Resin curing in the middle with no object there.

[Alienfrog]

Good afternoon,
Situation : Resin curing in the middle of the Tray area, no printing set for the middle. Moved the print object to the side(s) and they print fine. When I printed those two items, there is still resin curing in the middle of the tray as if this was a failed print. I tried this due to my prints where "ragging" and incomplete - missing sections-failed, but no holes. Changed settings etc with no luck. Placed two mall objects to the opposite ends and printed perfectly, but the cured resin still occurred in the middle.
Printer: Mars (S/N - M24xxxxxxx)
Notes: Changed the Screen due to holes appearing in prints. Screen sits flat as per manufacture requirements. All items are new and clean, and used a test print with a confirmed print from previous use.
Resin: Elegoo Grey resin - new/not expired.
FEB: Elegoo replacement sheets
Screen: Elegoo screen
Light check shows no issues, tried with white paper.
USB: tried two different USB sticks.
Firmware V4.3.4

Pic shows the ragging that has occurred on a larger print. This only occurs in the middle; when there is no object to print in the middle resin curing still occurs.

Any help would be appreciated.

Cheers

AF

[cliffyk]

What exposure times are you using? My first thought is time that are too long allowing curing light to "bleed" through the resin and initiate curing in the unexposed areas...

[Alienfrog]

What exposure times are you using? My first thought is time that are too long allowing curing light to "bleed" through the resin and initiate curing in the unexposed areas...

Recommended levels (been using 8s typically) and have tried may different timings and the same thing occurs. Cured resin in the middle of the vat with no objects placed there. I am having very successful prints when i place the objects on the very outer edges only. So right now I am restricted to printing smaller items on the outer edges for now. I do get some very minor ragging with in this prints as well. I would change out the screen but, there seems to be none avail anywhere at a reasonable price >$30.
Cheers
AF

[cliffyk]

How old is the printer--or more specifically how many hours of printing?

Download and slice this file LCDTest.stl.

Then "print" it with the resin vat and platen assembly removed and a sheet of paper over the LCD--it will "print" a 120 x 68 x 5 mm flat block that will let you see how well the LCD and curing lamps are working. If all is well you should see a bright rectangle like this:

[img]http://www.paladinmicro.com/TestEquipment/ElegooMars/NewLCD-00.JPG[/url]

If not the LCD is shot and needs to be replaced.

Here's one on Amazon for $30, it's not a genuine Elegoo branded part, but it is from the same manufacturer. Comparing the pictures to my spare screen it looks identical.

[Alienfrog]

How old is the printer--or more specifically how many hours of printing?

Download and slice this file LCDTest.stl.

Then "print" it with the resin vat and platen assembly removed and a sheet of paper over the LCD--it will "print" a 120 x 68 x 5 mm flat block that will let you see how well the LCD and curing lamps are working. If all is well you should see a bright rectangle like this:

[img]http://www.paladinmicro.com/TestEquipment/ElegooMars/NewLCD-00.JPG[/url]

If not the LCD is shot and needs to be replaced.

Here's one on Amazon for $30, it's not a genuine Elegoo branded part, but it is from the same manufacturer. Comparing the pictures to my spare screen it looks identical.

Good evening, I will carry out this test tomorrow, thank you for the help/direction.

The printer is new last October - replaced the LCD screen in Jan/21 due to holes in the prints. Printing was working very well up until this issue. Replaced the screen in mid/end Jan - New screen installed. Bought the screen from Amazon Jan 5th 2021. I am military and could not install due to work load and other personal priorities. So unfortunately had to wait. When I installed it was working okay, but noticed some unusually issues with respect to "ragging". Stopped using for a few weeks due to frustration and work. Had some time off and was re-trying and troubleshooting for the past week with no success.

MTF (more to follow)
Cheers
AF

[cliffyk]

Open up the case and check that pathetic little thing they felt was a suitable connector for a user installed consumable component--make sure it's seated properly...

[Alienfrog]

Open up the case and check that pathetic little thing they felt was a suitable connector for a user installed consumable component--make sure it's seated properly...

Good morning,

I have done the following:
Reseated the pin connector for the LCD (a few times before was thinking the same); and
Ran the exposure test quite a few times prior over the last few weeks, no "holes' or abnormalities seen; and
Printed a two small objects placed at the end of the build area, successful prints with cured resin in the middle of the vat since purchase/replaement; and
Ran the LCD Test no issues:
Tried another print; same concerns; and
Tried the LCDtest seen one hole (link didn't work got one from thingverse); and
Tried another print; and
Same results - objects placed on the end of each of the print areas and successful and resin cured in the middle;
Tried LCD test and NOW I have about 13 holes on the screen at random spots throughout the print area.

Going to order a new LCD screen...*sigh*.
MTF in a few days.

Just frustrated that this new screen didn't work form the beginning, now that I ran so many tests and troubleshoot I may have reached the end life of the LCD screen without having full capability.
NOTE: also noticed two little red lights on the board that has the LCD pin attachment point on it. The one lite is nearest the pin connection point, upper right and one lite on towards the back of the board, same side but further to the rear of the printer.

AF

[cliffyk]

My 3rd "new screen" lasted for only about 11 hours of printing--complained to Elegoo and they sent a new one...