There are multiple stages to producing a 3D print. The first stage is the actual design. Not all models are suitable to be printed on a domestic 3D printer. There are two types of domestic 3D printer - resin and filament. Resin printers are capable of high levels of detail but they have the disadvantage that the chemicals used do smell and can cause burns. They are also not very good at printing large flat surfaces. Filament printers are good with large areas but are not the best for detail. That said, printer technology is advancing all the time.
Understanding the printer characteristics is part of the actual design. Sometimes it is better to choose a thickness that matches the resolution of the printer. Sometimes you realise that a detail is so small it will not print so there is no point in including it. Filament printers print upwards. Resin printers print downwards and that affects how you do your design.
The computer Aided Design (CAD) software that I use is Fusion 360 by Autodesk. It is hard work to learn but pays off well once the basics are mastered. It is free for personal use and also allows up to $1,000 of revenue to be made off the personal license. CAD software is all about creating shapes in 3 dimensions. Typically you create a 2D sketch and then extrude it into 3D. Many objects are simply a collection of rectangles and circles and the trick is to know how to put them together to create the design. Fusion 360 uses what is known as parametric modelling. What this means is that you can go back to part way through a design and you can change a parateter such as the diameter of a circle and it will play that change thorugh the rest of your edits if at all possible.
Once you are happy with the design then it needs to be exported. This is the stage where you produce a file with a .stl extention. It's known as a Standard Tesselation Language file, shortened to stl. This file contains your design as a collection of triangles. It is a standard within 3D printing. An .stl file can be used to print a model on any printer.
The next stage is to convert the .stl file to a file that your printer can understand. Anycubic has a program called Photon Workshop. This program understands the setup of the printer and the size of the printer bed. Within the Photon Workshop program you can bring in any number of .stl files and arrange them on the bed. At this point you may also have to add supports. Although you can print on the bed, you are likely to get an elephant foot so to get a quality base to the model you raise it up on supports. Items with flat surfaces are also best printed at an angle. I usually use 20 degrees if I need to
The next part of the process is to slice the file. Resin printers work in layers and the output file from Photon Workshoip is simply a set of all the layers. Before slicing the model you have to decide how detailed it needs to be. On teh horizontal plane the printer has a resolution of 0.047mm but you can set the vertical layer down to 0.01mm. However, the print time is proportional to the number of layers since it prints a layer at a time. A further complication is that the thinner the layer the shorter the time the LCD has to be on. There are test files available to help determine the best paramters but experimentation plays a big part and every resin behaves differently.
Once the design has been transfered to the printer then you are good to start the printer. The way the printer works is that the bed travels downwards into the vat of resin. It goes down to the predetermined resolution of the print leaving just the tiniest of resin between the bed and the bottom of the resin VAT. The LCD beneath the vat shines its light upwards for the predetermined time which causes the resin to solidify. It then pulls up, waits for a set time and then repeats the process. This whole process usually takes a few hours. Large prints can be done but the typically need you to remember to top up the vat part way through the process.
At the end of the print run the model is left hanging upside down in the printer, dripping resin. The next stage is to gently remove the models and clean them in IPA. This is best done with two containers of resin, a dirty one to remove the worst of the resin and an cleaner one to get rid of final residue.
Once removed from the IPA, the resin is still relatively soft and needs to be hardened. At this point it is sometimes best to remove the supports as they are less brittle but sometimes there are advantages to leaving the supports on until after hardening is complete. Hardening is done by exposing the model to ultra violet light of the correct frequency, in this case 405nm. Various containers are available but mine is created from a coupel of boxes lined with kitchen foil onto which I glued a strip of ultra violet LEDS and it works fine. Hardening can be done by leaving a model in teh sunshine but the timing is hit and miss and sunlight is hit or miss. Curing can be as little as 20 minutes in the box but does depend on the thickness of the print.
At this point you have a print that can be painted. A wash with soap and water is usually sensible after which it can be primed and painted with acrylics or enamels.
Besides the big ticket items mentioned above there are several consumables to be aware of with running a resin 3D printer.
- Resin - Resin comes in many variants and colours. Besides the staple grey resins there are resins that are low odour, resins that are washable, resins that are flexible, resins in a myriad of colours. The choice is large. The particular ones I am using are the low odour ones as I print indoors (and even they smell). I usually print in white or grey. The volume of resin used in items is usually quite low. For example the coupling height gauge is 1.6ml. With losses and print failures it is probably that I only used 50% of my first bottle of resin. With time and experience that percentage should go up. The fumes of resin are a major issue. Low odour resin helps enormously, as does printing in a well ventilated space. However, resin operates best above 25 degrees centigrade so ventilation and temperature are always operating against each other. Some people build enclosures for their printer making use fo cahrcoal filters. Others design intricate ventilation system to go out of open windows. One last note, resin should always be cured before being disposed of. I keep a lidded jar on the window ledge and any excess resin goes in there and the whole jar gets thrown away after a time when it is completely solid.
- IPA - Isopropyl Alcohol is the method of cleaning prints. When a print comes off the printer it needs to have the excess resin cleaned off. To do that you use IPA and it has to be of a very high proof level. Greater than 99% is considered to be the right strength to use. The IPA quickly becomes clouded with excess resin and becomes fairly useless unless filtered. IPA is noxious and a mask is definitely needed.
- Filters - The life of IPA can be stretched by filtering the gunge out of it. This requires the use of filters, a coarse one as used to strain paint and then a fine one similar to coffee filters. These are single use and often multiple of the fine ones need to be used every filtration.
- Gloves & Masks - resin is toxic and has the capability to give a nasty chemical burn. Gloves and masks are necessities. Disposable gloves can be reused but only so many times. A mask should be worn. Both resin and IPA give off fumes. People who are always printing will sometimes invest in a professional mask.
- Kitchen paper - you will get through copious amounts of this. The cleaning process is messy and can involve several sheets per print run. You will need your own supply.
- Screen - the printer will keep going with a little care and attention. Keep it clean and grease the thread occasionally and it should be fine. There are two consumable parts and the first is the screen. The UV LCD display has a lifespan of between 200 and 500 hours. The coupling height gauge takes 2 hours on a 0.05mm print and 3.5 hours on a 0.2mm print. This is one reason to always fill the print plate where possible.
- FEP - The FEP is the film on the bottom of the vat that holds the resin. It has to be clean. It also has to be unmarked and stretched taut. With care it can last a long time but it is under enormous pressure in the printing process and can become damaged at which point it must be replaced.