New Member, probably known issues :)

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New Member, probably known issues :)

Postby Angelus » Fri Nov 04, 2016 10:56 pm

Hi together,

I'm a new member from Germany. I already tried some Bits casting some time ago. I used "2 pieces fold mould". Which means I create a two part mould which is rather even, fill the two halves of the mould with resin, wait a Little and then bring it together having something heavy on top of the mould. This worked but not really well and only for solid and simple parts.

Now I have created a vacuum Setup which I used the first times this week. Unfortunately the results are also bad. I have made 6 Tests until now for some heads with 2 part moulds bringing the resin from the top (with a Reservoir). Results: big bubbles or many small bubbles. The last 2 attempts additionaly had "bloody" parts where some not hardened resin came out of the bubbles.

I will try to generate my own FAQ which I want to share then.

So hopefully I will get some Support to find the traps and come to satisfying results.

My current equipment:
Resin: TFC PU Giessharz Resin 9min 1:1 500g+500g (https://www.trollfactory.de/Giessmassen ... g500g.html)

Silicon: TS-PK-Sil-Mint-Silikon-A20 (https://www.pk-pro.de/TS-PK-Sil-Mint-Silikon-A20)

Vacuum Setup: ca. 10l pot, Kaleep 1stage vacuum pump, Free Air displacement: 2.5CFM, Ultimate vacuum: 5Pa. On my Manometer I managed to get -13 PSI (-0.9 bar)

I do not have preassure Equipment at the moment. I want first to understand what I currently have and maybe later.

I did not use any release Agent ( will try to buy Baby powder by today)

Current mould style:
I have a two part mould with a big Reservoir on top from which I also insert the material. Looks similar to what mangozac is showing here on the right picutre:
Image
The Reservoir is not cubic but becomes narrower towards the Elements beeing cast (sorry do not know better to explain)

Current Problems:

a. still some bigger bubbles where the resin is not flowing completely in the mould.

b. a lot of small bubbles even if I squeeze the mould and degass it 1-3 times (somewhere in between -0.5 / - 0.9 bar for 30-60 seconds)

c. in the last 2 attemps bloody areas where the resin did not react to solid state (I assume this Comes either from not having the right Ratio between the 2 resin components or from older component B in my mixing pod. I regognized some White film when bringing the resin to the mould in my latest attempt which is currently hardening) in this attempts I did the Maximum vaccum of -0.9 bar at least 1 time per attempt for around 30-90 seconds. Maybe this is the Problem?

Current Questions
1. If I only have access to vacuum setup, how to degass?
1.1 Maxumium possible vaccum?
1.2 How Long /often should I degass?


Currently I'm also reading a lot of threads here in the board but I hope you will help me here in my learning by doing thread.

Cheers
Thorsten
Angelus
Casual
 
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Joined: Sat Apr 02, 2016 7:22 pm

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