Resin casting and bubbles: would this work?

[BrundelFly]

DEGASS RTV...

PRESSURE CAST..resin (cured mold for casting)....

Glue a TINY strip of styrene strip to the part..or...USE a TOOTH Pick to POP bubbles as you pour.

 

[micdavis]

A monkey could do it. Right?

 

[trooper]

ive never realy had problems with resin, been doing it for years, the only problem ive had was with clear resin, trust me i now all about tooth picks lol i find trying to cast 2mm size windows the resin does not like to kick off for a looooong time, and will make new bubbles when your not looking !!!! :lol

 

[Jedifather]

I have the same problem trying to cast "Graflex" style recharge pins. Still can't get the to come out right.

So, I am casting a set of parts for the training remote and the last piece is a small round part with a very thin post.

When I pour the resin, the post is so thin that air gets trapped in the post. I have tried several different ways to get the air out, but I am getting mixed results and its a real PITA.

So, here is my question.

Could I pour the resin and then put these molds in a vacuum chamber to suck out the air bubbles trapped in the thin areas?

Would that work?

 

[88reaper88]

Could you not just use a bit of metal rod???

 

[Alaneye]

When I was casting the jaw piston for my Terminator I had the same worry as it's a very thin part (about 1mm, maybe a bit less at the thinnest part).

I used the single stem as the pouring end and I vented the ends of the twin stems into little 'bubble' air spaces. But when I poured the resin it still didn't run in as it is too viscous, but I found that when I squeezed the mould where the 'bubbles' are, it forced out the air which rose into the pouring spout and when I released it, the resin was sucked back into the 'bubbles', completely filling every part of the thin casing. Up to now it has worked for every one I have cast. I also dust the mould with talc.

I'm at work at the moment, but if you like, I'll take a pic of you mould in case the description is a bit hard to imagine?

Al

 

[adamata]

A monkey could do it. Right?

I don't get the joke.

So, I will try the squeeze method (Thanks Alaneye) or maybe trying to add a *very* little amount and then going back an adding more after the bubble has risen out (Thanks Franz Bolo).

We'll see how that works

 

[Alan Castillo]

No love for the toothpicks ? :lol

 

[adamata]

already tried them :-(
same results as using a dental tool

 

[pfillery]

Not a solution but a related question. I'm thinking about casting a replacement Exactra calculator bubble strip out of clear resin as I can't afford or justify the real thing and I'm not 100% happy with the blastech one. Is this prone to failure? It is also quite thin and clear and any bubbles are bad. Any ideas? Was just going to mould using clay and pour in clear resin.

 

[Ozymandius]

I cast thinner pieces up to .5 mm all the time without pressurizing, so it can be done if you know the tricks and how to combine them.

1. Talc the mold. (already been said, but still good advice.
2. Pour the resin.
3. Cap the pour spout with your finger (you should be wearing gloves for this), and then tilt the mold to the side about 30 degrees and gently tap it on the table to dislodge the air. Tilt it to the other side and repeat as necessary.
4. Take your finger off the pour spout and top off the level if it needs it.

Adding extra vent tubes to the mold definately helps (especially for more complex parts or two piece molds, but I'm assuming here that you are using a one piece open top mold with the pin facing down, in which case there would be nowhere to put a vent.

 

[Ozymandius]

Not a solution but a related question. I'm thinking about casting a replacement Exactra calculator bubble strip out of clear resin as I can't afford or justify the real thing and I'm not 100% happy with the blastech one. Is this prone to failure? It is also quite thin and clear and any bubbles are bad. Any ideas? Was just going to mould using clay and pour in clear resin.

Pressing your part into clay for a temp mold almost never works because the clay will stick to your part and wreck the mold. However, if you lay a piece of cling wrap over the clay and push your part down into that, then you can pull on the cling wrap to cleanly remove your part and have a usable mold. You should also talc the clay mold as well for the best results.