Anyone used vacuum jigs

[Kim]

A 200 - 250mm length of class 18, 40mm PVC pipe with end caps, one of which you tap to screw in the brass connector will work perfectly as a buffer tank and should fit neatly in under the top deck next to the two main tanks...PVC pipe works very well, I used thread tape on all the fittings, both vacuum storage and the buffer tank. I was out in the shed late on a shop tour and demonstrated the vacuum rig to a mate about a month ago...I showed him the foot switch and what not and in that process bent down and shut off the ball valve at the reserve tank. We had had a few refreshment by that time so after the demo I turned off the power to the rig and walked out. About 2 weeks later I went to use the rig and when I turned on the power the pump would not run..I stood their scratching my head for a moment thinking how it had worked perfectly just a few weeks back. Then I looked at the gauge, yep, still had full vacuum in the tanks after two weeks so the pump did not need to run...just like Hoover, that's one bloody impressive seal.

Cheers

Kim

[Dominic]

Yes I agree Martin, I am not saying it would be the most efficient method, but vacuum will pull moisture out of a glue joint and it will set up faster than normal clamping. So we may not be talking about much but it should work.

And my point is, I wonder how much it would strip the moisture out of the crystals and how quickly. If we knew this we could get some idea of how vacuum and moisture in wood or glue interact. I wonder if you can measure water content of the crystals by looking at their colour.

Cheers
Dom

[kiwigeo]

I wonder if you can measure water content of the crystals by looking at their colour.

Cheers
Dom

Silica gel is basically sodium silicate.....the presence of water in the crystal lattice will change optical properties of the substance but you'd require a petrology microscope and a trained petrologist to detect the subtle difference in optical parameters.

From my experience the Gel is either pink or blue......the indicator chemical is a cobalt compound. Because the individual beads don't all flip colour at once the mass of beads as a whole may give the appearance of grading through pinkish blue or bluish pink as water saturation increases.

Regeneration of the saturated silica gel by heating generally takes about 2 hours.

[Dominic]

A 200 - 250mm length of class 18, 40mm PVC pipe with end caps, one of which you tap to screw in the brass connector will work perfectly as for a buffer tank and should fit neatly in next to the two main tanks...PVC pipe works very well, I used thread tape on all the fittings, both vacuum storage and the buffer tank. I was out in the shed late on a shop tour and demonstrated the vacuum rig to a mate about a month ago...I showed him the foot switch and what not and in that process bent down and shut off the ball valve at the reserve tank. We had had a few refreshment by that time so after the demo I turned off the power to the rig and walked out. About 2 weeks later I went to use the rig and when I turned on the power the pump would not run..I stood their scratching my head for a moment thinking how it had worked perfectly just a few weeks back. Then I looked at the gauge, yep, still had full vacuum in the tanks after two weeks so the pump did not need to run...just like Hoover, that's one bloody impressive seal.

Cheers

Kim

You raise a good point Kim, get all your seals done carefully with tape as you go, and don't take any short-cut because it hard to find a leak later on but will make the unit less efficient. I used a squeeze of silicon gasket stuff to assist, remember it is going to get sucked into any cracks and seal them so it works well. My pump stays switched on all the time but never runs unless I am using it. I actually have trouble working out which is one and off because like Kim, I turn it on and nothing happens. I hit the foot switch to drain a bit and get the pump going.

The point I was making about materials is that there are a wide range of suitable things to use for tanks and buffer tanks etc and so make the rig with what you have available. If you look at the home made rigs on the joe woodworker site you will get heaps of ideas. I had to buy two brass fitting to make my rig. Everything else I had lying around and it all works great. So have a scrounge around before you buy stuff, you may well already have everything you need.

Cheers
Dom

[simso]

Whats the purpose of the buffer tank

[Kim]

Steve,

A buffer tank provides a small amount of free air...that is air at normal atmospheric so it is without vacuum, to the pump. This allows the pump to start and begin evacuation at full speed before it comes under load from the residual vacuum within the system...if you don't have a buffer tank, the system will still work, but, pump life will be heavily reduced.

Cheers

Kim

[Dominic]

Kim has it correct. Read this pdf with instructions how to build one and how it works.
Cheers
Dom
http://www.joewoodworker.com/docs/ProjectEVS.pdf

[simso]

So just waiting for the evs kit.

The vacuum pump takes up so much less space than a compressor

Does vacuum work the same as pressure, that is can you put a pressure regulator in the line to wind down the amount of available vacuum, I ask becuase the current rig up allows you to display available and regulated, and this is not a bad situation, obvioulsy I would have to swap out the pressure gauges for vacuum gauges, and the quick couplings to the vacuum couplings

[Dominic]

Steve, you will get gauges and a trim pot in the kit. Once you have a load on your pump you set the trim pot and check the result on gauge. Simple. What the gauge says is what you get as the pump will operate until the vac pressure in your tanks equals your set amount.
Have fun
Dom