that that controlled amount can be deposited in an exact location.

so to me the end result (the calibrated amount of molten plastic) is more important.

in my case i build each unit to carry out a specific task e.g a unit to print nothing but PETG etc etc so I have always calibrated in the method David describes above, I.E. heating to operating temp and pushing filament through it the slowest speed possible, that method has never failed me.

but that's the thing about opinions everyone has one and everyone thinks their's is correct when in reality there is more than one way to do things and each of us just have to accept and respect that. Now facts, well that is a completely different discussion.

fcwilt

@deckingman

Perhaps I am not being clear.

I am not adjusting the steps/mm to achieve a specific result. I am testing the performance of the complete extruder system at various speeds, temperatures and materials to determine exactly how it is behaving under real world conditions.

The behavior of the extruder only is of no interest since you cannot print very well without a hotend.

Frederick

WilcoE

Guys,

Thanks all for the answers and other information.
My latest print with extruder steps on 415, jerk settings lower and y and z steps to 80

Result is almost the same. Not much diffent

Changed now the thermistor settings and also did a temp calibration.
Now printing a new train, will post picture within 2 hours

A Former User

@fcwilt said in quality issues with Ender 3 and Duet Wifi:

@deckingman

Perhaps I am not being clear.

I am not adjusting the steps/mm to achieve a specific result. I am testing the performance of the complete extruder system at various speeds, temperatures and materials to determine exactly how it is behaving under real world conditions.

The behavior of the extruder only is of no interest since you cannot print very well without a hotend.

Frederick

I agree with this, why you might ask. Symbiosis is why because one without the other means the system won't carry out the intended purpose of the two separate parts. Akin to entering a one legged man into an ass kicking contest.

deckingman

One last go at this.

Let us suppose that you've just built a machine and you start to commission it. And let us suppose that you won't bother to set the steps per mm for extruder on it's own - you'll just wait and do everything as one entire assembly. When you go to set the steps per mm, you find that you need to use say 20% more than the manufacturer states for that extruder. Or maybe you don't have any data so you just accept whatever value you get with the hot end fitted. Then later you find that you have yours set much higher than anyone else using the same set up. Do you question the result or do you just say "that's what it needs so that's what I'll use"? (even though the prints turn out like crap).

Or maybe you have the sense to realise that if you need a much higher value than anyone else, then there might be something wrong. So where do you start to look? A logical thing to do would be to check the extruder on it's own to see if the fault lies in the hot end or the extruder. Low and behold, it's much better. Why is that you may wonder? On further investigation you find there is a small piece of swarf or some other debris in the nozzle. That's the reason why you had to set the steps per mm so high - because that partial blockage was making the extruder slip.

Had you set the steps per mm for the extruder alone in the first place, you would have immediately known that there was a problem with the hot end as soon as you started to print something. As it is, you've started off by applying an inaccurate value to the extruder to compensate for a fault in the hot end.

It matters not to me how others do what they do. But in terms of advising others - well I've stated the reasons why I think one method is better than another - let the OP decide which method he thinks is preferable.

WilcoE

Here is the latest print.

fcwilt

@deckingman

Really?

Setting the steps/mm to the correct value according to the specific hardware is a given and I assumed you knew that I would do that.

Even if you don't have the manufacture specified setting it is easy to determine what it should be.

Frederick

bartolomeus

@WilcoE To me it looks like an improvement. Hard to tell, beacause the other pic is very small.

Other thing I noticed, is your motor currents a pretty low. I think tou can safely try 800-1000ma. The motors are rated for 1.5a, so 1a should still be on the safe side.

How is the printer mechanically:

belts tight?
Z-axis running smoothly up and down?

WilcoE

@bartolomeus said in quality issues with Ender 3 and Duet Wifi:

@WilcoE To me it looks like an improvement. Hard to tell, beacause the other pic is very small.

Other thing I noticed, is your motor currents a pretty low. I think tou can safely try 800-1000ma. The motors are rated for 1.5a, so 1a should still be on the safe side.

How is the printer mechanically:

belts tight?

Z-axis running smoothly up and down?

Belts are tight maybe to tight? got also here the other printer with the SKR and the belts from that machine looks not so tight.

z-axis running smooth, it's easy to get it up and down by hand

Going to change motor currents to 800ma

bartolomeus

@WilcoE Also check if the mount that holds the leadscrew nut is square.

A Former User

@deckingman said in quality issues with Ender 3 and Duet Wifi:

It matters not to me how others do what they do. But in terms of advising others - well I've stated the reasons why I think one method is better than another - let the OP decide which method he thinks is preferable.

That's only piece of sense you have typed in the whole thread, everything else is as I have stated is an "opinion"

I would never be so arrogant as to state that one person's opinion is better than anyone else's, it is all about perspective and what works.

And I would never be so arrogant as to state that anyone providing someone assistance based on THEIR real world experience should be considered wrong, just because someone else thinks so based on their opinion.

deckingman

@CaLviNx I respect your opinion of my opinion, even thought it differs from my opinion of my opinion. Whilst I always look forward to, and enjoy out little tete-a-tetes, I fear I must decline any further response as this is neither the time nor the place to do so.

dc42

@WilcoE said in quality issues with Ender 3 and Duet Wifi:

Here is the latest print.

How does that compare with the one produced by the other printer? Are they both printed using the same slicer and slicer settings? Do both printers have exactly the same part cooling?