Considering Switching To Liquid Resin 3D Printing

Recently, I’ve been pre-occupied with a few other things in life and my “home office” has been less “office” and more “storage corner” for all of my halted projects.

After some thought, I realized that I no longer wanted to do 3d printing with a filament based printer, but that I wanted to go for a liquid resin light cured printer.

The reasoning is as follows, or the cons of PLA/ABS filament printing:

  • Hot ends and heated beds = potential for fire hazard. Let’s face it, while the design of printers have more or less stabilized, the safety aspects remain more or less the way they have been since around the start. I generally don’t feel safe leaving the printer to operate on it’s own, unattended, and feel like I have to baby sit it lest a big blob of plastic forms over the hot end and the hot end doesn’t realize Bad Things(tm) are happening, and continues heating things up. No fires to date, nor any 2nd hand accounts of fires, but it weighs heavy on my mind.
    • As an add-on… hot end jams SUCK… just… suck.
    • Heat related expansion causing changes to the calibration and tuning of the frame ALSO SUCK
  • Filament standards(or lack thereof) are a sore point with me. “1.75mm” is supposed to be the standard size, but it’s really that +/- 0.1-0.2mm depending on the tolerance factor of the manufacturer, the middlemen, and the ambient humidity/temperature. What worked for one spool at the start of the month might not work for the same spool at the end of the month or from another spool from the same order.
  • Issues with PLA and ABS “printer flu” symptoms. Every time I fire up my PLA filament printer, I will start experiencing the symptoms by day 2. Itchy eyes, runny nose, mild headaches, and feeling like I’ve been hit with the flu. I’ve been wondering about this and came to the conclusion that PLA and ABS can release microscopic “hairs” or “fragments” with similar quality of spider webs and/or dust in your home. Except the “dust” being released by the printer is highly irritating to mucous membranes… at least my mucous membranes. So while PLA doesn’t smell like melting plastic, it does have some mild health effects. With ABS, I’ve not seen the filament dust fragments yet, but the smell and off gassing from ABS makes me feel unwell.
  • Surface quality and print times. For each of the dozens to thousands of layers, the printer has to fill in the solid parts like one would with a pen or pencil. There is no “printing a whole layer at once” concept. So if one went with .1mm or .2mm layers, it will take a good deal of time to complete large prints or multiple object prints. If one of the objects fail, then the whole print will fail. This really sucks.

So let’s look at how a resin based solution would address some of the cons. Let’s call these the pros of DLP/LCD resin printing:

  • 1 layer at a time. Regardless of the number of objects being printed… the whole layer takes the same amount of time. So if I printed one chess piece, it’s 3-4 seconds a layer… if I print 16 chess pieces, it’s 3-4 seconds a layer. Let that sink in for a bit.
  • Layers can be about the same 0.1-0.2mm thickness or I can go down to 0.05mm thickness.
  • Layer edges are more rectangular than filament edges which tend to be cylindrical. So the perception of layers on a liquid resin print is significantly less.
  • No heat. It’s light cured and the heat comes from the stepper motor driver for the Z axis and the LED drivers. Both of which are fairly low heat devices when compared to the hot ends and heated beds. This also translates into smaller power requirements.
  • Minor VoC and some resins have no VoC. Though touching the uncured resin itself is a BadThing(tm) in that it can cause skin irritation and/or allergic reactions. Use gloves.
  • Consistency between prints and reloads of resin. No filament and manufacturing tolerances to deal with here… just a bottle of consistently made light reactive resin.
  • If one object on the print fails… the worst that will happen is a clump of resin curing over that spot… no dragging around. Good chance the other objects will print just fine.

Where to get a printer? Which printer?

So with this in mind, the question of which printer to get and where to get it comes to mind.. There are certainly some affordable printers out there. The WanHao Duplicator 7($500-$800 base model) and the Spark Maker($300-$400 base model)… both look like decent printers. But here’s the thing… I’m pretty sure I can build my own. Perhaps not for less, but certainly as a means to learn more about resin printers. 🙂

At the heart of it, a resin printer is comprised of the following components:

  • Z axis movement via a screw drive powered by a stepper motor and guided by linear motion rails or rods.
  • A print arm that holds the print bed pointing down towards the resin. There needs to be a height/angle adjustment mount for the print bed.
  • A tray/basin which holds the resin, with a light permeable film on the bottom which the resin doesn’t stick well to.
  • A transparent LCD panel connected to the driver board to create the “mask”. A clear sheet of glass under the LCD to provide support.
  • An even light bank underneath the LCD/glass panel to provide the curing light source.
  • A controller board to handle controlling the Z-axis motor, the on/off of the LED curing light panel, the LCD mask panel, and an endstop trigger for homing the z-axis.
  • Optional LCD and buttons for independent control.
  • Resin printer printing/slicing software.
  • Source for STL models to print.

So, it just so happens that I have the following things as raw materials for starters:

  • A box of Raspberry Pi 2 boards
  • A Printrbot Simple Metal V2 which has a VERY robust z-axis frame and stepper motors/control board that can handle gCode commands.
  • A Monoprice i3 which is a Prusa i3 clone with reinforced Y/Z axis stage. So the arm is VERY rigid.
  • Boxfuls of stepper motors and stepper motor control boards.
  • Several 12V laptop power supplies.
  • Access to good open source software like NanoDLP which can handle the printing of STL objects to g-code running systems.. and it runs on a Pi2….
  • Several 2K LCD panels on order from AliExpress with the backlight already removed. Have several sizes coming: 5″ 8″ and 10″ displays.
  • 2000 count 7000mcd LED(s) on order from AliExpress for the curing light source. I also happen to have a nice large perfboard to install the LED(s) on. No need for custom PCB here….
  • Glass backing can be bought from the local HomeDepot or Lowes.
  • The basin tray plan on milling using my Nomad 883 Pro CNC machine from Delrin/HDPE.
  • And a box of micro-switches, cables, soldering equipment, etc.

So it looks like I have enough spare parts or building materials to turn both of my filament printers into resin printers.

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