Pressure Pot Lessons

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Fibonacci

Fibonacci

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Joined
Feb 9, 2011
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Location
Ridgecrest, CA
1. Ensure that your mold will stand up under pressure.

For my first pressure casting, I used a homemade mold that I have used on the table a number of times. When I went to check on it, It had developed a hole and leaved 3 oz of Silmar into the pot.

This leads to the next lesson:

2. When casting, ensure you have sufficient acetone on hand.

The "new" bottle that I thought I had was actually almost empty. I was up for several hours cleaning up after it.
 
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I had a similar experience. I made molds out of Cutting boards and stuck them in there. Well the pressure forced mich of the resin out. I am locky I had a dam around my rack that caught it. Now I use plumbers putty on the molds to seal them.
 
I've been reading thru the casting threads and I can't decide whether I need to have a setup to provide pressure or vacuum or both. My first goal is to cast tubes that have been painted so I just want to eliminate air bubbles. For my first try I just tried to heat up the resin a little and then slowly poured it in a resin saver mold and it came out pretty nice. But if I do several more of these I don't want to just hope I get lucky and ruin a piece of artwork my wife painted...

I was wondering for a resin saver mold wouldn't putting it under pressure force resin into the inside of the tube? I wasn't sure how good that seal is where you slide the tube on the mold.

Thanks,
Gil
 
Fibonacci said:
1. Ensure that your mold will stand up under pressure.

For my first pressure casting, I used a homemade mold that I have used on the table a number of times. When I went to check on it, It had developed a hole and leaved 3 oz of Silmar into the pot.

This leads to the next lesson:

2. When casting, ensure you have sufficient acetone on hand.

The "new" bottle that I thought I had was actually almost empty. I was up for several hours cleaning up after it.
Click to expand...

I used the cheap plastic cutting boards from walmart.They are 5/16 inch thick.For a single blank mold for my waste wood blanks I can get 3 molds from one cutting board.I have a few I need to cut up to make other molds.For $2.17 per cutting board you cant go wrong.
 
I used HDPE as well, but it leaked out one of the corners. I apparently did not seal it well enough.

Next time I will use some silicone or RTV or something on all the edges.
 
Fibonacci said:
I used HDPE as well, but it leaked out one of the corners. I apparently did not seal it well enough.

Next time I will use some silicone or RTV or something on all the edges.
Click to expand...


Plumbers Putty works well for this. I only open one wal of my molds t remove and put fresh putty there but the putty on the rest has help up for a while w/out needing to be refreshed.
 
I use Goop to seal up my molds. Actually, I use it to seal the edges and I glue up my UHMW and cutting board molds, rather than screwing them together. It works really well and the molds break down easily.
 
So if I was to put a resin saver mold in a pressure pot...how long do I need to keep it under pressure? I'm using Silmar 41. And it sounds like I would goto 25-35 psi...is that enough to clear the air bubbles that might be near the tube?

Thanks,
Gil
 
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