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#1 2020-04-20 21:42:03

Registered: 2020-04-15
Posts: 12

DIY High-end DLP 3D printer, ugly looking parts

Hello everyone!

In the recent free time due to cv, I've managed to finish my DIY DLP printer.

I've chosen good parts for the build, but when I try to print it just fails to give good results,

Parts used:

-genuine 2x 15mm linear rail guide
-4x rail block,
-genuine ballscrew
-closed loop nema23 motor.
-NanoDLP, RPI 4, Ramps 1.4
-Benq TK800M 4k DLP projector
-VAT with PDMS installed

The Z axis is very rigid. I've attached some photos. This is a big printer (500x280mm) and 700mm on Z axis. However I'm currently not printing with the bigger build platform (I've attached smaller one  (200x120mm) for testing purposes).

There is no play in the Z axis whatsoever (checked with dial indicator).

It seems like there are always some sort of Z lines present + some sort oz Z ragging?
I'm guessing my problem is in the separation force when peeling cured layer, since Z axis does not bend at all, so I'm trying to separate the cured layer by only pulling upwards.
But Z lines also appear on smaller surfaces (where separation force should be lower?).

Things I've tried:
-Different resin brands, different exposure times, different lift speeds and distances.
-Different burn in layers, layer heights of 50-100um.
-Tried really curing a solid foundation for the model, but did not improve..

I'm struggling/failing to get stable and good result. I noticed that when I lowered the Z axis feedrate between layers, the results got better, so I'm currently lifting with a feedrate of 1mm/min, and problem is still present, but less noticeable.

I'll try to prototype some sort of tilt mechanism into the VAT or Z axis itself, to try and lower the separation force.

Does anyone have any further idea? I'm loosing my mind here..


BTW: Some more specs:

current settings:

After layer:
G1 Z{[[Layer Position]]-0.6} F1
[[Delay 1]]

Before layer:
G1 Z[[Layer Position]] F1
[[Delay 1]]

Exposure time: 10-15s, depending on resin
Layer height 50-100um


#2 2020-05-17 08:43:35

Registered: 2017-06-09
Posts: 9

Re: DIY High-end DLP 3D printer, ugly looking parts

Am I correct that you are using a rigid base vat with no tilt mechanic?
Thats where I would start troubleshooting. The no-tilt builds usually use fep film to get some peeling mechanic with the elastic film.

Out of curiosity: why did you choose a bottom up design with projector? Im asking because I used the corona timeout to finish my 3D printer design, too smile
However I made it a simple top down with glycerine support resin tank .


#3 2020-06-10 11:56:03

Registered: 2018-06-06
Posts: 25

Re: DIY High-end DLP 3D printer, ugly looking parts

Try lower exposure time. Maybe layers are cured to much and thus sticking to much when trying to peel off.


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