<![CDATA[Latest posts for the thread "Silicone molds and Vacuum pumps "]]> http://www.dakkadakka.com/dakkaforum/posts/list/8.page JForum - http://www.jforum.net Silicone molds and Vacuum pumps Now I am not sure if I need to build/buy a degassing chamber.

Has anyone molded their own pieces? How big of an issue are air-bubbles? (With silicone in forms, and with resin when casting)

If you have done some molding, could attach few close up pics?
Thanks!

]]> http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9227994.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9227994.page GMT Silicone molds and Vacuum pumps
It will be my first try at casting something and just like you i am unsure if vacuum/pressure chamber is needed.
And after my first tests i will decide.

I am a complete newbie but could keep you updated with the results.]]> http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9228240.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9228240.page GMT Re:Silicone molds and Vacuum pumps
Been looking a lot into that. Not THAT many options here in Sweden, and of course you want to get the best quality possible.]]> http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9228392.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9228392.page GMT Silicone molds and Vacuum pumps http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9228396.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9228396.page GMT Silicone molds and Vacuum pumps http://kinn.com/product.html/polyuretanharts?category_id=27
and this:
http://kinn.com/product.html/rtv-silikon-181----original-formula?category_id=62

I did not find any other sites in Sweden. Not sure if they are trustworthy, So i cant say i recommend it yet. We will see next week]]> http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9228455.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9228455.page GMT Silicone molds and Vacuum pumps
 realmbuilderproductions wrote:
I've done both simple one part molds and some two part molds. Depending on how many undercuts you have a vacuum pump maybe necessary for the silicone or else air bubbles will get trapped and be incorporated into the final mold. Depends on how exact and fine you want your final piece or if you can live with a small bubble here or there. Viscosity of the silicone can sometimes mitigate having to use the vacuum too, as some pour "thinner" than others to alleviate some bubbles getting trapped.


Any chance you can share a few pics of your models /bits you have casted? Some closeups would be lovely to see! ]]> http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9228627.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9228627.page GMT Silicone molds and Vacuum pumps
 wenturi wrote:
 realmbuilderproductions wrote:
I've done both simple one part molds and some two part molds. Depending on how many undercuts you have a vacuum pump maybe necessary for the silicone or else air bubbles will get trapped and be incorporated into the final mold. Depends on how exact and fine you want your final piece or if you can live with a small bubble here or there. Viscosity of the silicone can sometimes mitigate having to use the vacuum too, as some pour "thinner" than others to alleviate some bubbles getting trapped.


Any chance you can share a few pics of your models /bits you have casted? Some closeups would be lovely to see!


Here are some bases I recently poured from one part mold. You'll notice some inward bubbles/voids in them. This isn't caused by the mold, it is bubbles in the resin when poured.



The silicone molds themselves turned out fine, no bubbles - but I used a viscosity that flowed better on these with no vacuum needed. But bubbles in the resin
is another matter. I have had good luck in some cases eliminating bubbles in the cast by jabbing a q-tip in the mold immediately after pouring to clear voids, etc.
Kinda heavy handed but works. Hope this helps.

Btw, I used Smooth On Mold Star 20T for these molds. It has a viscosity that pours thinner and minimizes bubbles in the mold itself. ]]> http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9229579.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9229579.page GMT Silicone molds and Vacuum pumps Maybe that is an alternative, if you have one?
]]> http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9229587.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9229587.page GMT Silicone molds and Vacuum pumps
 wenturi wrote:
I want to create my own bits and pieces, and decided to get some silicone + resin.
Now I am not sure if I need to build/buy a degassing chamber.

Has anyone molded their own pieces? How big of an issue are air-bubbles? (With silicone in forms, and with resin when casting)

If you have done some molding, could attach few close up pics?
Thanks!



Hello Wenturi, we had some contact regarding mold making.

I never really had any problem with air bubbles regarding the silicon mold itself, as long as you're aware of the possible holes/angles that could capture air. After I added the silicon I always tap gently on the container and then all remaining small air bubbles come to the surface. But air in the resin is a different matter. When you stir the resin after you added the two substances together it's possible that you stir small air bubbles in the mix. The resin I use dries very quick so I don't get the time to wait because it could get to thick. Sometimes I got no problem with air bubbles and sometimes I don't understand why I got so many.

A pressure pot + compressor could help with this but I got no experience with this myself.

You could ask 'Sersi' a dakkadakka member for this:
https://www.dakkadakka.com/dakkaforum/posts/list/30/235930.page

I do think that it's a big investment compared to the resin parts that failed. I just keep making resin parts until I got enough and all the failed ones I just trow away. Resin is cheap compared to the silicon. Also remember, you always need more silicon then you think when pouring and you always need less resin than you think when pouring.

]]> http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9229817.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9229817.page GMT Silicone molds and Vacuum pumps
 Farseer Anath'lan wrote:
I've heard of moulds being put into an Ultrasonic cleaner, to vibrate out the bubbles.
Maybe that is an alternative, if you have one?


Interesting, im gonna try this since i already have one.]]> http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9229840.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9229840.page GMT Silicone molds and Vacuum pumps
 realmbuilderproductions wrote:
 wenturi wrote:
 realmbuilderproductions wrote:
I've done both simple one part molds and some two part molds. Depending on how many undercuts you have a vacuum pump maybe necessary for the silicone or else air bubbles will get trapped and be incorporated into the final mold. Depends on how exact and fine you want your final piece or if you can live with a small bubble here or there. Viscosity of the silicone can sometimes mitigate having to use the vacuum too, as some pour "thinner" than others to alleviate some bubbles getting trapped.


Any chance you can share a few pics of your models /bits you have casted? Some closeups would be lovely to see!


Here are some bases I recently poured from one part mold. You'll notice some inward bubbles/voids in them. This isn't caused by the mold, it is bubbles in the resin when poured.

The silicone molds themselves turned out fine, no bubbles - but I used a viscosity that flowed better on these with no vacuum needed. But bubbles in the resin
is another matter. I have had good luck in some cases eliminating bubbles in the cast by jabbing a q-tip in the mold immediately after pouring to clear voids, etc.
Kinda heavy handed but works. Hope this helps.

Btw, I used Smooth On Mold Star 20T for these molds. It has a viscosity that pours thinner and minimizes bubbles in the mold itself.


I think there is something wrong with the links/image location you provided
Would love to see your projects, so if you have time, could you please check the links.

When it comes to the viscosity I can chose between 2 options, 8k and a bit thicker one 20k. So if I dont build a vacuum chamber, Il go for the lower viscosity one.


Automatically Appended Next Post:


You could ask 'Sersi' a dakkadakka member for this:
https://www.dakkadakka.com/dakkaforum/posts/list/30/235930.page




That is a WICKED sculpt. Checked the post and helped me get more than a few answers. Thanks a lot mate! ]]> http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9229902.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9229902.page GMT Silicone molds and Vacuum pumps
Here's a link to my blog posting for the bases: http://realmbuilderproductions.blogspot.com/2017/02/recently-ive-started-to-work-on-some.html. maybe this will work better. ]]> http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9230505.page http://www.dakkadakka.com/dakkaforum/posts/preList/719476/9230505.page GMT