Why am I having to run with an extrusion multiplier of 60%?
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PSU is 24V 15 Amp (350Watt) but it's only doing the steppers and hot end heater and Duet. The bed is 240V via a SSR. Main motors (X,Y and Z) are 2 amp but I'm running them at 1.8. Extruder motors are the next size up to the pancake ones. 0,4 Amp but I'm running them at 0.3. No sign of any skipped steps. Current draw with everything running is about 7 amps max from the PSU so plenty of spare capacity.
I agree about the CoreXY kinematics and that if you ask for 10mm of movement and 10mm of extrusion, that's what you should get but for whatever reason, it seems I'm getting 30% more.
I've just printed your test pieces that I found on Thingiverse. Started at 100% extrusion multiplier. Then reduced it to 90% and printed another, and so on down to 60%. I need daylight to see properly but 100% is way too much and 60% is a bit too little. Crazy…...
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Well all I can say is that the steps/mm calculated for this extruder and what it actually needs to be set to are not the same. Unless you want to be running with a 0.6 extrusion multiplier all the time. It doesn't really matter though how you set it, there are a lot of different ways of adjusting the amount of material extruded flow, steps/mm, multiplier they all do the same thing. As long as the amount you get out matches the amount you need you're there. I'd change your steps/mm to a corrected value and set your multiplier to 1.
I've always set the steps/mm fairly arbitrarily then adjusted based on calibration objects. When I first got a titan I figured since I was running around 100 steps/mm on a mk8 which was not geared and the titan was 3:1 I'd try 300 and see how I got on. On the mini kossel I nudged it down to 250. On the large kossel I started at 250 and went up to 330. Now that I can't explain but the large kossel has been nothing but trouble, at the moment its a genuine e3d v6 jamming (with abs!) if I even look at it funny. Might send it back.
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Mine is a Delta and something that maybe of interest is that the first batch of Titans towards the end of that first run had the hobbing tool wear which caused the drive gear to be the wrong size.
Myself and a few others that I know had this issue and in my case caused horrendous stripping issues.
E3D Swapped them out FOC as indeed they should have done all it needed was to send them a photo of the drive gear.
When you calculate your steps/mm you are measuring the amount of filament going into the extruder arn't you and not the length coming out of the nozzle tho I doubt you are making that mistake but stranger things have happened.
Doug
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DjDemon, I just don't understand why if you're using the same extruders you have that much variability in the steps per mm. If they are the same extruder it should be the same steps per mm. If i am pushing 100mm into my hotend it should print correctly or close to it with an extrusion multiplier of 1. I understand that a bowden setup could cause some slack in that but didn't think it would be a difference of 30%. But how does the same extruder have such different values and once dialed in to push 100mm through it? if the amount of plastic going into the nozzle is the same it expects why do i have to drop it 30%?
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Mine is a Delta and something that maybe of interest is that the first batch of Titans towards the end of that first run had the hobbing tool wear which caused the drive gear to be the wrong size.
Myself and a few others that I know had this issue and in my case caused horrendous stripping issues.
E3D Swapped them out FOC as indeed they should have done all it needed was to send them a photo of the drive gear.
When you calculate your steps/mm you are measuring the amount of filament going into the extruder arn't you and not the length coming out of the nozzle tho I doubt you are making that mistake but stranger things have happened.
Doug
Hi Doug,
Yes, I'm aware of the bad hobbed bolt issue and I was extra careful to check mine when I got them - they are a later batch and look fine. In any case, if it was stripping the filament, I'd be getting under extrusion issues, not over extrusion.
Yes, I am measuring the filament going in to the nozzle and not what comes out. I'm reassured that my settings are about right because they are very close to the theoretical value that E3D state (the theoretical value is 418.5 and I need 424).
I'm getting good quality prints but it's bugging me that I have to use such wild extrusion factors to achieve them. I'll continue my investigations.
Ian
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Okay so the first titan I bought was an early one (May 2016) but, and here's another anomaly, it feeds filament very well, no stripping. The second one I bought about a month ago and it strips filament and feeds less well albeit into the v6 hotend I have been having a lot of problems with. Both hobbed drive gears look the same and feel the same.
I understand the accepted calibration procedure perfectly well, measure filament going in and adjust steps/mm to get the exact amount fed in mm that you requested. However If, as is clearly the case when printing (which after all is what this is about) you need only 70% of that amount of filament to make good objects, then either this process is incorrect, or there is some titan related oddness going on, or there is a firmware issue here.
Having so many variables to modify to basically determine the number of step pulses that get sent for each 1mm of filament to be extruded is not necessarily helpful.
Has anyone actually counted the teeth on the gears to check it really is 3:1? That would throw the calculation off.
As for why one of my titans prints beautifully with 250 steps/mm and the other with 330 steps/mm - its interesting sure and I will try to find out why if I get the opportunity, but when its printing well I am not going to take it apart to satisfy scientific curiosity.
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Guys
I was not trying to cast aspersions on you guys at all (But had to ask very tongue in cheek lol).
Mine just works as expected and is now even better since I converted to Flying extruder (Only change was to reduce motor current to around 400) oh and reduce my retraction from 9 to 2 mm again I am using a Genuine E3D V6 hotend with 0.4 mm nozzle and pt100 sensor. oh and use ABS or PETG usually. and only 1.75mm filament.
I will keep an eye on this thread and hope you guys find the answer.
Doug
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@DJ,
It's strange indeed. I'm leaning towards the fact that it's not Titan related - other users have no probs with different geometry machines.
Ref the difference you are seeing between the two - could it be due to nozzle diameter? Has one got a bit worn compared to the other?
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Hi Doug,
No probs. I've got a flying extruder variant on my CoreXY. The 3 Titans are suspended above the centre of the bed with a counter weight/pulley arrangement. It means I can have Bowden tubes around 300mm long with a bed that's 400mm square. Like you, my retraction is low - 3mm (but I've yet to refine it).
I'm also using PT100. Printing PLA at 195 which seems best on my machine, with that particular filament in tests I've done. Also, only using 1.75 mm filament (and yes, I've checked the diameter).
Ian
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Ian just going back to basics. If you have the extruder set to move 100mm of filament through it when you command G1 E100 then your steps are calibrated correctly for the Titan. At that point if the amount of filament being extruded is less then you would suspect an issue with high pressure causing the extruder to skip steps/strip the filament, or in your diamond setup the hot filament taking an alternative path other than out the nozzle. All that does not apply though because you are experiencing too much extrusion, rather than too little.
With that in mind can you explain why you believe it is over extruding? I suggest going back to printing a single wall cube with no base, using only one extruder with no extrusion multiplier set and see what results you get. Also try a different slicer (say cura) on the same simple object and then compare the gcode to see how much extrusion is being asked for.
For a very simple print (say a single wall, single layer height square) you can measure the amount of filament that goes through the extruder for the.print and compare it to what the gcode extrusion amount was.
Basically trying to locate if the error is with the slicer settings or the firmware having eliminated the mechanics of the extruder.
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Hi Tony,
Thanks for the input. For these tests, I'm only using a single extruder so we can discount any effects of mixing ratios. Although the large, multi coloured vase I posted was printed using an extrusion factor of 0.7 so I'm fairly confident that the issue is common to all 3 extruders.
Yesterday I started using DJDemon's calibration object from Thingiverse - (can't find it again otherwise I'd post a link).
Using an extrusion multiplier of 1.00, the surface finish is crap with blobs all over it, there are bulges on the corners, lumps on the sides and lack of detail. The dimensional accuracy is good though. Printing again at with an extrusion factor of 0.9 makes little difference. Dropping to 0.8 gives a much better surface finish and good detail. Dropping it to 0.7 with this particular object shows signs of under extrusion with gaps appearing between the lines.I think what I need to do next is accurately measure the actual nozzle diameter.
Not sure what you mean by the single wall, single layer height thing - can you elaborate please?
Cheers
Ian
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Hi Ian
I mean print a cube that is only 1 wall thick with no base and top. If you grab a model of a cube, set base and top layers to 0, set the wall thickness to 1 and the infill to 0. You then get a very simple start point to pinpoint where your issue lies.
Something like this:
http://www.thingiverse.com/thing:271736
Although I would scale it up to 40x40 at least
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Hi Tony,
I'm aware of the single wall cube method for adjusting the extrusion multiplier but not a big fan. There was a recent post on the RepRap forums which detailed why it's not a good idea.
What confused me was this
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"For a very simple print (say a single wall, single layer height square) you can measure the amount of filament that goes through the extruder for the.print and compare it to what the gcode extrusion amount was."
end of quote.
Are you saying a cube one wall thickness and only one layer - effectively a square shaped string. Then how to measure the filament that goes through the extruder? The same way as for setting the extruder steps per mm?
Sorry if I'm being thick.
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Hi Ian
I was not thinking of the single wall cube to measure extrusion width, rather that as simple print rather than complex calibration object it would be easier to isolate the source of the issue.
For the single wall single layer print, or other simple short print, you can make the filament a known distance from the extruder input, run the print, measure the new distance and so see how much was extruded. Comparing this will the gcode will then isolate if the issue is with the printer - I.e it's extruding more than it should be, or with the slicer - I.e. the amount of extrusion requested is greater than what is appropriate.
Be careful with slicer setting that increase extrusion widths etc for first layers so they don't muddy the waters.
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So, here is an update.
I made a simple cube 10mm x 10mm x 10mm in OpenScad. Then sliced it in Slic3r with 100% infill, no skirt or brim. Checked the gcode file and at the end Slic3r reported that it would need 417.8 mm of filament and the volume would be 1.0cm^3. All good so far. I checked Slic3r's maths. 1.75mm dia filament so (1.75/2)^2xPi which gave me the cross sectional area of about 2.405something and multiplied this by 417.8 and got 1000mm^3 (=1cm^3). Still good. Then I pulled a load of filament off the reel and marked it at 700mm above the extruder. Then I printed the object (which looks bloody awful) and measured the filament to the top of the extruder and got 263mm. So 700-263 = 437mm. That's what actually went through the extruder.
So on that basis, my steps per mm are about 4% high. Also, if I measure the 10mm cube, it is a bit lumpy and bulging but as near as I can tell, it's about 10.4mm in all three directions which correlates remarkably well.
Actually, I think setting the steps per mm this way under "real world" printing conditions is probably not a bad idea. It'll take into account the effect of retracting and un-retracting which may wear the filament down as it goes back and forth across the hobbed bolt and also the pressure and friction effects of the hot end and Bowden tubes.
So, I'll set the steps per mm down from 424 to 405.
In conclusion (so far) it seems that my extrusion isn't far out - maybe 4% high which I'll rectify. I need to look elsewhere to find why I need to use around 30% less extrusion to get a decent print. There must be something else wrong that is masked by under extruding. I've done repeated tests on tall cubes with different temperatures every 10mm or so and keep coming back to 190 to 200 deg C as being the best temperature with this particular hot end/filament combination. So I don't think it's temperature and I've lowered the speed and acceleration to less than I was using in my old Mendel.
There has to be an answer so all suggestions, however obscure will be greatly appreciated.
I'll keep digging…..............
Edit. Sorry Tony, we must have been typing at the same time - anyway, I think I've done what you were suggesting.
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To be honest whilst the difference in how we are each getting good results from our titan extruders is of academic curiosity I think you use the value which works for you. Maybe its to do with hobbed drive gear differences, maybe there have been revisions to the titan over time, maybe its pinch wheel pressure. But if you are printing okay then set it up however it makes most sense to you.
I printed this two days ago on my T3P3 kossel mini with flying titan extruder at 250 steps/mm. Those fan cowls are single walled.
So can be in any doubt its dialled in correctly its just around 60% of the steps/mm that the calculation for a titan suggests.
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Hi DJ,
(Nice prints by the way). I agree with what you say but it's bugging me.
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Ian
Yes posts crossing. If after your adjustments you get to the point that what you ask the extruder to extrude in gcode is what happens then you need to focus on the slicer settings to get good results.
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Hi Tony,
Yes, Slic3r settings or machine mechanics. I'm using more or less what I've always used with Slic3r but maybe for some reason a CoreXY needs something completely different. Or maybe, it's the actual nozzle diameter that's incorrect - the micro drills I ordered haven't arrived yet so I can't measure it. I guess I could try another slicer but I know my around Slic3R
Either way, I'm now reasonably confident that the extruders are doing what they should do - it's just that I have to under extrude to mask some other defect.
I'm not going to give up - there has to be reason.
Ian
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I seriously think that assuming its a corexy issue is a red herring - I'd be interested if you prove me wrong but corexy is just a kinematic scheme I can't see how it requires any different extrusion settings. The two titans I have to "under extrude" with if you follow that logic are both installed on deltas.
I will when my current print finishes closely inspect and measure the drive gears on each titan.
