Plexiglass vacuum chamber

[SamHarper]

A friend of mine (Dave, pbuh) had a bunch of 1/2" plexiglass he said I could use, so I made a vacuum chamber. I just finished it. This is me holding it up by the lid so you can see that it's holding a vacuum.



I'm going to put some rests on the bottom to lift the wood up a little. I'll probably also add a gauge at some point.

I'm using Gold's Gym 6' stretch band (same stuff as Theraband) for a gasket. I originally got it to make slingshots, but it works great for a gasket because it's wide enough that I can just cut out the middle of it, and there's no seam around the edges.

Originally, I used some silicone glue to glue it to the lid, but it wouldn't hold a vacuum. So I pealed that off, cleaned it up, and put another one on there without gluing it. It's just sitting between the lid and the rim. It seems to work!

I bought one of those round vacuum chambers made out of a pyrex dish on ebay a while back, but I don't like it because with its shape, it's not as easy to put square pieces of wood in it. And it's not very tall, so you have to be really careful when you initially put on the vacuum and all those bubbles rise up. With this square plexiglass one, I can get more wood in it at a time, and it's taller, so I don't have to worry so much about the bubbles getting up in the valves and pump and stuff.

I found a guy on craigslist who makes grills, and he had some scrap pieces of expanded metal. I'm going to use that to make a weight like Curtis Seebeck uses to keep the wood submerged in the Cactus Juice.

<--happy me

[SamHarper]

Well, the vacuum only held for a couple of hours. I guess I'll go ahead and get a gauge so I can see what kind of vacuum I'm getting.

Any idea how I can check to see where it's leaking?

[SamHarper]

I decided to set the timer on my phone and see how long it would hold a vacuum and compare it to my old one, so I propped the lids up on props so when the vacuum broke, they'd drop a little, and I'd hear them so I didn't have to go check. My new one held a vacuum for 44 minutes before it dropped. The old one is still holding.

[LivinADream]

ill be the dummy. what in the heck is this for?

[Dale Moser]

ill be the dummy. what in the heck is this for?

I'll ride that pony with ya....


I assume we are trying to treat some wood in some way?

[SamHarper]

It's for stabilizing wood for knife handles.

https://www.youtube.com/watch?v=uvII1FTm3YM

[Texas Grown]

You might try submerging it in food colored water to locate the vacuum leak. That should give you a clue as to what area of the chamber the leak is in. Or you could use a spray bottle with colored soapy water and spray all the joints to see if it sucks color bubbles inside.

If you clamp the lid down and reverse the air flow, it should hold some light pressure as well. Then check with soapy water. "Light pressure" being the key

[LeanMachine]

Yea I think id spray the outside seems with colored water and see where it sucks in at. I've heard of people running a constant vacuum. I'm not sure how this is accomplished. Perhaps some kind pressure valve. That is assuming you can't just let it run at max without burning out the pump. I assume the pumps are not strong enough to create too much force.

[Texastaxi]

If you wanted to get all fancy, you could wire in a pressure indicating transmitter, and a control to cycle your vacuum pump on, when the pressure dropped.

But, by the time you did all that, you could just buy one of Curtis' chambers.

I wonder if a small clamp, on each corner, would fix the leak.
Heck, it might not even be the lid. It might be one of the valves.

[TexasBob]

Awesome. What pump are you using?

[SamHarper]

I'm using this pump. I got it at a pawn shop.

I tried coloured water, and it's definitely leaking at the lid. I've got my edges as smooth and flat as I can, so I guess I just need a better gasket. Maybe I could try using two gaskets, one on top of the other.

[SamHarper]

Curtis Seabeck runs his pump continuously, but I'd still like to have a chamber that doesn't leak. My other chamber is still holding a vacuum this morning.

[Texastaxi]

Do you know anyone that has a machine shop, with a mill?
It'd take about 58 seconds to mill that top edge perfectly flat.

[SamHarper]

It looks like it didn't leak between the chamber and the gasket. It only leaked between the lid and the gasket. Hmm. When I took the lid off, the top of the gasket was wet, but the bottom of the gasket was dry. I sprayed water on both sides of the seam.

[SamHarper]

The way I got the top of the chamber flat was by using double sided tape to tape a sheet of sand paper to a flat slab of polished granite, then rubbing the chamber on the sand paper. I went down to 400 grit. But like I said, it's not leaking on that side. It's leaking on the lid side. That surprises me because the lid side is the smoothest part of the plexiglass. I don't see how it's possible to get it any smoother.