Cheep DIY low vacuum pump idea

[sscherin]

I found this on one of the RC groups..

I thought anyone who wanted to try vacuum laminating or a vac vice might be interested..

The short version is that he made a vacuum pump using a sheet of MDF, a pair of aquarium air pumps and 2 - 1 gallon paint cans.

Check the last page.. Someone figured out that some models of Aquarium pumps (Tetra Whisper) can be converted to vacuum buy simply flipping over the valve assembly inside.. No cans.. Just plug and play..
Yeah they only pull 5" of vacuum but that's still 150lbs pr square foot of pressure.

http://www.rcgroups.com/forums/showthread.php?t=966524

[BobSch]

Yeah they only pull 5" of vacuum but that's still 150lbs pr square foot of pressure.

150 lb/sq Ft= ~ 1 lb/sq in. Is that enough?

[LCHIEN]

do you veneering guys pull a vacuum pumping continuously or do you pull a vacuum, close off a valve and hold it without leaking it off? I'm not familiar with the fixtures.

If you can pull a vaccum and close it off w/o leaking much then you can probably plumb a shop vac to pull enough vacuum in a couple of minutes.

[crokett]

Dumb question but would one of those space saver bags work for vacuum clamping? They are designed to hold a vacuum after you pull your vacuum out. It would be easy to adapt a 2" shop vac hose to fit one.

[sscherin]

We got a set of those bags.. They didn't hold vacuum for more than a few days and the plastic was easy to puncture..

For smaller projects I know of people who use the food saver vacuum bag systems.
Seal the bag and put it somewhere till the glue sets.
Width is the only limitation.. length is however much bag you want to roll out.

[Pappy]

For smaller projects I know of people who use the food saver vacuum bag systems.
Seal the bag and put it somewhere till the glue sets.
Width is the only limitation.. length is however much bag you want to roll out.

Any idea how much TROUBLE you just got me into?

Got one sitting on the kitchen counter...gotta give itr a try!

[poolhound]

We got a set of those bags.. They didn't hold vacuum for more than a few days and the plastic was easy to puncture..

For smaller projects I know of people who use the food saver vacuum bag systems.
Seal the bag and put it somewhere till the glue sets.
Width is the only limitation.. length is however much bag you want to roll out.

I wonder how much pressure each of these can apply. Not holding for "more than a few days" should'nt really be a problem as most glue ups would need much less than that with 24hrs being an upper limit.

[LCHIEN]

I wonder how much pressure each of these can apply. Not holding for "more than a few days" should really be a problem as most glue ups would need much less than that with 24hrs being an upper limit.

Speaking from a physics point of view, The most you can get is 15 pounds per square inch - that's one atmosphere of pressure or about a ton per square foot with a perfect vacuum (e.g. 30 inches of mercury).

Even if you leak half of that its still 1000 lbs per square foot. A lot more than you can get with a few bricks.

[Wood_workur]

Dumb question but would one of those space saver bags work for vacuum clamping? They are designed to hold a vacuum after you pull your vacuum out. It would be easy to adapt a 2" shop vac hose to fit one.

no, I remember someone here tried that and it lost the vacuum. I suppose it might if you kept the vac on all night, but I'm not sure.

[poolhound]

Speaking from a physics point of view, The most you can get is 15 pounds per square inch - that's one atmosphere of pressure or about a ton per square foot with a perfect vacuum (e.g. 30 inches of mercury).

Even if you leak half of that its still 1000 lbs per square foot. A lot more than you can get with a few bricks.

I just noticed a typo in my post, (should vs should'nt) and I have edited it.

Anyway I guess the question is how much pressure can you get from one of these food saver or space saver vacuum bags using either the hand pump or shop vac? DM says he gets around 1500lbs/sq ft from his vaccuum press but thats a pretty fancy setup.

[tribalwind]

theres a few on the site instructables.com i've wanted to try. this one looks especially simple n cheap...
this site has a bunch of other interesting articles to check out !



make a manual vacuum pump for
under $20 by converting a bicycle pump

heres another cheapie one
convert a tire inflator-type air compressor into a vacuum pump

[cgallery]

To keep the bag vac longer, do multiple (at least two) seals on each end.

And be careful how much glue you apply. The Foodsaver will suck extra glue into the juice reservoir, which can cause problems of the matrimonial variety.

[drumpriest]

My press reportedly does 1650 lbs per square foot, and the pump runs continuously, though it probably does not need to. Prior to owning this setup (vac-u-press) I had the roarockit setup, which was hand pumped, and you relied on it keeping the vacuum. Sadly it did not do a great job of it, so I would have to periodically go and pump again.

The space bags are just not strong enough, by the time you get enough pressure in there you blow out the bag, I've tried it. :-(

[poolhound]

The space bags are just not strong enough, by the time you get enough pressure in there you blow out the bag, I've tried it. :-(

Have you found a minimum strength/thickness of bag (MIL) that is required to maintain the pressure and NOT blow out?

[atgcpaul]

I built my pump from a JWWer kit. It switches on a off based on a preset. I
pretty much let it run continuously right now because of some holes in the bag.
If I'm doing a simple flat piece, I leave it on for at least an hour. If I do a
curved piece, then overnight. The gauge says I'm getting 27".

I use a 15mil polyethylene bag. I pad any sharp corners to prevent holes and
patch all holes with Gorilla tape. I bought several yards of 20mil vinyl for a new
bag but haven't gotten around to making the bag yet.