PLA Lifting - Conflicting Advise?
New MK4S & I’m new to 3D. I was printing a wide box and the finished product showed some lifting on the four corners. It was somewhat minor compared to some photos I’ve seen posted.
In any event, Prusa Tech support said raise temp of bed 10c to 70c, and print first layer at 0.15mm, no other advice. I’m using Jessie PLA. A Prusa search came across someone suggesting lowering hot end 5c & raising bed 5c. This made a lot of sense to me, although I have not tried it yet.
The lowering of the filament temp seems like it reduces the temp differential with ambient air, hence, reducing the thermal shock. Jessie manufacturer suggested printing 10c hotter & raising bed 10c. The bed-recommendations aside, one says print hotter & one says cooler from Prusa’s default settings for said filament.
can anyone add their insights?
Thanks, Dan
RE: PLA Lifting - Conflicting Advise?
I found this article (attached) on the web. In general, it seems to suggest that if you are having issues, one should lower the filament temp, as much as you can, and raise the bed temp as high as you can. Hence, you reduce the temp differentials: ambient-to-filament temp and filament-to-bed temperature. It’s these temperature differentials that cause the corner lifting…theoretically, you are striving for homogeneous temps across the model.
The article also addresses all the other, known, causes of warping, etc. In my case, however, I wasn’t experiencing any warping, just a bit of corner lift. My first layer always printed perfectly…it was then that shortly into the print I noticed slight lift on the corners.
Lastly, I’m understanding, via my research, that different color PLA filaments from the same manufacturers yield their best results at different temperatures…some require a hotter temp, and some require cooler temps. That seems to be one reason why manufacturers provide a range of recommended temps. That’s all great, but given the manufacturer knows this, why don’t their temp guides reflect this. When you see a very wide range on, say, all their PLA filaments…you should suspect the variation across colors in addition to other factors. If I recall correctly, Jessie PLA shows: 200-240c…that’s a fairly wide range. Bed just shows ~60c.
I hope this provides some thoughts for additional comments. I’m new at this, so just trying understand it all…
RE: PLA Lifting - Conflicting Advise?
I'm quite sure that these variations on recommended nozzle temperature aren't related to different colors of the same filament. It's only that manufacturers must take into account the vastly different setups of their customers. Some people use brass nozzles, others hardened steel. Some printers are faster than others. Different models of hotends have different thermal properties. Thermistors aren't always very precise. Those and several other factors mean that it's impossible to recommend an exact nozzle temperature and the manufacturer, to avoid complains, tends to play safe giving a wide interval. Some more than others, because 200 to 240c is a very wide range indeed.
RE: PLA Lifting - Conflicting Advise?
You make some great points on the variations out there; however, the filament maker alerted me to the filament color versus the heat variations…stating that some colors need different levels of heat. I’d say it all rolls up to the wide range specified.
My question is more focused on the temp recommendations and the associated inconsistency that I discuss above versus the lifting. I’d like to hear users comment on this. Thanks, Dan
RE: PLA Lifting - Conflicting Advise?
@dan82
I found this article (attached) on the web.
Take care. It may have been published only a year ago but most of the article is very out of date and some is just wrong. It appears to have been written with only sketchy research to attract affiliate link payments.
There are many threads here about warping - corner lift is warping (sometimes causative) 'though mild.
Cheerio,
RE: PLA Lifting - Conflicting Advise?
I thought I’d share the latest on my research & print experience relative to my interest in what guidance makes sense here. To recap, briefly, I experienced some lifting of a large box’s corners on my Prusa mk4s. Some user/expert advice said raise bed temp and start with a 0.15 first layer; others said lower filament temp by 5c and raise bed temp by 5c; still other advise said make everything hotter…by 10c. Hence, the confusion, and not all can be correct. Relative to the article attached, at least one person felt it was outdated, and, in some cases wrong…I didn’t feel that way, but I’m not an expert. In addition, some felt the color changes within a manufacturer’s PLA line didn’t impact properties; however, directly from Jessie PLA maker, it does; some filaments like more heat than others, etc.
So, my instincts say that the filament goes down hot and it creates a level of (for lack of a better term) thermal mass. For this discussion, we will assume Thermal Mass is a function the amount of material (volume) extruded and its Temperature. Everything else stays constant or has no impact…bed is level, filament is natural (no color), room temp constant, etc.
So, if you extrude a 0.3mm thickness at a temp of “x” it will have more, so-called, Thermal Mass than, say, a 0.15mm thickness at temp “x.” At, say, some constant cooling rate, the 0.3mm layer will cool from a higher temp, and because of its thickness will likely create more contraction force. For illustrative purposes only, think about 220c at 0.010mm thickness versus same temp at 0.35mm with some constant cooling rate. The very thin layer (regardless of cooling rate) just can’t generate enough force to matter much, although in reality, it cools quicker. A lot of moving pieces here, perhaps that’s why everyone has an opinion.
Also, cooling too quickly, everyone agrees, creates a contraction force greater than cooling slowly.
Given all this, I tried a few simple experiments. I gave some credit to the thinner thickness cooling quicker, but at the same time, likely, having less contraction force and an overall narrower temp differential impact. I also thought about the bed temp and what role it plays in first several layers…keeping things a bit warm to slow down cooling.
I found that Jessie PLA, Mystery Orange color warped the most, so I used it exclusively for my experiments….here’s what I did & the results;
I lowered the Filament Temp by 5c and printed the first layer at 0.2mm, and then 0.15mm (lowering the so-called volume and thermal mass) for the next several layers before returning to 0.2mm. At that point I felt like the model was strong (cool) enough to offset any increased forces from the thicker filament. I also raised the bed temp by 8 to 10c, larger models at the 10c as I felt it helped the 0.15 layers cool slower. But, after several layers it had less of an impact.
I added 0.2mm mouse ears at corners, not so much to help with lifting, but to be able to see the tiniest lift. If the ears lift just a tiny bit, the blistering it creates is very obvious.
Bottom line, all prints were perfect, zero lift.
I hope this helps others. One closing note, the Jessie website says 200-240c for pla, 60c bed. But actual filament reel says 200-235c, same bed temp. I’m not sure if Prusa’s presets were using the 240c high end to develop their presets, but that would explain my issues. In any event, with my adjustments, I’m running 225 1st layer & 220c all others with a tapered layer from 0.15 to 0.2mm…with a o.2mm first layer. All on a bed that runs 60c to 70c adjusted up for size.
thanks for all those that commented and I look forward to other thoughts and experiences.