Possible New Vat Idea for Mike

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Metalcaster
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Possible New Vat Idea for Mike

Post#1 » Sat Nov 29, 2014 4:29 am

After running the B9's for a long time, I am wondering if the waterfall or cliff Idea is needed.
The reason I say this is that the second the tray begins to move to the closed position, The components on the platform have already been released from the PDMS tray or the Evert glass, so a slight rise for safety after moving about 10mm is all that is needed.
What that allows is a tray built with 1 long piece of glass from one end to the other. Now, when you pour the pdms and cover the whole glass bottom of the tray, you can now use both sides of the tray for growing purposes by reversing the tray when the pdms on one side is used up.

Any reason this won't work? The other thing this would do for the tray is give a perfectly flat bottom from one end to the other. When glueing the glass down with a simple jig, this would help align and flatten the aluminum tray as well, giving you a much better tray bottom.

I bring the idea of the long flat bottom up as 2 out of 3 of my aluminum trays were warped when I received them and leaked. I had to remove the glass and re-apply it after straightening the aluminum... not hard to do and not a complaint... it can happen.

In the case of the Evert Glass being done as 1 long piece, this may eliminate having to recalibrate when changing trays as there is no pdms to create different thicknesses.

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mikej
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Possible New Vat Idea for Mike

Post#2 » Sat Nov 29, 2014 4:43 am

I did a lot of testing with this "no cliff" method early on (with pdms), it did not work with larger items as the "lift to the next layer and slide" did not refill the gap (suction force too great). Might work on ring sized items and the ability to just "flip the vat" for another use on pdms would be nice. Someone could mod. a vat now and just print with zero overlift to test.
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Robert Howle
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Possible New Vat Idea for Mike

Post#3 » Sat Nov 29, 2014 4:57 am

The reason for the waterfall or cliff is to break the suction caused by the liquid and the seal it creates. if u want to test that put resin in the vat push the build table against the glass or PDMS and try to pull it straight up or slide it to the left and try to pick it up without tilting.

I had the waterfall (almost non existent) in one coating and the build table would try to pick up the vat even when it had moved all the way to the right. The suction is very strong.

Edit: Was posting at same time as Mike.

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Possible New Vat Idea for Mike

Post#4 » Sat Nov 29, 2014 5:42 am

I was not thinking of lifting first, then slide... I was thinking of starting the slide and when the slide got to a sufficient distance, begin lifting the platform while it is still sliding. I understand the concept and it would probably work for someone doing builds in the 30x30 area... giving them the maximum pdms use. specially when they can move it around on the platform on both sides. Just a thought really.

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Possible New Vat Idea for Mike

Post#5 » Sat Nov 29, 2014 5:45 am

The problem is that the suction is the greatest at the beginning when u just have attachment layers (even with small items) and u are dealing wiht the entire build table surface regardless of print area. Thinner the slice stronger the suction is.

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Possible New Vat Idea for Mike

Post#6 » Sat Nov 29, 2014 6:14 am

Quote from Metalcaster on November 29, 2014, 12:42
Just a thought really.


A good thought, I think. That's why I suggest someone using 30XY give it a try. No need to rewrite the software, just run it at zero overlift and it should work (if it's going to). At zero overlift, it would slide all the way right, lift ever so slightly (30 microns z for example) and slide back left. That "should" be enough to fill the gap for small items done at 30 XY.

You wouldn't even need to mod the vat, just fill it flat all the way across with pdms (as a test of the idea).
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Robert Howle
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Possible New Vat Idea for Mike

Post#7 » Sat Nov 29, 2014 6:55 am

A level PDMS will be critical at 30 z lift any slope (thicker on right side will be bad). Am I thinking wrong here.
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Possible New Vat Idea for Mike

Post#8 » Sat Nov 29, 2014 6:57 am

All you need then in this case of a flat glass vat no water fall is a V shape dip in the very middle of the vat to release suction from either side.
then you could switch the vat. around and use the other side as the V in the middle will be the same.
and then you could add a lift at XX degree at or after the center position was achieved but you would always have to use a base foundation layer because not all of your individual supports and build items will have released the suction. so the lift would have to happen somehow at the end of the last layer. or it would still have to shift all the way left to be safe. even though you could still use the whole bottom of the vat with a glass.
Just cut out the center of the vat to match the ope area already there and get the glass to fit it.
Now if it were possible to do this without a release you could then have another calibration setting for the X to start printing and return to that same area each time. better yet you wouldn't even have to return the vat to the same position each time because it could land anywhere in the X slide sideways.
Even now if we could control the side direction's stop and start point you could use all of X area by stopping the position of the vat in a different place on the return to the open position.
I have always wondered why it can't stop in a different spot then always in the same place causing the PDMS to cloud that area. then again I am only printing in the smallest area of the table at 50.
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Post#9 » Sat Nov 29, 2014 7:10 am

If this got figured out, it may be possible to print on both sides of the vat during the same printing session... Not sure how much added software would be needed. I don't think any machine on the planet is doing that!:-)
If I had my machines set at 30,I would test it... I may try it a 50xy with just some small parts on it during next week and report back..

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Post#10 » Sat Nov 29, 2014 8:13 am

Quote from Metalcaster on November 29, 2014, 14:10
If this got figured out, it may be possible to print on both sides of the vat during the same printing session... Not sure how much added software would be needed. I don't think any machine on the planet is doing that!:-)
If I had my machines set at 30,I would test it... I may try it a 50xy with just some small parts on it during next week and report back..


I've tried that too, the only downside is there is no longer a way to block the light (closed position). This is actually important when turning on and warming up the projector. BTW, don't sit a piece of paper on the lens to block the light, it can catch on fire... 8O
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Robert Howle
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Possible New Vat Idea for Mike

Post#11 » Sat Nov 29, 2014 9:39 am

Could u just use a piece of square or rectangular "refrigerator magnet" material to just stick over the "window" until warmup was over, then pull off when vat cycles before the first layer. Just thinking out loud.

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akgold
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Post#12 » Sat Nov 29, 2014 10:05 am

mmm Mike brings up a challange.
maybe a piece of tin foil on a spring loaded roller attached to the underside of the vat in the middle with a spring attached to it so when the vat slides over the foil is pulled over the opening
ok this is getting to be too many moving parts
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Post#13 » Sat Nov 29, 2014 11:01 am

I think Mike has already gone through all the scenarios on this one :-)

It can be done, just cost a whole lot more... Probably incorporate an Iris system like exists on a camera... just bigger so it fits over the Lens of the projector. That can be opened and closed through software or mechanical switching... then you could have 2 sides printing

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Post#14 » Sat Nov 29, 2014 1:10 pm

Perhaps using 2 pieces of glass and leave the center separation as the cliff ( or 1 long piece of glass). Now if you wanted to reverse, All you need do is put a black painted piece of steel and a couple thin glued high power magnets on the bottom of the aluminum tray to hold the thin steel in place. The black steel can be used on either side , depending on what side you are growing on. That now gives you a 2 sided tray so you can pour the pdms 1 time and get 2 complete uses.

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Possible New Vat Idea for Mike

Post#15 » Sat Nov 29, 2014 1:38 pm

"I have always wondered why it can't stop in a different spot then always in the same place causing the PDMS to cloud that area."
AK you may be on to something. I have watch my friends dws printing and wondered why it prints in such a random pattern. the laser was shooting all over the place. My conclusion was it was to reduce heat on the silicone.
If the vat positioned at a different spot ever time it should have the same effect.

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Post#16 » Sun Nov 30, 2014 9:24 pm

Wonderful! I got the same on my mind - why not to open/close VAT to random positions? It should allow for much longer PDMS life. Should be very simple to implement in code, but downside - VAT coating should be very uniform and flat.
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Possible New Vat Idea for Mike

Post#17 » Mon Dec 01, 2014 4:12 am

I had originally tabled the random vat position idea because it doesn't work when you have a full build table (at low res). But I should revisit it, since many use less than the full build area. I'll bump up the priority on this.
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akgold
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Possible New Vat Idea for Mike

Post#18 » Mon Dec 01, 2014 7:11 am

Quote from mikej on December 1, 2014, 11:12
I had originally tabled the random vat position idea because it doesn't work when you have a full build table (at low res). But I should revisit it, since many use less than the full build area. I'll bump up the priority on this.


yes Mike it could be written in the SW to be used in only one config. of the say 50 or 30 but in 75 or 100 it would be a limited movement.
I could also be conf. to be "added" like auto generated supports. Identifying the outer edge limits of the largest area of the print by the layer say every 25 layers the shift or exposed area is redefined to another position based on the model think about it like following the outer shape of a curved vase. as the vase curves in the outer edges are smaller and the shift back to exposure position perimeters would be more than where the curvature is further out on the build where the shift would be limited.

It would definitely impact all the print times and settle times
I'm so far behind I think I'm First !!

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