New Vat; PDMS leaks through waterfall

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cassio
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New Vat; PDMS leaks through waterfall

Post#1 » Sat Sep 12, 2015 11:17 am

Recently purchase a new vat through the website, I used it a couple times and then had to replace the pdms. When it was done curing I noticed there was a puddle of pdms on the counter where it cured. I looked under the vat and noticed pdms is leaking through around the clear window and the waterfall area. I haven't use the vat since I noticed the problem and after sitting for a week or so the pdms now has air pockets under it. What should I do? Thanks in advance!

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akgold
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Re: New Vat; PDMS leaks through waterfall

Post#2 » Sat Sep 12, 2015 2:07 pm

This would be better sent as an Email to customer care.
I would imagine they would exchange it for another one.
Tim
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Robert Howle
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Re: New Vat; PDMS leaks through waterfall

Post#3 » Sat Sep 12, 2015 9:27 pm

Why only two prints and then needed a new PDMS (damage or fogging). What resin are u using?


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jamest42
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Re: New Vat; PDMS leaks through waterfall

Post#4 » Mon Sep 14, 2015 12:12 am

I've encountered the same problem. So this seems not to be a unique case.

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Robert Howle
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Re: New Vat; PDMS leaks through waterfall

Post#5 » Mon Sep 14, 2015 2:44 am

Leaking before or after PDMS replacement.

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cassio
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Re: New Vat; PDMS leaks through waterfall

Post#6 » Mon Sep 14, 2015 10:27 am

My pc did an auto update during a print. It wiped out a square in the middle of my pdms so I had to change it out. It was not leaking before. I did send a message to the B9 cust. serv.

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akgold
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Re: New Vat; PDMS leaks through waterfall

Post#7 » Mon Sep 14, 2015 1:04 pm

cassio wrote:My pc did an auto update during a print. It wiped out a square in the middle of my pdms so I had to change it out. It was not leaking before. I did send a message to the B9 cust. serv.


I am guessing you did turn off auto updates as well as any PC security scans since this happened?
Is the computer your using to run the B9 connected to the internet?
If it is then any auto updates or scans will happen unless you set it to manual update or download update to install later
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Robert Howle
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Re: New Vat; PDMS leaks through waterfall

Post#8 » Mon Sep 14, 2015 1:43 pm

How much PDMS did u use. I use 66 grams.

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jamest42
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Re: New Vat; PDMS leaks through waterfall

Post#9 » Thu Sep 24, 2015 3:16 am

Robert Howle wrote:How much PDMS did u use. I use 66 grams.

Robert


Yes, I also used 60+6=66 gramms.

But I just received a new vat as warranty replacement. So just do the same...

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BruceTrick
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Re: New Vat; PDMS leaks through waterfall

Post#10 » Thu Nov 12, 2015 7:28 am

I've also just started having this problem. I've re coated PDMS more than a few times now and this just started happening. Not sure why the resin is getting under the PDMS layer but as soon as I see the fogging, I know what's happened. It's a super pain to clean off the window but it can be done.

Any ideas as to why this is happening? I'm also using 66ml of resin, same as I always have. You can see I have good coverage.

I have just changed to 50xy 30z and re-calibrated everything. I did one print successfully and then this happened. It's like the build table is hitting the pdms on the opening of the shutter maybe? I'm not sure how else it can leak in. Maybe my build table is calibrated too 'heavily' and it's dragging on the shutter opening? Which would mean I should increase the initial overlift. Is that correct? Not sure, just some thoughts. I'm thinking it's the overlift issue because I did a table calibration and the B+ side pegs are clipped off... the same general position where the lifting occurred. Thoughts on this?

Thank you for any input you can give.

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mikej
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Re: New Vat; PDMS leaks through waterfall

Post#11 » Thu Nov 12, 2015 7:36 am

If the pdms is thicker/thinner front to back (ie, the vat wasn't completely level front v back) then the dam flow over may not be as consistent and that can lead to this issue. Especially if the sweeper get's bent and starts going over the dam, or if a part is dangling (detaching from the build table or not enough supports) and hits the edge of the dam during the release/re-position cycle.
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Metalcaster
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Re: New Vat; PDMS leaks through waterfall

Post#12 » Thu Nov 12, 2015 7:41 am

what I see is a large amount of pdms on the other side of the the tray. Almost complete coverage.
Thats not normal with 66 grams of pdms... it would normally just fill the overflow.
I believe what Mike said would be correct. when you made the new pdms, your tray was not dead level flat
when the material cured.

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BruceTrick
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Re: New Vat; PDMS leaks through waterfall

Post#13 » Thu Nov 12, 2015 12:46 pm

Great thank you guys! I'll check the level that I'm using and re-coat.

Cheers!

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Robert Howle
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Re: New Vat; PDMS leaks through waterfall

Post#14 » Thu Nov 12, 2015 5:26 pm

I would suggest u chect the vat window for level and not just the surface u place the vat on.

Picture of the level i use for coating and for oven shelf leveling.

Level for oven.jpg


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cassio
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Re: New Vat; PDMS leaks through waterfall

Post#15 » Tue Nov 24, 2015 10:27 pm

I received a replacement vat a while back for the original one that was leaking liquid pdms near the dam area. I used it for a while and then needed to replace the pdms. Now I am having a new problem. I removed the old pdms and mixed the new batch 66mls. I poured the pdms in the vat and waited about 30 minutes, then I popped all the bubbles that were remaining with a needle. I let it sit about another 30 minutes then I placed it in the oven level and cured it for about 1 hour 30 minutes at just under 200 degrees. When I removed it from the oven It had a cluster of larger bubbles near the dam area and a defined line of smaller bubbles that traced the outside of of the pdms where the window meets the vat for joining, so basically a defined rectangle trail of small bubbles. As a result , due to the large cluster of bubbles, the build table will not seal flat against the pdms for a good build table calibration.
I thought that maybe the glue that joins the window to the vat did not make a good seal (just enough to keep the pdms from leaking out) and was allowing air to creep up through the seal when it got warm during curing. I removed the pdms and went to hardware store and purchased a two part epoxy and made a nice thin filet of epoxy on the bottom side of the window/vat joint and let it sit for a day. Today I mixed up some new pdms and followed the same steps that I did previously, same result! Bubbles in the pdms near the dam and in the rectangle pattern around the window. I wasn't asked to return the original vat that leaked so I used the same epoxy on it and got the same result. Any clue what I am doing wrong? Thanks

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Robert Howle
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Re: New Vat; PDMS leaks through waterfall

Post#16 » Wed Nov 25, 2015 3:57 am

U are not suppose to let the vat get near 170 degrees, that is the maximum. I cure in the oven at 150 F for 2 hrs. There have been many posts about this. U will destroy the "Window" if u go over 170 degrees F.

It's best to ask questions before u do things like this, if u are not going to read the documentation.

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cassio
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Re: New Vat; PDMS leaks through waterfall

Post#17 » Fri Nov 27, 2015 8:52 pm

Thanks for the input RHOWLE.
I didn't see any info in support videos or in documentation on what temps to oven cure the vat!! Believe me I did look. Please point me towards that "Documentation"...although I did read several threads where it was stated not to get it near 170°
My oven has "warm" as first option in temperature and next is 200°. I actually set it halfway between warm and 200°. I used two different thermometers today and found one read 148° and one read 158°.

Does anyone have any ideas why I am getting bubbles? I believe my vat was clean, dry and free of any debris before I started. When I added the pdms to the vat I made sure to spread it around the vat and push it into any corners.

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Robert Howle
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Re: New Vat; PDMS leaks through waterfall

Post#18 » Sat Nov 28, 2015 4:32 am

Watch the vat recaot video in the "Support" section. There is no mention of heat curing, but when we first started recoating vats we had acrylic vat, then moved to metal and glass. With the metal and glass you could go a little hotter than with the new improved poly vats. Because of this we started posting questions relating to max temp for curing to avoid the 48 hr curing time. Mike answered with info regarding the window and the fact that temps above 170 F could damage (cause the window to distort or droop).

Before u pour in the PDMS, and after leveling, elevate the end away from the "window" about 1/2 inch. After most of the bubbles break, lower it back to level. U should not have to "push" the PDMS around.

The vat needs to be clean and dry. After many many recoats I have only had one vat with bubbles and I figured it was due to moisture or an unclean vat. I clean my vats throughly for the recoat and dry, then I remove the old PDMS, avoid touching the area to be recoated.

The bubble issue is all about clean, dry, and technique. When I move my vats to the oven (leveled glass shelf) I preheat the oven to 150 F and "cook" for 2 hrs. My oven has a convection fan to distribute heat more evenly, this avoids hot spots, especially when the bottom elements are being used. I "cook" on bake (this uses only the bottom elements. Broil uses the top elements. You may try that and check your results. Maybe start from room temp and heat from there to the 150 F.

As far as "documentation", it is in the threads with regards to the temps when oven curing. If u are going to do anything that u don't see explained in the "documentation" ask questions on the forum, there are always many willing to help based on experience.

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scottkeatingdesign
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Re: New Vat; PDMS leaks through waterfall

Post#19 » Tue Dec 29, 2015 5:31 pm

I just recoated one of the new Vats and it is leaking from the side seam of the window. Making a mess of my hot box! How many people are having leaking issues with the new Vats? On the two that I have, it does not look like the glue seam is very clean.

Scott

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scottkeatingdesign
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Re: New Vat; PDMS leaks through waterfall

Post#20 » Tue Dec 29, 2015 6:35 pm

Also, just to check, I put water in the second VAT that I was recoating and that one is leaking too, at the dam seam. I will try and add some epoxy and see if I can seal it that way, as I need to print! Should I return them to the factory? These are both the first recoating's.

Scott

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