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SLT / Tilt bed assembly creates loud popping sound  

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Kevin
(@kevin-14)
Active Member
SLT / Tilt bed assembly creates loud popping sound

Any thoughts on what could be making the SL1 create a popping sound and cause the bed-assembly to 'bounce"?

Symptoms:
Occurs when Tilt-bed raises to the print-position
Loud popping sound
Machine physically shakes
Tilt-bed assembly bounces 1 to 6mm, continues to raise
May occur once, then a second time more dramatically

Conditions:
Printing a large area print-job that occupies ~75% or more of the print-platform
(currently running the prusacek clay army demo since the surface-area is approximately similar).

Settings:
.015mm layer height (also experienced at .025mm)
35 second exposure for foundation (tested to 45 seconds)
7 second exposure for layers (tested to 15 seconds, which appears to have some effect, but not lasting)

Detail:
First few layers (possibly upwards 20 to 30 layers) will print as expected - sounds, movement, timing
While raising the bed assembly, the machine will pop, the bed assembly will bounce downward by 1 to 6mm or so, then continue to raise.
When this first occurred, I immediately stopped the job and removed the stage to inspect.
The print had adhered properly to the stage, but did have some layer separation. Nothing was stuck to the FEP film.
After adjusting the initial duration to 45 seconds and layer-duration to 10 seconds, the same job was re-run, and produced a similar result - but the time it took until it started creating the effects (sound and 'bounce') was on a later layer (30 to 40 vs ~20 on previous print).

After several attempts at the same result BUT stopping the print out of caution, increasing the cure-duration to 45 & 15 seconds extended the point further, but eventually resulted in the same. After allowing it 100 layers, the print-job was cancelled and discovered that a very small amount had stuck to the FEP.

Concerns:
1) Suction and fluid viscosity may induce resistance that causes the bed-assembly gearing mechanism to skip a cog, despite allowing for it to drive to the correct position due to servo-feedback.
2) Compression between the bed-assembly and print-stage may introduce force against the LCD that could lead to damage or failure.
3) Skipping a cog will eventually cause mechanical damage & failure, as well as possibly damaging the LCD element.

 

** Note - by this point of writing, the 'clay army' print has not experienced the above symptoms and is nearing completion.

Veröffentlicht : 13/12/2020 7:31 pm
gnat
 gnat
(@gnat)
Noble Member
RE: SLT / Tilt bed assembly creates loud popping sound

Yeah I wouldn't let that continue once noticed. From what you describe I would expect damage to the LCD and a shortened life won't surprise me.

Is there a void in your print (e.g. hollowed)? Maybe there is a pocket that isn't properly vented?

If not, then I would open the printer and inspect the whole mechanism and something binding up would be the next option.

MMU tips and troubleshooting
Veröffentlicht : 14/12/2020 1:29 am
Kevin
(@kevin-14)
Active Member
Themenstarter answered:
RE: SLT / Tilt bed assembly creates loud popping sound

Thanks Gnat
The machine (I actually have two), will do the same thing when densely populated / same parts, different parts, same results.
If I scale back the volume to about 75% of what it was (less than 60% total coverage of the stage).

** Note - the "Clay army" test printed fine at .050mm, and this covers 80%+ of the stage.
The point of which I would see the bouncing-effect begin was still during the early layers while printing the Pad.

 

 

Veröffentlicht : 14/12/2020 11:48 pm
Kevin
(@kevin-14)
Active Member
Themenstarter answered:
RE: SLT / Tilt bed assembly creates loud popping sound

Hmm couldn't re-edit the text...
To reiterate:
If I scale back the volume to about 75% of what it was (less than 60% total coverage of the stage) - the same parts will print just fine without any issue.

Veröffentlicht : 14/12/2020 11:55 pm
gnat
 gnat
(@gnat)
Noble Member
RE: SLT / Tilt bed assembly creates loud popping sound

Do you have a specific layer height where it starts? As I recall from the army it has a very short base where it is near solid. Maybe that has something to do with it.

Not that I think highly of them, but I would get support engaged ASAP and get their guidance. Continuing to print is wasting resin and LCD life and potentially damaging something.

I would try figuring out where the issue starts and then create various tests that have different cured volumes approaching that height and see if there is some critical mass that causes the issue.

MMU tips and troubleshooting
Veröffentlicht : 15/12/2020 12:17 am
Kevin
(@kevin-14)
Active Member
Themenstarter answered:
RE: SLT / Tilt bed assembly creates loud popping sound

@gnat

This had begun somewhere around layer 20 @ .015mm = .3mm, with the same thickness as the clay army.
I could try a test with the clay army itself and slice it to .01-.015mm to see if it produces the same effect.

However, overall, I think this may be somewhere of an issue with exposure time & layer separation.

Veröffentlicht : 15/12/2020 6:20 am
Mitchimal
(@mitchimal)
Eminent Member
RE: SLT / Tilt bed assembly creates loud popping sound

Did you resolve this? Not sure if it's the same thing I'm getting but here a video.

https://youtube.com/shorts/fZUQO9pJtIc?feature=share

 

Veröffentlicht : 24/11/2021 12:02 pm
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