Flexvat V5, the best of both worlds.

Forum dedicated to discussion and technical support centered around the LittleRP affordable, open source 3D resin printer.
HTL
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Flexvat V5, the best of both worlds.

Postby HTL » Sat Feb 18, 2017 11:03 am

I have been getting requests for a vat that supports the FEP film release layer on a sheet of transparent acrylic. I have resisted designing a vat with an acrylic window for a couple of reasons first of which is the inferior release characteristics of a vat that uses FEP film sitting on a support. When FEP film is sitting on a transparent window it does not easily flex upwards when the build plate rises during the peel stage of a layer exposure because of it being stuck to the support plate due to vacuum and other issues. A big reason that drumkead flexvats work so well is the fact that when the build plate rises the FEP film can bulge slightly upwards and peeling edges tend to develop at any edge that is touching the FEP film so peeling starts pretty much anywhere it needs to, this is not the case for FEP film sitting on a support, on a support FEP film acts as a rigid "plate" rather than a flexible "drum". The bottom line is that drumhead flexvats when properly tensioned work and vats with supported FEP film work less well and I was not willing to put a vat into the wild that worked less well.

The people who asked for a vat design using supported FEP film do however have valid reasons for wanting such a vat. At the top of the list seems to be user friendliness, a vat with supported fep film doesn't require tension adjustments, also, the film is more resistant to puncture due to catastrophic build failure ("hey joe the stiletto build just went south"). A lower focal plane is also often mentioned.

I think I have a design that will both satisfy the need for a "supported" vat and a "drumhead" vat in a single package that has the advantages of having both a lower focal plane and fewer parts while allowing vat users to switch between the two vat types. The new vat uses transparent acrylic inserts (drumhead and supported) that are held against the FEP film under tension by a snap in retainer. The snap in retainer allows you to change the vat type when needed (if you need the lowest possible release forces use the drum insert, if the release force is not so critical use the support insert)

I will finish my testing on the vat next week, if everything pans out the vat should be available in a week or two over at flexvat.com.

HTL

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goopyplastic
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Re: Flexvat V5, the best of both worlds.

Postby goopyplastic » Tue Feb 21, 2017 8:21 pm

Really nice work, I like the embedded rivnuts.

Yianni-VJ
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Re: Flexvat V5, the best of both worlds.

Postby Yianni-VJ » Tue Feb 21, 2017 11:35 pm

I also like it very much !

Can you tell us what is the distance from the focal plane to the bottom of assembly?
Depicted is the unsupported configuration, correct?

cerriousdesign
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Re: Flexvat V5, the best of both worlds.

Postby cerriousdesign » Wed Feb 22, 2017 10:22 am

This is very exciting news indeed. The focus length looks much closer, like the petri. Following closely.

HTL
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Re: Flexvat V5, the best of both worlds.

Postby HTL » Wed Feb 22, 2017 11:54 am

From the bottom of the base plate to the focal plane is approximately 10.5mm ( I may need to increase that to 11mm to better accommodate the molded in threaded inserts). The focal plane is the same for both supported and "drum" configurations so no adjustments are needed when switching between the two inserts. The unsupported "drum" configuration is shown in the photos, the only difference between the supported insert and the drum insert is that there is no cutout in the supported insert. Also, the base plate and inserts are compatible with the current LittleRP top plate/vatwall so I will probably have that part available separately for those who have the LittleRP vat but want to use the convertible base plate.

HTL

obelix
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Re: Flexvat V5, the best of both worlds.

Postby obelix » Mon Feb 27, 2017 5:14 pm

Hello,

I made something crazy and found the solution for me.
I have on the side, on which the FEP foil rests, sanded the acrylic plate with a very fine sandpaper (800..1000), diagonally crossed (only one-sided!).
The FEP foil now does no longer adhere to the acrylic floor.
In the edge area, I made holes in the acrylic floor to ensure, that the FEP foil is vented.
But the FEP film has then to be tensioned, then it works almost like an one-sided Flex-Vat.
At my resolution of 100 microns in XYZ direction I could not notice any impairment of the printing quality,
also the exposure time remained the same.
Now I can exposure the total area of ​​192x108mm at once , and there are no more problems with the peel process,
and this without tilting.
Previously, this was impossible, also with Tilt.
The distance for the light scattering between the polishd side of the acrylic plate to the exposure layer is here only the thickness of the FEP film. However, I can not say how this works with lower resolutions in XY.
For my needs, however, it was the final solution.
Last edited by obelix on Tue Feb 28, 2017 12:19 pm, edited 3 times in total.

HTL
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Re: Flexvat V5, the best of both worlds.

Postby HTL » Tue Feb 28, 2017 10:19 am

Vents do help, I have a "vented" insert for the vat that is not shown in this thread but is shown here: . To help break the vacuum between the FEP and the acrylic insert I am testing a few things but the simplest solution seems to be to put a line of thin tape along the edges of the insert that overlaps the vents, the tape slightly lifts the edges of the FEP film away from the face of the insert so that when the printed part needs to peel there is a path for air to enter the space between the FEP film and the insert. The main issue with a vented insert is that when the vat is cleaned liquid can get between the insert and the fep film which would require you to remove the insert when cleaning the vat. I am also testing an insert that has had one face slightly abraded (I put the laser cut insert with the protective paper removed from one side into a vibratory tumbler filled with sandblasting medium for a short time).

HTL

HTL
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Re: Flexvat V5, the best of both worlds.

Postby HTL » Wed Mar 01, 2017 11:13 am

Vented vat insert :

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Bottom
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HTL

goopyplastic
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Re: Flexvat V5, the best of both worlds.

Postby goopyplastic » Wed Mar 01, 2017 12:53 pm

Really smart leaving the film on like that!

cerriousdesign
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Re: Flexvat V5, the best of both worlds.

Postby cerriousdesign » Thu Mar 30, 2017 11:31 pm

Any updates on the new Flexvat V5, looking forward to it.


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