3D Printing Exploring 3D printing, questions

[c0c0m0ke]

I am Exploring 3D printing., and there is a lot to know, and I know very little. I don't know where to begin.

Back in November & December, I met a flyer who constructed a non-cylindrical rocket, with 5 fins. Imagine 5 long isosceles triangles bound together on the top half and 5 shorter isosceles triangles on the bottom half, with 5 fins sticking out. The bottom is squared of and the rocket motor sticks out about .5" The center tube is the motor mount, and a channel for the launch lug lies adjacent and parallel to the center tube. Entrance and exit holes are beveled for easy rod insertion access. The fins are made of basswood, and I think they are TTW.

The flyer tells me he started with a dodecahedron, Playing with the sides in some sort of CAD program (I assume), he shaped it to what he thought was suitably aerodynamically acceptable. He says his printer uses a special type of printing material that allows him to raise the temperature to make the material foam as it prints. Doing this also increases the speed at which he can print, and it reduces the weight, because it is expanded, yet still durable. He calls the rocket, "Crystal" as it resembles a natural forming crystal.

He allowed me to pick it up. I have hefted 3D fin cans in the past and they felt heavy. This rocket which is 95% 3D printed, it seems very light for a 20" tall rocket.

Do all 3D printing machines have this capability or is it some sort of special feature? What kind of material would have this capability? I am under the impression it is unique. How does one determine this capability when shopping for 3D printers and printing material? I am also under the impression that CAD software is very expensive. Is it easy to integrate CAD with 3D printing software? Am I asking the right questions?

I look forward to all comments and I thank you for your input and patience.

c0c0m0ke

 

[Kelly]

The material is called LW-PLA, or lightweight PLA. There is a variety that foams as it comes out the nozzle, and another variety that is pre-foamed. The latter type, any FDM (filament) printer should be able to handle. The former type, you need to be able to heat the material to about 250°C to get the foaming action, but I think that is within the realm of any FDM printer. I've used this a lot, it's really nice material. Lightweight, and it forms a material with the feel of balsa - very sandable.
There are many CAD programs that are free to use, others that are very affordable. Just about any 3D CAD software should be able to export an STL file, which is general the starting point for 3D printing - you feed that file into another (free) piece of software (called a slicer) to get the file you feed to the printer.

It's pretty easy, and very useful - jump in!

 

[thzero]

Pushing the bounds on Bowden tube based FDM printers.

That PLA just might melt in the sun.

 

[cwbullet]

Pushing the bounds on Bowden tube based FDM printers.

That PLA just might melt in the sun.

Very true.

To the OP, practice and learn on generic PLA and PETG and then try your hand with more exotic or expensive filaments.

 

[Huxter]

https://www.tinkercad.com/ is a free cad program. It's very basic, but you get the idea of creating 3d objects. Watch some youtube videos to come up to speed. Then you'll be able to decide on a better cad program - like Fusion 360 maybe?

You would love a 3d printer! You feel like you never have to buy any thing again (save more 3d printers!)

 

[c0c0m0ke]

The material is called LW-PLA, or lightweight PLA. There is a variety that foams as it comes out the nozzle, and another variety that is pre-foamed. The latter type, any FDM (filament) printer should be able to handle. The former type, you need to be able to heat the material to about 250°C to get the foaming action, but I think that is within the realm of any FDM printer. I've used this a lot, it's really nice material. Lightweight, and it forms a material with the feel of balsa - very sandable.
There are many CAD programs that are free to use, others that are very affordable. Just about any 3D CAD software should be able to export an STL file, which is general the starting point for 3D printing - you feed that file into another (free) piece of software (called a slicer) to get the file you feed to the printer.

It's pretty easy, and very useful - jump in!

Thank you for this information! I don't know how soon I will get to it. But I will try to soon.

c0c0m0ke

 

[BlackBrant2]

Thank you for this information! I don't know how soon I will get to it. But I will try to soon.

c0c0m0ke

I am also interested in a 3d printer, will PLA work for rocketry or should I be looking at another filament like abs?

John

 

[Bravo52]

I am also interested in a 3d printer, will PLA work for rocketry or should I be looking at another filament like abs?

John

PLA works great. You just have to consider it's properties when deciding where to use it. I've printed and flown a few PLA rockets and have had no problems. PLA is remarkably strong and resilient. The only issue I've had was soot on the tail and since I didn't paint the rocket, it stained the PLA by getting in the .3mm layer lines. I've never had one melt...only because I don't generally leave them in a hot car or laying out in the sun. I use a short paper tube between the MM and BT.

ABS is great and is a little more finicky when printing, but once you get it dialed in, it's almost no different than PLA to work with. I buy my ABS off of Amazon and just wait for a sale and can get it as cheap or cheaper than some PLA.

 

[Azimath]

It was a remarkable coincidence that today I finally had an opportunity to get out to the field, and happened to come across c0c0m0ke in person as I walked back from recovering the rocket.
Re: the sun, I did have some problems on a sunny afternoon when letting paint on the first version dry, because that one had printed fins, which warped noticably. I fixed them pretty easily by printing a sort of form then using a heat gun on low to set them back in place. Version 2 and 3 have balsa fins, and I haven't had problems with the main body in the sun. I also launch in the first round of the day, which helps, but is mostly for my own sake. ABS would solve the problem pretty handily, some ABS parts I did for a car dashboard have had no problem when parked in the sun.
The rocket in question was modeled in Fusion 360 then everything was printed except the fins which were printed from wood, and the clear parts of the nosecone that were lasered from acrylic. All the printed parts were done on my Bambu X1C.
The lower portion of the body was done with an active foaming PLA from eSun, printed at it's maximum ~200% foaming ratio. My gram scale agrees with the expected density reasonably well.
Initially I had printed the whole body out of regular PLA, but switched to printing the rear portion out of LW PLA because the aerodynamics were even less conducive to stability than I had expected in my openrocket file, so between that and a bunch of lead in the nose the CG is much further forward than the first version.
I left the front half of the body in regular PLA since it wasn't doing much to the CG, and the LW PLA is a little soft and makes a big mess in my printer. This part held up pretty well when the shock cord detached from the rear and the body drove itself a few inches into the dirt.
The avionics bay/nose coupler is in regular PLA for the reasons above, and since it prints cleaner I printed in some threads so the nose could be screwed on by hand after powering up the altimeter/tracker.
The frame around the nose, the launch lugs, and motor mount + retaining nut/boat tail were all printed in PC. In the nosecone frame and launch lugs this is for it's high strength, in the motor facing parts this is for heat resistance. I did add an extra couple walls and a couple hundreths of extra space around the motor since PC wasn't enough to stop it from softening around a G80 in a previous rocket. So far no further issues with it, but I did design it as a replacable part that screws into the bottom of the LW PLA body.
On the first iteration I printed the fins in the same part as the lower body. I had thought the size limitations this imposed were acceptable but that wasn't the case, and trying to print a taper in the trailing edge like that was unpleasant at best. It might work on a less unconventional rocket that doesn't need the extra fin span. Instead a simple rectangular slot is printed in the body and the laser cut fins are epoxied in place.
The outstanding issue at the moment are that the shock cord mount was damaged due to a tangle on deployment, I'll adjust my packing and add a PC insert to give that part more strength. The Av bay could use a redesign to keep the wires neater, since having a gopro in the nose when I close it up tends to twist them a little, but they usually just slide against the gopro rather than catching and becoming a real problem.

 

[ZeroGPrints]

It was a remarkable coincidence that today I finally had an opportunity to get out to the field, and happened to come across c0c0m0ke in person as I walked back from recovering the rocket.
Re: the sun, I did have some problems on a sunny afternoon when letting paint on the first version dry, because that one had printed fins, which warped noticably. I fixed them pretty easily by printing a sort of form then using a heat gun on low to set them back in place. Version 2 and 3 have balsa fins, and I haven't had problems with the main body in the sun. I also launch in the first round of the day, which helps, but is mostly for my own sake. ABS would solve the problem pretty handily, some ABS parts I did for a car dashboard have had no problem when parked in the sun.
The rocket in question was modeled in Fusion 360 then everything was printed except the fins which were printed from wood, and the clear parts of the nosecone that were lasered from acrylic. All the printed parts were done on my Bambu X1C.
The lower portion of the body was done with an active foaming PLA from eSun, printed at it's maximum ~200% foaming ratio. My gram scale agrees with the expected density reasonably well.
Initially I had printed the whole body out of regular PLA, but switched to printing the rear portion out of LW PLA because the aerodynamics were even less conducive to stability than I had expected in my openrocket file, so between that and a bunch of lead in the nose the CG is much further forward than the first version.
I left the front half of the body in regular PLA since it wasn't doing much to the CG, and the LW PLA is a little soft and makes a big mess in my printer. This part held up pretty well when the shock cord detached from the rear and the body drove itself a few inches into the dirt.
The avionics bay/nose coupler is in regular PLA for the reasons above, and since it prints cleaner I printed in some threads so the nose could be screwed on by hand after powering up the altimeter/tracker.
The frame around the nose, the launch lugs, and motor mount + retaining nut/boat tail were all printed in PC. In the nosecone frame and launch lugs this is for it's high strength, in the motor facing parts this is for heat resistance. I did add an extra couple walls and a couple hundreths of extra space around the motor since PC wasn't enough to stop it from softening around a G80 in a previous rocket. So far no further issues with it, but I did design it as a replacable part that screws into the bottom of the LW PLA body.
On the first iteration I printed the fins in the same part as the lower body. I had thought the size limitations this imposed were acceptable but that wasn't the case, and trying to print a taper in the trailing edge like that was unpleasant at best. It might work on a less unconventional rocket that doesn't need the extra fin span. Instead a simple rectangular slot is printed in the body and the laser cut fins are epoxied in place.
The outstanding issue at the moment are that the shock cord mount was damaged due to a tangle on deployment, I'll adjust my packing and add a PC insert to give that part more strength. The Av bay could use a redesign to keep the wires neater, since having a gopro in the nose when I close it up tends to twist them a little, but they usually just slide against the gopro rather than catching and becoming a real problem.

Have you tried using bambu lab ASA-aero? it looks interesting as a foaming filament.

 

[cwbullet]

He allowed me to pick it up. I have hefted 3D fin cans in the past and they felt heavy. This rocket which is 95% 3D printed, it seems very light for a 20" tall rocket.

Those new to 3D printing often add too much infill. Adding 4-6 external parameters can reduce weight and allow a lower weight and lower infill.