Help needed to design test for lamination technique

[TomMcKinney]

I am wondering if I can use my vacum bagger (the kind for freezing food) to help laminate things(not sure what yet, but just go with it for a while).
The rolls you cut a bag from are vey long so while any one piece would have width limits, it could be very long. (maybe vacum bag a scarf?)

But how do I go about testing if the lamination is strong enough and that the bag really works as a clamp. It would seal the pieces together, rather than continually run like traditional vacum bag methods. Will this work?

Might not be more practical than current methods, but I wanted to try something different Any thoughts are appreciated.

[George Roberts]

It will work. It will be much better than clamps. It will be more difficult.

[mmd]

The motor on a kitchen appliance is pretty lightly built. I suspect that you will burn it out by running it the length of time necessary to allow epoxy to cure. Vacuum pumps intended for industrial use are usually expensive for a reason. A better solution might be to use the bagging film from your kitchen, but create the vacuum with an inexpensive (read: throw-away) shop-vac taped & sealed to the bag. We used them for production of small parts at a boatyard I managed, and the $50 shop-vac lasted about 3 months before the motor bearings died. Four shop-vacs per year was cheaper by far than the nearest alternative.

[Rocky]

If you know any local rescue squad members ask them about the automatic splint that instantly hardens around a broken limb. This would work like a charm. Clamps down to whatever shape and stays clamped til you open a valve. They could probably get you one. Uses a hand pump, I used to have one around here somewhere.

[Bruce Hooke]

Does your vacuum bagger provide a reading of the vacuum drawn inside the bag before it is sealed? This would seem to me to be the critical factor. Without this information it is going to be hard to get a good check on where you stand. Part of what I am implying here is that, assuming the laminatations are not obviously bad, unless you have access to some good testing equipment it will be hard to test your finished laminates, so what you need to do is make sure you are providing enough clamping pressure for the glue you are using.

My vacuum bagging system pulls around 20" Hg, which has worked fine for me, at least with epoxy, which does not call for that much pressure (20 is in fact almost certainly a good bit more pressure than I need). As long as you are using epoxy I think you will be fine. If you are wanting to laminate using Resorcinol I would check on the recommended clamping pressure and compare that to what your system can provide. Resorcinol is supposed to require fairly high clamping pressures to work well.

As long as the clamping pressure is sufficient you should be OK. There are, of course, plenty of other issues, like how well the system is set up to handle the insertion of glue covered laminatations. How easy it is to keep the laminates lined up as you insert them into the bag, and draw the vaccuum, etc. Laminating long thin things like frames may not be the most logical way to use a vacuum bagging setup. Frames can easily be clamped with regular clamps, and that would probably be the quicker way to go. I usually use my vacuum system for either large flat objects that are hard to clamp by any other means, or objects with a shape that is hard to handle using regular clamps...

[ 03-04-2003, 04:22 PM: Message edited by: Bruce Hooke ]

[ishmael]

Ditto what Michael (mmd) said.

How expensive is a small vacume pump?

When I was apprenticing I visited Walter Green's shop and helped vacume on a layer of cedar for a tri or a cat hull. He was using the inlet side of a small compressor, and was a bit nervous he was going to burn it out. But it was working.

[Mrleft8]

I got my vacuum press from one of the catalogs. Woodcraft I think... It's small, but does a really good job. Cost about $170.00 with 5'x3' bag. Since then I've bought several other size bags. Biggest is 6'x6' (cost about $200.00). The little pump does just fine. I've vac-clamped curved laminations, veneers, flat panels, and compound curved laminations... It might be cheaper than replacing your seal-a-meal....

[Bruce Hooke]

Tom did mention this in his original post but I wanted to re-emphasize it since it strikes me as an important part of the method he is suggesting. With a kitchen vacuum sealing set-up the pump does NOT run continously, it just runs long enough to create the vacuum and then it seals the bag to retain the vacuum. So, in some ways this is a fairly elegant solution because you can pop the part in the bag, draw the vacuum, seal the bag, and then set it aside and either turn off the pump or move on to the next part.

One point that would concern me is that I think for the most part the seal is a heat seal so at best you would have to cut off the end of the bag to get the part out. So, over time your bag would get shorter and shorter. This seems like it might get a bit pricy over time because I imagine the bags in question must cost at least a bit more than your average plastic bag because they have to be gas impermiable...

[TomRobb]

I've read where some have used old junked refrigerator compressors to pull the vacuum. You'd want to get the freon removed by a reputable recycler of course. Our weather is screwed up enough as it is :rolleyes: