Anybody tried PETG annealing? What are experiences?

@dav1dbone

11 ай бұрын

I use petg for making gears, very keen to know too😊

@themountain59

11 ай бұрын

kzread.info/dash/bejne/qICmq7Wrm8qaZso.html. Good video about it !

@vincylobo261

11 ай бұрын

Can u help me? in my ender 3v2 the filament is getting scraped off on the extruder stepper motor which is near the x axis stepper help me also the filament is wol3d India pla pro + the filament always warps no matter the perfection of the bed level it never sticks so what is the problem here?

@vincylobo261

11 ай бұрын

The filament won't get pushed every 1 or 2 hours

@vincylobo261

11 ай бұрын

(i tried every type of tips on KZread but it still warps)

I think yiu should avoid the objects touching the metal pan. It may hotter than the water. Something like a double boiler for cooking might work.

@isstuff

11 ай бұрын

Maybe just a fine mesh propped up 1cm by something underneath. The water can circulate and not be that far past 100C. Steam bubbles shouldn’t be that bad if you just simmer the pot.

@Christiaanammeraal

11 ай бұрын

Thats not how heat distribution of a pan works, you can boil water in a paper bag that’s because the water cools the paper to the same temperature as the water so it never reaches combustion temperature. This also works when te pan is metal the pan will not be warmer than the water in it.

@Uzumaki350125

11 ай бұрын

​@@Christiaanammeraalcame here to say that

@koffiezet

11 ай бұрын

​@@Christiaanammeraal but the metal of the pot touching the plastic suddenly has something with a higher melting/boiling point to transfer heat to: the PLA parts. So those areas of the pan - while tempered by the water of surrounding it, can be hotter.

@FullSpeed_only

11 ай бұрын

@@isstuffA normal Cooking Sieve that fits the Pot without touching the Bottom would be easiest.

You should be using a double boiler in order to spread the heat around more evenly. Placing the parts on the bottom of the pot is going to lead to only slightly different results from just placing them directly on a hot bed, it barely even spreads the heat at all. This should reduce the warping a little bit, but TBH most of the warping is due to internal stresses of the plastic's layerbond inconsistencies, so it'll always be at least a little warped. You'll likely need some sort of additive like the fiber filament you mentioned at the end.

@BuzzBazzJ

11 ай бұрын

I wanted to write a comment regarding this, but you did it for me😂 There needs to be a grate/platform or as you said, double boiler to avoid the parts getting affected by the direct heat of the stove.

This reminds me of my days in school. My Science Teacher was always giving us assignments and then we had to take notes and compare our observations with the rest of the class groups. Great video and such awesome note taking, thanks for sharing.

I have a suggestion: You should try a sous vide device. Many sous vide devices can go up to 90°C and they come with vacuum bags so water absorption should not be an issue. They also have a very precise temperature control, plus they circulate the water for even heating. You could also perform the annealing by stairstepping the temperature. Start out low, and gradually increase it for each test.

@SianaGearz

11 ай бұрын

You know that most of your post describes a 3D printer heatbed.

@carlosjosejimenezbermudez9255

11 ай бұрын

I would not want to cook with that sous vide after doing that.

@cinemoriahFPV

2 ай бұрын

​@@SianaGearz no

@TastySlowCooker

2 ай бұрын

@@carlosjosejimenezbermudez9255could you explain why not? Is the issue that PLA could leach out of the vacuum seal bags?

I saw an earlier video from you. I am really impressed with your progress. I never saw someone do experiments and present the results properly in a video. Really cool, creative and valuable! Thank you.

That was fascinating. Thank you for doing such careful, methodical work!

Man, you're always coming up with the most interesting videos, love your channel!

I have successfully annealed PLA with minimal warping using an oven before. The key is to slowly bring it up to temperature and then slowly bring it back down again. It's the sudden temperature changes that lead to warping. It's a very similar process to annealing a piece of steel. Suddenly heating and cooling steel is a great way to get it to warp as well. IIRC I had some very consistent shrinkage and expansion, it was -2% X and Y and +2% in the Z direction. Compensate for those in slicer and after annealing you end up with reasonably accurate parts.

@randywatson8347

11 ай бұрын

But is it worth it compared to PLA+?

@vasiliynkudryavtsev

11 ай бұрын

@@randywatson8347 PLA+ is nothing like a standard, unlike PLA. Companies insert random additives and call the result a PLA+. Only Carbon-Filled and Glass-Filled would have consistent properties.

Thank you for doing real world practical science. The internet is full of opinions. You provide data. One good test is worth 8,437 expert opinions.

Fascinating, Igor. Thanks. Looking forward to the next ones.

A good try is to fill a container with sand, and then heat this container up to 80 degrees (oven or using the heated table technique)... The sand will help maintain the dimensions of the pieces, in addition to being an excellent thermal conductor.

@scottpeal60

11 ай бұрын

Or dried rice. Oven would be best to heat uniformily.

@karatos

11 ай бұрын

Yeah, I use calcium carbonate and the results are pretty good.

@maraz666

11 ай бұрын

Fine salt also works.

@AlexanderBukh

11 ай бұрын

PLA goes sticky, so you never getting the sand off later, lol

@scottpeal60

11 ай бұрын

@@AlexanderBukh Good to know. Think the salt way will wash off better?

That was a very good series of tests - great work!

Wonderful! This is a truly excellent job. Very methodical. I have been 3D printing for more than 5 years and I just learned a lot. Thank you for all this work.

Regarding warping, this is why people anneal in packed salt or sand instead. The material keeps the shape whilst allowing the material is heated.

Klassz! Wicked video man, seriously excellent procedure and testing, I love your stuff.

Really cool viedo and thorough testing, as always! Keep it up

Hi, I was watching you video, good stuff. Also have a suggestion. For annealing, I put my prints into a bowl filled with bird sand and then put it in the oven for some time. Works great for me with minimal deforming only some shrinking. Good luck

I really want to try something similar with a sous-vide immersion heater. My idea is that slowly stepping the temperature up (maybe even down), the deformation may be less.

@randywatson8347

11 ай бұрын

Gravity is also an issue unfortunately.

@mandryd

11 ай бұрын

Sous vide would definitely be the way to get uniform heating. I've heard this mentioned on 3dprintingtoday podcast a long time ago. I'd love to see annealing with a sous vide machine to compare the amount of warping.

@SianaGearz

11 ай бұрын

That reminds me of the CNC Kitchen livestreams. Where he always cooks meat sous vide, but he uses a Prusa bed and a freezer bag as the cooker.

Really love this type of videos! Thanks!

You did a great job with this meticulous experiment!

Thanks for a thorough test. In order to improve my PLA prints, I paint my parts with Chloroform. Due to capilary action the chloroform is "absorbed" by the part. The chloroform dissolves the PLA and bonds the print grains. The surface also becomes impenetrable and shiny with a very good surface finish. When my PLA parts break, I bond them with chloroform which renders a stronger part. In some cases where I have to fix surface imperfections or need some sort of build up, I dissolve PLA in chloroform in a glass tube and paint the "glue" on the part. I've done some informal testing on single layer prints and the results are astounding. After painting the single layer print with chloroform there is no delamination between the print string. A test of the influence of chloroform on PLA will be most interesting. Will you please consider it?

@Ed19601

4 ай бұрын

Tnx. I bought some chloroform the other day and also had bought zipties (for my bike) some ducttape (as I ran out) and I always have a shovel in my car (to dig myself out if car stuck). If the police had stopped me, that would have rendered some difficult questions. Good thing I didnt by bleach, a hacksaw and garbage bags that day

@henkvaneeden9054

4 ай бұрын

@@Ed19601 😂

@Ed19601

4 ай бұрын

@@henkvaneeden9054 i am sure i am on some watch list already

Why are we trying to figure this out still? Put the parts in a bucket of sand and heat the sand however you want. Worries about fine details? Add baby powder. Or powdered Epsom salt. No deformation. Slow even cooling for recrystallization. It's like reinventing the wheel.

Didn’t know that. Thank you for experimenting and sharing

Issue: 1. The parts are touching the metal which is directly touching the heat source 2. The formation of air pockets between the pan and the part is causing uneven temperatures across the surface of the part and causing the warping. Suggestion: - Boil water and pour into a shallow tray or cake pan - place the parts in and allow them to sit a minute or two. - slowly add warm water until the temperature reduces enough to touch - remove and let dry. This should fix warping. I also suggest using triangle or honeycomb infill. The water may be best at 90c and not 100 due to air trapped in the inner infill. The air pressure inside will cause issues as it moves toward equilibrium. The annealing process is really meant for solid parts unless your top and bottom layers are a minimum of 4mm with 1mm infill. Hope this helps.

Igor very nice video and test! As someone else mentioned in the other video there are modifed PLAs that deform less during annealing, like Volcano PLA from FormFutura. I am looking forward to the PLA GF tests. I think the latest hype material for annealing is *PET CF*. Not to be confused with PETG-CF. PET can be annealed, while PETG can't (glycol prevents crystalization, at least that is what I have read online). PET CF has been recently introduced by Ultimaker and with annealing it can reach 181°C heat resistance (note that Ultimaker says there is still some deformation from the annealing process even with the carbon fibers). But for your tests, I think you can get 1.75mm PET CF from brands you have worked with in the past, like Phaetus aeForce PET CF or QIDI PET CF or BambuLabs PET CF. It is definately an interesting material, prints at about 280-300°C and these brands also claim very high heat resistance properties. It would be interesting if you could verify those claims and see if the HDT they claim is after annealing or straight off the print bed.

I am just a hobby metalsmith but. I think you could gain great results with annealing if you try putting your parts in a very fine silica powder or a fine play sand, maybe even powered aluminum and putting that into your kitchen oven. bring it up to the temp you require then let it cool. what ever powdered medium you use it will support your parts and aid in even heating and cooling, the presser of the material around your parts may also help with limiting deformation an warping of parts. try researching the annealing processes of metal parts because i cant really explain it well

A useful and interesting video. Based on this, I can't see any purpose for annealing PLA. I had assumed that it had the potential for increase layer adhesion, but it doesn't appear to noticeably help. Keep up the good work!

Really fascinating, I would love to understand more why the temperature resistance improves so significantly.

Great data! Thank you sir

For the tensile tests, did you measure the cross section and find that the deformation didn’t effect it? Or did you assume that the cross section stayed consistent?

Wondering how nylon is effected? Also, thinking performing on a grate or something above the surface due to the surface of the kettle temp compared to the water, unless maybe some agitation somehow like maybe even a transducer or speaker?

Protopasta sells their brand of High temperature PLA which claims to have better properties when annealed. They also recommend using carbon fiber filled version for minimal shrinkage.

You should test what is the minimum annealing temperature that gives improves heat resistance. Thank you for another excellent video!

@themountain59

11 ай бұрын

It is 70° 😉

Nice to see you taking a methodical approach to your experiments! I wonder if some sort of chemical treatment might yield interesting results as well.

If annealing is only about drying/heating the PLA it might be possible to anneal at lower temperatures without warping. Going by Arrhenius, if annealing at 90°C 1h is sufficient, then 80°C 2h, 70°C 4h and 60°C8h and 50°C 16h and 40°C 32h and 30°C64h. So annealing might be possible without warping at 40°C if you heat it for two or three days?

I really enjoy and appreciate all the work you put into your videos. The PLA going from 50 to 150 degrees is mind boggling. If we could figure out a way to control the warping/shrinkage this would be a game changer for functional PLA prints. I can't help but wonder how metal filled PLA would respond to this post processing method.

@christiangogol6658

11 ай бұрын

Placing the part in sand, then baking it at annealing temps reduces warping.

In my opinion, to avoid deformations, long or gradual annealing should be done starting from a temperature close to the melting/softening ones.

What if you print pla encapsulated in pva then anneal and than dissolve pva?

I've tried putting PLA parts in a ziplock bag and suspending in boiling water, but still warped, and slight change in color. I might try at lower temps, or bring on and off heat slower.

I'm curious if a steamer might be a better solution, you can keep the parts far away from the heating element to avoid hot spots and it might prevent the plastic from absorbing water

I think the warping is because they need to support their own weight. If you use a bed of rice, for support, then I think the annealing will work better. Also I'm wondering if the rice trick and a microwave might work as well.

I can't help but wonder if doing the annealing with a sous vide set up could stop the deformation and the absorption of water at the same time... Just a 🤔'

So I have to ask, what is the reason for annealing PLA? If one prints the object at a very high temperature, like 235C and the layers blend well, is there still a reason to anneal? I'm kind of lost on the reasoning here. ??

I wonder if more can be done with print settings. Maybe higher bed settings, or hotter nozzle with slow speeds and with a pause between layers, maybe on a non-heated bed so each layer heats the previous layers up some then they cool before the next layer. The time it takes to anneal parts, maybe different slicing could achieve similar results without the fear of warping or shrinking. CNC Kitchen did some testing with different layers heights, over extruding, etc. I wonder if those results are similar to annealing. You guys use different test objects so it's hard to compare.

How about making a jig from Petg or nylon to hold the shape of the parts while heating?

very informative, nice.

What if you add some sand and in the water and à weight on the top ?

What if you printed it, then while still attached to the print bed. Try to anneal it in the oven?

@MyTechFun

11 ай бұрын

I tried something similar kzread.info/dash/bejne/qGermqmlk6u7o8Y.html

What about modifying the gcode to iron on each layer before the next layer is printed? Would probsbly take for ever to print but interesting what the result would be

@jokerace8227

11 ай бұрын

Yes, PrusaSlicer 2.6 can be set to iron all solid layers, so at 100% infill it should iron all layers. There is also an ironing line width variable, which could probably be set as wide as the exterior tip diameter of the extruder nozzle. There is also the ironing speed variable. Maybe playing with those variables could significantly increase the speed of ironing all the layers of a solid part.

I would suggest using a convection oven or air fryer on low temperature. This should give an even application of heat.

I did experiments with annealing during covid 2 years ago. Annealing was done by boiling in microwave oven. The only filament brand on my hand which had the least warping was White PLA from Creality shipped with my Ender 3 Pro. Other tested green Esun PLA+ and black Bestfilament PLA had severe warping. Right away, I ordered the set of two (white+black PLA) from Creality, but still did not test them after moveover.

I wonder about them being in contact with pot bottom, I think it would be better in a double boiler or maybe a large sieve, to lift if off the bottom.

Annealing is such a PITA that it would be better to have filament that stands heat without processing (and is easy to print, sorry ABS 😕 ) I wonder what Aurapol PLA HT110 would be mechanically and temperature-wise 🤔

@MyTechFun

11 ай бұрын

Something line Engineering PLA by Filaticum? (Tested, 150C no annealing) Maybe this is their secret?

What about in a steaming chamber like what woodworking use to steam wood for bending but just a small shoebox size then you can go over 100° but still be surrounded by water

Ok, my question is why we dont print directly with annealed PLA from the spool? Is there any problem to produce it?

@MyTechFun

11 ай бұрын

Could be something like Engineering PLA by Filaticum? (similar thermal resistance without annealing, tested)

@dekurvajo

11 ай бұрын

@@MyTechFun exactly my thought. Do you think that's an annealed raw material? Because it starts to yield at the same temp

@daliasprints9798

11 ай бұрын

If you melt a crystal it's no longer a crystal. You'd just have more rigid (and thus more brittle) filament before printing, no difference from unannealed after. I've actually done this by mistake with excessive dryer temperatures and it's a pain to salvage the material.

Yes, it shouldnt be touching the pan. But the surface should still be flat too. Maybe a plastic food container full of water? Also would the speed make a difference? Maybe a slow ramp. I like the emersion heater idea from another comment.

An idea: put some sand in the pot, place the objects in the pot, cover them with more sand, then add water and heat up. It should limit, if not eliminate warping. :)

@maraz666

11 ай бұрын

You could use casting sand, and bake it in the oven to reflow the plastic into one solid piece. Needs to be 100% infill though.

Would using sand or small metal beads in the water as support work?

@3dprintedhardware

11 ай бұрын

I would use crumpled up aluminum foil to keep the items up off the direct heat of the bottom of the pan. I anneal carbon fiber nylon in an oven to strengthen our 3d printed wrenches for testing and I use crumpled up aluminum foil to keep the wrenches up off of the baking sheet.

Slightly off topic, but Amazon Basics PLA is actually quite good for it being so cheap. Nozzle 207°C, bed 80°C for first layer then cooling down to 30°C and continue printing, 0.2mm layer height. Works 10/10 times for me. Good strength and perfect bed adhesion. Bed is cleaned with window cleaner and leveled with BLtouch before every print. Ender 5 Pro with 0.4mm nozzle and stock bed surface.

You might wanna try that again but while using a sieve/frying cage/steaming basket to store the objects in. I think the direct contact to the bottom surface (=quick direct heat transfer) might contribute heavily to their deformation, so creating some space and reducing direct contact area in general could help.

The bottom.of the pan is hotter than the water above it. This caused the part of the extrusions ttouching the metal o soften faster than the area not touching the bottom. Perhaps putting them on a sheet of non conducting material will allow for an equal exposure to heat and avoid warping.

Thank you. It would be interesting to see if maybe 70'C or even 60'C would impart some of the temperature tolerance with less of the warping. Just getting PLA useful for things in a car in a hot climate would be a great thing.

can you do the boiling in a vacuumed sealed bag?

I wonder if another method to anneal using the properties of water, without absorbing water. With your pan, the element heats up very high for a second or two, then turns off, during this time the PLA is VERY soft. so... to avoid it sitting on the pan, AND not absorbing any of the water, seal the parts in a plastic bag, and sous-vide them at exactly 90-100degrees! I have a sous-vide machine, I'd like to try this.

What about steaming for anneal?

Now I'm wondering how these samples would fare being annealed in a vacuum sealer bag (like FoodSaver). For the shrink test, you'd have to have support media in the bag (sand or salt). My theory is the bag would provide some level of stabilization and prevent some warping. And if you use an immersion circulating heater like used in sous vide cooking, you could ensure the water around all parts is evenly heated. Doing it on the stove means the bottom surface will always be hotter than the surrounding area (unless the parts are lifted off the pan). You probably wouldn't want to do this with uncontained parts, but in a vacuum bag, they should be protected from the strong circulation.

What if you use sand? Like a turkish coffee basically lol. But making sure the parts aren't touching any metal directly

interesting results

Is it because of heating or because of water? Maybe you could heat treat it in hot sand without bending. Would improve layer adhesion because of melting layers together

Could you make another video with more tests on the KLP1?

@MyTechFun

11 ай бұрын

Yes, I gave some PC ABS, and with klp1 I can reach highest temperature in enclosure.

Try packing the objects in fine salt in a container and annealing them in the oven. The salt supports the objects and they keep their shape and it evenly distributes the heat.. I've done it, it works great. I got a big bag of pool salt and ground it in a blender as fine as I could. After you remove the parts from the salt and clean off as much as you can, water will dissolve the rest, as some sticks to the parts some times.

Great work. I think annealing in sand and water together may minimize deformation 👍

Here's another keyword to trawl scientific papers, "solvent induced crystallisation of PLA". Ethanol and acetone are among the candidates. One thanks Alex Kenis for drawing this to our attention. Annealing is probably not quite the right term, i think temperature resistant PLA is actually crystallised. Is that so?

@MyTechFun

11 ай бұрын

Hm, yes, but everybody is searching for "annealing" word :-)

I pack the prints in green casting sand. Would be interested to see how that method works compared to water.

@randywatson8347

11 ай бұрын

That is actually a great idea, but still an issue with shrinkage and gravity I imagine?

@vasiliynkudryavtsev

11 ай бұрын

This method is long known as remelt in sand/salt/gypsum. Even if you only anneal and not remelt, still the amount of work is the same.

If you bury the printed items in sand, press it down, and then put it in boiling water, there might be less distortion

What about trying to aneal with salt or some fine powder instead? completly cover the object with salt (or powder) put it in pre-heated owen to target temperature and leave it until anealed. Salt should hold object in shape as well as prevent it from absorbing any moisture, event drawing it out

Oh, I really want to watch this one! I already did it once - it worked, but it deformed a lot. Let's see what you got!

@GeekDetour

11 ай бұрын

Suggestion for your next annealing test: let it stay on a Food Dehydrator at 65ºC for 8 hours... It should deform much less and yet, it would give the annealing benefits.

@MyTechFun

11 ай бұрын

Personal experience or just guessing? I am thinking to try PETG annealing

@Sembazuru

11 ай бұрын

​@@MyTechFunNot all plastics can benefit from annealing. I've heard that the glycol additives to PET that creates PETG interfear with crystal growth making PETG not able to get any benefit from annealing. I'm not saying to not do the experiment in case what I've heard is wrong, but I would be less confident of any measurable results from trying to anneal PETG.

I did some annealing tests a while ago with eSun PLA+. Material got harder. But layer adhesion seemed to be notatbly worse. Could not properly test impact resistence. But if it's the same (like shown in your test), that's pretty good, because usually harder material tends to be more brittle. So annealed PLA+ is still interesting to me.

I did't read all comments before, but you should use 100°C steam, and completely avoid metal contact, there is always a temperature gradient which may contribute to the bending. Anneal your parts on a metal mesh in steam, with enough distance to the boiling water to avoid splashes. The heat transfer btwn steam and your parts is at least 100 times faster and far more homogeneous, without a temperature gradient..

Please try with heated dried rice and/or sand? I would like to see a video on that. Also a test video comparing the same print with and without annealing in a oven or hot car. 😊

The best thing people have reported using so far is ultra fine table salt, which can be bought in bulk quantities as "popcorn salt". The only measurement I can find right now says 0.2mm grain size, but I could swear popcorn salt was smaller than that. It can go right into your lungs if you're not careful though. I don't know if anyone has tried corn starch, which one source I'm looking at says averages 0.005 to 0.020 mm grain size. Might possibly work better though IDK if it's as easy to remove.

@claws61821

11 ай бұрын

Ironically I was just looking up whether someone had tried corn meal after suggesting this, and it seems that washing powder, in the form of preheated baking soda (100+°C, 60+ min) is a more recent recommendation.

I believe that the issue with deformation is due to uneven heat penetration. I would suggest running a more lengthy annealing process when first water is heated to 50C and held and that temperature for 1 hour. Then increse it to 55C for one more hour, then 60C and 65C. I believe there's no real point in going above 65C in this scenario. Slow heating like that should release internal stresses gradually and keep geometry intact.

Instead of adding CF to minimize PLA warping, other things might be a better compromise. I.e. HTPRO PLA (Trček) might have just enough additives to be better at annealing, though it does warp a bit when printing (like ASA, nothing much). But I just love that filament and use it almost exclusively instead of PLA. Also, maybe it would make sense to add rebar to PLA in x/y directions like we do with concrete? Rebar could be made of ASA, though it would require a pause mid-print to insert it which is a PITA. Alternatively, maybe there's an infill geometry that could help with this problem too? Or maybe cleverly positioned supports and brim which would be removed after annealing? Those all feel like they could be more predictable than adding a bunch of CF to PLA and losing all the characteristics that make PLA so wonderful.

@SianaGearz

11 ай бұрын

I would try fumed silica as a filler but idk the resulting material might turn out pretty funny. Anyway this is volume preserving so it won't induce warpage and is likely to cancel it out, i think. It will also probably kill stringing dead. It might kill printing dead as well though, that's the concern. Has anyone tried to make such a material?

what if you placed the parts inside vacuum bags, similar to how food items are vacuum packed. Further you can place them on a rigid surface before wrapping them. This will avoid the contact with water, reduce the warping and reduce contact with the hot pan - that is way above boiling point

I wonder if using heated sand would achieve the same results without the issue of water absorption.

@Sembazuru

11 ай бұрын

As I recall, CNCKitchen did some heated sand annealing tests with decent results as long as you don't mind a sand textured surface (and potentially some sand stuck to the surface).

Good testing, but you have to realize that by placing the parts at the bottom of the pan there will be more warping/shrinkage/degradation because of the thermal profile of the water bath and the heat conduction across the bottom of the pan, right? A better test would be to submerge the parts without leaving them in contact with any surfaces of the pan. Also adding it some form of steering would be optimal for thermal homogeneity.

Maybe packing the PLA pieces in greensand like in sand casting, as in metallurgy, and heating the whole thing, could help with the warping. I think this could be another way to approach annealing plastics. Or maybe using plaster moulds? Something that keeps the basic dimensions of the piece while the heat fuses the layers. Other thing that crossed my min, increasing the medium (water) density by adding starch and thus keeping the pieces heated by all sides evenly... Maybe using heated oil?

I wonder if you could do sous vide annealing 🤔

When I’ve tried this the bubbles in the water cause deformations.

Good chance that the heat transfer into the print is higher on the side in contact with the metal bottom of the pan that it is with the water and that this uneven transfer of heat is the cause of most of the warping. Would try doing this in a Sous-Vide bag suspended in the water hung from a piece of wood across the top of the pan...(bonus, no water exposure of the print...)

Would a pressure cooker be better

Very good. I make model train parts. Some parts are used in making smoke, which can reach 120-140C I am using CF PETG and CF PLA but i want to have a safer product. Boiling these parts make sense. Since they fit together warping is not allowed. Thoughts, Dennis

What you should do is to use Pressurized Salt. When the salt is packed tight in a closed can, it cannot move around and there is zero deformation. Using PLA is kinda pointless however, because ABS will be much stronger and heat resistant. One hour at 200°C and ABS will be equal to pressure mould.

I wonder how other 3D printing techniques would do. I don't have a 3D printer but this is interesting nonetheless.

Any form a heating that does not include a medium to maintain the shape will always create warping. The process of 3d printing creates temp differentials that results in internal stresses (see Prince Ruperts Drops).

Why not use a sous vide?

Maybe multi stage annealing? Up to 50c the first time then cool so you're not hitting the 52c warping temp, then 75c & cool. Might bring you to the 80c results with less deform.

I used Fiberlogy HD PLA, used oven with 40 deg C and it is a lot stronger that regular PLA

Maybe sous vide them, vacuum bag the prints on a flat surface. Sous vide will get you a precise and uniform temperature without the need for drying