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Model Railroading > New 3D Printer (Part 6) – Drain & Filter

Date: 04/19/21 00:11
New 3D Printer (Part 6) – Drain & Filter
Author: tmotor

This is Part 6 of a series on my recent experience with a Phrozen “Mini 4K” 3D printer.  (Parts  1 thru 5 were posted earlier.)
Care and Feeding of the FEP
One of the most critical, yet vulnerable components is the FEP (Fluorinated Ethylene Propylene) film at the bottom of the Vat. Ideally it is clear, and free of deformations.  Keeping it that way takes lots of effort.  If the FEP is not treated with care, at a minimum the surface is scratched and the part details become “soft”.  Worse-case scenario, the FEP will tear, and the resin will leak out of the Vat. 
The FEP is a “consumable”.  It is a temporary component, with a limited life expectancy.  So if it is going to be replaced eventually, why treat it with care?  Because, every layer of resin comes in contact with the FEP.  If the FEP has a surface defect (is dimpled, has a scar, or abrasion) the mask image is altered, which translates to a defect in the part being printed.  It is bad enough to have the part affected, but if the FEP gets really thrashed, the printer is at risk.  Generally, the resin will leak beyond the face of the LCD and flow around the edges.  Gravity takes over, and the resin is now dripping into the internals of the printer.  There are “gaskets” that are available to seal the edges of the LCD screen, preventing resin from entering the printer.  The Mini came from the factory with some black tape applied to seal the LCD.  Eventually I replaced the stock tape with a gasket.
After a print run, is it better to keep the used resin in the Vat as is, or should it be filtered before the next run?  I vote to filter it.  If there is a dinky little chunk of cured resin swimming in that Vat, I will NOT see it.  When the Build Plate lowers to create the first layer, say 20 microns, and the chunk of resin is 100 microns, the Build Plate will pile-drive that chunk into the FEP.  At a minimum it dimples the FEP.  But it can also tear the FEP, or crack the LCD screen.
Merely rubbing a plastic spatula along the FEP to “feel” for resin stuck to the FEP will not do the trick.  Even if the resin is dislodged from the surface of the FEP, how will I get it out of the Vat?  Short of filtering the resin, it won’t happen.  So just leave it in there, and press START?  If the FEP survives, that just reinforces bad behavior.  Eventually the odds will run out, and the FEP will suffer.   
Drain & Filter
To prevent these nightmare scenarios, I’m pretty anal about filtering ALL of the used resin between runs.  Have an empty bottle with a filter above it.  Pour all of the resin from the Vat through the filter, into the bottle.  Use a squeegee to remove all of the resin from the Vat. 
I reuse the same filter for at least 25 tiimes.  As long as the resin is NOT exposed to UV light, the filter is wet with resin, but allows resin to flow thru.
Use a microfiber cloth (paper towels will scratch it) to wipe the FEP.  Inspect the FEP.  Replace the Vat on the printer, and secure it.  Shake the bottle of resin.  Pour it into the Vat.  Add more “new” resin as needed to keep the Vat topped-off.
Does this take time?  Yes. 
Has this saved my FEP?  YOU BET! 
More than once I found a piece of resin attached to the FEP.  Every once in a while, there is a small chunk of resin caught by the filter, which I would not have seen and would have trashed the FEP.
After a hundred+ print runs, I have yet to experience a FEP tear.  Lord willing, I will maintain that track record.  I’ve had some FEPs get dimpled due to part failures, but no tears so far.  I attribute it to the Drain & Filter routine I follow between print runs.
There are some clever contraptions on Thingiverse.com to hold the Vat while it is draining into a filter.

Edited 7 time(s). Last edit at 04/19/21 09:09 by tmotor.

Date: 04/19/21 07:39
Re: New 3D Printer (Part 6) – Drain & Filter
Author: sixaxlecentury

I the 2.5 years of owning a resin 3D printer, I have only filtered my resin twice, both because of catastrophic failures.  

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