Here's a picture of a moisture trap. It'll go at your compressor outlet before any other attachments. That one is at Home Depot.....$12.99.
Most of the time, you need to get into the habit of de-gassing any mold making. I'm not sure about your latex, but it will NEVER hurt to degas your RTV.
For de-gassing RTV, you won't need 29HG. 29HG (Inches of Mercury) will ALWAYS mean big dollars. To put this into more perspective, 30HG is a perfect vacuum and is all that's possible, so 29HG, consistently of course, is big money AND hard to come by. In fact, if I bought equipment that was suppose to be able to maintain even the 29HG they claimed, I would have to see that.
You can get away with less than any 29HG of vacuum for de-gassing RTV and it doesn't have to be able to get it to max vacuum quickly either. You'll want to apply the vacuum in increments anyway because as your RTV releases (actually a type of boil), it will expand a great deal. If you do this too fast, RTV will expand and overflow the container you've got it in inside your vacuum chamber. You'll actually apply the vacuum and as it starts releasing the trapped air, you'll need to stop the vacuum for a bit, let it stabilize and then re-apply the vacuum a little more. Once you've done this a couple times, you'll see it slow down with the expansion and you can apply the vacuum and leave it on until you see very little action taking place.
There are several things that can be acquired that are fairly inexpensive that you can use to de-gas RTV. Here's an example that you can use to get started. At one time, there was a product for sale on an "infomercial" called a "Pump-n-seal". This item can STILL be bought online and only costs about $10 bucks. Get one of those and then go to Walmart and buy one of the clear acrylic containers they sell as a food container. There are several different sizes of these things and they have a seal around the lid with a snap-type closure that allows for it to be opened and closed quickly with a lever type lock. I'll search and see if I can post a picture of one.
This will get you started nicely:
http://www.kaboodle.com/reviews/pump-n-s...food-saver
I know I said $10 bucks, but it looks like they are NOW $29.99. That sucks. They WERE $9.99 just a few years ago when I bought one. These babies pull a GREAT vacuum. I even picked up a set of those sealing lids. You won't need those if you use the containers I mentioned from Walmart, but those lids come in handy on a variety of different bowls and such, so you may want to consider those?
The containers you should be able to find at Walmart look EXACTLY like these in this Walmart link, except that they are clear, thick plastic and WERE sold individually in the container aisle. I haven't purchased any in a few years, but they certainly used to be available.
http://www.walmart.com/catalog/product.d...id=7855714
These two items will EASILY work and keep you well within budget until you figure out if you even need way more expensive equipment.
On your large molds, de-gassing the RTV isn't as important if you can't get them into a pressure pot. The reason why is, when you place a mold into a pressure pot, you are compressing any gases (air mostly) in your resin to keep them as small as possible until the resin cures to the point that the bubbles they make won't be able to re-expand once you release the pressure. What happens when you don't de-gas RTV when you use a pressure pot is that when you leave those small bubbles in your RTV mold, the pressure pot wiil ALSO compress THOSE bubbles too, so that when you remove your parts later after the resin has cured, you'll have little marks all over your parts, sorta like the dimples on a golf ball only they'll be raised dimples. You won't be able to actually see these dimples in your mold either. They are voids under the surface of the RTV that the pressure you placed on that mold while you were trying to compress the gases in your resin also compressed in the RTV mold. This is why de-gassing RTV ESPECIALLY if you'll be placing it under pressure, is an important step. Generally, this won't be too big a factor in a mold that you won't be placing in a pressure chamber. It CAN happen though. If there happens to be a void in that mold that can flex from the resin (such as the simple weight), then it WILL show up in your parts. De-gassing RTV is a practice you can afford to get into no matter HOW you'll be using the mold.
On your hollow cast parts, yes, a rotocaster is a nice piece of equipment, especially for parts that are larger. They aren't cheap and will take some practice, patience and perhaps some special resins.
If you'll be keeping the parts to an average size, a two part mold will do the trick. Now, these will take some learning too because you'll need to put a little more thought into your mold creation than you would with an open faced (single part) mold. Indexing, liquid flows and venting will all have to be considered when you make two part molds, but you'll catch on to what is needed quickly.
Most of the time, you need to get into the habit of de-gassing any mold making. I'm not sure about your latex, but it will NEVER hurt to degas your RTV.
For de-gassing RTV, you won't need 29HG. 29HG (Inches of Mercury) will ALWAYS mean big dollars. To put this into more perspective, 30HG is a perfect vacuum and is all that's possible, so 29HG, consistently of course, is big money AND hard to come by. In fact, if I bought equipment that was suppose to be able to maintain even the 29HG they claimed, I would have to see that.
You can get away with less than any 29HG of vacuum for de-gassing RTV and it doesn't have to be able to get it to max vacuum quickly either. You'll want to apply the vacuum in increments anyway because as your RTV releases (actually a type of boil), it will expand a great deal. If you do this too fast, RTV will expand and overflow the container you've got it in inside your vacuum chamber. You'll actually apply the vacuum and as it starts releasing the trapped air, you'll need to stop the vacuum for a bit, let it stabilize and then re-apply the vacuum a little more. Once you've done this a couple times, you'll see it slow down with the expansion and you can apply the vacuum and leave it on until you see very little action taking place.
There are several things that can be acquired that are fairly inexpensive that you can use to de-gas RTV. Here's an example that you can use to get started. At one time, there was a product for sale on an "infomercial" called a "Pump-n-seal". This item can STILL be bought online and only costs about $10 bucks. Get one of those and then go to Walmart and buy one of the clear acrylic containers they sell as a food container. There are several different sizes of these things and they have a seal around the lid with a snap-type closure that allows for it to be opened and closed quickly with a lever type lock. I'll search and see if I can post a picture of one.
This will get you started nicely:
http://www.kaboodle.com/reviews/pump-n-s...food-saver
I know I said $10 bucks, but it looks like they are NOW $29.99. That sucks. They WERE $9.99 just a few years ago when I bought one. These babies pull a GREAT vacuum. I even picked up a set of those sealing lids. You won't need those if you use the containers I mentioned from Walmart, but those lids come in handy on a variety of different bowls and such, so you may want to consider those?
The containers you should be able to find at Walmart look EXACTLY like these in this Walmart link, except that they are clear, thick plastic and WERE sold individually in the container aisle. I haven't purchased any in a few years, but they certainly used to be available.
http://www.walmart.com/catalog/product.d...id=7855714
These two items will EASILY work and keep you well within budget until you figure out if you even need way more expensive equipment.
On your large molds, de-gassing the RTV isn't as important if you can't get them into a pressure pot. The reason why is, when you place a mold into a pressure pot, you are compressing any gases (air mostly) in your resin to keep them as small as possible until the resin cures to the point that the bubbles they make won't be able to re-expand once you release the pressure. What happens when you don't de-gas RTV when you use a pressure pot is that when you leave those small bubbles in your RTV mold, the pressure pot wiil ALSO compress THOSE bubbles too, so that when you remove your parts later after the resin has cured, you'll have little marks all over your parts, sorta like the dimples on a golf ball only they'll be raised dimples. You won't be able to actually see these dimples in your mold either. They are voids under the surface of the RTV that the pressure you placed on that mold while you were trying to compress the gases in your resin also compressed in the RTV mold. This is why de-gassing RTV ESPECIALLY if you'll be placing it under pressure, is an important step. Generally, this won't be too big a factor in a mold that you won't be placing in a pressure chamber. It CAN happen though. If there happens to be a void in that mold that can flex from the resin (such as the simple weight), then it WILL show up in your parts. De-gassing RTV is a practice you can afford to get into no matter HOW you'll be using the mold.
On your hollow cast parts, yes, a rotocaster is a nice piece of equipment, especially for parts that are larger. They aren't cheap and will take some practice, patience and perhaps some special resins.
If you'll be keeping the parts to an average size, a two part mold will do the trick. Now, these will take some learning too because you'll need to put a little more thought into your mold creation than you would with an open faced (single part) mold. Indexing, liquid flows and venting will all have to be considered when you make two part molds, but you'll catch on to what is needed quickly.
~Recycle~