3D Printing Tips and Techniques

[robunos]

Otherwise known as the 'pick Frank3K's brains' thread, as it says in the title, this is a thread for asking questions about, and exchanging information on the techniques of using 3D printers, especially for newbies like me . . .   
I'll be posting some questions in due course, but for now, here's a link to a post about 3D resin printing made by Frank previously :-


https://beyondthesprues.com/Forum/index.php?topic=8451.0


Would it be too much to make this thread sticky ?


cheers,
Robin.

[Frank3k]

Overview

The most popular 3D resin printers are made by Elegoo, Anycubic and EPAX. These printers (and several others) use a common controller made by Chitu Systems. They work by shining a 405nm UV light through an LCD screen into a vat of UV sensitive resin.

The vat has a film of FEP, tautly stretched  across the bottom. The FEP is in direct contact with the LCD screen, so images displayed on the LCD are transferred to the resin without distortion.
When an object is printed, very thin slices (10-100 microns thick, typically 50 microns) are displayed in sequence on the LCD.

• At the start of the printing process, a metal plate (the build plate) comes to within a layer thickness of the FEP
• The LCD displays a slice and the UV light is turned on for a few seconds.
• Under ideal conditions, the cured resin sticks to the build plate (and not the FEP.) The UV is turned off and the build plate moves up another layer height
• A new slice is displayed, the UV light is turned on for a few seconds, which should cause the resin to cure to the previously printed layer... and so on, until the object is printed.

, 



Before an object can be printed, it has to be oriented on the build plate to minimize overhangs and excessive force on the FEP (which is thin and relatively delicate). The object will also need to be supported and finally the object and its supports have to be sliced into layers.

Slicing and Verification
There's software to slice your 3D file. Chitubox is the standard slicer program. There are others, like Lychee and PrusaSlicer.

The slicer program will slice your 3D object into cross-sections spaced by the layer thickness you've selected (10-100 microns) and will produce a file for the printer chosen. In a perfect world, you put this file on a USB stick, take it to the printer, and the object prints. Unfortunately, without doing a file verification check chances are good that parts of the model will not print properly and the cured bits will float in the uncured resin. This is a bad thing; cured resin can puncture the FEP which in turn can cause the resin to leak out of the vat, making a mess out of the printer or worse, leaking under or into the printer.

There are several ways of verifying a file: via manually inspection, prayer (never works) or by using a program like UVTools

I've settled on PrusaSlicer and Chitubox as my slicing programs and UVTools as the verification program. UVTools has printer settings to import into PrusaSlicer to allow it to produce slice files for non-Prusa printers.

Design Software
Unless you're downloading and printing other people's 3D files from Thingiverse or similar repositories, you'll want to create the 3D objects on your own. This is a whole different universe with a learning curve, often steep.

Blender This is a free program and can be used for 3D animations as well as static, 3D objects. It use to have a very confusing interface and steep learning curve, but it's greatly improved in the last few years. The Blender organization has tutorials, but they're not great; find a beginner's series on Youtube and follow it.

Fusion 360 Free for personal/hobbyist use.

Rhino 3D Not free, but they have a 30 day demo. This is what I've used over the years.

Meshmixer This is more of a 3D mesh editing tool.

Netfabb standard. This program was bought by Autodesk and is free. It will check and fix your 3D object for printability. Then you slice it.

3DBuilder - comes with Microsoft Windows 10. It will also let you check and fix 3D models and works as well as Netfabb

There's also Sketchup... but it doesn't do a great job at creating printable 3D objects.

Resins
There's a wide variety of resins; soft and squishy, ABS-like, clear or translucent, resin that can be tapped and machined (without shattering) and even dental resins. Most resins are brittle (as brittle or more so than the common resin used in resin kits)
Many "Clear" resins usually aren't - they can yellow over time when exposed to UV, even after they're fully cured.
Elegoo and AnyCubic sell a a wide variety, including plant based and water washable resins. Siraya Tech makes some of the best resin around and they're my favorite resin manufacturers .

Resin exposure and test
All resin manufacturers will list recommended exposures for their resins and for different printers, but it's a good idea to dial in the best exposure. There's the Resin exposure finder, which I find difficult to interpret at times.
The Amerlabs town will test the limits of the printer.

Other sources for help or instruction

Both reddit groups are very helpful:
https://www.reddit.com/r/AnycubicPhoton/
https://www.reddit.com/r/ElegooMars/

These two Youtube channels are also very helpful:
https://www.youtube.com/c/3DPrintFarm
3D Printing Pro

I avoid "Uncle Jessy"'s channel - I haven't found his ideas to be helpful or useful.

[Buzzbomb]

Excellent Frank, great overview.

Personally I still use the original type 3D FDM printer (Up 3D Plus) with the spools of ABS or PLA plastic. For actual models, these are now terribly passe as the build texture is awfully hard to get rid of. But they still have a place.
Typically I am using the printer more and  more for producing gadgets, where detail texture is not important.
As described by Frank, using available software and fairly simple shapes enable you to produce your own stuff.

Having a drawer section full of collets from various tools rattling around, led me to design the Collet Holder in 3D Builder provided free as part of Windows 10
Simple cube shape sized to fit the drawer section, then other shapes were used to remove parts of the shape, to leave the finished item



Using this software, it is also possible to edit other models from elsewhere, such as thingiverse to suit your own needs.
This Airbrush holder was modified to change the angle of the holders to suit my workshop, buy cutting all off and keeping one. Get the position right then simply copy/paste and move into position. Again using 3D Builder in Windows 10


Really the possibilities are endless, but the key is have a go at designing your own stuff, that is where the satisfaction lies

[Frank3k]

FDM printers still have a place in modelling, especially if it's capable of printing in ABS. You can use Acetone vapors (or just Acetone on a rag) to smooth out the surface. It will obliterate most details, but for things like wings, frames and hulls (ships or planes) etc., they're very handy.

Plus as Brian said, they're really handy for making non-model "things". I'm working on n LED strip and battery holder for my Donegal visor.

[robunos]

Thanks, Frank, for the useful post, a lot of good information there.
@Buzzbomb, I made a few simple tools myself, designed them with Tinkercad, then had them printed by Shapeways.
A set of small squares, AFAIK you can't buy them this small . . .





a centre finder for marking the axle holes in replacement cast resin wheels,





and finally a 'Square Checker', for making sure eg. ARV hull parts are square to each other, also tailplanes and fins.





cheers,
Robin.

[robunos]

Okay, so my first question.
Where is best to site a 3D printer, both in terms of position in the room, for access, ventilation, etc. and what it stands on, furniture wise.
The Elegoo manual, I have a Mars 2 Pro, is less than useful here, it mentions that the printer should not be subjected to 'shaking', I assume that means vibration, and I also see that the unit has levelling feet. I also assume therefore, that the printer has to be set level horizontally, in order to print properly.


cheers,
Robin.

[Buzzbomb]

Okay, so my first question.
Where is best to site a 3D printer, both in terms of position in the room, for access, ventilation, etc. and what it stands on, furniture wise.
The Elegoo manual, I have a Mars 2 Pro, is less than useful here, it mentions that the printer should not be subjected to 'shaking', I assume that means vibration, and I also see that the unit has levelling feet. I also assume therefore, that the printer has to be set level horizontally, in order to print properly.
cheers,
Robin.

No clear direct answer from my point of view, but you are correct about being level as a base starting point. Most printers have a leveling procedure as part of the manual. FDM printers also relied on heat, so advice was to keep out of draughts or in a box to keep a stable environment. Where it goes will typically rely on space. Resin printers for instance, seem to need two units, the printer and the washing/curing station for optimum use. Washing can be done elsewhere likewise, curing can be done outside, but I have heard mixed reports on the efficiency of both those options. Resin printing does also appear to be somewhat messier than FDM because of the multistep process of printing, washing and curing.

My personal solution was to put it in a cupboard, so I have a printer cupboard in my workshop, which because I have the environment to do that, works. It keeps the printer, setup and level, warm when in operation, quieter and more to the point, very out of the way when not being used.


I have thought many times about getting a 3D Resin printer, but as quite a number of my modelling buddies have them, I thought what's the point, I can use their gear and pay them for the small amount of Resin printing I might ever need to get done.

BTW, great gadgets. Really like the wheel Centre device. Much sleeker than the one I found.
How legal is resin money 

[Frank3k]

Unlike FDM printers, the Elegoo itself doesn't shake when printing; it only has one motor that moves vertically (in the Z axis). You do want the printer level (you don't want the resin to slop over an edge) but more importantly, you want the build plate to be parallel to the FEP and screen.

As far as location, a sturdy table that doesn't vibrate every time someone walks by should work.

You want it near a window or near good ventilation, since some resins can have a strong smell.

You also want the resin temperature to stay constant and above 68F/20C

If you place the printer near a window, make sure it doesn't get sunlight or any UV on it. The clear plastic cover will block much but not all UV light. If you get a few hours of Sun on the printer, it may start curing the resin in the vat.
An opaque box over the printer or a darkened room should be enough.
You can see my "lab" setup here. The resin printer is in the black enclosure... which has a clear window in the flap. I covered it up.
Brian's setup with the doors would work well with a resin printer.

You can leave the resin in the vat for a few days, as long as it doesn't get ambient UV exposure.

Use a "waste" container for resin that was in the vat, and strain it; never pour it back in the original container. Keep it in a dark place and reuse it.

[Frank3k]

Great resin printing FAQ

[GTX_Admin]

Great thread guys.

[Frank3k]

Robin - how do you use the "square checker"? sounds handy.

[robunos]

Like this . . .








Also with things like tailplanes and fins, basically anywhere you have two parts that need to be at a true right angle . . .


cheers,
Robin.

[robunos]

Unlike FDM printers, the Elegoo itself doesn't shake when printing; it only has one motor that moves vertically (in the Z axis). You do want the printer level (you don't want the resin to slop over an edge) but more importantly, you want the build plate to be parallel to the FEP and screen.
[SNIP}

Thank for this, most useful.


cheers,
Robin.

[Frank3k]

The square checker looks handy!

[robunos]

That's why I developed it !   
If you don't get the pieces square, when building those AFV kits with the hull made from separate plates, the model never comes out right . . .


cheers,
Robin.

[apophenia]

... I made a few simple tools myself ...

Dang those are clever 

[Frank3k]

A video by Scale-a-ton where he uses Blender and his new printer to print some model parts. He doesn't go into details, but it's worth watching.

[robunos]

Okay, so I've managed to get my printer set up and try using it, with shall we say 'mixed' results . . .
After having levelled the machine (or so I thought), and then levelled the build plate, I made my first test print, the 'Rook' model included with the printer's software. The results weren't bad, for a first attempt.








There's some roughness and white deposits around the base, which I understand to be due to not washing off all of the uncured resin / not drying the piece completely before curing. Also this test print does not have supports with it, and is printed directly on to the  Build Plate. This made them difficult to remove, and I did crack one while doing so, although you can't see it unless you look closely. I also discovered that the machine was not properly levelled after all.
I levelled the printer properly this time.  A 'problem' I've found is that the adjustable feet have no locknuts, so there's nothing to retain the setting once you've made it . . .
I decided to add supports this time, so I used the supplied 'rook .stl' file and addded the supports and sliced it myself using the supplied Chitubox software. This was the result . . .





I made sure I washed this one completely before curing, so no  roughness or white deposits this time, but the print came out wonky. I put this down to having not re-homed the Build Plate when I levelled the whole machine. So I levelled and zeroed the Build Plate once more. The other major problem was this . . .





the size was completely different to the first print. I have absolutely no idea why this should be . . .
So for my next attempt I decided to use an object I'd designed myself. After letting the printer do it's stuff, I was presented with . . . nothing, a clean build plate. Another attempt gave the same result. A third go, and now the printer is producing loud grinding noises when the Build Plate goes to the Home position to start printing. Googling informs me that this is due to the Home position not being correctly set. After two attempts at re-homing with no change I decided to give up for the day. After emptying the resin vat I find the reason for the grinding noise . . .





The 'missing' prints were in fact stuck to the FEP, and not the Build Plate ! 
So today's questions are :-

How do I get the prints to stick to the Build Plate, and not to the FEP ?

How do I get the print to come out at the correct size ?
and finally, I've managed to lose on of the screws that secures the resin vat.         

Are replacements available, or if not, what size is the screw, so I can get a substitute ?


cheers,
Robin.

[Frank3k]

Leveling the machine is important to keep the resin from sloshing out one side of the tank, but not critical.

Leveling the build plate so it's parallel to the FEP is critical. Not doing so can lead to print failures. Follow the leveling instructions carefully - the build plate bolts have to be adjusted in the sequence they recommend, or the build plate can get twisted out of level.

In your failed print, how many base layers did you use? You'll have to carefully remove the stuck on resin. Don't use a metal spatula! A silicone scraper should work and won't scratch the FEP. I've used denatured alcohol to help remove stuck on bits and some will come off by picking at them (carefully) with your fingernail (through a glove).

When all clean, check the FEP for tears, deep scratches or holes. Make sure the build plate is clean, too.

If you poured the resin back into the bottle without filtering it first, use a filter before you pour the resin in the vat again to catch any bits of cured resin.

The screws are metric; M4 0.7 x 12mm for the Mars 2 Pro. Contact Elegoo and see if they'll send or sell you a replacement. They're pretty large - how did you lose one?

3D Printing Pro has really helpful videos on printing.

Leveling the Plate for Resin 3d printing - Flint Read v Paper method!
How many bottom layers should you actually use for resin 3d printing?!?
Base layer exposure
How to clean the resin vat

[robunos]

Frank3k said :- Leveling the machine is important to keep the resin from sloshing out one side of the tank, but not critical.


That's how I found out the machine was not level, I could see that the resin level was deeper at one end of the tank than the other . . .


Frank3k said :- Leveling the build plate so it's parallel to the FEP is critical. Not doing so can lead to print failures. Follow the leveling instructions carefully - the build plate bolts have to be adjusted in the sequence they recommend, or the build plate can get twisted out of level.


I've done that, and I'm satisfied that level is good, I've even used a square to make sure that the edges of the Build Plate are parallel to the sides of the printer.


Frank3k said :- In your failed print, how many base layers did you use?


I used the software default; 5 layers of 0.05mm thickness, with an exposure time of 35 seconds.


Frank3k said :- You'll have to carefully remove the stuck on resin. Don't use a metal spatula! A silicone scraper should work and won't scratch the FEP.


I'm using water washable resin, so after I emptied the tank I left it filled with water for about 30 minutes, then emptied and dried it. The stuck on prints came off with a bit of work. There are some dents in the FEP, but no tears or holes. I only have one spare, so I'd like to try and get a bit more life out of this one, if I can.


Frank3k said :- Make sure the build plate is clean, too.


I've cleaned it thoroughly with water, and now I have some IPA, i will clean it with that too. Or would cellulose (lacquer) thinners be better ?


I decided to dispose of the unused resin, as it had been hanging around while I was messing about. How long can the resin be left exposed to light before it starts to cure and is unusable for printing ?


Frank3k said :- The screws are metric; M4 0.7 x 12mm for the Mars 2 Pro. Contact Elegoo and see if they'll send or sell you a replacement. They're pretty large - how did you lose one?


When I loosened it to take the resin tank out, I overdid it, and dropped it in the resin tank. I took into the kitchen to clean it in the sink. then dried it, then put it down to dry completely while i went to fetch the Build Plate. When I returned I couldn't find It . . .


Thanks for the video links, that's my evening entertainment sorted . . .


cheers,
Robin.

[Frank3k]

I've cleaned it thoroughly with water, and now I have some IPA, i will clean it with that too. Or would cellulose (lacquer) thinners be better ?

IPA or any alcohol should be more than enough. You don't want any high spots that can puncture the FEP.

I decided to dispose of the unused resin, as it had been hanging around while I was messing about. How long can the resin be left exposed to light before it starts to cure and is unusable for printing ?

Resin will cure slowly and will form a skin as it cures. If you're going to get rid of it, the best way is to cure it (leave it in the sun until it solidifies completely) then dispose of the solid resin.

When I loosened it to take the resin tank out, I overdid it, and dropped it in the resin tank. I took into the kitchen to clean it in the sink. then dried it, then put it down to dry completely while i went to fetch the Build Plate. When I returned I couldn't find It . . .

could it be in the sink trap?

Thanks for the video links, that's my evening entertainment sorted . . .

You can play it at a slightly higher speed or skip a bit. He does tend to go on... but it's top notch info.

[robunos]

I poured the resin into an empty small clear yoghurt pot, then put it in my wash/cure machine, then let it cure in there. When it was solid, I binned it.
I definitely put in on the worktop, away from the sink. The knob on the bolt head is too big for the holes in the sink drain anyway. I've taken a break from video watching, you're right, those videos are excellent, and just been on Amazon to order some more FEPs, and also some replacement screws, will be here tomorrow (isn't Prime a truly wonderful thing . . .    )


cheers,
Robin.

[robunos]

Okay, today I had the chance to try some printing again. The parts I ordered had arrived last Friday, the replacement FEP films, in a nice pack, to keep them safe from damage,





and a packet of bolts to replace the one I somehow managed to lose . . .





The original bolt is on the left, a replacement on the right, effectively identical . . .


This time I decided to print some parts that I had CADed myself, to check that the way I had done things, design, build plate layout, supports, slicing, etc, were correct, and also to see if the scaling issue I had previously was still present.
After 30 minutes or so, success !





After removal from the build plate, washing and curing,





and finally after removal of the raft and cleaning up.





So to today's questions. I had some trouble with the machine not recognising the Chitubox files at print time. After some messing about, I did get things to work. Have you experienced this ? Also, a new version of Chitubox is available, but in order to use it, I have to update the machine's firmware. Have you ever done this ?


cheers,
Robin.

[Frank3k]

Don't print from the USB stick that came with the printer; they aren't always the best. Buy a good quality USB stick and print from that instead. That may be causing the issues with Chitubox. Also, make sure it was saved properly.

I updated the firmware on my two Elegoo printers since it fixed some minor issues on the Saturn; I'm still using Chitubox 1.18. I do most of the supports, slicing and file checking with PrusaSlicer and UVTools. These days, I use Chitubox mainly for playing with supports and checking files.

[robunos]

Don't print from the USB stick that came with the printer; they aren't always the best. Buy a good quality USB stick and print from that instead.

I read about that when I was trying to figure out what was going on, so I ordered one from Dr Evil Amazon. Arrived today via Prime, but I haven't tried it in the printer yet.
[/size]

I do most of the supports, slicing and file checking with PrusaSlicer and UVTools.

I tried Prusa slicer, but I wasn't really sure what to do = . . . haven't tried UVTools, will have to investigate further.


cheers,
Robin.