newbie in 3D printing with a requirement for smooth surface

[prg281]

Hi Everybody,

I'm a newbie in 3D printing with a specific requirement for a smooth surface (need a laminar flow in the boundary layer instead of turbulence)

I'm interested in the Max v2 but I'd like your recommendation based on my goals: I need to print a tube of 200mm in diameter, at least 150mm height (preferably taller), 6mm wall width, with 4 helices inside the tube (each helix having a width and a height of 20mm), and the whole thing with a surface as smooth as possible (cf. the laminar flow note above).
I am trying to figure out which printer I should use and with which nozzle, filament size, filament material, print settings, etc...
Printing accuracy, very smooth surface, and build size are my primary requirements; I don't mind if printing takes a long time.

I contacted SeeMe support but the responses were slightly different than what I expected:
"The printer comes stock with a .5mm nozzle and I would recommend using that with .2mm layer heights for a high quality resolution. The filament required is 1.75mm diameter, and with a part of this size I would say that you would definitely want to use PLA. We have print settings on our website available for download which would more than get you started."
"If it were me then I would use PLA and start with a .5mm nozzle. Basically I would use the stock settings provided on our site with temps at 60C for the bed and 210C for the hot end."

For example, it seems that some work has been done on the matter with some good results using ABS, a .35mm layer height and acetone bath as per some other discussions I found on the SeeMeCNC forum (http://www.3ders.org/articles/20130226- ... vapor.html).

How could I best combine both recommendations considering that they use different materials?
Should I use:
.5mm nozzle, .2mm layer heights, ABS filament 1.75mm diameter, Max v2 stock settings with temps at 60C for the bed and 210C for the hot end?

Issues / follow-up questions:
1) why did SeeMe support recommend PLA for a part of this size?
2) temperature settings listed above are for PLA; should I use other settings for ABS?
3) draft is a recurring issue reported on the SeeMeCNC forums and the v2 is wide open; should I consider boxing 2 or 3 sides of the v2 to maintain a more controlled environment?
4) some users noticed an adverse effect of humidity on filament which I plan on mitigating by using high quality filament as soon as I receive it (living in Tampa FL, humidity is omnipresent); are there best practices I should follow to prevent filament humidity from impacting by smooth surface requirement?

What else should I consider?

Thanks for your guidance!

[DavidF]

The rostock is a very capable machine.
Filaments vary greatly when it comes to getting high quality prints. I print mostly in pla at a .125 mm layer height with temps any where between 180 and 195C.
Some filaments I can push to a .08 layer height, others don't like to print under .15 mm.
This component that you are making, does it need to withstand any mechanical force or temps??

[Polygonhell]

They recommend PLA for a large part, because the warping forces for large ABS prints makes them frustrating to say the least, doesn't matter which printer you are using. If the pipe has no end cap, you would probably get away printing it in ABS because the ammount of cross sectional area is small enough to get away with it.
For ABS you want to be in the 230-240 range temperature wise, but filament varies.
Humidity has a negligible effect IME, it can affect printing to some extent, but I live in WA, and I've printed with PLA that's been sitting out in my garage for over a year without any real issues.
With a 0.5mm nozzle you can usually get down in the 0.1mm layer height range, much below that, you run into issues and really need to drop To a smaller nozzle.
One last comment, there is sort of an art form to printing, and you will probably struggle to get the finish you want without a lot of experimentation, if your expecting to just put it together and print the part, you probably won't be very happy with the results.

[teoman]

These are common to more or less all printers that can print in this size.

You will have to look at acetone vapour polishing.

Have a look at this. It will give you an idea.
On youtube look for doodaddoes. Cant copy paste from phone.

[Captain Starfish]

I love the versatility of these machines but they do have limits and all of the layer based printer technologies will leave you with strata lines. You might get away with a super fine print in ABS followed by a vapour bath though, just to take the lines off.

Get a smaller nozzle with your kit (as well as the standard size). With the 0.3mm nozzle I've printed 0.08mm layer height to a level of finish I could almost use it as a mould for casting. Almost. One thing to bear in mind is that overhangs of more than about 60º tend to distort so those helices may need support underneath them. And support structure nearly always leads to a rough interface where the support meets the part.

:edit: heh. Beaten by teoman.

[PartDaddy]

Captain Starfish and all the replies are all excellent information / advice. FFF (fused filament fabrication) layer printing has limits.

Here's some more information from the industrial (injection molding) side of the tracks. Bare with me, this ties into layer height and surface finish limits of FFF. When you make an injection mold, you vent it. Venting let's air escape the cavity of the mold. The vent is cut 0.0008" deep. This lets out the air in the runner and cavities, but not the plastic. For PP, ABS and PE we'd vent .0008". Under more than 500 to 1000 psi of injection pressure, the plastics won't fit through the gap. So, when DavidF approaches 0.08mm (.003") layer, on a low pressure extruder, we reach a limit of what these little printers can do. We'll loose consistency of extrusion, so you back off some, and you have a normal operating limit. A 0.1mm layer is a limit, even though our steppers step at 0.02"mm increments. Captain Starfish recommend the 0.35mm dia nozzle, and so do I. I also recommend setting your extrusion width to 0.3mm. You might want to print 4 or 5 perimeters, infill probably 20 ro 30 percent. Depends on your part geometry.

Since you have a tube shape (open both ends) and probably symmetrical helices, your vortex tube might print out of ABS. Then vapor polish (which I still haven't done) for a smooth surface. I still have not heard of anyway to finish PLA this smooth, other than probably painting, but I haven't painted PLA either. I just asked Oly, and an acrylic paint should finish a PLA part with a smooth finish.

[DavidF]

@PartDaddy, you can vapor polish some pla's with ethyl acitate the same way you do abs parts. Unfortunately it does not work with the color fabb filaments but does work with the see me filaments. the protopasta gave the best results for vapor polishing, but I heard they are reformulationg?? Translucent pla's dont seem to vapor polish no matter who makes them. Maybe someone with a chemical background will chime in and provide some insight as to what it is in thier compositions that allows for vapor polishing...

[teoman]

I think that almost all that can be said has been said.

Would you min posting pictures or renderings of your intended parts? We may be able to come up with other ways for you.

Also what type of gas or fluid do you intend flowing through? And why do you need laminar flow?

If you are at liberty to disclose then we mught come up with more solutions.