# How thin a void/mould can a resin printer reliably produce?

I am trying to print a very thin casting mould. Once printed, I then pour an epoxy resin mix into the printed void. After curing the resin and demoulding, the final product is a mesh/web-like set of channels. The aim is to make these channels (aka the void) as thin as possible.

With lots of careful adjustments, I have succeeded in making these channels approx 0.4 mm thick with an FDM 3D printer and a 0.15 mm nozzle diameter.

However, I'd like to go thinner. I have little experience with resin 3D printers. I often see an XY resolution advertised of 0.05 mm. Does anyone have any experience printing extremely thin voids - and if so - what is the minimum reliable void thickness that a well-tuned resin printer could achieve in relation to the XY resolution?

i.e. a 0.05 mm XY resolution (aka pixel size) might equate to a reliable void thickness of quadruple the XY resolution i.e. 0.2 mm? If I attempted to print two sides of a box with only a single pixel gap in between these two walls, would there be lots of overlap and cured regions in the middle where light leaks and therefore cures in the intended void space?

According to one of the many resources available for x/y resolution of resin printers, specifically DLP and MSLA, Chitubox provides a formula to determine the minimum resolution.

How to calculate the pixel for DLP/LCD?

As XY resolution is fixed for DLP/LCD systems, so there is a equation:

Width / X Axis = Height / Y Axis = Native Pixel Size

If there is a 3D printer with a build area 68mm wide along the X axis. Divide 68mm (the X axis) by 1440 (the LCD width resolution in pixels), this will equal 0.047mm (47µm). And the native pixel size is 47µm.

0.047 mm is certainly close to the referenced 0.050 mm, but as also noted, there can be overlap/smear/filling created in the process.

There are test files for downloading and printing to use on a specific printer, allowing one to optimize exposure times and other settings. Cleaning of such small details could be a complication, perhaps resolved by an ultrasonic device and multiple passes of cleaning solution.

The linked site also provides these images for comparison of resolution settings:

47 micron resolution

100 micron resolution

A one pixel wall between channels is going to be incredibly fragile and may not survive a suitably complete cleaning process.

• The walls can be thick and strong, 1 mm +, no problem. Its the void space between the walls that I want to be extremely thin. Commented Nov 2, 2022 at 15:29
• That sounds promising for your project. There will be uncured resin removal and curing considerations but I think your un-referenced (lack of) depth will take care of that. 0.050 might be possible, but it's not the usual 3D printer test sequence. Some experimentation will be required. Consider to visit Reddit for someone to create a prototype for your testing purposes. reddit.com/r/3Dprintmything Commented Nov 2, 2022 at 15:35
• Depth might be challenging as it will need to be upwards of 100 mm in some areas. I can incorporate vacuum ports into the design though so I can have vacuum assistance if required. Many thanks for you time and suggestions, I will be sure to post on the subreddit. Commented Nov 2, 2022 at 16:04
• That's astonishingly deep! You've not mentioned the material being used for casting, but note that if it's silicone, there are complications there too. Platinum cured silicone will not cure on resin printed molds. Commented Nov 2, 2022 at 16:52
• I'm hoping to print the mould using a dissolvable resin (perhaps like this 3dresyns.com/products/…). Then fill the mould/thin void with an epoxy resin and filler mix, place in oven to cure, then dissolve away the mould using water and an ultrasonic bath. Commented Nov 3, 2022 at 9:25