Cracking sound at release from FEP film

Various topics related to Vat design, construction and coatings.
radi2k
Posts: 19
Joined: Mon Sep 28, 2015 8:22 am

Cracking sound at release from FEP film

Postby radi2k » Fri Apr 01, 2016 12:04 pm

Hi!

I recently built my own DLP based bottom-up printer using a FlexVat consisting of a original DuPont FEP/Teflon film (50um). There's no extra acrylic in between and just the highly tightened film itself. I have no special peel mechanism but only the Z-axis movement. My prints come out well after many failures. After reading in this forum I was able to fix the issues. However, I still have sounds during release which I think are strange.

Is is normal that the release from the printed object off the FEP film makes a kind of cracking sound? The loudness depends heavenly on the area to be released.
The film gets pulled up like 3mm before its released. I thought Teflon FEP film has a special coating so nothing adheres to it!?

Is that sound related to too much exposure or any other issue? I cannot find good videos on the net including great audio.
Might that become better with a peel mechanism like here: https://www.youtube.com/watch?v=-K0bb5_Pjkw (around 0:50)?

Resin: Fun To Do Standard Blend in black.
Object: http://www.thingiverse.com/thing:291323 (scaled down a bit)

Thanks,
radi2k

AndersonTa
Posts: 189
Joined: Mon Dec 09, 2013 4:28 pm
Location: Houston, TX
Contact:

Re: Cracking sound at release from FEP film

Postby AndersonTa » Fri Apr 01, 2016 3:55 pm

It sounds like you could use more tension on your teflon, it shouldn't pick up 3mm before releasing.

When it's tensioned, and you tap it, does it sound like a drum?
@AndersonHTa

radi2k
Posts: 19
Joined: Mon Sep 28, 2015 8:22 am

Re: Cracking sound at release from FEP film

Postby radi2k » Mon Apr 04, 2016 3:41 am

Hi AndersonTa,

it did sound like a drum but probably not high pitched enough. I tightened it a bit more and prints were getting much better. Also the release sound is almost gone now. However, a redesign is needed for my FlexVat since there is no more room left for more tension. I'll also integrate a separate peel mechanism to improve it even more.

Thanks,
radi2k

AndersonTa
Posts: 189
Joined: Mon Dec 09, 2013 4:28 pm
Location: Houston, TX
Contact:

Re: Cracking sound at release from FEP film

Postby AndersonTa » Tue Apr 05, 2016 9:30 pm

radi2k wrote:Hi AndersonTa,

it did sound like a drum but probably not high pitched enough. I tightened it a bit more and prints were getting much better. Also the release sound is almost gone now. However, a redesign is needed for my FlexVat since there is no more room left for more tension. I'll also integrate a separate peel mechanism to improve it even more.

Thanks,
radi2k


Yeah, it should more or less have a high pitch "TWANG" to it...

It would seem in looking at the various flexvat designs, it'd be best to have a way to secure the FEP film flat independently and then have it tensioned over some sort of frame. That way it is less likely to slip.
@AndersonHTa