Moving from FDM to resin 3D

I have done 3D printing for a long time, since the days of 3D printers being kits and burning out stepper motor drivers.

My latest 3D printer was Lulzbot Workhorse, and it is pretty good. The Bamboo ones are, as I understand it, way more impressive than that even.

But this is FDM - using reels of filament, melted and deposited. It works well. But there is another whole 3D printing world with resin printing.

My new printer is an Elegoo Saturn 4 Ultra 16K - a resin printer.

Print size

Downside number 1 is the print size, way smaller. FDM can do all sorts of large sizes, my Lulzbot is 279x279x284mm which is quite big.

The resin printer is 211.68 × 118.37 × 220 mm. The reason is the print bed has an LCD or some such that prints a layer at a time. Where as the FDM has X/Y/Z motors and is limited only by physical size. Bigger LCDs are expensive. Longer bits of metal to make a larger FDM printer are less so. 

Resolution

Upside number 1 is resolution, and this is where it gets crazy. FDM is good, but resin printers are crazy. For Z axis the Lulzbot can go down to 50µm, but the Elegoo starts at that, and can, AFAIK go down to 20µm or perhaps lower. As for X/Y, both do well, with Lulzbot down to 10µm, but the filament is a 0.5mm (500µm) nozzle. The resin can print down to pixel at 14x19µm.

The result is resin printing sharp points and groves, and features really well where FDM is 0.5mm nozzle limited, and printing with way lower layer size. This allows sharp and exact features for resin printing.

Also the print is per layer textured, the layer has a bulge in centre of filament track. Not so with resin. Vertically resin is smooth and clean. So even at same 50µm layer, resin printing is way cleaner.

Level surfaces

Another difference I was amazed to see for resin was the top edge flat surface of a print was level, exactly level, I mean shiny level and smooth. FDM has ridges and texture. The bottom not so different as both print against a base plate and tend to be as smooth as that plate.

Levelling for the start of print is important and the resin printer seems better.

Print speed

This is more of an interesting one - FDM prints depend on time to trace the print layer by layer. So more detail in any layer takes longer. Adding support takes longer.

With resin a layer takes a number of seconds, end of story - no matter what.

So a biggie is if I have a small thing to print, for FDM, if I print 5 (assuming they fit on build area) is 5x longer, or worse. For resin it is same time as same height. Uses more resin but not more time.

Similarly the complexity of a design, the detail, the supports, all matter for FDM print time, but no issue for resin.

All that matters for resin is height and layer thickness. I.e. how many layers. It is a very different way to consider complexity.

Smell

The resin printing has a smell, but very minor. I have an air filter on order, but to be honest I am not sure I need that.

Sound

Resin printing is way quieter. I like this. Really way better.

Sticky

With FDM, print finish, take off bed, done.

With resin, messier. I am working on the best way to handle this, but you remove print, it drips, take to tub for cleaning (or maybe tap for water cleaned resin), put in curing for a few minutes, remove from bed. It is more work, and more chance of stuff dripping. More chance of "mess".

Changing material means pouring resin back from tray, cleaning and new resin, maybe changing fluid for cleaning (water/alcohol), way more hassle than a filament change on FDM.

So yes, a bit more, but working on it - not sure it is a lot more hassle in the long run. The results are amazing.

Prototype

The main reason for this is prototype designs - I can order bulk resin prints from China, but they take a week. This allows way quicker design refining before ordering, and quick one-off prints.

That alone makes it worthwhile.