Advice about getting into 3D printing for rocketry.

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rocketgeek101

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Hi all,

3D printing has been something that I have been wanting to get involved in for quite a while now (as a new hobby with lots of potential for use with my other hobbies :)). I have been recently doing extensive research on printers/filaments and have a few questions that I'm hoping those with some experience in 3D printing can potentially answer.

First off: ABS vs PLA.
From what I've gathered PLA is by far the most popular and the easiest of filaments to work with. Weaknesses seem to be low melting temp and strength/brittleness of printed parts. ABS produces stronger more heat resistant prints but is difficult to print with and requires a heated printing bed/printing environment (as otherwise parts will warp/crack). It seems to me that ABS is probably more suited for rocketry then PLA, but I would be interested in hearing others experiences. Is PLA suitable for making 3D printed nose cones, fin cans, and avionics bay parts? How does it handle exposure to a motors ejection charge?

Secondly: Printers
I have been looking at various printers (mostly on Amazon as I happen to have a $100 Amazon gift card that I could put towards it). Seeing as I'm a total noob at this, I would like to keep it fairly simple for now and avoid DIY kits that require a lot of fiddling to get up and running. That being said, I do want to purchase a printer that is reasonably capable and reliable, and produces good quality prints (and has a decent build volume). The ability to print ABS would be nice too. So far I have identified a few candidates including the Creality CR-10 mini (or S -- same printer other than the size. With these printing ABS is a bit iffy without making some modifications from what I've read.), and the Flashforge Creator Pro (bit pricey though). Does anyone have experience with these machines or ones that they would like to recommend? My budget is flexible though I would prefer to keep it at around $5-700 (or at most not much above $1k).

Finally: Software
What software do you guys use to design 3D models to print? Personally I have only used TinkerCad (which is great but a bit limited in my opinion). I would prefer something more powerful but that is still easy and intuitive to use (needs to run on Macs).

As far as slicers go (which seem to be quite important in producing good quality prints), it seems the only ones that I have heard consistently good things about is Cura (free) and 3D Simplify (about $200). The Flashforge printer linked above from what I gather is not compatible with Cura and would require one to purchase simplify 3D in order to get the best results with it from what I've read. Again I would be interested in hearing what it is you use.

Thanks in advance for any advice you may have to offer! :) Please feel free to post pics of your printer setup or rocketry related prints you have made with them.

For the curious: attached is an image of a design I've been working on that I am hoping to build one day, and that makes use of a variety of 3D printed components (including a fully 3d printed av-bay, nc, and fin can). The construction will be mostly modular and will use minimal adhesives so as to facilitate a variety of different fin shapes and make for very easy repairs if needed. I am also planning to build a static display model of the Falcon 9 rocket and am aiming to 3D print the oddly shaped parts such as the landing legs, grid fins, etc.
Juno3D_v1.0.jpg
 
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First off: ABS vs PLA
There are many more choices than just those two, at least provided you have the right hotend on your printer. I've only done PLA (or derivatives like eSUN's PLA+) so far, but I have PETG I'm looking forward to use once I swap-out the hotend in my printer (currently have an E3D V6lite, not good for the higher temperatures, but I have a V6 and a Titan, the former would be a pretty easy swap, the latter's going to take a lot more work but is my end-goal to get some more print volume out of my printer). Early on I also bought some ABS, but I'm not sure I'm ever going to use it after hearing more negatives about it (including wanting to be well-ventilated when printing with it).

Since all I've printed is PLA so far, I'll say that it works quite well for most everything. All of my sleds are PLA and I haven't had any issues. I did have one of Landru's Mobius shrouds (also PLA) deform when left out in the heat (nothing obvious, but the camera no longer fit in it), I'd primered it and painted it black to match the rocket, so obviously would have made it hotter in the sun also. I'm working on a camera shroud for a different camera next, and I'll start with PLA for that also.

Secondly: Printers
I'm using a Robo3D R1+ (which seems to have come down to $499, it was $699 when I bought mine) and am very happy with it. But there are lots of choices and there seems to be several that are liked by folks on this forum.

Finally: Software
For modeling, I tried FreeCAD but found I had to start over too often if I wanted to make changes to the base elements in the design because of the constraint system it uses. Didn't try any other packages of its ilk, I learned about OpenSCAD and I like programming anyway, so I fell in love with it and haven't considered anything else.

For slicing, I've been very happy with Cura (15.0.4, haven't tried the newer versions). Both of these work fine on the Mac, and even have command-line forms for each, so I have a rather complex makefile that lets me just say "make print <file.gcode>" and it will automatically build the .stl(s) using OpenSCAD, feed it to Cura to make the .gcode file, upload the GCODE to the printer and start the print. Love it!

I find it hard to believe any printer wouldn't work with Cura, unless it doesn't use GCODE. But I think they pretty much all do.

The basic things I'd mention is that I don't think any printer out there is truly plug-and-play. 3D printers can be finicky beasts, so there will be a lot of tinkering getting started, bunches of failed prints, etc. And then if/when you catch the upgrade bug then there's even more tinkering (but more fun, also!). Once you get things dialed-in they can be pretty reliable. And when creating models, you either need to think a lot about the physical limitations of printing (overhangs, etc), or else do a lot with supports. I do the former, I haven't done a single print using supports in years as I find I can make my designs work without them. I haven't printed any fin-cans though, I'm more about sleds and camera holders/shrouds, guides/jigs and the like.
 
First off: ABS vs PLA
There are many more choices, but so far I've printed almost exclusively in ABS. I don't have too much of a problem with it, but I do have a chamber that can be moderately heated (~45C, with plans for higher). I don't notice the smell, in a room with moderate ventilation, but maybe I'm nose-dead. I haven't had any complaints from the wife or visitors. I've been meaning to do more with PLA, and I have a new roll, but I'd have to change print surfaces and I haven't been inclined.

Secondly: Printers
I can't offer much knowledge of the current crop; mine is ~5 years old and going strong, but I think it would qualify as 'extremely modified'. "The basic things I'd mention is that I don't think any printer out there is truly plug-and-play. 3D printers can be finicky beasts, so there will be a lot of tinkering getting started, bunches of failed prints, etc. And then if/when you catch the upgrade bug then there's even more tinkering (but more fun, also!). Once you get things dialed-in they can be pretty reliable." +1. If I were buying/building today I would be looking for these features: Cartesian, CoreXY, enclosable/heatable, absolutely no 'ink-cartridge' proprietary filament, heated print bed, direct non-Bowden extruder, and print cooler. WiFi and flashy control panel are nice extras.

Finally: Software
Slicers: I've used Simplify3D from the beginning, so I don't know how well it compares to Cura or Slic3r, though I've heard good things about both. I use a lot of the advanced features in S3D, particularly the multiple processes per print ability. Knowing your slicer is critical to getting good prints.
CAD: I'm very happy with OpenSCAD, and I like the programming format (see attachment), but I see the need to use something more drawing oriented. I have SolidWorks (student) ($20 for veterans), that I need to learn, but I've heard of a lot of people getting good results with Fusion 360.


NH_Sustainer.JPG
 
Not to rain on your 3D printing parade, but I find that I use my CNC router much more than I do my 3D printer for rocketry. My first choice is CNC router for parts. The last thing I printed for rocketry was a 3D sewing foot for parachutes.

Edward
 
you've gotten sound advice from woferry and vcp already. I currently print mostly with PETG filament. I've found PLA to warp and ABS printing should be done in an enclosed environment with exhaust (exhaust is thought to be carcinogenic). I mostly print non-structural items such as altimeter sleds, switch enclosures, and camera sleds. The z-axis is relatively weak and given temperature & stress bearing restrictions, fins or nose cones may not hold up to mach + flights or descents in which the main parachute didn't fully open. I'd suggest that you visit/join a makelab in your area to learn about 3D priniting, software (e.g. Onshape, Fusion 360, Solid works etc). Many labs have experienced individuals that do training, CAD design, and assist in printing. The latter suggestion may save you time, money and frustration. Finally, printing with carbon fiber hybrid filament may improve stress bearing; however, the filament is more costly and it requires more robust printers.

Fred, L2
member of ICBM
Cambden, S.C.
KG4YGP
 
Checking out the Flashforge Creator Pro - it looks like it checks most of my boxes. Mine is an original Replicator (wood frame, though I've had no frame-related problems). The original Flashforge was a clone of the Replicator. It looks like this current Flashforge has incorporated most of the modifications that I've made to my Replicator. 3-point leveling is great. I'm so satisfied with my Replicator that I have a XYZ Davinci and a Delta-something that sit idle.

These are test print parts for my current project. Most of these bits are at a coarse print and have had little/no finishing effort applied. The widget center rear is a tube marking/alignment guide for the fin position. The main body is a standard 29mm paper tube.
NH test parts.jpg
 
For plastic, my favorite is for most rocket parts is PETG. It's nearly as strong and heat resistant as ABS, has better layer adhesion, doesn't stink as much, and doesn't warp as easy. I don't print it with an enclosure and have good results. My L3 AV-bay was printed from PETG and it worked great. I wouldn't do the fins that way, but for lower stress areas, it's a great way to go. Though I know many do use printed fin cans and such for L1 class rockets, I'm playing with building one, but haven't finished it up yet.

One thing to note, there's not really a set-and-forget printer. The hardware can be great, but the slicer settings vary between filaments, even colors of the same brands. And some parts do better with different settings. Mine is one of the best that way, a Lulzbot Mini, and I'm constantly having to tweak things based on the part and filament I'm using. The hardware has been fine, normal maintenance stuff. But software changes require that I tinker a bit in many cases. I also do small prints with new filament, then destructively test them to make sure I get good layer bonding etc..

For design, I've been liking onshape. It's free for personal use, with the downside that all your stuff is public. Since I don't plan to make money at it, I don't mind. One thing I really like about it is that they have a very nice Android app that I can do real design work in. Most of the others have a view-only or other restrictions. This means I can tinker with designs anytime I have my phone. With one downside, it does need internet access. In practice I don't mind that, but it would be nice if I could run something like it locally for those times I don't have connectivity.

For the higher power levels, things like CNC routing fins makes more sense to me. For LPR/MPR/L1 sport flying, I use the printer for a fair number of things. I've even made bulkheads with charge wells that I have a dozen ground tests on so far with no signs of weakness as a result. I'll likely fly it in the coming year.
 
Another thing I'd add to my checklist would be all metal. Aside from the wooden case, all of the plastic parts in my Replicator have been replaced with metal. I just checked it's odometer: it has printed for over 3000 hours and 11km of filament.

Actually, a plastic carriage is why I haven't tried PETG up to now. As soon as I run out my ABS I'll probably switch.
 
I work with a TARC team and we are 3D printing tail cones and transition sections. The last transition they created had built-in locations for the altimeter and ballast and screwed into the payload section. Creating those threads in CAD was the hardest part. We are printing in ABS with a Makerbot Replicator 2x. What we've learned :

You don't want to get carried away with the 3D printing or you will end up really heavy. I printed the nose cone, launch lugs, and fin can for an Honest John that was built around one section of BT50 for the airframe and a BT20 motor mount. You can do it, but it's a bit heavy and doesn't go that high. Use printing for things that are difficult to make any other way. The TARC kids hated rolling tailcones and hollowing out a balsa transition to accommodate the ballast and altimeter was a chore, so those were obvious places to use the printer.

ABS shrinks which is the source of all the warping issues. We design the part to the desired dimensions, but when we import the STL file into the Makerbot desktop, we scale up by 101% to account for shrinkage. This may vary with the type of ABS, the build plate temperature, etc., but 101% is a good starting point.

You have to build the parts with the axis of rotation pointing up or they will warp to the point of being unsuable.

You can't print something hanging in mid-air. That's obvious when said that way, but it impacts what you can print and things like whether you print your tailcone big end up or little end up. You can print overhangs as long as each layer overlaps the one under it. I've found that a 45 degree slope works, but if you go steeper, the layers start to sag.

A 10-15 second dip in acetone will bond the layers together and make the part stronger, but you must drain the excess acetone out of any crevices or the part will dissolve. This also makes the surface smoother. Sanding followed by a dip in acetone will give a fairly smooth surface.

As far as CAD goes, I'm using SolidWorks, but don't even ask how much that costs. A lot of schools get cheap or free educational licenses. I have a free educational license by virtue of being a member of the Experimental Aircraft Association. I had tried TurboCAD but the cheap versions only do 10 degree resolution when creating the STL file you send to the printer, so things that were supposed to be round really weren't. TurboCAD 21 Pro gave acceptable resolution but was still somewhat awkward to use. Once I found that I could get SolidWorks free, I've used it exclusively. It is so much more intuitive and easy to use.
 
ABS shrinks which is the source of all the warping issues. We design the part to the desired dimensions, but when we import the STL file into the Makerbot desktop, we scale up by 101% to account for shrinkage. This may vary with the type of ABS, the build plate temperature, etc., but 101% is a good starting point.

You have to build the parts with the axis of rotation pointing up or they will warp to the point of being unsuitable.

I am in the fortunate position of using a printer at work (Stratasys 1200es). It is a $25k unit (when we purchased) but does not appear to suffer from either of those problems so far. The software likely deals with the scaling error, if any. I recently printed a transition laying down so there was some extra strength going up the rocket. I guess it might be more noticeable on thinner parts. Mine were for a 4" rocket.
 
PETG
Anything with a good hot end, heated bed & auto-bed leveling (I love my modified Prusa i3 clone w/E3D V6 & BLTouch)
Tinkercad, Fusion 360 (free hobby license), Simplify3D
 
A guy I work with just bought one of these for home. Really good print quality, straight out of the box.
https://www.lightinthebox.com/creal...n-coffee-and-black_p6344041.html?prm=1.1.92.0

Good build volume too! $380 shipped.


What kind of work/prints have you achieved with this printer? The sale is very tempting for a first time 3D printer purchase. What filaments run the best on this printer? I would like to use ABS, but PLA is not out of the question.
 
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All PLA. I’ve never attempted another filament material with either of my printers. If something is structural it’s made on my lathe or CNC router


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All PLA. I&#8217;ve never attempted another filament material with either of my printers. If something is structural it&#8217;s made on my lathe or CNC router


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Do you have a source for filament? The lightinghouse link sells filament, but I'm not sure of pricing. Also, is color based on choice, or the ability to see imperfections etc?

I watched the 20-min review of the CR-10S printer, and I teetering on the edge of hitting the purchase button...
 
I have an opinion, although it isn&#8217;t very nice or helpful. But it is based on my experience & what I&#8217;ve seen & heard. I do think they are cool, and they do have a place. I am no expert, but manage 2 printers at work (Makergear MkII & Fusion3 306). I did the research for the 2nd one, and have read numerous reviews. I&#8217;ve researched all the way up to metal 3D printers (very cool, very $$$$$!!) A lot of what is written below came from a few 3D forums, and I was getting tired of the constant same questions, and the constant same frustrations many had.

First off, it&#8217;s plastic. Most printers will be FDM &#8220;Fused Deposition Modelling&#8221;. It&#8217;s a melted plastic &#8216;string&#8217; that&#8217;s layered upon itself, relying solely on the plastic sticking to itself when it&#8217;s soft. A few complain that they aren&#8217;t getting a smooth finish, like they&#8217;d be getting with the plastic parts of everyday items (those are typically molded parts, not the same thing!) Secondly, the parts are layered plastic (I think I said that), so there isn&#8217;t a lot of strength. When it fails, it&#8217;ll fail along the layer lines. SO, unless you orient the part to have the layer 90° to the stresses, it&#8217;ll eventually break. And, printing it in such an orientation may not be feasible, without adding a tonne of supports. Again, molded / machined parts are one continuous piece, that&#8217;s where the strength comes in.. if the part isn&#8217;t going take any stress, and you&#8217;re OK with a somewhat rough finish, and a possible 4-8 hour print time along with the design time, then it has a place. And, for what we want, weight of the plastic can also be a factor.

Thirdly, the bigger complaint I hear, is the designing of the parts. I&#8217;ve been doing CAD & mechanical design for a long time. (Creo Currently, if you need to ask..) Learning 3D CAD design has a learning curve, and can be very steep for some. There is a bit of an art to modelling a part in the virtual 3D land.. And it takes time to model something well.. Too many times I hear the question that someone wants to know how to make a 2D PDF &#8220;picture&#8221; into a 3D model.. No, it&#8217;s not just a couple of keystrokes..

We use Simplify 3D as it was highly recommended. (And it comes bundled with the Fusin 3 printer). It has a lot of control, and I&#8217;m still learning / playing with the settings to get it right. (The Fusion 3 came with pre-set printer / material profiles, the Makergear is a hit & miss approach). It is something else you&#8217;ll need to learn play with, and dial in to get consistent & quality prints.
We use PLA. It works, it does what we want, it&#8217;s fairly hassle free. But it does have its own quirks. We are looking at PET-G, and have talked ABS (and have a budget for a vent hood).. Store your filament properly. PLA left out / on the printer absorbs water, and gets brittle. Absorbed water & and dust can impeded a print. PLA can also be finicky to glue to other parts, as well as to itself.

We are looking at a 3rd printer, or were. We, the department, feel the monies are better spent on a CNC mill. The printers are cool for &#8216;toys&#8217; and prototypes, but a properly milled part is better for prototyping, testing, manipulating, etc..

Bottom line is, do your research! I feel spending anything less that $1000 will get you garbage. (Although the prices are coming down, I might be right in saying &#8216;anything less than $600&#8217; at this point..) Get one with a heated bed, period. Our filament supplier recommends their PLA be printed at ~ 215°C with a bed of 60-80°C. Expect to tinker with it, you&#8217;ll need to play with it, and do a few prints to get the settings dialed in for what you want. Different filaments (different colours even) will require slightly different settings. Some people are driven mad by the &#8216;singing&#8217; of the machine, the stepper motors whirring & squeaking as it prints, and the hum of the fans turning on & off.. They aren&#8217;t quiet. Whatever design software you get will take time to learn & design with. They all basically work the same, and model the same, but it can be a daunting task if you want to make a &#8216;1 into 4&#8217; tube transition as your first attempt. (Making a simple Ogive type nosecone for some is a daunting task)

Join a maker space, you&#8217;ll get a tonne of help, and they will probably have a better quality. Make your parts from wood & other materials. It&#8217;ll usually result in stronger & lighter parts in about the same time (or half) than designing & printing them out. Some schools & libraries now have them as well. Again, help, and the parts, with no initial $$$ outlay.

And remember, they are cool, and you want to print a few parts. But after the dozen or so parts, and the 2 rolls of filament, and the replaced head, and the re-zeroed bed.. then what..
 
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