SnapMaker extruder calibration


#1

I have been exploring deeper into 3D printing and how I might improve the already excellent SnapMaker. I read about calibration of the extruder. It seems that most printers need to be calibrated so that the GCode which sends an extrusion command matches the amount of filament extruded. Quite simply, when a command is sent to extrude a certain length of filament, we need to be sure that the amount actually extruded matches.

For my Snapmaker I carried out the test here: https://mattshub.com/2017/04/19/extruder-calibration/

I found that my Snapmaker was under extruding by 10% (A command to extrude 100mm of filament actually extruded 90). I ended up changing my E value from 92.6 to 102.9. I did this using the machine control panel in Simplify 3D with the Snapmaker directly connected to my PC (iMac) with the supplied USB cable.

10% seems like a lot, and I was not noticing any significant under extrusion in my prints. Since changing the firmware calibration factor for the extruder I have done a couple of prints and not noticed any significant differences, but I guess it can’t hurt?

I’m just about to print a 25mm cube and see if I need to see my extrusion multiplier (for PETG I currently have it set to 1.00).

Has anyone else done this calibration on their Snapmaker?


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What might cause these effects?
#2

OK. I have printed the 25mm cube at 0.3 mm layer height. Single bottom layer and single perimeter. It’s 0.48mm thick! This seems way too large. Or maybe there is an inner and outer perimeter (0.6mm total) and it’s too thin? I have a thin wall overlap of 10% set in Simplify 3D (0.6 less 20% would be 0.48mm). I think I need to do some more reading before I muck around with the extrusion multiplier.

Anyone able to offer some advice?


#3

Hi Rick!

I’ve have this same issue, however, it is with a inner circle which is coming out as 3.7mm instead of 4.8mm. I’m unsure how to fix it myself as I haven’t fiddled with the controls enough. I’ll get back to you if I figure something out :slight_smile:

-Greg


#4

Thanks Greg. I think I need to print it again with all of the Simplify 3D fancy thin wall settings off.

We’ll see…
Cheers
Rick


#5

@rick can you check if the cube itself is the correct width? As in the outer width? Is it 25mm or approx that width?

-Greg


#6

@X_Pilot Yes. It’s within 0.05mm on the outside.
Rick


#7

Have you attempted printing it with 0 overlap? It may be because of the 10% overlap which would be 0.04mm being added to either side. Which would technically equate to a 0.48mm width.


#8

I think you are onto it. I reckon Simplify 3D has been smart enough to make the sides thicker but keep the overall outside dimensions intact. I’ll try printing without the side wall enhancements tomorrow night. Cheers Rick


#9

Actually. Using that logic, a 10% overlap would be 10% that is not overlapping. as the nozzle width is 0.4mm but 0.4 x 2 is 0.8 which would be the width if it was printed with 2 layers. 0.4 is 10% as we already discussed. I thought overlap was the stuff that was actually overlapping :confused:

Sorry was just thinking about it maybe a bit too much haha

Keep us updated on your findings!


#10

Just did the extruder calibration myself(ran the initial feed two times and wrote down both of them down and they were the exact same) , and i got the exact same values as you. I adjusted for it and went for a second test just to see if i got it right, wich it for some reason didn’t and it started grinding the filament. So i went down to 50 in feed speed instead and got consistent readings after that, so i would suggest others to run “G1 E100 F50” so they avoid the same frustrating problems :slight_smile:


#11

Hi @Exerqtor,
That’s interesting that we had the same extruder calibration. I wonder if SnapMaker intentionally tunes the extruder to under-extrude?


#12

Well it will sure be fun to see what others get as well, two is a pretty small sample size lol.
Did u figure out your width settings btw? I had to turn down the filament flowrate to 82,5-83% to get it to print at a stable 0,4mm with 1layer walls (and it scalled perfectly to 0,8mm and 1mm with 2 or 3 layers).


#13

Hi @Exerqtor. Yes, I have been working on my width settings. For PETG I am now down to 81% flow rate and still getting good results. I am still experimenting but this is getting close.


#14

Hi @X_Pilot and @Exerqtor. I’ve had some time today to try out some more calibration cubes. I’m currently working with eSun PETG so my work may not apply to PLA.

Remember that I have calibrated my Snapmaker extruder which was 10% under extruding before I reset it, so now it is 11% over extruding when compared to my original.

My findings so far is that 0.81 for PETG is too low - I am getting under extrusion. I have finally narrowed it down to 0.86. Even dropping to 0.85 gives under extruded bottom layer. My readings on PETG say that it is best to under extrude as much as possible to reduce blobs and stringing. My PETG prints to date have had some ‘zits’ and my aim is to have as few of them as possible. I am going to try a bigger print today and see how it goes with the new calibration.

Regarding the wall thickness. I looked at my extruder settings and realised that I have the vertical height set at 0.3mm but the extrusion width set to auto - which in Simplify 3D sets the width at 0.48 for a 0.4 mm nozzle - there’s my 0.48 right there!

I am now trying different speeds. I have been using a maximum of 60mm/s and various reductions for perimeters and first layer. I think I will be OK with higher speeds but will have to put up with stringing.

I recommend reading the forum post at here for advice on using PETG - http://forum.makergear.com/viewtopic.php?f=11&t=2593


#15

3rd data point, my friend’s snapmaker also only extruded 90mm of filament when told to extrude 100mm. Changing the extruder calibration, adding a part cooling ducted external fan, and checking “connect infill lines” in Cura finally improved incomplete infill with PETG.


#16

Wow, That’s quite the improvement. I have been getting excellent results with PETG, but of late have been getting layer separation issues. I suspect water in the PETG as it is known to be quite hygroscopic. I have dried two spools in the oven but haven’t had a chance to confirm yet. When PETG is printing well, the prints almost look and feel like regular injection moulded plastic.


#17

Hi!
I’m printing in PETG too. Since I tried it the first time I decided to never use PLA again…
My infill looks like the left part as soon the nozzle/heat block gets “older”. I think there are some residues from burnt plastic inside the nozzle.
With a fresh nozzle I can print without any trobles and after a few weeks I do notice some kind of clogging noises when printing the infill @150% width (when I want to get stronger infill in less time) creating these holes/weak infill. Then I have to reduce the print Speed by about 20-25% or choose a reduced flow rate for the infill.


#18

Hi @rick and @roja

Has anyone tried the nozzle cleaning kits that are available. Amazon has a number for sale such as Nozzle Cleaning Kit or Nozzle drill cleaning kit

A search on Amazon will return a number of different kits. This may be the answer to clearing out remaining burnt residue… just like honing a car cylinder

Keep having fun.

Doug


#19

Hi Doug!

Yes I have bought some cleaning needles (these are just acupuncture needles…).
I don’t think that the nozzle itself is the problem but the inside of the heating element. When I have more time than now I’ll try to clean some of my used hotends.
Also I’ve tried a claning filament but with our filament feeding system it’s quite hard to handle (with my Ultimaker this works wonderfully).

Michael


#20

Hi @doug Doug and Michael @rojaljelly ,

I think I have ‘destroyed’ a hot-end now using PETG. My experience echoes yours Michael. A gradual loss of quality and layer adhesion as the hot-end starts failing. My theory (backed by one sample) is that the high temperatures needed for PETG cause the accelerated decay of the teflon lining of the metal tube in the hot-end (heat break?). Here’s some photos showing the burnt teflon tube. I was running at 250 degrees C, I’ve now dropped to 245 and the current nozzle seems to be holding out. I’d really like to try an all-metal hot-end on the Snapmaker.

Is it really as simple as replacing the metal tube with one designed not to have a teflon lining? I assume that the flow wouldn’t be as good because of the greater friction and that the PID would have to be retuned (I’ve already done this once for the PETG temperature setting)?

Photos of my destroyed hot end below…

I have another clogged one that I haven’t taken apart yet,