Plexiglass Barrier for a flat PDMS and smooth edge

B9Creator - Ideas and Discussions
Guest

Plexiglass Barrier for a flat PDMS and smooth edge

Post#1 » Tue May 13, 2014 4:30 pm

Hi

I made a plexiglass barrier and i glue it on my original vat.
As we can see on those picture and my 2d sketch.

The point for the plexiglass barrier is that we can cure the pdms perfectly flat in 48h without the need of cutting any extra pdms.
(as the exemple of a clamp in a other topic !)

I use only 25 gr of PDMS for this vat
While the PDMS is curing the excess of liquid will overflow on the deeper side of the vat and leave a smooth edge and a flat table.

We can see on the reflection of the PDMS, it is perfectly flat !

A other thing with the bridge is that the PDMS is always at the same height !
And it is very hard for the resin to go under it

I think that if all our vat was made this way, (PDMS calibrated at the same height) with a bridge, we would have no problem changing the vat without re-calibrating the built table. even in a pause print, because every VAT would have the exact same height of PMDS.

I did't test to change the PDMS without re calibrating the built table because i have one vat curing while a other working so i always re calibrate the built table. and i made the bridge by hand, so i can't make two exactly the same it would need (micro precision)

The only thing about the barrier is when the PDMS is curing the vat need to be perfectly level with no mistake

But it never happen yet and i always have a perfectly flat PDMS cure in 48h.

Am not use to speak or write in English !
i did my best !
Thanks for reading !










Image
Image
Image

User avatar
akgold
B9 Wizard
B9 Wizard
Posts: 2094

Plexiglass Barrier for a flat PDMS and smooth edge

Post#2 » Tue May 13, 2014 5:22 pm

your English was just fine you did good.
Looks interesting how are the prints coming out?
I'm so far behind I think I'm First !!

User avatar
Robert Howle
B9 Creator
B9 Creator
Posts: 6626

Plexiglass Barrier for a flat PDMS and smooth edge

Post#3 » Tue May 13, 2014 6:49 pm

As long as the PDMS has enough volume to just overflow the barrier it should be fine as long as the overflow went past the dam and sealed to the bottom of the vat. I use overlift on all prints so I don;t think it would be a problem just has to be in same plane ( top edge, left to right, has to be in a plane parallel to the waterfall, and slightly below. Also thick enough to withstand the movement of the table and prints when breaking the suction.

Am I getting this or am I incorrect.
Dance like nobody's watching!

etienne
B9 Maker
B9 Maker
Posts: 152

Plexiglass Barrier for a flat PDMS and smooth edge

Post#4 » Tue May 13, 2014 8:52 pm

It looks like an interesting idea.

Although I have to say that I prefer to have a VAT made out of aluminum and glass, such as kirk designed it.
Mike's new approach with the Cliff versus the waterfall seems to make everything even simpler, and seems to even improve print-quality.
So why re-invent the wheel?

User avatar
brumbaer
B9 Maker
B9 Maker
Posts: 343
Contact:

Plexiglass Barrier for a flat PDMS and smooth edge

Post#5 » Tue May 13, 2014 9:05 pm

The method is not limited by material, you could use it with a metal/glass vat as well.
I find the idea intiguing. It wll give quite consistent Pdms levels.
You might still want to calibrate the platform to compensate for possible pitch and roll - as small as it may be.

Guest

Plexiglass Barrier for a flat PDMS and smooth edge

Post#6 » Wed May 14, 2014 12:21 am

HI

akgold Thank you

Robert-Howle Yes the PDMS need to overflow ! And the PDMS is practically impossible for the machine to ''un-stick'' the PDMS accidentally

etienne as brumbaer say, this method can be apply to any material ! and it is a very small modification. steel plastic Plexiglas aluminium.

brumbaer Yes it is true that it would be better to re-calibrated the built table each time ! a small roll on the length is permitted but not on width of the vat, We just need to use a level.

Why i came with this idea !

Because i never use a oven to cure the PDMS and i never succeed to print with the CHERRY resin with the default setting.
Because the PDMS while curing in 48h, the center of the mass is lower than the perimeter of the mass.
And for the CHERRY, the PDMS need to be perfectly parallel with the built table.

When i did this modification i was so sure about it, that my first print was made with the cherry using the default projector setting ! it was my first success with cherry (with default setting), and until this small add-on i don't have problem anymore. i made so many print with that VAt with only the matter of re-coating when foggy and wait 48h

No cutting no clamp no temp-barrier.
I think it is a very simple solution for user that cure the PDMS in 48h

This small barrier now is permanent.

Before that method i was installing a temporally very high Plexiglas barrier while the PDMS was curing, same way of the clamp !
After i was using a surgery blade (same we cut rubber mold in jewelry) to re-cut the cliff, and remove the Temporary barrier
(i put some silicone oil on the temporary Barrier to avoid the PDMS to stick to the barrier) I remove the temp-barrier after cutting
to leave a sharp 90 degree cliff.
Using this method ! it was printable but i always had a lower level of PDMS on the center of the mass.

And from that experience i can say that cutting the PDMS ! even with a surgery blade it is not a joke, i had to use some hand soap on the blade because the PDMS is extremely sticky and it is easy to damage or un-stick the PDMS while doing the cutting.

The principle of my new Barrier, is to use the way of nature make the liquid flow.
Fill a cup with water to the top and let it overflow slowly and look at the result of how the water stay on top of the cup like a little bump !
still the PDMS silicone is more fluid than water !

I have to say that English is far from my comfort zone and if i post this it is because i really think that is a good solution.

The B9 Creator is a AMAZING machine open source i read and learn a lot in the forum so i think it time for me to put a little of my experience because this is the point of open source i guess !
Am not trying to reinventing the wheel or confuse any started project.

I have two other concrete picture to show the result but i don't see how to post them..

Thank for the reading

tobyramp@hotmail.com
B9 Maker
B9 Maker
Posts: 255

Plexiglass Barrier for a flat PDMS and smooth edge

Post#7 » Wed May 14, 2014 1:04 am

Thank you for sharing. I think it is a great idea.

kirkrhino
B9 Maker
B9 Maker
Posts: 202

Plexiglass Barrier for a flat PDMS and smooth edge

Post#8 » Wed May 14, 2014 6:35 am

Looks like a great method for those who don't want to bother with ovens.. : )

So there is no meniscus sticking up at all? Must be exact perfect size radius built into the barrier? Interesting.

You will still have the "downward suction" Mike speaks about because it still has traditional "waterfall"?

But you said this prints better for you than the edge when you trimmed with blade?

Thanks for sharing! Food for thought. Glad it's working well for you!

And yes, agreed, trimming with a blade is not exactly a walk in the park, takes more time.. and a bit of getting used to. : )

Best, Kirk

Atso
B9 Maker
B9 Maker
Posts: 29

Plexiglass Barrier for a flat PDMS and smooth edge

Post#9 » Wed May 14, 2014 7:37 am

This looks like a great idea! I also cure at room temperature over 48 hours so as to ensure level and have reported in another thread on the problems that this gave me. As I reported there, the problem was solved by adopting the dam and cliff edge approach. This barrier technique solves the taper problem of a slow cure over the waterfall and avoids the problems of cutting the PDMS. It also introduces a defined curve to the edge of the PDMS that may eliminate the need for over-lift.

User avatar
mikej
B9 Moderator
B9 Moderator
Posts: 4190
Contact:

Plexiglass Barrier for a flat PDMS and smooth edge

Post#10 » Wed May 14, 2014 8:03 am

I think this is a great idea, my only concern would be how fragile the thin pdms layer over the waterfall edge would be. Maybe it's not an issue?
Measure Twice, Cut Once.

Guest

Plexiglass Barrier for a flat PDMS and smooth edge

Post#11 » Wed May 14, 2014 12:07 pm

kirkrhino Yes because i never had the advantage of curing the PDMS in a oven, i search a way to cure at the room temp !
There is really 0 meniscus at all this way.
For the "downward suction" am not so sure to understand it !
For me i had less trouble with this solution than the trimmed edge. with the trimmed edge while cleaning i had to be careful to the trimmed edge for not to un-stick the PDMS because it is more susceptible to un-stick ( and it happen to me that the water go under the PDMS while cleaning and its not pleasant ) but i saw your solution to put a second time new PDMS on the deeper side of the VAT that would prevent anything to go under the PDMS. The meniscus trimming solution is very good but with this solution there is nothing to trim and i am sure that user using a oven for curing and the Bridge solution would make perfect PDMS ! better than 48h cure !

Still i really like your VAT and i have the intention to have one :)


Atso With this Technique i never use any over-lift not even on the initial layer setting ! i just increased settle time and lower closing speed to 50%

mikej I never had any issues with the thin pdms layer over the waterfall edge. because there is no thin layer !
the pdms separate on the top of the bridge ! and the top of the bridge is fillet and smoothed with fine sand paper.

Back to the example of the cup !

If you put water Half the cup, you will notice meniscus all around the border
but if you make the water over flow you will notice that there a ''inverted meniscus''

But the silicone is more fluid than water !

When i put the PDMS in my VAT, the first 12h there is a ''inverted meniscus'' at the bridge ! after the PDMS start to slowly Over Flowing on the Bridge until the ''inverted meniscus'' disappear and become a perfectly flat surface.

I hope that we all understand !
I have difficulty to express my self..

I am willing to send my VAT to a experience user to make the experience himself !!
If possible MIKEJ are you able to receive my VAT to take a look and make the experience on it ?
The only thing about this vat is that it is not nice as in the picture anymore ! i print a lot with it since !

Thank you all !
Image
Image

User avatar
akgold
B9 Wizard
B9 Wizard
Posts: 2094

Plexiglass Barrier for a flat PDMS and smooth edge

Post#12 » Wed May 14, 2014 1:58 pm

Just a suggestion for you curing without an oven.
If you can take some Plastic wrap ( what we call it here is saran wrap) and cover the vat or somehow place a black cover over it in the sunlight it will cure faster than 48 hours.
I can imagine it to be difficult to do this but any heat source you can get to the vat will reduce the time it takes to cure.

150 deg/f cures it in about 2 hours. that temperature could be archived even by using a solar oven.
I'm so far behind I think I'm First !!

User avatar
mikej
B9 Moderator
B9 Moderator
Posts: 4190
Contact:

Plexiglass Barrier for a flat PDMS and smooth edge

Post#13 » Wed May 14, 2014 2:10 pm

Solar powered vat ovens. Somebody should do it!
Measure Twice, Cut Once.

User avatar
mikej
B9 Moderator
B9 Moderator
Posts: 4190
Contact:

Plexiglass Barrier for a flat PDMS and smooth edge

Post#14 » Wed May 14, 2014 2:11 pm

No need to send one, too busy here to test right now. But it sounds like it works great, thanks for sharing!
Measure Twice, Cut Once.

cl2635
B9 Maker
B9 Maker
Posts: 371

Plexiglass Barrier for a flat PDMS and smooth edge

Post#15 » Wed May 14, 2014 2:53 pm

instead of the plexiglass barrier, I'm wondering if its possible to make one out of high heat silicone (the type they use on a cooking spatula).. Might be softer/flexible and still hold back PDMS

User avatar
mikej
B9 Moderator
B9 Moderator
Posts: 4190
Contact:

Plexiglass Barrier for a flat PDMS and smooth edge

Post#16 » Wed May 14, 2014 3:30 pm

That's a great idea. I wonder if PDMS sticks to silicone.
Measure Twice, Cut Once.

Guest

Plexiglass Barrier for a flat PDMS and smooth edge

Post#17 » Thu May 15, 2014 12:13 am

akgold Thank you for the suggestion, it is ecological to ! in my case i am not worry about the time because i use 2 VAT, i will keep your thecnicque in mind :)

cl2635 You know it is very good idea ! the only thing about high heat silicone it need metal mold and Vulcanizer machine, and we have one in the shop for rubber mold and we make vulcanize silicone mold. we only need a perfect aluminium mold in two part and a small production may start ! (it can be one big 2 part mold that can make 50 bridge at the time) To make a mold like this it would be good to have a 3 axis cnc that i don't have !

As Mikej we need to see how the PDMS and the silicone will react together if they don't fuse, we can still use traditional Castaldo rubber put if the plan is to put it often in a oven, the rubber will quickly deteriorate.

Or we can make a simple open source mold to print with the B9creator that user can make PDMS bridge that we install before each re-coating !
It is a good start !
Vertically we may be able to print 20 Resin mold at once. and make 20 PDMS bridge each time (if we want to) and we already know that the RESIN and the PDMS as no reaction and don't stick together.

I really thing this will help user using a 48h PDMS curing, to have perfect flat surface.

cl2635 you had a very good idea ! (cl2635) is already a good name for a silicone Bridge ;)

In my plan ! any new vat i will buy, i will find a way to make a bridge, because i have the best 48h VAT PDMS coating each time this way
In my experience !

For the ''downward suction'' ! i made my home work, i read on it yesterday :)

Its seem that i don't have any downward suction, i print the other day a very fine circular little spring with the cherry with not much support, and it came out really good ! i will post a picture tonight. (if i don't make any bike accident !)

User avatar
Robert Howle
B9 Creator
B9 Creator
Posts: 6626

Plexiglass Barrier for a flat PDMS and smooth edge

Post#18 » Thu May 15, 2014 4:26 am

When all is said and done you can always coat the whole vat and just use the "no dam" method. When I'm in a hurry that is what I do. I still do the half vat coating myself. Kirk's method with the tape still works well, and even good with the dam he just created.

Robert
Dance like nobody's watching!

Guest

Plexiglass Barrier for a flat PDMS and smooth edge

Post#19 » Thu May 15, 2014 3:14 pm

Hi

I was thinking about all this during the day and i think it will be to much work !
Compare to the simplicity of the modification that we can do it our self.
We can even use wood ! if we can't work with Plexiglas.
I think that a VAT already built with a barrier would be great, but i can't prove my theory enough for the moment !

On my side i really believe that with the bridge it is simpler in all the way.
because there is no tape dam clamp oven or cutting involving this method. and the result is very good (for me i say perfect)
And maybe no need of recalibrate the buit table if all Vat are leveled the same height.
And if we want to avoid a waterfall the bridge can be install at 90°.
This is why i wanted to have a second user to experience this technique to have a second thought about it.
If its a fail but at least we would have try it !

The bridge is a very small modification for User that would like to try it !

So to make everything more simple !
I have a other vat that i want to install a barrier on it !
I will make picture of the step by step of what to do !
And interested user still can make this Easy modification !
I will show how i make the bridge, how i install it
and I will demonstrate the result of how the PDMS flow while Curing for User to understand it. all with picture

I would need 2 week. ( if i don't make a bike accident ( living in Montreal ! )) : )

Here is the picture to show that i don't have any ''downward suction''
But it may be the fact that it was print inside a Ring diameter and that the ring absorb the suction instead of the little spring !

Thank for the attention !
Image

User avatar
Robert Howle
B9 Creator
B9 Creator
Posts: 6626

Plexiglass Barrier for a flat PDMS and smooth edge

Post#20 » Thu May 15, 2014 6:41 pm

NIce print, what is the diameter of the "spring wire"?

Robert
Dance like nobody's watching!

Return to “General Discussion”

Who is online

Users browsing this forum: No registered users and 1 guest

cron
Close Menu Shop Forum