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deadwooddick
Guest
Anybody using a vacuum chamber, when bedding rifles ?
IanRobertson
New member
You could always degas before applying the epoxy which is the only way that might work. When you degas epoxy it in effect boils and makes a really big mess. If you applied the bedding and stuck in the action before degas it would boil out of the gaps and make a really really big mess. The cleanest way to degas this sort of thing is to use a large plastic bag, about 10x12 for a couple of ounces, 6mil thick and you MUST leave the top open, if you don't it will blow open and cover everything. Put this in the vac chamber and when you are happy with the degas take it out and squeegee the contents into a corner, nip off the corner and squeeze it out as needed.
Vac gauges don't really tell a lot because the vac pressure changes with atmospheric pressure (so don't waste your money). Best way and only way I know is to mix some fumed silica into a clear epoxy so you can see when and if the bubbles are removed. This mix will entrain literally millions of bubbles so it looks white, a successful degas will make it almost clear. Obviously with a coloured epoxy it is impossible to tell. The thicker the mix the more vac pressure is needed as well as time. The only pumps that will pull enough vac are the ones used for air condition service or lab work, they can be had fairly cheap, ~$300. I last used a big SS pipe coupler, about 12" dia for a chamber with a 1/2" alu bottom epoxied on and a 1/2" alu top that sealed with an O ring (you really don't need to see inside and 1/2" plexi or lexan will fail eventually). Microscopic leaks will really bugger your day preventing a degas, some yellow vac bag tape will help seal things up. It is always a fine line between getting a proper degas and not. Vane, refrig etc pumps will not pull enough vacuum to degas, the contents will bubble away but nothing will be accomplished. You will be down into the Torr range of vacuum 1 mmHg = 1.000000142466321... Torr ie parts of a mm of HG.
Unfilled laminating epoxy does not need to be degassed as it is thin enough for the bubbles to come out as is. Any time you add any filler you will entrain a lot of air, ie Brownells "flock" which is glass mill fibre, a fine example of white epoxy that will be clear when degassed.
Vac gauges don't really tell a lot because the vac pressure changes with atmospheric pressure (so don't waste your money). Best way and only way I know is to mix some fumed silica into a clear epoxy so you can see when and if the bubbles are removed. This mix will entrain literally millions of bubbles so it looks white, a successful degas will make it almost clear. Obviously with a coloured epoxy it is impossible to tell. The thicker the mix the more vac pressure is needed as well as time. The only pumps that will pull enough vac are the ones used for air condition service or lab work, they can be had fairly cheap, ~$300. I last used a big SS pipe coupler, about 12" dia for a chamber with a 1/2" alu bottom epoxied on and a 1/2" alu top that sealed with an O ring (you really don't need to see inside and 1/2" plexi or lexan will fail eventually). Microscopic leaks will really bugger your day preventing a degas, some yellow vac bag tape will help seal things up. It is always a fine line between getting a proper degas and not. Vane, refrig etc pumps will not pull enough vacuum to degas, the contents will bubble away but nothing will be accomplished. You will be down into the Torr range of vacuum 1 mmHg = 1.000000142466321... Torr ie parts of a mm of HG.
Unfilled laminating epoxy does not need to be degassed as it is thin enough for the bubbles to come out as is. Any time you add any filler you will entrain a lot of air, ie Brownells "flock" which is glass mill fibre, a fine example of white epoxy that will be clear when degassed.
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Dusty Stevens
Hollow Point Dispenser
Try not to fold it as you stir it so it doesnt entrain bubbles as much.
IanRobertson
New member
If you are using a commercially prepared bedding it will come degassed so try not to whip it up when mixing. I should also mention for anyone that wants to get into degassing - the hose to connect the chamber and the pump should be proper vac hose from the guy you buy the pump from and needs to be quite large. The wrong hose can collapse and even worse some materials are actually permeable and with the vacuum required it can prevent degassing, working like a leak. Polyethylene hose is an example of a problem material, this is why food in poly bags still gets freezer burn. You will need a ball valve to vent the chamber, slowly or you get another big mess and put the material in the bottom of the bag and just fold over the bag. And bubbles can be part of the structure of the material, they actually do add lightness and reduce strength at the same time if that's what you need.
Vac is very safe, it can't blow up on you, obviously. Pressure can also be used to reduce bubbles, if you have a pressure chamber you can put the parts in to cure. Pressure can make things blow up, obviously and low pressure over a large area has a lot of force, car jack bags for example that use exhaust to lift a car. I never did much with pressure.
That's all I remember for now, I think.
Vac is very safe, it can't blow up on you, obviously. Pressure can also be used to reduce bubbles, if you have a pressure chamber you can put the parts in to cure. Pressure can make things blow up, obviously and low pressure over a large area has a lot of force, car jack bags for example that use exhaust to lift a car. I never did much with pressure.
That's all I remember for now, I think.
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J
JamesP
Guest
Holey KuhRapp!!!
Thank You Ian
al
This made me chuckle.. Guess the reply was more informed than you expected.