GEN 2 ALUMINUM "KAT VAT" coming soon!

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akgold
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GEN 2 ALUMINUM "KAT VAT" coming soon!

Post#441 » Mon May 12, 2014 12:59 pm

.
I'm so far behind I think I'm First !!

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Post#442 » Mon May 12, 2014 1:19 pm

Hi Tim:

The mix ratio is 10:1. 20ML x10% =2 I have been using the 20 plus 2 all along, that's 10:1. The .2 of a gram just went over a tiny hair on the video mix, but no need to split hairs. .2 of a ml is not enough to change the ratio, especially if you are using a scale, it's maybe a couple of drops over at the most.

Doubtful that your PDMS has gone bad, but I guess it's possible if it ever got frozen or anything?

If bubbles are your problem, you can allow the mix sit longer before putting it in the oven,15-20 minutes all bubbles should be already be cleared out on their own, save you the work. I honestly can't endorse the put it on top of the heater method, does not sound like that has ever worked well in the past. If there is air coming out of the heater it's creating the swirls on the surface..

Otherwise, if the VAT is level, gravity does not lie, PDMS should come out perfect every time. Make sure you don't move the VAT once you put it in the oven?

If that does not work perhaps try the method for the plastic VATS. (plastic can't take over 200 degrees looks like). Do as metal caster suggests and go with 150 oF to 175 oF for 2 hours. When it cures slow like that the bubbles have much more time to clear on their own.

I wish I could fly out there and help you in person. With losing 3 coatings in a row perhaps your best bet is to keep it simple and coat like you would your plastic VAT, forget about I-beam for now? You are able to coat your plastic VAT OK in the past? There should be no difference, should be simple as pie. Mike has a video you can watch for a refresher.

Otherwise ship it back to me, I will coat it for you?

But I know you can do it! : )

Best, Kirk

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akgold
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Post#443 » Mon May 12, 2014 1:58 pm

that is what I am going to do Kirk,

i just have to wait till closing customers interrupt me.
as for the heater method I honestly have done this since I started replacing the PDMS always level on the heater and it is covered with aluminum foil so nothing gets in it and to hold the heat overnight. My thermometer showed my steam heat register to be 150-180 deg.f.
so that is why it sat overnight. I think I replaced it using that method twice since last Oct. And the method I used on the first aluminum vat.
I am doing something wrong here I never seem to have this problem with using a toothpick to swirl out the bubbles.
going back to basics here using the save method and tape 20:2

I honestly think that removing bubbles in the PDMS before pulling the tape or with mikes method for 50 g. of pdms it is constantly moving back across the window and down into the lower part so any disturbance of the surface is changed by the slow flow where the other way of it just stopping and setting at a static state doesn't allow the surface tension to be released and all the little marks made come out when it cures.
just my thoughts on it. so to test that theory I will (not this time I got to get this back to work) use the other vat build a dam remove all the bubbles rock it back over the window and allow it to slowly flow back in place then put it in the oven after it seem stable. I am betting it has something to do with the surface tension of the PDMS.
I'm so far behind I think I'm First !!

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Post#444 » Mon May 12, 2014 2:44 pm

Good luck Tim,

Not sure what else to say? Let us know how it goes.

Sending you out a "blue divider" to replace one you put in the oven- next post office run. : )

Eventually I should have some kind of I-beam that fits these VATS tightly to make the "I-beam" trim method simpler.

Working on it.

Best, Kirk

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Post#445 » Mon May 12, 2014 2:53 pm

Thanks Kirk,
it is in the oven now again.
using the tape method with 20grms.
this time I poured it in let it flow out then tilted it back to the glass so all the pdms flowed across the glass evenly.
let it sit blew on it no tooth pick this time. covered it let it sit for about 10min. while over warmed up.
10minutes to go at 275.
When you make the I beam it has to take the heat. of up to 300deg to be safe.
I like the seals on the sides it would be even better if the I beam had them as well as one along the bottom.
that is where it leaked out on my little experiment drilling the 1/8" and pining the blue dam to it.
Thanks for send me one I will pay for it I knew better.
Tim
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Post#446 » Mon May 12, 2014 4:00 pm

It's a fail

I am cursed
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mikej
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Post#447 » Mon May 12, 2014 4:40 pm

If I understand, you are getting "pot marks" in your pdms AFTER it's been cured?
I've never attempted to cure the pdms at temps above 190F. I wonder if something in the glass is out gassing at the high 300F and causing bubbles to form during the cure?
Have you tried curing at moderate temps, say 150F? It only takes a couple hours at that temp to cure, in my experience.
Measure Twice, Cut Once.

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Post#448 » Mon May 12, 2014 6:20 pm

Agree with Mike. I got my best results in oven at about 170F (75C). For me it takes about 2.5 hours. I always use two vats to have one in working order while have enough time to coat another with fresh PDMS.

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Post#449 » Tue May 13, 2014 7:49 am

thanks Mike,saab,
I will try that next.
the thing is I didn't touch this pdms except I lightly blew on it a couple of times to pop a few bubbles but let it sit for 30 minutes covered.
I looked at it and again the pdms was clear as glass. I use a black paper under it to see and a flash light. it was Pristine just like the one before it.
The pdms flow perfectly level after pulling the tape off ( using the 20grm pdms saving method that has worked in the past)
I did use the 250- 10min then 275-20min. the pdms was cured solid. there was an area this time like the other times where it looked like an area was touched and the pock marks were less but still there were plenty.
this time I removed the pdms very carefully as one piece. I used a razor to cut into those pock marks and each one of them had "wet" un-cured pdms that would ooze out using the razor blade on them. Mind you these pock marks are about only 1 to 2 mm.
so maybe I am not getting it mixed well enough? even though I think it is mixed thoroughly for at least 5 minutes.
I am not giving up but knowing that I will mix it even more now.
I will set it at 170 deg like you suggest. I will overcome.
Thanks
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kirkrhino
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Post#450 » Tue May 13, 2014 8:24 am

Hi AK,

What is the blowing on the PDMS about? Perhaps the condensation from your breath is ending up on the surface adding moisture to
the mix? I have heard some jewelers use the "oxygen" side from their torch on the PDMS to disperse bubbles, but would not suggest blowing on it.

Keep this in mind: At the (low) safe temps Mike mentions, the bubbles are never a concern., Just pop in oven, (make sure it's level) and don't touch it until it's finished.

Otherwise beginning to wonder if perhaps maybe your PDMS has gone bad? Is there an expiration date or something? Tim I think we are all as baffled as you are at this point.

There are at least 30+ others out there an not a single mention of such a thing by anyone else. Have never experienced such a thing myself.

If there is anyone else having any similar issues, please let us know?

Have no idea really what is going on. The glass is pyrex, (borosilicate)..can easily handle low or high temps in the oven. but again have had no issues myself or heard complaints @ higher ones. The PDMS by dow is rated to 300. But yes, please try @175. Bubbles have time to disperse on their own at that temp.

If there was just one other person experiencing the same problem maybe we would be onto something, but I have every confidence it has nothing whatsoever to do with the VAT if that's what you are thinking?

But if that's your conclusion, please will be happy to take it back immediately.., can't go on like this. : ) Too painful to see you having no success! Have exhausted all possible ways to assist.

Best, Kirk

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Post#451 » Tue May 13, 2014 8:35 am

What if his oven is not accurately calibrated... It could be hitting temperatures above 350 oF and combine that with the amount of time that it is in the oven, that would certainly spell disaster!
I use a lot of RTV rubber similar to the pdms ... they don't recommend going over 200 oF .
At 150 oF it cures in 2 hrs or less. At 200 oF it should be done in less time.( about 1 hr)

If you are at 300... you should be done in 10 minutes or less... perhaps by using high temperature, you need to reduce the time in the oven to 10 minutes... Just a thought.... or, just do it at 150 oF for 2 hrs... Better safe then sorry!

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Post#452 » Tue May 13, 2014 8:44 am

Only once I used my DIY vacuum chamber to remove all air bubbles from the mixed Sylgard prior to covering the vat. Then I got lazy and just waiting few minutes while shaking the vat from one side to it's other, letting the pdms to flow as free as it wants :D Thus way let's say more than 99% of bubbles disappears in minutes when passing the waterfall. Then I make the pdms flow all the way to the work zone (high one) and after that I put it in the oven (vat should be calibrated), which is already heated to 175F. Check your oven to turn off ventilation if it's equipped with and for best results set the oven to use both heaters (top and bottom). To avoid any fats and greasing from the oven I cover the entire vat with aluminium foil. All this is pretty much easy to follow and I got constant great pdms with nice waterfall each time.

Oh yes ... I used 600 grit sand-paper to make a small radius through whole waterfall line. No sharp waterfall edges - no more pdms rips at waterfall problems.

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Post#453 » Tue May 13, 2014 10:09 am

Quote from kirkrhino on May 13, 2014, 14:24
Hi AK,

What is the blowing on the PDMS about? Perhaps the condensation from your breath is ending up on the surface adding moisture to
the mix? I have heard some jewelers use the "oxygen" side from their torch on the PDMS to disperse bubbles, but would not suggest blowing on it.

Keep this in mind: At the (low) safe temps Mike mentions, the bubbles are never a concern., Just pop in oven, (make sure it's level) and don't touch it until it's finished.

Otherwise beginning to wonder if perhaps maybe your PDMS has gone bad? Is there an expiration date or something? Tim I think we are all as baffled as you are at this point.

There are at least 30+ others out there an not a single mention of such a thing by anyone else. Have never experienced such a thing myself.

If there is anyone else having any similar issues, please let us know?

Have no idea really what is going on. The glass is pyrex, (borosilicate)..can easily handle low or high temps in the oven. but again have had no issues myself or heard complaints @ higher ones. The PDMS by dow is rated to 300. But yes, please try @175. Bubbles have time to disperse on their own at that temp.

If there was just one other person experiencing the same problem maybe we would be onto something, but I have every confidence it has nothing whatsoever to do with the VAT if that's what you are thinking?

But if that's your conclusion, please will be happy to take it back immediately.., can't go on like this. : ) Too painful to see you having no success! Have exhausted all possible ways to assist.

Best, Kirk





Kirk,
let me be very clear this is not a problem from the vat. I ran into this one other time last November when I had to replace it for the first time. I didn't know any different so I did it again and all was good. To be honest I have never had any issues that I can relate to the aluminum vats. I don't expect this to be a problem with your knew vat. this is all PDMS or me.
thanks for the offer but NO!! that is not the problem.
Thanks for mentioning the Expiration date. That made me look for one and it is 15 march 2015. so apparently it is not an expiration problem.
as for blowing lightly on it I have seen where several people said the just blow on it to release the bubbles and I have always done that as well. I have replaced the pdms maybe 4 or 5 times since I got it due to several reasons most recently because of clouding. I have honestly not printed anything since what February? I ran into some puter problems that have been corrected and then I was waiting for the mod for the projector almost a month before I received it to put it back together and it took me another week to run down and modify the projector modification so it fit better.
then taxes
then work got in the way.
Practice makes perfect that is what I figure.
thanks
I'm so far behind I think I'm First !!

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Post#454 » Tue May 13, 2014 10:16 am

Saab,
I did it exactly how you describe it but I let the pdms settle on the counter covered as well.
I used the higher temps instead and I don't allow the fan to blow either. Brand new oven so now foreign material running around inside either.

I well succeed. I just have to hold my mouth right.
Tim
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Post#455 » Tue May 13, 2014 10:19 am

Quote from Metalcaster on May 13, 2014, 14:35
What if his oven is not accurately calibrated... It could be hitting temperatures above 350 oF and combine that with the amount of time that it is in the oven, that would certainly spell disaster!
I use a lot of RTV rubber similar to the pdms ... they don't recommend going over 200 oF .
At 150 oF it cures in 2 hrs or less. At 200 oF it should be done in less time.( about 1 hr)

If you are at 300... you should be done in 10 minutes or less... perhaps by using high temperature, you need to reduce the time in the oven to 10 minutes... Just a thought.... or, just do it at 150 oF for 2 hrs... Better safe then sorry!


I have an oven temp gauge in the oven on the rack to see if it is accurate. I seems to be about 20 deg. off so I have to increase the digital temp by 20 degree to reach the oven temp gauge.

going for the 170 degree method.
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Robert Howle
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Post#456 » Tue May 13, 2014 3:14 pm

Tim if u are still having probs let me know if I can help.

Robert
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akgold
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Post#457 » Tue May 13, 2014 4:11 pm

success !!!!!!!!!!!!!!!
one down one to go.
the only think I changed was to mix the resin using the end of a plastic spoon instead of the wooden small tongue suppressor and i put it in at 250 then to 275 again. Thought I would give that one more try it is pristine not a blemish anywhere except I forgot to remove the tape LOL rushing out to a meeting.
but I just cut the PDMS like it would be if I used the dam. works for me .

I can't imagine that being the problem since I have been using them since last winter on at least two replacements.
Also this is the original alluminum double dog vat from Kirk.
next I will try the new Cat vat again. I don't get it
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akgold
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Post#458 » Tue May 13, 2014 4:54 pm

oh yeah I also measured out the pdms curing agent first and added the pdms to the curing liquid.
doing the second vat now cross your fingers
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Robert Howle
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Post#459 » Tue May 13, 2014 6:53 pm

I use the 200 and 250 and get great results. Glad u are having success now. I had no idea what could be causing the problems u were seeing. In about 15 vat recoats I have had no bad ones yet.

One thing I make sure of is a min of 3 to 4 min of vigorous mixing. I use wooden chopsticks. Chinese rest next door. Food is good too. Lady makes everything from scratch and all fresh veggies. Best egg rolls ever eaten. Needed to say that because her husband is my landlord. Retired Colonel.
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Post#460 » Tue May 13, 2014 7:21 pm

:D

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