DIY Vacuum chamber.. What to use for the base?

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sschering

sschering

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I have been gathering parts to make a vacuum chamber for stabilizing and scored the most important parts today..

I got 4' of 10" schedule 80 PVC from the Re-Store for $1.50. No I don't plan to use all 4 feet.. I'll lop it off at 18-24" or so. I also hit the local plastics store and scored an off cut 12" circle of 1/2" acrylic for $20.

I have pipe taps so I can just screw the gauge and vacuum line fittings right into side of the pipe. I would rather not drill any holes in my acrylic if I don't have to. Some silicone fuel line split and slipped over the edge of the pipe should make a good seal.


Vacuum power comes from a Robinair A/C service pump..

So the last bit is the base..

Do you think a 1" thick piece of MDF ( 2 x 1/2 sheets laminated) with a 1/4" deep slot cut to set the pipe in with some caulking will work as a base? I would paint the MDF to seal it..
If not I could try to convince my wife that the 1" thick UHMW cutting board needs to be replaced :rolleyes: That would make a nice base.. it has handles and rubber feat..
 
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If you have that much time invested I would go with the cutting board or at a minimum laminate the MDF with some HPL. Then caulk in your groove and between the HPL and your pipe. It is very hard to get MDF to seal, it would take 5-10 coats and it probably still wouldn't be sealed on the sides of your groove.
 
Well I could mix up a batch of gel coat (West 404 filler, 423 graphite powder and laminating resin) and coat the inside of the base with that.. If that won't seal I don't know what will.
 
We use MDF as a spoiler board on our cnc because you can suck vacuum right through a piece that's 1/2" thick.
The cutting board you will have trouble getting an adhesive to stick to. We use E6000 or Scotch Weld 8005 to glue polyethylene(HDPE AND UHMW) with limited success.
I might have some pvc sheet fall down I could send you. I know I have 1" but I will look for some 3/4". You could use pvc solvent cement to glue it to your tube.
 
I will be happy to send you a reject base that I have for one of my Juice Proof Chambers when I ship your Juice tomorrow if you want it. MDF will NOT work as vacuum will pull air right through it.

The cutting board is not going to work either since not much of anything will stick to it, at least not permanently. If you are building a chamber that you will physically pour the resin into, then caulk is not going to be the best choice. Silicone will be affected by the resin and will not hold up at all. Been there, done that. Even urethane caulks won't work well. The only thing that I know works well for the long haul is PVC cement but then you have to have PVC for the base.
 
BTW, the reject will work fine, it just may not be up to my standards. It may not be as pretty or may have a miss cut but nothing that will affect the performance.
 
TLTHW.. Thanks!! I'd be happy to take that PVC off your hands. You have a PM waiting.

MesquiteMan.. You bent my arm.. I'll take the reject base.. It may not work for my giant chamber but a smaller more sane size I can give to a friend would be nice..
They had a ton of 4" grey pipe at the Re-Store I can get for a buck or two.

I don't plan to put juice directly in the 10" chamber.. It would take gallons of juice to fill the thing. I'll probably set open trays or jars inside or a bowl blank in a ziplock bag..


Hmm the swing on my lathe is about 1/4" shy of being able to turn this pipe.. Guess I better figure another way to trim the ends smooth..
 
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This is the pipe I bought today.. Not bad for a buck and a half.
 

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This is the chamber that I just built. It will do14 of the 5" X 3/4" blanks in one layer or 8 of the 1 1/4 round blanks as in the picture at a time. I haven't tried 2 layers yet. I would have to raise the vacuum slowly to keep from overflowing the foam into the tube. FYI, that is a jug of Cactus Juice on the left. Thanks for Curtis' help.
 

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I happened to be in Portland this weekend and met up with Dave (TLTHW) to get the perfect thing to finish this project.. A big beautiful piece of 3/4" pvc plate... I can't thank Dave enough for his help. A nice collection of stabilized blanks will be on the way as thanks for the help.

This afternoon I made a lot of noise getting the pipe cut down and trimmed flat, tapped and plumbed for a valve and gauge port.

I couldn't wait to give it a test run so I used a few sheets of craft foam as gaskets for the base and lid.. (yeah it's not even glued to the base yet)

With the Robinair pump topped with fresh oil I hooked it up and took it for it's maiden voyage. The pump only took a minute or two to pull it down to 28 Hg.
I shut the valve, disconnected the pump and it held! For the 2nd test I pulled it down to 25 Hg, disconnected the pump and left it. An hour later it had only lost 2 Hg..

Next up I put a piece of scrap wood in a open jar of water with a weight to keep it submerged. As I watched the water bubble away while the wood degassed I had a thought.. Will it boil room temperature water? The answer is YES!

At full pull the 1/2" acrylic lid drops about 5/32 in the center.

Mission accomplished! If I had enough Juice I could stabilize in 1 gallon batches.. :)
 

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OK I got the Juice and a new B&D toaster oven from Kohls for $15 (on sale for $19 and 20% coupon). That was less than a well used one from Goodwill.

Time to get busy. Three spalted blanks in the drink with blocks of PVC to hold them under.

The 10" pipe appears to be the remains of a big DIY telescope.. That explains why it's painted black inside.
 

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Folks, a word of wisdom when dealing with vacuum pumps and tanks,

Listen to the pro

I'll bet Curtis has tried most types of materials and sealers by now.

If he says it won't work, believe it. If he says it will, got that way and don't look back...

Mike B

MesquiteMan said:
I will be happy to send you a reject base that I have for one of my Juice Proof Chambers when I ship your Juice tomorrow if you want it. MDF will NOT work as vacuum will pull air right through it.

The cutting board is not going to work either since not much of anything will stick to it, at least not permanently. If you are building a chamber that you will physically pour the resin into, then caulk is not going to be the best choice. Silicone will be affected by the resin and will not hold up at all. Been there, done that. Even urethane caulks won't work well. The only thing that I know works well for the long haul is PVC cement but then you have to have PVC for the base.
Click to expand...
 
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Wow that went fast.. I only had a little juice left so I thought I should try something different with the last batch..

Maybe if there in enough left I can mix the remains together and do purple :)

Guess I should order a gallon next time..
 

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Phenolic works fine as a lid. The cost, however, is much higher. Yes, it is stiffer but in the sizes we are typically working with, other, cheaper materials work just as well at a lesser cost.
 
MDF with several coats of lacquer would work fine , but I don't know how it would last (because of chemical reaction with the lacquer and Cactus Juice and how it would hold up over time. with the chemical reaction.)

Phenolic, would work well for a base or a lid if you don't want to see bubble escape (I don't recall seeing clear phenolic.)
 
steve worcester said:
MDF with several coats of lacquer would work fine , but I don't know how it would last (because of chemical reaction with the lacquer and Cactus Juice and how it would hold up over time. with the chemical reaction.)

Phenolic, would work well for a base or a lid if you don't want to see bubble escape (I don't recall seeing clear phenolic.)
Click to expand...

MDF with lacquer does not work well, Steve. Been there, done that! First, the lacquer will not hold up to Cactus Juice exposure. Second, even with the lacquer, you will be loosing some vacuum through it. Again, been there and tried that! In my experiments, the difference between MDF with lacquer vs. a solid material such as PVC or phenolic, was a full 1/2" Hg
 
So far the PVC plate with the craft foam gaskets is working great..

I've run 3 batches on the same set of gaskets with no air leaks.
 
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