A few weeks ago I got a Mini, which is a delightful step up from my Solidoodle 2 that I’ve been struggling with for years. The prints I’ve gotten from it have all been beautiful, but anything that required some manner of dimensional tolerance has not worked at all. So I finally got around to debugging the problem, and it’s been over-extruding.
I measured out 100mm of filament and extruded it, and it extrudes pretty much 100mm, which is great, except that it’s over-extruding. After running some tests, reducing the flow rate to 60% seems to do what I need it to. It’s not quite there, but I can get a wall/gap test http://www.thingiverse.com/thing:420754 print to at least fit together, which is significantly better than what I had before.
But 60% is a terrible multiplier for flow rate. The filament I’m currently using is Green HIPS from the LulzBot store. I measured the filament 10x, averaged, and adjusted its diameter to 2.93. I did a temp test, and 240 seems to be a perfectly lovely temperature between 220 and 240. Just to be sure, I’m using Cura and the official profiles.
Does anyone have any ideas what’s going on? I can just adjust the flow rate in all my slicer settings, but this seems ridiculous.
Brian, for parts I haven’t completely dialed-in, which is most of them, I will sometimes adjust the steps-per-mm up or down in about 5.0 increments, watching for the telltale signs of under or over extrusion. On the Taz4 with 2.89mm filament, the base is in the 800’s, so moving +/- 5 is a very tiny amount, allowing for very fine-grained tuning. Keep at it, you’ll eventually find a combination of heat, mm/s movement and extrusion rate where it’s amazingly “just right”. It can be hard to find, for sure. I recommend writing down/recording your settings, since I’ve seen different plastic types, even with nominally the same size filament, will feed plastic through the nozzle at different amounts, even with the same settings, so I assume they might need slight adjustments.
There are two variables to worry about with overextrusion. Amount of filliament extruded, which you seem to have dialed in well, and actual width of filliament. Your slicing program will have a filliament width setting somewhere inside of it. Depending on where you get your filliament, it may be a variety of possible diameters. 2.85mm is probably the most common, but I’ve seen anywhere from 2.65 up to 3.10mm. Further complicating matters, the width of the filliament on a given roll can also be variable. You need to measure your filliament with calipers, and adjust that value accordingly. If you are overextruding, chances are the filliment setting is set to a smaller diameter than the filliament actually is.
Piercet, I used calipers for my measurement of filament diameter. 10 places, averaged, and it was a little wider than expected, but I’d already put that into the slicer.
ThomR, I would expect that for small adjustments, but when the flow rate has to be set to 60%, I would expect that it’s something more significant going on. I would think maybe +/5% would be no cause for concern, but it’s odd that it would be such a large adjustment.
For now, I will just keep on with the big multiplier, but I’d love to figure out what’s happening here.
Post your slicer onfiguration file and we can see if anything odd is going on there. If it’s extruding 100mm when you tell it to extrude 100mm, it’s not the e-steps. If the nozzle size is set correctly (it’s a 0.5mm on the mini not a 0.35 if I remember right) and the filliament size is set right, you should get the correct flow. The only other thing i can think of is if somehow your layer thicknesses are off from what you have them set to vs. what you are actually getting. That would be a Z steps issue, but that would be beyond wierd.
Here’s the modified profile with the functioning flow rate. Modified HIPS Profile.ini (12.2 KB)
It’s mostly the stock HIPS profile for the mini from the downloads page, except that the first layer isn’t quite so dramatically different from the others and I’ve modified the flow rate / diameter.
I did chat with tech support over email the past week, and we’re at the “well, it works, so ¯_(ツ)_/¯” stage, which I’m good with for the moment. I may just do a bunch of prints for a while and then poke at the calibration again. I’ll be sure to check the z-steps next per your suggestion. Could be my layers are just getting squished too much; that would make a lot of sense, though odd if it happened.
Z Steps seem fine. I auto-leveled, moved z to 0, moved Z to 150, then measured, and it’s within 1/2mm of 150 in either direction depending on my measurement with the calipers. I can print something out, but I even if it’s off, it’s not going to be off that much.