# Window & door resin casting



## CliffyJ (Apr 29, 2009)

I'm wanting to tool up for some resin casting (for door & window parts), and have been reading the GR series (Aug 07 - Feb 08) again for ideas on the vacuum pump. 

The author (Burl Rice) recommends a pump that pulls 27" mercury, but I'm finding those to be pricey. I was hoping for a Harbor Freight pump, both their specs are confusing, and I'm suspecting they don't pull near that amount.

Here's the question, is 27" overkill perchance? And would a unit pulling, say, 20", be ok? 

BTW, I'm getting the masters made from Shapeways: 3 window and 3 door styles. It was about $60, but I suck at styrene work, so what the heck. 

Cliff


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## CliffyJ (Apr 29, 2009)

I found this conversion chart, relating Pascals and Inches Hg and Microns:
http://www.engineeringtoolbox.com/v...d_460.html

So, the Harbor Freight pump claims to do 25 microns / 3 Pascals, that seems to be 29.9 inches Hg... could that really be right?

The HF unit seems mighty like the 2-stage Robinair pump:
http://www.amazon.com/Robinair-1530...amp;sr=8-3
and their manual says it will do 35 microns (still 29.9"Hg).
http://catalog.otctools.com/newcata...79%20E.pdf

I'm guessing the real Robinair is far superior in quality. Has anyone used either, and can confirm them pulling that much vacuum?

Thanks,
Cliff


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## bnsfconductor (Jan 3, 2008)

Cliff, 
I went with the option of only buying the pressure pot (aka paint pot). I would like to buy a vacuum pump in the future, but for the amount of casting that I do I feel that the wait time for the mold to cure under pressure is worth the cost of a vacuum pump. That said if a nice vacuum pump comes up for a good price most likely I'll bite. You might want to message Burl and ask him directly. 
So here's how I cast- master/RTV mold cast in pressure pot 12-14 hours at 60psi. Mold with resin 2-3 minutes (I think the resin has a 90 second life before it starts to harden) in pressure pot at 60 psi. If you go this route make sure that your compressor has enough capacity to fill and maintain the pressure in the pressure pot. I have a 5 gal. pancake compressor and it seems to work just fine. 
Craig


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## CliffyJ (Apr 29, 2009)

Hey Craig, thanks for the info. I've read that pressure's ok for the parts, but not so great for the silicone master. But I guess you're saying that you degassed the silicone ok that way? 
Also, does your pressure pot seal ok for vacuum, or would you use a different chamber w/ a vac pump? 

Cliff


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## Totalwrecker (Feb 26, 2009)

http://www.riogrande.com/Product/Vacuum-Pumps-5cfm/700350?Pos=19 

used ones are half that... and worth it. I have a newer and an old. 

Check a discount jewelry supply house for plexiglas domes on a rubber pad on a flat surface. Investment/ casting table 

http://www.riogrande.com/Product/Rio-Side-Draw-Bell-Jar-14-3-4-dia/702167?Pos=57 

These are professional grade, go to a discount house for hobby grade or find used. 

John


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## CliffyJ (Apr 29, 2009)

Thanks John. Do you know who the manufacturer is? That's a lot more expensive than the Robinair 5cfm, have you heard if Robinair's are not so good? 

Cliff


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## bnsfconductor (Jan 3, 2008)

Posted By CliffyJ on 30 Dec 2013 01:11 PM 
Hey Craig, thanks for the info. I've read that pressure's ok for the parts, but not so great for the silicone master. But I guess you're saying that you degassed the silicone ok that way? 
Also, does your pressure pot seal ok for vacuum, or would you use a different chamber w/ a vac pump? 

Cliff 

I've never had a problem using the pressure pot with the RTV. What I typically do is mix the RTV, and then pour in a thin stream into the master and mold outline. This eliminates a lot of the bubbles but doesn't get rid of all of them. Then after I'm done pouring the RTV I seal it in the pressure pot, and crank up the pressure for 12 hours. The pressure in the pot then forces the microscopic bubbles into the cavities of the mold. Sometimes this results in a bubble forming on the edge of the cast. This is where using a vacuum chamber would work much better. I'm not really degassing, but more pressurizing the remaining gas. 

The problem with pouring resin is that you get a lot of bubbles that you can't shake or pour out in a thin stream because of the short pot life. Casting under pressure forces the resin into the same voids created by the RTV in the pressure pot. Where as if you vacuumed the RTV first you might not have any problems. So the cheap or entry level casting works good with just a pressure pot. Now I'm sure the more complicated 2 or 3 part molds would benefit much more from the vacuum. But I'm no expert. Ask Burl as he has done a fair amount of casting. 
Here's one of my first castings I did. RTV pressurized to 50 psi.








The resin result








Now I'm not sure if the big air void was a result of me or a result of the RTV being cured under pressure.
Here's another cast








And here's one that had a master a bit more complicated. 








As you can see if you look closely, tiny air pockets are evident. 
Based on my casting experience using a pressure pot for the RTV will result in okay castings, but if you want a perfect cast use a vacuum chamber for the RTV.
Craig


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## Burl (Jan 2, 2008)

Cliff, you won't get rid of all the bubbles at 20" Hg. You'll have to hit at least 25" Hg for good results.


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## Michael Glavin (Jan 2, 2009)

Cliff, 

I have several Robinar vacuum pumps as well as others (quality product recognized as a major player in the industry for refrigeration work) most have hundreds of hours on them appear to pull down to near one atmosphere or 29.92in/hg = 100% vacuum (digital field gauge suggests 29.9in/hg at 100 microns as I recall). 

You can get a new 15500 Robinair 5.0cfm two-stage pump for $170.00 shipped online. I also viewed Robinair vacuum pumps beginning at $100.00 on up for smaller displacement units shipped. 

I suspect but have no direct experience that either pump mentioned will suffice nicely for your needs... I haven't tried to vacuum cast anything yet but some day I'll give it a try. 

Michael


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## Totalwrecker (Feb 26, 2009)

Posted By CliffyJ on 30 Dec 2013 06:38 PM 
Thanks John. Do you know who the manufacturer is? That's a lot more expensive than the Robinair 5cfm, have you heard if Robinair's are not so good? 

Cliff 
My used one is a JB FastVac , the newer one is out in the shop... same I think.

I don't know nuthin about no air conditioner vacuum pumps I was casting gold and silver and we pulled a lot of air out of 2 or 3, 6" sections of 4"pipe at a time.
Back then spending more ensured better value.
I did say over kill...
John


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## Michael Glavin (Jan 2, 2009)

John 

The JB FastVac was/is a refrigeration vacuum pump as well, I've owned several of these units too, good product. 

Michael


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## CliffyJ (Apr 29, 2009)

Thanks John, and you have a nice pump! USA made, 2-year warranty even. I'm tempted, I'm always overkilling... 

The 5CFM Robinair pump, at 1/3 the $$, seems the way to go for me though, given Michael's testimonial for that brand. I'm going to avoid the HF knock-off for this though, the risk isn't worth the savings. 

Craig, great pics, and thanks for the explanation on pressure vs. vacuum casting. And thanks for the confirmation Burl, and those articles! 

Thanks all for your help, 
Cliff


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## CliffyJ (Apr 29, 2009)

FWIW, the doors & windows are shown here, at the bottom of the listing:

https://www.shapeways.com/shops/comstockcliffy?sort=name


Here's some questions about the vacuum chamber. The PVC pipe approach in Burl's article looks nice and straightforward, but I'd like a little more area to cast a few windows / doors at a time. 

I've seen several articles on how people have used a thick aluminum stock pot, and there's even this $170 kit with pot, window & etc. included:

http://www.amazon.com/Chamber-Ureth...amp;sr=1-2

Been looking to see if I can beat that price much by rolling my own...


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## SD90WLMT (Feb 16, 2010)

Cliffy.. if you like Burl's PVC pipe method...why not build several and run them tied together for increased use? 

I don't think the vac pump will mind... 

I'd suggest a good vac pump myself... a good one will pull down faster and maintain a vac longer and easier.. it is the root of the system.. 

Thanks for the thread 2!! 

Dirk


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## Totalwrecker (Feb 26, 2009)

The working time of your media will set your limits, how many can you pour, before you must close and vacuum. 
John


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## CliffyJ (Apr 29, 2009)

Thanks guys. Good thoughts. 
You can tell I'm starting from intellectual scratch on this topic, ha ha! 

Question after reading more of Burl's article #2, why not use the vacuum chamber for the casting as well? Is the pressure method superior, and how?


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## Totalwrecker (Feb 26, 2009)

The older I get, the less I know. 
Push 
My Experience was pushing hot wax into molds, rubber molds held in a clamp between two steel plates. Bubbles could get trapped in undercuts and corners where fluids tended to eddy. I cut the molds I packed in opaque rubber. They were vulcanised .. cooked... and the silver original cut out. I had to visualise my cuts and hope the master hadn't shifted by a forced pack. I studied fluid dynamics.... I was; caster, fabricator, lapidarian and bench jeweler and most things in between. Had the same boss at 2 companies for 24 years 
I cut vents and we powdered them with unscented talc powder to help the air out. That was old school, woof, it's evolved to vacuum assit because it's easier to suck air with control, than to push. Waxes with bubbles had to be fixed or tossed. 
I once bought a resin kit for an On3 passenger car body that had so many holidays (holes) I never built the car. A complaint got a shrug of their shoulders... 
Pull 
After the waxes everything was vacuumed ... Castings had to pass. 

There is no way I'm going to say other methods won't work, that's part of what I don't know !








John


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## bnsfconductor (Jan 3, 2008)

Posted By CliffyJ on 31 Dec 2013 10:08 AM 
Thanks guys. Good thoughts. 
You can tell I'm starting from intellectual scratch on this topic, ha ha! 

Question after reading more of Burl's article #2, why not use the vacuum chamber for the casting as well? Is the pressure method superior, and how? 
Burl might now better, but I'm guessing it has to do with the short pot life of the resin. With only 90 seconds of pot life before it starts to cure, is that enough time to pour the resin in the mold, and vacuum out all the air before it sets up completely?

Or is the reason that a vacuum wouldn't force the resin into all of the recesses of the RTV mold? Just educated guesses on my part.


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## CliffyJ (Apr 29, 2009)

All good points Craig and John.


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## Burl (Jan 2, 2008)

I know people that have vacuumed slower setting resins, but you're right - 90 second pot life is what keeps you from it with Alumilite regular.


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## SD90WLMT (Feb 16, 2010)

So to be clear here... 

Is a 90 second "window" for pot life toooo short to ...mix..pour .. and draw down? 

Pour and hope for the best thru a slow pour.. creating fewer air bubbles.... 

Trying learn to..my turn will come!! 

Thanks guys.. Dirk 

....H.N.Y. .... 

..... ;-)


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## CliffyJ (Apr 29, 2009)

Howdy Dirk! 

I'm not sure what I'm supposed to be using, but here's what I'm starting with, one way or the other: 

http://www.amazon.com/s/ref=bl_sr_a...+Plastic+Casting+Resin+28+oz.&node=2617941011 

It claims a 3 minute set time. I went with this because it seemed reasonably tough, heat resistant, and is white. All my windows for this first project are white, so it would be nice to get out of painting. 

Cliff


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## Totalwrecker (Feb 26, 2009)

OK been pickin' my brain, yuck. 

A flat mold might best be poured with a slight crown and a backing board applied to force into corners and recesses. 

A mold filled through a sprue could be set in a vacuum to assit the pour, not the cure. 

I wonder if a centrifical pour would suffice... back in my early days , we could cast with a hand sling. When the metal went liquid the torch man would pull back and the slinger would woop the mold and crucible up in a circle.... yeah ya gotta woop. 

A vacuum form table and a pourous mold.... The vac assists the pour, not evacuating bubbles in the mix. 

Fold the resin when you mix, we hated bubbles in the epoxy. 

Yeah Happy New Year back at ya. 

John


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## SD90WLMT (Feb 16, 2010)

With out paint.. 
Will the raw resin tolerate U.V. exposure? 

Ya. Cliff...this will be a whole new world to explore in modeling....for me! 

All my life projects have been in the production group...keep makin more parts till you have what you need. 
Wood... 
Steel... 
Concrete.. 
Still plastic falls in this group also.. 
But some detail parts would be nice to have... 

Dirk


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## bnsfconductor (Jan 3, 2008)

Cliff, 
This is what I use. Alumilite Regular. I buy it direct, and also in 1 gallon containers. 
http://www.alumilite.com/ProdDetail.cfm?Category=Casting Resins&Name=Alumilite Regular 
Dirk, 
90 seconds is a really short pot life. I barely have time to mix, pour, place a backing on, put into pressure pot before 20-30 seconds. I found out waiting to long allows a partial set under no pressure, and partial set under pressure. As for unpainted resin and UV I've had mixed success. I left this building out without paint (1/8" styrene roof, the rest is Alumilite Resin castings) and the only thing that I noticed was the roof and the walls faded to a pale yellow. 
Brand new








After I left it out for some time (about 6 months? or a year?) The building is the pale yellow one in the background. Sorry I don't have a better picture. But you can see the difference between UV faded styrene and 'fresh' styrene.


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## Michael W (Oct 10, 2012)

G'day and happy new year! 
I have done some casting in the past and found that resin has a fair bit of issues when you cast it, is unhealthy to work with and usually it has issues with heat and temperature. If you are using the molds for building parts i suggest dental plaster as an alternative, it is durable reasonable cheap and has a long shelf life, as it takes longer to cure you dont need vacuum equipment just a good mold. 

http://www.hirstarts.com/ 

I got a few molds of this company and they are really good, i did several casts using dental plaster and they work great for building models ( the molds he has are 25 mm and to small for g- scale) but it might be worth contacting him to make your molds rather then spending a fortune making them yourself ... 
Kind regards 
Michael


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## SD90WLMT (Feb 16, 2010)

Interesting thoughts Michael. 

Any idea how long or how many times dental molds can make parts before the quality drops off? 

Thx.. 
Dirk


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## SD90WLMT (Feb 16, 2010)

Oh...plus dental molds are good only for certain types of parts. 

I think the flexible resin can be removed from more complex shapes where a rigid plaster mold will not.. 

Dirk


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## Totalwrecker (Feb 26, 2009)

I don't think we are ready to cast our car sides in dental plaster, think Hydrocal from your hardshell days. 
I went to the link; It's plaster in silicone rubber molds. Would be ok for Craig's wall, not cliffy's window frames.... 
Michael's suggestion is to have another make the rubber mold for you. 

Next year ya may haveta figger this yerselves, buddy! Nudge Nudge. 

Laffin John


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## Michael W (Oct 10, 2012)

Yap you are right, the mold is rubber, casting in deltal plaster, i actually made 1/25 th scale tank sides dropcasting with that method and it holds up fine for tabletop wargaming, i dont know how well it would work for the main components of cabooses or similar. But it certainly would work for walls of buildings i.e. Stone or pavement parts. As far as i understood the windowframes were for buildings .. Anyhow it should still work fine as long as it is purely ornamental... 
Kind regards michael


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## CliffyJ (Apr 29, 2009)

Thanks for all the further ideas and suggestions guys. 

Craig, I was going to do Aluminite regular, but since the tan version requires painting, I went with their other stuff. We'll see, Maybe I'll get some regular and do some comparisons, maybe even with Michael's dental plaster. Thanks for putting up the pics. For me, yellowing is fine, because a) there's nothing to flake off and b) the crap white paint of 100 years ago probably yellowed some too. 

Hey Michael, thanks for the reminder. The plaster would stay nice and white, I'll reckon. But I wonder how it holds up in the rain? 

Then comes bonding. I need to adhere these things to a styrene substrate, hopefully with a good chemical bond / weld. I was thinking the chances would be good with resin, because in Burl's articles I think I see resin and stryene parts married (GR October '07 p70). Time for more reading. 

Cliff


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## Michael W (Oct 10, 2012)

Hi Cliffy 
Not sure how rhe dental plaster works unpainted it comes in different colours, the stuff i got is white, i usually undercoat it with black primer and paint it with waterbased acryllics ( i do the same with resin) i found that resin neefs a lot of preparation before it can be used ( i wash it in warm soapy water to get rid of the mold release agent and then i trim the flesh from casting off) to glue resin i use superglue, loctite works best for me, ill find out which one it is, its in my modelling box - thelaster just uses superglue it works great, inever exposd it to lots of water tho, i ll try that out and see what happens... 
Kind regards michael


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## Michael W (Oct 10, 2012)

Hi Cliffy 
Not sure how rhe dental plaster works unpainted it comes in different colours, the stuff i got is white, i usually undercoat it with black primer and paint it with waterbased acryllics ( i do the same with resin) i found that resin neefs a lot of preparation before it can be used ( i wash it in warm soapy water to get rid of the mold release agent and then i trim the flesh from casting off) to glue resin i use superglue, loctite works best for me, ill find out which one it is, its in my modelling box - thelaster just uses superglue it works great, inever exposd it to lots of water tho, i ll try that out and see what happens... 
Kind regards michael


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## CliffyJ (Apr 29, 2009)

Hi Michael, 
This seems similar to dental plaster, but I cant quite tell: 
http://www.amazon.com/Cast-Paint-10...1?s=arts-crafts&ie=UTF8&qid=1388591161&sr=1-1


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## Michael W (Oct 10, 2012)

Mhh never seen or used this product, but to try out the moulds by all means its a bargain for $8, 
Something else that came to mind, if you got the masters you could use soft alloys from casting suppliers, just get some cheap molding clay and carefully press the window master in and see how that works with the alloy, i never tried it but you would get metal that is easy to work with and you dont have to worry about making the molds too much... 
Kind regards Michael 

P.s. If you are stuck i might be able to send you some dental plaster i just need to check the legalities as customs might querie a bag with white powder from oversees..lol


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## Michael W (Oct 10, 2012)

Mhh never seen or used this product, but to try out the moulds by all means its a bargain for $8, 
Something else that came to mind, if you got the masters you could use soft alloys from casting suppliers, just get some cheap molding clay and carefully press the window master in and see how that works with the alloy, i never tried it but you would get metal that is easy to work with and you dont have to worry about making the molds too much... 
Kind regards Michael 

P.s. If you are stuck i might be able to send you some dental plaster i just need to check the legalities as customs might querie a bag with white powder from oversees..lol


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## CliffyJ (Apr 29, 2009)

Michael, here's the best I found for the real dental plaster, about $1/lb shipped: 
http://www.ebay.com/itm/DENTAL-LAB-...327?pt=LH_DefaultDomain_0&hash=item5d443bc14f 

For now though, I have my hands full w/ the molds & resin approach, but I like that plaster route too. We'll see how the experimenting goes. 

Thanks, 
Cliff


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## CliffyJ (Apr 29, 2009)

I'm still wondering if I can get away with only the vacuum chamber (for both mold making and parts casting), and what the advantage is with the pressure pot (for parts casting). That's another $100, so I only want to get it if I REALLY need it.


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## David Leech (Dec 9, 2008)

I have been using Smooth-On products for casting over the last 15 years, and never needed to use any vacuum or pressure. 
Are you sure that you need to? 
Actually, I did use vacuum once, for some 'clear' casting of special windows that I needed to make. 
A friend who had an aircraft instrument shop had a large bell jar hooked up to a very large vacuum pump. 
I mixed up the resin, placed it in the vacuum jar for about 30 seconds while it pulled maximum vacuum and the resin bubbled and boiled up to about 10 times it's volume. 
Release the vacuum and it settled right down for another 30 seconds of pouring into the mold. 
Most of the castings looked clear, but a few still caught bubbles as I poured. 
All the best, 
David Leech, Delta, Canada


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## CliffyJ (Apr 29, 2009)

Hi David, 
Sounds like you've successfully used the vacuum chamber to get the resin degassed -- before pouring it into the mold, keeping the part out in the open to cure. Interesting. 
With Burl's method, you pour the gassy resin into the mold, then put the whole thing into the pressure pot and pump it up, leaving it there to cure. 
Just thinking out loud... Thanks for your insights. 
CLiff


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## CliffyJ (Apr 29, 2009)

I received all the vacuum components & casting materials this week, including the masters (from Shapeways):










Been struggling with getting the vacuum chamber to achieve any vacuum though, and after a few hours of testing / siliconing am having to punt and get the vendor's input. (I'd gotten that BestValueVacs.com chamber). Seriously bummed. But at least the Robinair pump seems fine, pulls ~28" as advertised. Anyway, no mold-making this weekend I guess.

As far as the casting goes, I'm not sure about those doors, with their 1/32" think panels. I'm guessing I'll have trouble getting the resin to lay in that thin and evenly. We'll see. 

About that Alumilite "super plastic casting resin" product, they got back with me to say that yes, it's Alumilite Regular, or at least has been prior to 2014. Quote: "Now the Super Casting Kits for 2014 will carry the New AlumiRes which is a bit longer pot life 2-1/2 minutes and a thinner viscosity with a no shake B side." FWIW.

Cliff


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## bnsfconductor (Jan 3, 2008)

Posted By CliffyJ on 02 Jan 2014 02:28 PM 
Hi David, 
Sounds like you've successfully used the vacuum chamber to get the resin degassed -- before pouring it into the mold, keeping the part out in the open to cure. Interesting. 
With Burl's method, you pour the gassy resin into the mold, then put the whole thing into the pressure pot and pump it up, leaving it there to cure. 
Just thinking out loud... Thanks for your insights. 
CLiff 

Cliff,

You've got the steps messed up. For the vacuum & pressure pot method-
For the RTV you vacuum it, pour into mold box and let cure at room pressure. The vacuum should have taken out all of the air. Then after you have the RTV cured and you want to make resin copies you pour the resin into the RTV and cure the resin under pressure in the pressure pot.

For the pressure pot only. Repeat as above but cure the RTV in the pressure pot.

Craig


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## CliffyJ (Apr 29, 2009)

Seems like differing methods, Craig.

For the mold RTV, some people vacuum-degas before pouring (e.g., you), some after (e.g., B. Rice).

For the resin casting, seems like almost everyone uses a pressure pot. But I don't have one, and was hoping for evidence that a vacuum chamber could be used for that as well. The post you cited from me was in reference to that, not the rtv mold making. In that casting method, David seemed to be degassing (via vacuum) before the pour, and not after. But I suspect there's not enough time for that, at least for me.

So my question remains: why not put the just-poured cast part & mold into the vacuum chamber for degassing / curing, since it will set so quickly? Because I really don't want to set up a pressure pot if I don't have to.

Cliff


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## bnsfconductor (Jan 3, 2008)

Posted By CliffyJ on 11 Jan 2014 02:25 PM 
Seems like differing methods, Craig.

For the mold RTV, some people vacuum-degas before pouring (e.g., you), some after (e.g., B. Rice).

For the resin casting, seems like almost everyone uses a pressure pot. But I don't have one, and was hoping for evidence that a vacuum chamber could be used for that as well. The post you cited from me was in reference to that, not the rtv mold making. In that casting method, David seemed to be degassing (via vacuum) before the pour, and not after. But I suspect there's not enough time for that, at least for me.

So my question remains: why not put the just-poured cast part & mold into the vacuum chamber for degassing / curing, since it will set so quickly? Because I really don't want to set up a pressure pot if I don't have to.

Cliff 



Cliff,

Burl degases in the RTV in the vacuum chamber before he pours the RTV onto the master and mold box. 
This is how I understand Burl does it.
1. Mix parts A &B of RTV.
2. Vacuum mixed parts of RTV.
3. Pour in thin stream into mold box covering master, etc.
4. Let cure.

Making molds
1. Mix parts A&B of resin.
2. Pour into mold.
3. Place in pressure pot, and cure.

Here's how I do it.
1. Mix parts A&B of RTV
2. Pour in thin stream into mold box.
3. Place in pressure pot and let RTV cure for 12-24 hours.

Mold making.
Same as above.

If you pour the gased RTV into the mold box without degassing first your going to have the same problem as pouring a gassed RTV into the mold box. 
I cure my RTV under pressure and don't use a vacuum chamber. 
I would say once again spend the $50-60 bucks on a paint pot so you can have a nice pressure vessel. And if you ever happen to need it for a painting project you'll be thankful too









To answer your question.
Cure time! If using a vacuum expands the RTV to up to 3x's its normal size before being completely degased than if you pour resin into your mold and vacuum it your going to have a resin copy that looks like carp (sp) because the volume of the resin expanded 3x's and then settled back down. I don't think the pot life is long enough to vacuum the mold and the resin. You might be able to get away with vacuuming just the resin and then pouring into the mold.


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## Totalwrecker (Feb 26, 2009)

For this type of casting you need a vacuum table, where the vac pulls through the mold (sprues) from areas where air gets trapped. 
Kinda like the platern table of a vac forming machine. Set the mold on a perforated table and have a collar around the mold and box over vac table. Depressurise the box and pour, once mold is filled turn off vac. Let set. This is a vac assist cast. 

Depending on work time, degas mix and degas mold. 

John


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## CliffyJ (Apr 29, 2009)

After a little more investigation, I gotta exchange the vac chamber pot, it has an uneven rim that's preventing its sealing. Hopefully the vendor will make good... 

After some hemming & hawing, I finally faced facts, broke down and ordered the HF pressure pot. Arrgh... I would have bought it in the spring and used it to spray my deck stain; would have saved me a few days of hand brushing, and vacation time. And the extra expense will slow me down a bit. Whine whine. 

But, can't complain too much. Family's alive and healthy, home hasn't been wiped out by some catastrophe, and I'm still vertical... God is good, this hobby is great. Always learning something, and I sure appreciate my friends here. 

Cliff


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## SD90WLMT (Feb 16, 2010)

Cliffy...you've had a very good day indeed!!!!!!! 

D


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## bnsfconductor (Jan 3, 2008)

I hope this is similar to the one you bought. 









It's fairly easy to cap off one of the outputs. One the other one install a ball valve and a regulator. I also added my quick disconnect hoses. 
The other 'tool' you'll need is some scrap plastic for the molds. When you make a open face mold, if you place a piece of ABS? or glass down the resin won't still to the open face and you'll get a nice smooth backing. I think Burl discusses this in the GR articles.


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## CliffyJ (Apr 29, 2009)

Thanks Craig. Yes, same pot. 

Per Burl, I bought a piece of polypropylene for a base. Too thick though (.188), non-flexible; should have gotten .06. Shipping costs are the big spank. But that was all I could find at the time. 

I can't buy the plumbing bits until the pot comes in, since the connections aren't specified. But when it does, yes, I'll get the QD's and other fittings. 

C


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## Burl (Jan 2, 2008)

Cliff, you can't go too thick with the polypropylene. The thinner it is, the more it will warp from the heat of the curing resin. On large parts (boxcar sides) I use 1/4" to cover the top of open-faced molds. In my pressure pot, I keep a 1" thick piece for a floor for the molds to sit on. More expensive, yes... but it makes flat castings.


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## CliffyJ (Apr 29, 2009)

Thanks Burl. This PP board is very stiff, so thanks for pointing that out! 

Just heard from my chamber pot vendor, they're gonna replace it, no problems. I think though that I'll get a shorter pot (3" high, 12" dia, vs. the 5 gal), because I can't see needing something that tall, and the lower volume will evacuate quicker. Any opinions one way or another?


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## Burl (Jan 2, 2008)

Are you talking about a vessel for degassing, or a vessel for pressure casting? 

For a pressure pot, I'd go as big as I could afford. 

For vacuuming, lately, I have been making my 2.5 gallon paint pot double for a vacuum chamber. When I started getting into bigger molds, I found it was far more efficient. I have also been using the 1/2 gallon size polypropylene mixing containers (like you get at Lowes, in the paint section) to mix my RTV. I had been using Solo cups prior. These are wider & deeper, so I can get way more RTV degassed in one shot - somewhere between 1 and 2 pounds at a time. Remember that RTV will increase 3 to 4 times in height when you pull a vacuum on it. The narrower the mixing container, the higher it will get before it collapses back in on itself.


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## CliffyJ (Apr 29, 2009)

Burl, I appreciate your help! 

I'm talking about the vacuum chamber. The one I bought (basically a stock pot) is 5 gallons: 12" diameter x 12" high. Since I have to have it replaced (due to a defect in the rim), I was thinking of getting the vendor's short version: 12" diameter x 3" high. 
My thought was to reduce vacuum time, if I'm never going to make molds that big. But you're describing something I'd not considered (which is typical for me), so now I think I'll stick with the 5 gallon (tall) pot. 

Here's a link to the guy's "vacuum chambers": 
http://bestvaluevacs.com/ 

[edit]
Just after writing the above, I got an email from BVV saying the replacement pot was shipping tomorrow. So, I just emailed him back, asking for the same 5 gal (12" tall) pot. Anyway, I wanted to point out that he's making good, and I always want to do that for good vendors. 

Cliff


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## bnsfconductor (Jan 3, 2008)

Posted By Burl on 13 Jan 2014 05:51 PM 
Are you talking about a vessel for degassing, or a vessel for pressure casting? 

For a pressure pot, I'd go as big as I could afford. 

For vacuuming, lately, I have been making my 2.5 gallon paint pot double for a vacuum chamber. When I started getting into bigger molds, I found it was far more efficient. I have also been using the 1/2 gallon size polypropylene mixing containers (like you get at Lowes, in the paint section) to mix my RTV. I had been using Solo cups prior. These are wider & deeper, so I can get way more RTV degassed in one shot - somewhere between 1 and 2 pounds at a time. Remember that RTV will increase 3 to 4 times in height when you pull a vacuum on it. The narrower the mixing container, the higher it will get before it collapses back in on itself. 
Burl,

How did you go about using the pressure pot for a vacuum chamber? Did you just hook up a vacuum hose from the vacuum pump to the pressure pot intake? I'm curious to see what your set up looks like. 
I've been using the Solo cups as well for RTV, but I'll keep my eye out for some paint mixing containers. Now I just need to find myself a decent vacuum pump. 

Craig


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## Burl (Jan 2, 2008)

Craig, 

My small vacuum chamber is a piece of 6" PVC coupling, a steel plate for the bottom, and a 12"x12" piece of 1/2" lexan for the top, with corresponding gaskets. When I use my paint pot, I just put the lexan top on it with an appropriate sized gasket.


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## CliffyJ (Apr 29, 2009)

A little update. Today I set up the (3d printed) masters by crazy-gluing them to some acrylic backers, and making the little boxes to retain the silicone.










The acrylic and styrene were scrap I had around, both cut with an acrylic scoring tool -- which worked great. 

The crazy glue was recommended by Shapeways, and I used a formulation specifically for plastics. Seems to hold well.

The 3d printed doors were designed very thin (to cheapen them up), but now I've been concerned about going too thin on the resin castings. So I glued 1/32 sheet spacers to the backs of the masters, before gluing to the acrylic. This will theoretically result in 1/16" door panels (between "framing" bits). And it that doesn't work, my fallback is to re-do the doors to be frames only, and adhere real cedar planks to the backs of the resin parts.

Not very impressed with the hot glue adhesion to the styrene, so hopefully the joints won't blow out during the silicone pour -- which is the next step. 

Burl, on 1/13, you'd mentioned:
"On large parts (boxcar sides) I use 1/4" [polypropylene] to cover the top of open-faced molds." 

Would that help to keep the backs of my parts flat, and of a more uniform thickness? 

Thanks again, 
Cliff


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## bnsfconductor (Jan 3, 2008)

Cliff, 
Hot glue works just fine to hold the RTV when it's being poured. The 1/4" polypropylene is used on the backside of the mold (where your acrylic is now) and if you do it properly will result in a nice flat backing. I start at one corner and work my way across the part pushing out the air. 
Craig


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## CliffyJ (Apr 29, 2009)

Craig, 
the phrase "the top of open-faced molds" made me think it applied to the part casting process, so thanks for clarifying.


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## Burl (Jan 2, 2008)

For as big as your molds will end up being, you can get away with 1/8" polypropylene. But the thicker you go, the less error prone the process will be. And yes, this only applies to casting, not mold making. I'm afraid you'd really pull your hair out trying to glue your patterns to polypropylene.


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## Burl (Jan 2, 2008)

Also, some of you asked (maybe in another thread) about how I would seal 3d printed nylon. I ended up using thin CA (from Hobby Lobby). I used a q-tip to soak up the excess before it set (gotta be quick). 

I also had good results with future floor finish for sealing the "frosted ultra detail" parts I had made. I suspect it would work also on nylon.


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## CliffyJ (Apr 29, 2009)

Burl, are you referring to your 1/4" PP (or 1/8") as a stiff platform on which to set your silicone molds, to keep them flat during casting? 

Great tip on the floor finish idea. My (nylon) parts are a tad "grainy." 

I also used CA (per Shapeways advice) to secure the masters to the (acrylic) bases.


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## Burl (Jan 2, 2008)

No, but you will need something flat, and non-stick to set your molds on when casting. What I'm talking about is capping off the top of your mold after you have poured resin in (before it starts to set up).


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## David Leech (Dec 9, 2008)

Posted By Burl on 10 Feb 2014 03:50 PM 
No, but you will need something flat, and non-stick to set your molds on when casting. What I'm talking about is capping off the top of your mold after you have poured resin in (before it starts to set up).
I have never managed to work out how to do the capping off part very well.
I always manage to get far too much flash everywhere, and then if I try to move and re-postion my top piece I get air bubbles, so I am just very careful and pour 'just the right amount' to fill the mold.
Sometimes just adding a drop to get it right.
This photo is of wall used in a British Pullman car, as cast and painted with wood grain.
The cross pieces on the French door are .040" x .040".
One thing that I did find is important.
When you pour your mold - make sure that the master is sitting perfectly level.
Then your mold will have a back side, that matches the front.
Then when you pour your casting, also make sure that the mold is also sitting perfectly level.
Use a bubble level to make sure at both times.
Looking forward to seeing how it all works out for you. 
All the best,
David Leech, Delta, Canada


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## CliffyJ (Apr 29, 2009)

Posted By Burl on 10 Feb 2014 03:50 PM 
No, but you will need something flat, and non-stick to set your molds on when casting. What I'm talking about is capping off the top of your mold after you have poured resin in (before it starts to set up). 
THAT's what I was hoping you were referring to, a few posts back.

I've not even made my molds yet, so I'm just trying to anticipate what to expect later. 

As you can see, my parts are going to be broad and (vertically) thin. So after pouring the resin, let me guess, you scrape off excess, and put the PP sheet on the open top, against the resin; then put mold with the PP sheet into the pressure pot. Is that close? And does that give you a pretty flat back to the part?

Cliff


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## CliffyJ (Apr 29, 2009)

Thanks for posting that David, it looks like you were very successful so that's encouraging!


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## docwatsonva (Jan 2, 2008)

Cliff,

I'm now in the process of making some windows for a structure I'm about to begin building. I decided to try Smooth-On products since several builders have reported good results. The nice thing about them is that both the latex mold material and resin come in 1:1 by volume mixing ratios. That sure makes life easy. The other feature is that neither the mold making nor resin casting requires vacuum, at least for flat molds.

I simply made a master out of styrene and a simple basswood frame to contain the mold. The frame was 1/4" thicker than the window depth and about 1/2" longer and wider than the window. The latex mold material is very fluid and, if mixed to avoid adding bubbles, flows very nicely in and around the master. I laid the master and frame on some waxed paper on a flat surface. To keep the master and frame from moving, I used a little thick CA to hold them to the waxed paper.

After a day of curing, just to be sure, I removed the frame and waxed paper from the mold. I then placed the mold on another piece of waxed paper on a flat surface. After mixing the 2-part resin, I slowly poured the resin into the mold allowing plenty of time for it to flow into the nooks and crannies. I filled the mold to the top and used a popsicle stick to skim any excess resin from the top of the mold.

Here are the results. The first photo shows the mold and 2 of the windows. The widows have add a few minutes of cleanup.










The photo below shows what the widow looks like right out of the mold.










The widows are about 3.5" high and 2" wide. Hope this helps. If you have any additional questions, don't hesitate to ask.

Doc


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## bnsfconductor (Jan 3, 2008)

Posted By CliffyJ on 10 Feb 2014 05:41 PM 

As you can see, my parts are going to be broad and (vertically) thin. So after pouring the resin, let me guess, you scrape off excess, and put the PP sheet on the open top, against the resin; then put mold with the PP sheet into the pressure pot. Is that close? And does that give you a pretty flat back to the part?

Cliff 

Cliff,
I guess I should have clarified more in my previous statement. I place the PP sheet on top of the resin in the open face mold and slowly push down with light pressure to push the air bubbles out as I bring the PP sheet from one edge of the mold to the other. I don't think there is a way to scrap the liquid resin off before placing the PP sheet on top. Remember you've got 90 seconds to pour, top, band (I rubber band the mold between two pieces of PP one on the bottom, one on the top), and place in the pressure pot, and get the pressure pot up to a decent pressure. Believe me the 90 seconds goes fast!
If you use a PP sheet for the top, you should get a nice flat surface.


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## David Leech (Dec 9, 2008)

Looking good Doc. 
I would point out that the Smooth-On Oomoo mold is SILICONE rubber, not latex, and thus requires no mold release, and the casting is paintable right out of the mold. 
All the best, 
David Leech, Delta, Canada


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## Burl (Jan 2, 2008)

I over-fill my molds, then put the polypropylene down, starting at an angle and trying to work all the bubbles out. Then I put a flat metal weight on it and let it cure. Rubber bands can work too, but they can cause the polypropylene sheet to deflect if its much bigger than the mold. I don't like picking the cured resin off the rubber bands either, but its personal preference. 

 You can always cast a few how others are describing and see which way you like best. I personally like to keep the flash as uniform as I can because its easier for me to remove.


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## docwatsonva (Jan 2, 2008)

David,

Thanks for the clarification. I think that the Smooth-On products are the best I've used to date. One thing I've noticed is that the castings are quite flexible which doesn't matter for my application. Since I'm new to the product, I need to check to see if they make a resin that is more rigid. For people making large castings, that may be a critical factor. I need to do more research for future projects.

BTW, I've made 10 castings so far and have seen no bubbles nor wear on the mold.

Doc


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## CliffyJ (Apr 29, 2009)

Thanks for all the further tips guys. I'm slowly getting it! 
Doc, those are nice windows! Thanks for sharing your thoughts, I'm hoping mine turn out near that quality.


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## David Leech (Dec 9, 2008)

Posted By docwatsonva on 11 Feb 2014 10:33 AM 
David,

Thanks for the clarification. I think that the Smooth-On products are the best I've used to date. One thing I've noticed is that the castings are quite flexible which doesn't matter for my application. Since I'm new to the product, I need to check to see if they make a resin that is more rigid. For people making large castings, that may be a critical factor. I need to do more research for future projects.

BTW, I've made 10 castings so far and have seen no bubbles nor wear on the mold.

Doc

I have been using the Smooth-On products for some 15 years and have had no reason to look elsewhere as they have always done what I need.
Mind you, over those years there have been wonderful improvements of materials offered.
I am assuming that you are using SC300 resin, and my experience is that until the casting is quite thick, maybe 1/8", it can never be like an injection molded plastic.
I once asked at a seminar that Smooth-On held locally, why not, and he responded that it is just the nature of the material and the molecular structure.
Some of their stronger resins tend to be thicker (harder to pour), or longer curing, and I found that with thin sections the exotherm was just not enough for a complete cure. 
With Oomoo30, I find that after 25 castings, they don't come out of the mold as easily, so I just make another mold.
Since like yours, mine are small volume molds, so it is probably only $1.00 worth of material.
Cheers,
David Leech, Delta, Canada


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## CliffyJ (Apr 29, 2009)

I poured my first molds today, and it was quite interesting! Learned a lot. Nothing like a bit of reality to clarify things.









I used Smooth-on Mold Max 30, carefully weighed & mixed. I used Burl's trick of rice poured over the master to determine volume, and a digital postal scale for weight calcs. 

Wow, does that stuff boil! My mixing container wasn't tall enough, so I throttled the vacuum a bit with the shutoff valve until the whole blob "fell." After that, full vacuum. 

The bubbles didn't seem to quit though. So I waited until they were about 1/8" diameter, and shut it down. Then came pouring, in a thin stream, like Burl's article says. 

But I was a little concerned about more bubbles still in there. So I put the thing back into the chamber, and boy, things started seething again! Here's a pic taken about 5 minutes into this 2nd-stage vacuuming:










I stood there for another 10 minutes, and some quite big ones still developed -- like 1/2" or bigger. They gradually subsided though, but still with bubbles up to 1/4". Since I was at the limit of pot life (45 minutes, according to the instructions) I shut it down. 

For those that haven't done this, all the surface bubbles shrink and bury themselves once the vacuum is released. I'm expecting that they'll still be there. But hopefully, they will have been drawn away from the part at the bottom. 

Any tips guys, as to what I'm getting wrong, to have so many bubbles? Or is that normal? 

Tomorrow, I'll take the mold out and see what the part cavities look like. 

===>Cliffy


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## David Leech (Dec 9, 2008)

If I were you, as I have already suggested, forget about the vacuum bit. 
I have used MoldMax and never had a problem. 
Stir the mixture gently, try not to introduce air while mixing, and gently pour from one corner from a little height. 
As soon as your window pains are covered, I would use something pointed to gently go around the perimeter of each pain to make sure that air has not beed trapped. 
Then add the rest of the MoldMax. 
It works for me, and I don't see why not for you. 
It's a lot simpler. 
All the best, 
David Leech, Delta, Canada


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## bnsfconductor (Jan 3, 2008)

Posted By David Leech on 15 Feb 2014 06:48 PM 
If I were you, as I have already suggested, forget about the vacuum bit. 
I have used MoldMax and never had a problem. 
Stir the mixture gently, try not to introduce air while mixing, and gently pour from one corner from a little height. 
As soon as your window pains are covered, I would use something pointed to gently go around the perimeter of each pain to make sure that air has not beed trapped. 
Then add the rest of the MoldMax. 
It works for me, and I don't see why not for you. 
It's a lot simpler. 
All the best, 
David Leech, Delta, Canada 
Much simpler yes, but I look at Cliff's attempt to gain a new skill. A window mold might work fairly well with a non-vacuumed mold/non pressurized cast, but what about when he starts developing masters with deeper undercuts, or 2 or 3 part molds that need a pressure casting to work well? When I first started molding/casting I didn't think I needed a pressurized cast, but I discovered that it makes a much better cast, and I gained the skills and understanding of how to such. Now I'm no means an expert, but I have a basic understanding of how it works, and what doesn't work. 

Craig


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## CliffyJ (Apr 29, 2009)

Thanks guys, all good points. I didn't think about pointing the silicone into perimeters, and pouring twice, David; and Craig, you're right, the parts will probably get more complicated, and it has been an interesting thing to learn about. 

The main thing is, I have the vac system, and it sure brings the air out. And keeps bringing it out, to a puzzling degree. 

Today I'll pull the molds and see how they turned out.


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## CliffyJ (Apr 29, 2009)

It was fun breaking the molds out, and seeing the results.










The door molds had nice clean lines, even before cleanup. I had a lot of surface area with which to bond them against the plex, so the masters were tight against it.










The problem was with the window mold. Though they seemed flat on the plex, I clearly didn't have them tightly adhered enough. So lots of flash oozed in.










That silicone doesn't want to trim! It just folds beneath the razor blade. So using a popsicle stick to cut against, I spent an hour trying to trim the main flash away.










Not so clean. So, I think I'll remake this mold, after trying to seal those perimeters better (with CA). Still, I'll try casting with this mold, and see if it can be used as a backup.

===>Cliffy


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## Burl (Jan 2, 2008)

Stretch the flash out with tweezers and it will cut much easier.


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## CliffyJ (Apr 29, 2009)

Posted By Burl on 16 Feb 2014 03:51 PM 
Stretch the flash out with tweezers and it will cut much easier. I did that Burl, but it tended to snap back and leave a small gouge. That's why I ended up cutting against a (squared-off) end of a popsicle stick. Still not perfect, by any means.

What's your thoughts on my putting the just-poured mold back under the vacuum (see pic), and seeing it continue to boil?


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## Burl (Jan 2, 2008)

It won't hurt anything to degas twice, other than your mold box sides will have to be a little higher.

Be careful you don't get RTV in your gauges too. It will ruin them.


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## Totalwrecker (Feb 26, 2009)

Cliffy, 
When I was cutting jewelry molds, I used a scalpel blade they are much sharper than an Exacto or razor blade. Yoou can get non sterilized (cheaper) from discount jewelry supply houses. Just pull the excess taut, don't stretch it.

John


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## CliffyJ (Apr 29, 2009)

OK Burl, thanks. And yes, it got close to the gauge port! So I had my hand on the vent valve a lot. I need to get my deeper chamber working, it needs a different seal. 

Good tip John, I'll have to look into that. BTW, looks like a font change resulted in messing up your signature line.


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## Totalwrecker (Feb 26, 2009)

Yeah, the transition isn't all peaches and cream ... all threads have lost the OP's Original post and the first responder's name is the owner!
It's the Quotation marks in my signature line...

John


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## CliffyJ (Apr 29, 2009)

*Casting Update*

I've gotten my pressure pot set up, and did some casting this weekend.

My first attempt was just one window. And in my frantic pace to get all done in 90 seconds, I didn't pour it very well, and a big void resulted.. But in the second and third attempts (2 windows per), I took my time more, and all went much better. Here's a shot of these 3 attempts.









Those lower four cleaned up well.

























Next thing is some doors, the first one seen on the right here:









I've learned a lot with this, and it's been fun!

A surprise to me was that the mixed resin is so fluid -- like water. I was worried about forcing some thick goo into the thin mold cavities, but low and behold, it flowed right in! That was great!

Main quandary though has been the resin. Mine has had about 4x the work time before kicking, and it takes forever to harden up. Those 1st five windows only got stiff after about 20 hours. I can't really take these windows out of the molds too soon, because they deform easily otherwise. So I put a call in to Alumilite. They'd reassured me before that my "Alumilite Super Plastic Casting Resin" was actually Alumilite Regular (see an earlier post if you want clarification). But either that's not quite so, or the product has gone funky. And yes. I measured parts A & B VERY carefully. 

On the other hand, these window parts are thin, and they say that the thin parts take more time to cure.

So, we'll see what Alumilite says. But I'd appreciate any clues from you folks as well!

Bottom line, I'm very happy to finally make some progress on this front. I need about 50 windows and doors for my first mine building, and I'm glad to see some light at the end of that particular tunnel.

===>Cliffy


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## Burl (Jan 2, 2008)

When you measure out your A & B side, are you doing it in a fresh cup? The reason I ask, one side will want to hold on to the cup more than the other, due to surface tension. When I'm doing small pours (less than 1oz), I pour enough in each cup to coat the bottom, swirl it around, and dump it out - then re-zero the scales. That way when you measure the next tare weight, you're getting a more accurate idea of how much is coming out of the cup due, not just how much you put in.

With Alumilite regular, you should see a khaki tan color throughout your cured piece. If its dark brown, but consistently so, you've got more B than A. If you have streaks, you haven't mixed thoroughly. Hope that makes sense.


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## bnsfconductor (Jan 3, 2008)

Cliff,
When I first did my windows I had a similar problem of the resin taking a while to set on the thin pieces. I think it might just be the nature of the beast when its a thin casting? Looks good for the first couple of attempts. I tend to mix more resin than I need to alleviate the problem Burl talks about. I tend to keep a bigger mold on standby that I pour the left over resin into. That way I'm not mixing small amounts of resin. 
Craig


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## CliffyJ (Apr 29, 2009)

Great insights guys.

Craig, I'd read somewhere that the thin pieces do take longer. 

Burl, yeah, those small 1/2-oz pours seemed more finicky. I did one with a full ounce (the last one with the door), and it got hard quicker. 

Here was an answer to a "Performance 80D" question (on Alumilite's Faq's) that has a clue: 

*Full cure on almost all of our materials is 72 hours even though over 90% of your physical properties will usually be obtained within 6-8 hours.* This is very much part dependent though. Size, thickness, and overall part dimensions can play a role in the curing *especially if it is a small or thin piece*.​
So maybe what I experienced is normal. 

Thanks again. I'll post on what AL says back to me.


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## David Leech (Dec 9, 2008)

I know nothing about the Alumilite products, but reading their web site, I see that the Performance 80D is a translucent resin that you can add pigment to.
My experience with the Smooth-On line is that their translucent resins are a lot slower to kick, and cure then the regular ones.
I use their Smooth-Cast 300 with a three minute pot life and demold in 10 minutes, which means that it kicks very quickly and will allow even thin sections to set up quickly.
Sounds similar to the Alumilite White - maybe give that a try?
Anyway, the castings are looking good.
All the best,
David Leech, Delta, Canada


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## CliffyJ (Apr 29, 2009)

I spoke with Carol at Aluminite, and she felt that either I wasn't shaking Part B well enough before mixing (the dark part), and I had to agree. I thought it was more like a paint product where you shook/stirred and it was fine for a few hours, but not so: Part B has to be shaken immediately prior to pouring out, because it separates quickly.

The other thing was, like we've talked about already (Craig I thi nk you brought it up) was the thinness. She suggested microwaving the molds a little, just before pouring. 

I did the main batch last weekend, following these points. And I'm happy with how the parts turned out. 
















I think the splotchy ones were from my earlier casts, where I wasn't mixing well enough (or pre-shaking).

The microwaving makes a huge difference. Once I put a mold in for 1 minute; and the resin began to kick as soon as it hit the hot silicone. But with 30 seconds MW time, that gave me a good 90-120 seconds to work it. 

Need to make another mold today, and cast another round tomorrow. Then comes all the flash cleanup. 

===>Cliffy


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## bnsfconductor (Jan 3, 2008)

I noticed that shaking Part B introduces more bubbles into resin pour. Shake up part B and when you pour it into the mixing cup try to eliminate some of the bubbles if you notice that Part B has a too many bubbles. 

Casts looks good! 
Craig


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## CliffyJ (Apr 29, 2009)

Thanks Craig. Yeah, sometimes I just couldn't get the bubble out when pouring the mixed resin. But, at least it was on the back side of the piece. 

Prior to that, I think that leaving both parts in their measuring cups (after shaking, before mixing) a little bit helped to get some bubbles out.

I heard you were going to ECLST, so if you were there yesterday I'm sorry to have missed you!


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## bnsfconductor (Jan 3, 2008)

Nope I didn't go to ECLST... I wish, but it's a long drive from Bozeman, MT to York! Maybe one of these years...


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