Vacuum / pressure systems

[TonyL]

I am asking this on behalf of a fellow turner. He is getting very frustated with his castings (all poly resin, acrylic, etc). I told him while I am sure one can make quality blanks without fancy equipment, his success rate my improve significantly (especially with respect to air bubble control), if he would to use a vacuum / pressurized system. Knowing, and looking forward to all of the opinions and experiences out there from veteran casters, what do you think?

Assuming he was committed to buying a system, and had a budget under $500, what would you recommend? Let's assume he wants to make no more than 4 to 8 blanks at a time. He and I watched several videos yesterday and were even more confused afterwards.

If you can not only recommend a system (the hardware), but your process, I/we would greatly appreciate it. If it is propriety, and don't want to share, I understand and respect that.

Best to you and enjoy the rest of the weekend!

Thank you!

PS. We have consulted the library

 

[Jim Burr]

As usual...
http://www.penturners.org/forum/f43/simlar-41-a-123694/
http://www.penturners.org/forum/f43/stabilizing-plus-casting-122782/
http://www.penturners.org/forum/f43/first-cast-under-pressure-123135/
http://www.penturners.org/forum/f18/question-need-ideas-please-123124/
http://www.penturners.org/forum/f43/pressure-pot-122515/

Why is pressure necessary if you are just doing resin? Did you look at Youtube...couple hundred videos there.

 

[BSea]

If he's getting lots of bubbles, I'm guessing the problem is the resin he's using. You don't really need pressure or vacuum for PR. Pressure doesn't hurt, but I really don't think it's required.

If he's using silmar 41, then be sure it's fresh. It should be a light blue before color or catalyst are added. If he's doing a clear cast, don't worry, it will be clear when it cures.

What is he trying to cast?

 

[avbill]

What the difference between Silmar 41 & alumite

 

[sbell111]

He doesn't need vacuum to cast. That's for stabilizing. Just building the pressure side of the pot using the tutorial from the library is pretty easy. Using an HF pot and bits readily available at Home Depot, the build cost shouldn't exceed a hundred bucks. Using the HF coupon and catching a sale will push the cost way below $100.

Spend the other $400 on resin, colorants, molds, whatever.

 

[Jim Burr]

What the difference between Silmar 41 & alumite

Silmar is PR in a different package. All you need is vibration for resin casting...pressure is a waste of money if that's all you want to do.

 

[BSea]

What the difference between Silmar 41 & alumite

Silmar is PR in a different package. All you need is vibration for resin casting...pressure is a waste of money if that's all you want to do.

There is a world of difference between Silmar & Alumilite. You MUST use pressure for alumilite. Silmar 41 uses drops of catalyst, and alumilite uses 2 equal parts mixture. Silmar 41 takes about 15 to 20 minutes to start to cure (depending on coloring used, and temperature). Alumilite clear must be put under pressure with 7 minutes of mixing. Silmar 41 has a really strong odor where alumilite has almost no odor.

 

[Jim Burr]

What the difference between Silmar 41 & alumite

Silmar is PR in a different package. All you need is vibration for resin casting...pressure is a waste of money if that's all you want to do.

There is a world of difference between Silmar & Alumilite. You MUST use pressure for alumilite. Silmar 41 uses drops of catalyst, and alumilite uses 2 equal parts mixture. Silmar 41 takes about 15 to 20 minutes to start to cure (depending on coloring used, and temperature). Alumilite clear must be put under pressure with 7 minutes of mixing. Silmar 41 has a really strong odor where alumilite has almost no odor.

And Alumilite does not have the shrinkage rate that PR/Silmar has making it great for WW..which regardless of what resin is used...must be done under pressure.

 

[TonyL]

This is excellent. I am not aware of his exact process. I have just witnessed the results (and frustration). Thank you for assembling the links. Last night, we watched several youtube videos with and without pressure and was confused. We also attended a demo without pressure. Thought I would ask the "greater" minds. The library and posts are fabulous resources. However, I still like to ask in the event that something new is discovered and not pubically shared or documented. I have also found the to be an healthy influx of new members that may have ideas. Thanks again!

 

[BSea]

What the difference between Silmar 41 & alumite

Silmar is PR in a different package. All you need is vibration for resin casting...pressure is a waste of money if that's all you want to do.

There is a world of difference between Silmar & Alumilite. You MUST use pressure for alumilite. Silmar 41 uses drops of catalyst, and alumilite uses 2 equal parts mixture. Silmar 41 takes about 15 to 20 minutes to start to cure (depending on coloring used, and temperature). Alumilite clear must be put under pressure with 7 minutes of mixing. Silmar 41 has a really strong odor where alumilite has almost no odor.

And Alumilite does not have the shrinkage rate that PR/Silmar has making it great for WW..which regardless of what resin is used...must be done under pressure.

There are other differences too, but Jim's right about the shrinkage.

Oh, and Jim, I didn't mean to quote you in my earlier post. I got distracted, and then hit the quote on your post rather than avbill's post. Guess I was asleep at the wheel.:sleepy:

And just a few more differences:
Alumilite is much better for custom pens. It threads well, and is very durable where PR is more brittle. You can thread pr, but it's easy to break PR threads.

 

[Jim Burr]

That's fine Bob...as long as we get good info out and don't drive while sleeping!!!
Both media are great for there respective uses. Please, Tony...try stuff and see what happens. There was no IAP when a few of us folks started. Your fire for new infusion is great, but at some point...please try something on your own and learn from it...that is how you pass on knowledge...not by repeating what everyone else does...JMHO on learning.

 

[TonyL]

Agreed....I think he/we are looking to avoid repeating "mistakes". Thanks again!