3D Printer File Formats

Im using Chitubox and am just learning. The program saves the stl files as .ctb files. seems to work well with my Ellegoo Mars 3

I use .stl files but you can use .obj files.

The print quality is not dependent on the file type that I understand.

It's dependent on your printer's resolution capability such as the layer thickness.

The higher the resolution, the more detailed your object will be. There are three dimensions to consider: the two planar 2D dimensions (X and Y) and the Z dimension that makes it 3D printing.

Since 3D printers produce parts in 3 dimensions, you will have to consider at least two numbers: the minimum feature size of the XY plane and the Z-axis resolution (layer thickness or layer height). The Z-axis resolution is easily determined and therefore widely reported even though it is less related to print quality and surface finish. The more important XY resolution (minimum feature size) is measured via microscopic imaging and is therefore not always found in spec sheets.

The FormLabs 3 layer thickness is 25 – 300 microns (.001 – .012 in.).

Elegoo Mars 3 Layer Thickness: 10 -200 microns  (.0004 - .008 in)

So from this spec, it looks like the Elegoo M3 has better resolution that the FL.  However, you need to look at the laser spot size and xY resolution too.

Bill,  Ray turned me on to this... HUGE ...quality improvement for the Ender 3 Pro & CR10.  They have other heads for other FDM machines.

https://store.micro-swiss.com/...irect-drive-extruder

For FDM, the resolution is dependent on tip diameter, layer thickness and the resolution of the definition file.   No matter the system, fine detail equals more print time.  .stl is a best fit approximation based on tolerance settings when it is created.  Flat surfaces can be exact, no matter the tolerance, but holes and non-flat surfaces are heavily dependent on the tolerance when the file was created.  Too loose and holes and curves look like stop signs.   Adding more precision to the .stl file when it is beyond the ability of the printer resolution is useless.  Just more data to process.   .stl is the least common denominator for a shape, which means there is no other infomation to help define the part.

Add to this Intol vs. Outtol when a hole is made.  Quite simply intol as all the "extra" or stop sign effect on the inside.  Outtol would have all the extra making the hole "bigger" at the stop sign corners.   You are only asked for the tolerance, not what is intol vs. outtol when making .stl files.

.amf is .stl plus.  With the ability to infer circular/curve data that would adapt as it is scaled up and down.  Along with other data for process needs.  Colors are supported.   Your slicer software has to be able to handle all the extras. 

Materials and design of the part also effects the result.  I find small radii vs sharp edges may help many areas.  There are a myriad of things that effect the final part during printing.  

The liquid based systems can do finer detail based on laser beam size, but they are just as finicky along with post process cleaning and curing.  It has been in development for 35 years.   I think we had machine 003 when it was invented.  A gallon of liquid at the time was around $300.   It was called "rapid prototyping" then.

3D printing is fun, inventive and an industry in it's youth.   I think 3D printing still has a long learning curve to maturity.   

The liquid based systems can do finer detail based on laser beam size, but they are just as finicky along with post process cleaning and curing.

My 3D resin printer is not "FINICKY" and post processing is simple. The issue I have found with my  tube-printer is heated material flow that CAN compromise resolution and detail.

@AlanRail and @VHubbard very interesting responses! I feel like you two condensed a lot of articles and tutorials into two concise posts haha My biggest take away is the STL (with adjusted precision/tolerance) is probably sufficient for what we do and probably very sufficient for an FDM printer like I have. I ended up adjusting the settings for STL export so that circles look smooth on screen and coming off the printer. I don't know how all programs do it but the Solidworks for Makers has a little circle and you can watch it go from smooth to stop sign as you lower the settings. This has worked for me so far. I bet I'm exporting STLs that are more precise than my printer can handle but this works for me at the moment because I'm still working on getting structures made. I'll fine tune after the fact.

@Dennis-LaRock how tough is the upgrade? Just bolt on and go? Or will I have to fuss with the slicer settings? I'm quite pleased with most of my prints despite being a bowden FDM printer so I'm always concerned about making changes.

Bill,

For me  (Ender3 Pro) the install  was pretty straightforward... just followed the instructions.  Thereafter, maybe a couple of hours monkeying around with retraction, speed, heat etc., then, presto no more s~tr~ing~s and a much smoother finish.  Still not resin... but, pretty darned good.  I mean look at Ray's finished prints... AWESOME (of course he has a Pursa) but, his son did the upgrade with the CR10.

OH!!!  Read the comments on the link I posted... I think some of the guys have the CR10.  Also, YouTube vids... I found both helpful.

I did a lot of FDM printing, resolution will always be a problem. You can go to a very fine nozzle and low layer thickness and then hope all goes well over the next couple of days. I switched to resin printers, a HUGE difference. The first one I got (which is fantastic) is a Creality 002R, they have brought out a couple of models since, but this guy is under $200. Resin runs $35 a liter, and you will get a lot of parts from one bottle. A little messy, you have to solvent clean and post cure with UV light (or put out in the sun for an hour or two). but we are talking 50 micron resolution. You'll never get that on an FDM printer. I started with the CR10, which has a large 12 by 12 by 15 inch print envelope, did a lot of parts that required a lot of sanding and filling. Newest printer (and a little more finicky) is an Anycubic MonoX 4K version. does 5 by 8 by almost 10 inches, pretty good for O, I'm doing standard gauge, so splicing parts.

The standard gauge Zephyr below has a 3d printed nose and engine blister on top. about 4 inches wide and 12 inches long printed parts.

There are ways to reduce the faceting of the STL, I use Meshmixer. Some CAD programs do a better job than others converting solid models to STL's.

Jim

@Dennis-LaRock well that's good to know! Maybe I'll jump on it then! I'm pleased with my layer lines at the moment but I'll welcome an improvement.

@Jim Waterman I would have assumed the nose on that Zephyr was stock just from the photo. It looks great! I was curious about Creality's resin printers. I beefed up my CR10S Printer and I'm quite happy with it. I wasn't sure if the resin printers could be upgraded in similar ways.

I know this is a model railroading forum but this sharing of experience/know how has been really great. Hopefully OGR becomes the place for model railroad 3D printing.

Wayback when? I built a MakerBot tube printer. Disappointed with the quality, I kept buying MB upgrades. . . still not happy.

My resin printer prints the detail and surface quality that works for me.

The other resin printers also produce quality prints.

I am just happy that more modelers are realizing that an xacto knife, drill press, band saw and sanding paper are NOT the end-all to making quality detailed models.

I think scratch building and printing are an outstanding combo. I would suspect that using both together removes any hurdles you could imagine in terms of structures. What couldn't be scratch built could be printed and scratch building can beat printing certain parts.

There is a wealth of 3D information in this topis, thanks to all contributors. I am slowly learning what works and what likely won't. I have used an Elegoo Mars Pro resin printer for the last 2 years and Lots of stuff has been printed on it. But I have kind of outgrown it at this point.

I would like to get a replacement with a bigger platen. What would be a good step up, particularly in the Elegoo line?

I also just switched over to water washable resin about 2 weeks ago; what a GIANT leap forward that was. No more messing with IPA. Just warm soapy water and you are done. Not to mention the reduced fire hazard, and way less environmental impact. All good.

Rod

I want to print full size shells and larger freight cars like the USN Helium Car I designed. So I looking to obtain a FormLabs 3L printer to compliment my FL3 printer.

The cost is not cheap. It's the same cost as Five (5) Lionel top line Steam Engines!

@Rod Stewart posted:

There is a wealth of 3D information in this topis, thanks to all contributors. I am slowly learning what works and what likely won't. I have used an Elegoo Mars Pro resin printer for the last 2 years and Lots of stuff has been printed on it. But I have kind of outgrown it at this point.

I would like to get a replacement with a bigger platen. What would be a good step up, particularly in the Elegoo line?

The Elegoo Saturn 2 would be a nice upgrade, currently $550 preordered. I've got the Jupiter, if you check the Jupiter group on facebook there are people selling their Kickstarter Jupiters for less than the pre-order Jupiter price (but for a lot more than they paid for them).

@AlanRail posted:

I want to print full size shells and larger freight cars like the USN Helium Car I designed. So I looking to obtain a FormLabs 3L printer to compliment my FL3 printer.

The cost is not cheap. It's the same cost as Five (5) Lionel top line Steam Engines!

Alan could you print the helium car in two halves maybe standing on end, and join them up to make a complete car body?

Rod

Rod

yes, I could print it in two very smooth plastic-like halves. I could likely hide the seams. . . somewhat.

I have made several larger models that came in three pieces that have sea.ms BUT would you like or buy a Lionel or MTH freight car with a mid-SEAM?

Now I know that I am not Lionel or MTH but still if I produce a car there is a bar that I feel I must meet.

There is another Helium car made by another forum-ite that is printed with seams and has less plastic-like surfaces. It is not like the one I will be printing. It's still a fine and reasonably acceptable model of a helium car.

However, MY interest is printing that car to be as close as I can to the hard-to-find and costly brass model.

@AlanRail posted:

Rod

yes, I could print it in two very smooth plastic-like halves. I could likely hide the seams. . . somewhat.

I have made several larger models that came in three pieces that have sea.ms BUT would you like or buy a Lionel or MTH freight car with a mid-SEAM?

Now I know that I am not Lionel or MTH but still if I produce a car there is a bar that I feel I must meet.

There is another Helium car made by another forum-ite that is printed with seams and has less plastic-like surfaces. It is not like the one I will be printing. It's still a fine and reasonably acceptable model of a helium car.

However, MY interest is printing that car to be as close as I can to the hard-to-find and costly brass model.

I do a lot of printing in Standard Gauge, both finished parts as well as casting patterns. My resin printer will only do about 9.5 inches of height (which becomes length of the model), so I often have to splice together 2 parts. Zap a gap super glue works awesome, then a pad sander across the joint, fill as necessary, hand wet sand, high fill primer, then  top coat.

Jim

@Magicland posted:

The Elegoo Saturn 2 would be a nice upgrade, currently $550 preordered. I've got the Jupiter, if you check the Jupiter group on facebook there are people selling their Kickstarter Jupiters for less than the pre-order Jupiter price (but for a lot more than they paid for them).

I have been checking out the Saturn 2 and it looks like a nice step up for the price. 123 x 219 x 250 build space and 8K resolution. I would likely order it with the spare resin vat because having a second one is really handy. Only hitch is it wont be shipping until August, which could easily slip into Sept or who knows when?

OTOH I could get the original Saturn within 2 days and its a little cheaper, though not much. Only 4K resolution too. Hmmmm??

Rod

@AlanRail posted:

Rod

yes, I could print it in two very smooth plastic-like halves. I could likely hide the seams. . . somewhat.

I have made several larger models that came in three pieces that have sea.ms BUT would you like or buy a Lionel or MTH freight car with a mid-SEAM?

Now I know that I am not Lionel or MTH but still if I produce a car there is a bar that I feel I must meet.

There is another Helium car made by another forum-ite that is printed with seams and has less plastic-like surfaces. It is not like the one I will be printing. It's still a fine and reasonably acceptable model of a helium car.

However, MY interest is printing that car to be as close as I can to the hard-to-find and costly brass model.

Alan; sounds like you have covered all bases for your project. If you have a minor center seam, any chance you could use any of Jim Waterman's ideas? Or maybe disguise the seam with a surface ladder like a tank car? Or maybe an electrical conduit or something similar?

Rod