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  1. #1
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    Default Making a Vacuum Press

    Thanks to Ian (from Sydney), who provided encouragement and guidance, some laminated panels have been made in my shop.

    The first job was done with clamps and cauls. I loved the finished job, and so did my daughter (thanks, Ian) but I had a sense of humour failure with the clamps and cauls. Not my preferred approach. Some people love them. I don't.

    Bought a vacuum press from Carba Tec. It worked like a charm. The next job is a set of doors about 1,500 to 1,600 mm long, so a bigger press was needed.

    Making a vacuum press turned out to be one of the simplest things done in my shop. Bought a lump of clear vinyl a tad thicker than the Carba Tec bag. Folded it in half. Used the airtight tape to fit an outlet to the top of the bag. The outlet is a standard poly flange fitting from the irrigation section at Bunnings (see Pic). The only mods were to sand the base flange on the linisher to make it thinner and flat. I also cut very shallow grooves across the base with a hacksaw to create passages through which air could pass.

    The outlet was fixed in place with the tape and the flange screwed up reasonably tight to ensure a good seal. Two sides were sealed with tape. A piece of MDF was slipped into the bag and the final edge sealed with tape. Push the rubber valve (vacuum wine bottle closure kit is available from a zillion places) into the inlet, use the vac to get most of the air out, use the pump to create the vacuum. Done. Except this time, I scored a crook valve that would not hold vacuum. Ditched and replaced. The bag has now been holding vacuum for 6 hours.

    Folks, if you would like to get into laminating and if the cauls, clamps and presses have been putting you off making a start, a vinyl vacuum press is a cheap and effective solution. Again, thanks to Ian for giving me the nudge necessary to make a start.

    Have fun!

    John
    IMAG0426[1].jpg
    P.S: The mesh in the bag (from carba Tec) helps air move to the outlet. I reckon very rough hessian would work as well.
    Last edited by John Samuel; 27th November 2013 at 03:26 PM. Reason: Oops

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  3. #2
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    Well done, John. And Ian.

    Its success stories like these that make this Forum. Ian assisted John to as successful outcome, and John readily acknowledges the mentoring. Two gentlemen.

    John, How about a few more pictures - building and using your vacuum press.

    For those who have not used a vacuum press the numbers are rather surprising. I will work in imperial measures rather than metric as when someone talks about newtons I think of little old men getting hit on the head with apples.....

    Air pressure is 14 psi. A realistic pressure for a vacuum press is 10 psi, probably closer to 8 psi in my case. Nothing is perfect. Now suppose we wish to vacuum press something that is two square feet, or 288 square inches. At the minimal vacuum pressure of 8 psi - does not sound much - we have total pressure on our workpiece of 2,304 pounds - just over a ton! Just imagine trying to crank up a ton of pressure with a screw press. And hydraulics cost $$$'s.

    Thanks again, John and Ian.




    Fair Winds

    Graeme

  4. #3
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    John

    Any chance of a product number of the poly flange from bunnings? This is on my to do list (a fair way down I'll admit) but I'd never worked out how to do it.

    How did you join the long edge?

    Trav
    Some days we are the flies; some days we are the windscreen

  5. #4
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    Trav,

    Looked over the flange. If there was a product number on it, I ground it off when I flattened the base and made it thinner. The makers mark seems to be RXP. It has a 3/4" ID. The nut on the flange is marked both as 20 mm and 3/4". I made the bag by folding a sheet of vinyl in half. All the other three edges were sealed with that clever tape we use for vacuum presses and the like.

    Just do it, Trav. It is so darned convenient. Made my boy a desk recently and had intended to make a frame and panel door. When the NG Rosewood turned up, only one piece had the very pretty red colours I was after. But I cut this piece into four veneers about 150 mm wide and 3 mm thick and laminated a piece of MDF. This was then given rails and stiles and everything was sanded flat. It turned out very well ... the book-leaved laminates look great.

    Graeme,

    Thanks for the kind words.

    Had to think a long time about your request for more pics. There is not a lot more to show. It truly was a piece of cake. But for the sake of completeness, here come a few more details.

    The first pic is the flange, vacuum pump and rubber valve (the last two are purchased as wine stoppers ... to prevent air from turning an opened bottle of wine to vinegar). Note how the rubber stopper is simply pushed into place. No glues, sealants etc are necessary because atmospheric pressure seals it into the flange. The mesh that helps air find its way to the outlet can also be seen. After pulling vacuum I grabbed the flange and lifted the sheet of MDF off the table by the flange. And yet, just by pushing one edge of the rubber stopper with my thumb, the seal is broken and air rushes into the vinyl bag.

    Vacuum Pump.jpg

    The next pic is the base of the flange. from memory there used to be a nut moulded onto the base, but I cut it off with a hacksaw and then sanded the base smooth on the linisher and made it a bit thinner. The shallow cuts made with a hacksaw can be seen. These provide channels through which the last of the air can be drawn.
    Flange Base.jpg

    In the next week or so I hope to make the doors for the lingerie cabinet currently underway. I'll take some pics and will post them in the Frilly Nickers Cabinet thread in the Big Stuff Forum.

    The doors are 1,550 X 200 mm. Worked out the pressure applied by the atmosphere to be 2.2 tons ... on each side. And all it takes is some clear vinyl, tape, an irrigation flange and a wine stopper and pump. Marvellous!

    Cheerio!

    John

  6. #5
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    Thanks john. Sorry, I should have given you some kudos first, before asking my question. You got me all excited and I forgot my manners!

    I don't suppose you have a link to the tape do you?

    Trav
    Some days we are the flies; some days we are the windscreen

  7. #6
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    Quote Originally Posted by Trav View Post
    I don't suppose you have a link to the tape do you?
    Trav,

    The link for the yellow tape is: Vacuum bags / Tacky Tape : Adelaide Moulding & Casting Supplies a 9 M roll is about $13. They also sell the vinyl sheet, but I think the postage would kill you. Likely better to get it from Bunnings. My vinyl is about 0.5 mm thick (a bit thicker than the one bought from Carba Tec).

    Carba Tec sell complete presses as well as replacement black tape, pumps and the mesh, but it is not always in stock. See Search Results : CARBA-TEC

    For the pump and rubber valve, Google Vacu Vin ... you will be drowned in sellers. I think I paid about $25.00 for a pump and two rubber valves/stoppers.

    Have fun!

    John

  8. #7
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    Default

    I have always wondered about how the lack of air affects the glue drying.

    Glue in a sealed container does not set.

    Can you address this, please?

  9. #8
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    John,

    I just looked up the Vacu Vin thing, and found this

    "The Vacu Vin Concerto Wine Saver is a vacuum pump that extracts air from an opened wine bottle and reseals it with a reusable rubber stopper. A" click" sound will tell you when you have reached the optimum vacuum level. The vacuum slows down the oxidation process so that you can enjoy your wine longer. This set contains a black plastic pump with ergonomic handle and 4 stoppers."

    I presume the "stoppers" are basically a one-way valve. Referring to the description above, is the vacuum level reached when the "click" sound is heard sufficient for our purposes, or are you able to continue pumping to get a higher vacuum? Is this pump basically the same item as supplied with the Roarocket kits?

    I was all set to buy the kit from Carbatec, but it looks like you can put together a more versatile setup for slightly less money using the suppliers you have suggested.

  10. #9
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    Just a thought - it is worth making an adapter for the end of your household vacuum cleaner so it can be plugged onto the bag? This would allow you to rapidly evacuate the bulk of the air from the thing before conecting the handpump to draw the vacuum down.

    With bigger bags, and more volume of air, I suspect the little Vacu Vin thing would take a good while to get the air out !

  11. #10
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    I've read this thread several times but I have to admit I'm completely confused. I dont understand what you are using to create and hold the vacuum.

    Are you using some type of electric pump - if so, does it just create the vacuum then stay switched off while the sealed bag holds the vacuum ? Or does that simple loking wine pump thing create the vacuum ?

    It also seems that you use something to extract most of the air, then something else to actually create a vacuum. Is that true?

    I'm interested in making one of these - but just a small one to press up marquetry panels. If I could do it without an electric pump that would be great.

    Cheers
    Arron
    Apologies for unnoticed autocomplete errors.

  12. #11
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    Quote Originally Posted by Mr Brush View Post
    Just a thought - it is worth making an adapter for the end of your household vacuum cleaner so it can be plugged onto the bag? This would allow you to rapidly evacuate the bulk of the air from the thing before conecting the handpump to draw the vacuum down.

    With bigger bags, and more volume of air, I suspect the little Vacu Vin thing would take a good while to get the air out !
    After the pump starts clicking you can pump all you like ... nothing happens ... you are at maximum vacuum.

    The vacuum pulled is plenty for what we want to do. The Roarocket kit (which uses the Vacu Vin pump and rubber one way valve) was developed to form skateboards, which are not flat but are shaped. The vacuum is plenty to pull the veneers into shape over a form to get the desired shapes. So far, I have had a perfect glue seam every time.

    I use the standard nozzle on my shop vac to evacuate most of the air through the Vacu Vin one way valve before using the hand pump. It speeds matters up more than somewhat.

    I have had no problems with the bag and valve holding vacuum overnight. Some texts say to create the vacuum, and then to work the pump about 15 and then 30 minutes later, to scavenge any excess air that may come out of the timber. If you hear clicking, you are at maximum vacuum. Even after being left overnight, my presses are holding vacuum so well that as soon as I operate the pump the next morning, I get clicking immediately.

    Making the press yourself is especially a good idea for larger items (the doors I will make tomorrow or Tuesday are nearly 1600 mm long), but you can make any size you like.

    Initially I was put off the idea of making a vacuum press by all the pumps, valves and sundry stuff declared necessary. Now that I have made and tested my own large press, I am inclined to wonder why anyone would bother with all that gear. The vac gets most of the air out in seconds. The pump then pulls to vacuum in about a minute, and it holds vacuum well. Why bother with electric pumps etc?

    Finally, water based glues go off in the press when the water is drawn away from the seam into the veneer and substrate ... but it does so more slowly than when open to the air. Generally, if using PVA glue, I leave the job in the press overnight to guarantee that the glue seam is cured well enough so when I release the vacuum the seam will not fail. For the next job I am contemplating using a PU glue with a long (30 min) open time. That way I can pull the job out of the press in an hour or so, because it is a chemical cure and not a "drying out".

    Cheerio!

    John

  13. #12
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    Quote Originally Posted by Arron View Post
    Are you using some type of electric pump - if so, does it just create the vacuum then stay switched off while the sealed bag holds the vacuum ? Or does that simple loking wine pump thing create the vacuum ?
    Arron,

    It is as simple as it looks. A vinyl bag ... some sealing tape ... a PE irrigation fitting from Bunnings ... a vacu Vin hand pump and one way valve ... some netting. As the Looney Tunes cartoons used to say, yibbada ... yibbida ... that's all, folks!

  14. #13
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    Cheers John - you've answered all my questions.

    As for glue, I'd tend to use West System epoxy (with the slow or fast hardener depending on size of job), or PU as you suggest. Not keen on PVA for bent laminations, as you tend to get a bit more springback when the piece comes off the former, fine for flat stuff though.

    I've had a bit more success with the (very thin) Purbond PU on some recent jobs - looks like I was wetting the timber too much on previous attempts. Unless the wood is absolutely bone dry, there is enough moisture already there to make the PU go off.

    Another suggestion is Jowat Jowapur 686.70 structural PU which I saw being used on a recent visit to Monaro Timbers in Canberra. Absolutely amazing stuff - they will be buying in a drum and selling it in small containers (e.g. 500ml) shortly, so give Shaun at Monaro a call if you are interested in trying some. It's slightly thicker than Purbond (not much though - so easy to roll on), and gives a very nice glue line. Neither Purbond nor the Jowat glue foam up like traditional PU (e.g. AV515) - any squeeze out is rock hard and solid.

  15. #14
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    Default Billy265

    Hello There,

    The Australian Skateboard Kit company supply the whole vacuum bagging kit, including the vinyl bag (various sizes), sealing tape, stopper valves and pump. And cheaper than Carbatec!!!

  16. #15
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    Quote Originally Posted by GraemeCook View Post

    Air pressure is 14 psi. A realistic pressure for a vacuum press is 10 psi, probably closer to 8 psi in my case. Nothing is perfect. Now suppose we wish to vacuum press something that is two square feet, or 288 square inches. At the minimal vacuum pressure of 8 psi - does not sound much - we have total pressure on our workpiece of 2,304 pounds - just over a ton! Just imagine trying to crank up a ton of pressure with a screw press. And hydraulics cost $$$'s.

    Graeme
    Actually, Graeme, getting pressures many times that with a screw press is easy. I only have the gear to measure my home made press up to 1 ton, but I reach that using 6 screws with just a few turns - so I estimate that I press using 2-3 tons - that's tons per square foot, not for 2 square feet.

    I wouldn't consider pressing veneer using 1 ton over 2 square feet !

    I'm not interested in going into a which is better - screw (caul and beam) or vacuum bag method, because clearly the vacuum bag works and God knows I've had enough headaches from caul presses over the last few years so I would abandom them without a backward glance, but I have been told by people with many years experience that about 25-28" of hg is the minimum needed for long term reliable results. That's 1905lbs per square foot. That's why I was surprised to hear you guys are using a hand pump.

    And to answer the question that must be on many people's minds - why much use so much pressure. The standard answer is that you need to not just press the veneer onto the substrate, but actually compress the veneer, so you drive out the air and force in the glue.

    I could also add in my case that many of my pressings are marquetry and parquetry and it has the added benefit that it closes the gaps (which shouldn't be there but always are).

    I guess I should cut to it and say that I suspect you guys are pressing with way too little pressure - and that long term failures will result. I really don't think so many users are going the route of expensive electric vacuum pumps for no reason. Feel free to tell me I'm wrong - I'm not being dogmatic about it and I have zero experience with vacuum presses. Like I said, I'd love to make one of these vacuum press things myself - they do sound much easier and I'm particularly interested in the fact that they could probably be stored up against a wall giving me back lots of lovely floor space.

    I should also clarify what I mean about failure. The specific failure that I mean is when the veneer looks and feels like its pressed down well, there is no movement or gaps or wrinkles or booming or anything, but after a few years you realise you can chip bits off the edge with your finger. The glue is there - all hard and dried, but the veneer can just be chipped off along the glue line. I used to get this a lot when using caul presses which were too small and too weak and never understood why. Really, the bond between the veneer and the substrate should be stronger then the substrate, so when you chip off the veneer you get a fairly sizeable chunk of substrate come too, and this occurs right across the piece.

    cheers
    Arron
    Apologies for unnoticed autocomplete errors.

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