[Rozwiązany] 3D Benchy 0.6mm Diamondback Nozzle PETG prints curls up during print  

RE: 3D Benchy 0.6mm Diamondback Nozzle PETG prints curls up during print

Wish I had an answer, but all I have are similar experiences with the diamondback nozzles, both 0.4mm and 0.6mm.

The issue I run into is that the stringing/oozing is absolutely crazy. Yes, that indicates that it does, in fact, have very high thermal conductivity. But with that comes the need to tame it, and I haven't figured out how. I would have thought that increasing retraction would help, but that only has marginal effect.

I also thought that it just needed to be printing fast to overcome the constant oozing, but this was before input shaping was a thing for any of the printers, so I didn't really get a chance to test anything other than an epic failure of a 200% speed attempt on my mini. It might be worthwhile to attempt again, but I don't expect much, especially considering any small parts would necessarily still be printed slowly.

Your issue of curled overhangs sounds familiar -- too much heat is being localized at the tips without having a chance to be cooled down by the part cooling fan. Unfortunately, without changing the actual hardware, this isn't really something that can be addressed other than maxing out the cooling fan, lowering print temperature (if possible), and fiddling with perimeter/overhang speeds.

Personally, I've given up on the diamondback and switched to obXidian nozzles for everything. They're wonderful.

RE: 3D Benchy 0.6mm Diamondback Nozzle PETG prints curls up during print

Thanks Carl,

Apricate your reply, and since you never truly found a Diamondback answer, let me share the ones that I found.

TLDR; The result are pretty clear-cut when it comes to printing *straight PETG* with the DiamondBack 0.6mm on the Mk3s+, which is to say it works, if you are willing to accept the right trade-offs, which in my case I'm not.

Background:

All of this obvs. comes with a slew of standard disclaimers and "your mileage will vary" stickers on it. Also, since I only print with normal PETG, I will cover the answer we found for that material, while I refer to other materials (ASA PLA, PC-Blend and Carbon Fiber Reinforced PETG), those were only used for reference, to prove a point, and to compare/contrast. We got to here by printing (and finishing) 140+ 3D Benchies on various overall printer speeds (50%-100%), various temp setting (230/235 and 220/222), and various slicer setups. We ran identical slicing settings on both the Prusa, on the StrataSys (for reference). 

Now, after I posted my initial question above, and on the back of 3 frustrating weeks of tinkering, I finally broke down, and decided to call in the professionals. So with some help from a couple of work-place friends of the Stratasys certified engineers ilk and a "looks kids, this is what is actually happening" type senior guy from our material lab, we printed, analyzed and talked for a weeks or so, and we have drawn up - at least for now - several key observations, and for me a personal trade-off conclusion.

What the experimentations show is that we are essentially dealing with a "time-on-layer" vs. "thermal absorption and dissipation curve" issue. This is already a critical management point of printing *straight PETG*, and something that becomes critically amplified in small parts and overhang printing due to the accumulation of thermal loads over a smaller space (details is not the issue here). 

As with any material that experiences curling on non-first layer corners and overhangs due to thermal accumulation, it is to be expected that as the speed lowers (and thus layer time increases), the curling overhangs reduces dramatically, to a point where it eventually disappears. What was less expected is that for PETG, extrusion temp optimizations takes a distant second priority to speed in fighting said issues, as long as printing stays within the 220-235'ish thermal windows of a properly dried out Prusament PETG filament spool. What was even less expected is that the specific thermal properties of the DiamondBack nozzle and its extreme thermal conductivity (which is fairness is its main selling feature), actually amplifies some of the worst behavior in *straight PETG*, and thus require even lower speeds than what e.g. a brass nozzle does.

Many in the forums report that they love their DiamondBack nozzles, and I truly believe them, they are printing at high speed with low temps. The thing is though, they are using materials, which are seldom *straight PETG*, and in the control test we ran, The Diamondback nozzle actually performs admirably when paired with stuff like Reinforced PETG, PLA and ASA.

So what did we get to these finding?

The first step was to understand what problem we actually needed to solve for, and it was readily apparent it had to do with time and energy. For PETG specifically needed those things need to be properly dialed in, to produce a gradual and even multilayer cooldown which in turn yields the results we typically get with a 0.4mm brass nozzle and a moderate thermal load. For a 0.6mm nozzle this is made more difficult by the fact it clearly extrudes more, and thus deposits more energy that needs to get evenly cooled down in a controlled way. This was proven simply but turning down the overall speed of the printer, and observing that curling disappeared.

The problem therefore turned into "thermal management inside of a small model". We then started playing with the slicer layer timing and speed of the different features, only to come to the realization that what we needed to do could not really be done within the slicer, as features like "Slow down if player print time is below" actually produces a different outcome than the printer speed knob, and that adjusting down feature print speed across the entire print, completely defeated some of the main purposes of a wider extrusion, which is speed and bonding.

Here is the way to think through this one; If you set the print to say 50%, resulting in a layer time for the fastest layer of say 45 secs, it yield significantly better results in combatting curling, so why not set the "Slow down if player print time is below" to 45 secs in the Slicer?. Well, because one is a comprehensive and linear slow-down, and the other is relative to a target -- all you need to do is look at the G-Code, and it shows that since the slicer (as expected) only slows down the fastest layers (while the speed knob slows everything down), the relatively increased speed (and thermal load) of "non-fast neighboring layers" results in a cumulative heat load across the multiple layers that needs to cool down in a nice coherent way, in in return triggers non-obvious print issues.

That means that while the issue can be addressed, it is hard to do it using the slicer, and thus requires either a big hammer (overall speed nob) or post-slicing script-processing of the G-code -- neither of which is ideal, as it steals back that precious time you just though you saved with a bigger nozzle.

Another major factor here was clearly thermal characteristics of the DiamondBack Nozzle and how it either works with, or against, the material you print. Once that dime dropped, many things started to make total sense in terms of the outcomes we saw;

The aforementioned engineers and I (and indeed DiamondBack themselves in their literature), clearly observe a much higher thermal conductivity in the DB Nozzle design than in your typical brass or hardened steel. That combined with the much greater volumetric extrusion of the larger nozzle, is actually a really good design...when you are printing PLA, ASA, PC Blend, and most importantly abrasive modified PETG. The same is unfortunately not true when printing *straight PETG*, and especially not for smaller parts or for no-support overhang parts in *straight PETG*. This is due to the really stringent cool down profile of *straight PETG*, which is the setting we were solving for was only achievable by slowing down short-duration-layers (see above), or forcing a lower extrusion temps at the edge of the thermal sweetspot (which in turn creates its own issues).

That is not to say DiamondBack cannot print *straight PETG*; it actually does so well at lower speeds, and when printing PETG that is reinforced with other materials, it in many cases shines. We had several very successful tests where we used a *PETG BASED filament*, as in a PETG Filament that was reinforced with stuff like Carbon Fiber (which incidentally is touted in reviews and on forums as one of their claim to fame use-cases). The important part here is to understand that the success of printing a Carbon Fiber reinforced PETG ultimately came down to the fact that those added compounds significantly alter the thermal characteristics of that *PETG BASED Filament*, and thus we are not really printing "normal straight PETG" anymore. In this case we used a PETG filament with 40% Carbon Fiber, and works exceedingly well because Carbon Fiber absorb and dissipate massive amounts of thermal load very efficiently, thus managing a thermal situation that would otherwise lead to the typical PETG curling issues. The mentally picture here is a Formula 1 Carbon Fiber brake duct sitting right next to a 1200 degree glowing brake disc, it is a thermal balancing act that works because of excellent engineering and material choices.

At the end of the day, what we actually concluded that a DiamondBack 0.6mm nozzle is really fit-for-purpose, if that purpose is either large(r) functional PETG parts, moderately sized parts using Modified/Reinforced PETG (typically abrasive), ASA, PC Blend and PLA (which just wants all the cooling it can get). It is however less fit-for purpose for smaller PETG parts in general, and a really mixed bag when printing PETG parts with significant overhangs due to the aforementioned timing-on-layer issues. To be fair, you can state the same about other 0.6mm nozzles, but in the case of the DiamondBack which really excels at (and inherently exhibits) properties that is opposed to what smaller *straight PETG* parts actually needs, the problems are actually getting more pronounced than with brass.

And therein lies the rub - in an ideal setting, one would have an Prusa XL where different printheads would each instantiate nozzle/material/speed combo, and then match the correct model to the correct printhead, but alas that is not the world the MK3S+ / MK4 (with or without MMU) lives in. In the MK3S+ / MK4 world, one must perform a trade-off between a 0.4mm nozzle that is (slowly) printing rock-solid and reliable prints using as-is STL/G-code, or a 0.6mm nozzle where time have to be spent tuning each print to get to greater speeds (and potentially mechanical strength) -- understanding that the time taken tuning each model to a 0.6mm nozzle peculiarities is time *not* saved by the larger extrusion. The Diamondback nozzle only further reinforces that trade-off, and it is now even harder to ignore, especially when printing *straight PETG*. Now, if you most print PLA or reinforced PETG, if you re-run the same optimized and tuned print over and over, or if you generally just like to tinker with every print, those trade-off parameters clearly changes.

I do neither of those -- I make stuff, therefore I print stuff, so I can use stuff, and I do so in *straight PETG* -- which is to say; I prioritize a largely fire-and-forget print experience over the theoretical promise of speed increases.

So in summation; I will be taking off my 0.6mm nozzle and putting my ol trusty 0.4mm hardened steel nozzle back in. When my XL arrives one of these days, I'll likely revisit, but for now the trade-offs I have to make does not align with my stated goals, and thus is just not worth it.

RE: 3D Benchy 0.6mm Diamondback Nozzle PETG prints curls up during print

Thank you so much for the write up. It seems to make sense now that the localized thermal characteristics of PETG's cooling is what plays the critical part in why it's hard to throw the DB at it. Thinking back, I believe I had only tried it on straight PETG, which would explain why it was such a difficult thing to figure out how to use well.

I'll give the 0.6mm another shot with Prusament PCCF and see how it does the next time I've got a project that needs it. From the sounds of things, because the filament itself is so well behaved in general, it should be able to actually benefit from what the DB has to offer.

RE: 3D Benchy 0.6mm Diamondback Nozzle PETG prints curls up during print

Thanks Pa1nless.  As Pa1nless experience shows, it isn't cheap to gain the knowledge. 

This reminds me of many other thermal problems with 3D printing over the last 40 years.  I do not claim to be an expert, but have been working alongside 3D groups.   Time on layer or time between passes related heat load has been noted on SLS and FBM printers.   Advanced solutions may be in  3D business companies as proprietary software currently.  

I see the input shaper as a beginning of Prusa understanding the machine and environment conditions.   Could "time on layer" and thermal be addressed in a free slicer?  Possibly, but I don't see it in the near future.  There is a long way to go to understand and then adapt to the many variables of 3D printing.

RE: 3D Benchy 0.6mm Diamondback Nozzle PETG prints curls up during print

I see the input shaper as a beginning of Prusa understanding the machine and environment conditions.   Could "time on layer" and thermal be addressed in a free slicer?  Possibly, but I don't see it in the near future.  There is a long way to go to understand and then adapt to the many variables of 3D printing.

I agree that the input shaper *could* become useful for this. The issue as I see it, though, is that the input shaper is touted as an option for increasing speed, not for "optimized printing", and indeed the very proof-point given of the input shaper goodness is...tada...a super fast 3DBenchy.

In my book that is a bit of a shame, and somewhat narrow in it usefulness; yes, a input shaper will provide speed in several cases, and will print just fine with 0.4mm nozzles for people who are looking for ok prints. But for people who are looking to do great, functional, prints the input shaper is a bit of a "sure, whatever", as an optimally implemented input shaper *should* actually slow stuff down to take things like overall heat load and time-on-layer into account -- and the current one does not.

So while Prusa will clearly focus development on input shaper for speed creation (at least initially), advanced logic and material modelling will likely have to be addressed via the slicer (where one could argue it actually belongs). Maybe it is time to get the Cura crowd to think along these lines, as PrusaSlicer will then surely follow suit.

RE: 3D Benchy 0.6mm Diamondback Nozzle PETG prints curls up during print

Many many thanks for this write-up. I'm also struggling with curled overhangs with PETG on both my 0.4mm (Prusa XL) and 0.6mm (Prusa MK3S+) Diamondback nozzles. This helps give me some direction as to what to tweak to reduce the issue.