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Thread: tips for a vacuum pressing ......

  1. #1
    Join Date
    Feb 2007
    Location
    oswego county , upstate n.y.
    Posts
    280

    tips for a vacuum pressing ......

    hi all

    ok so heres the scoop. i pulled the trigger yesterday and bought a vacuum press setup from rockler WW in maine . (its all joan's fault )

    ok so i got it home and have already made my platten board with the cross cut groove grid, and a matching top platten or caul the same size. both are about 30x30 with corners and edges rounded over with an 1/8th inch bit .

    after dinner i would like to try it out . and i have a few questions .........

    1. is it better to use MDF or baltic birch ply for a substrate ?

    2. i will be using cold press veneer glue on the substrate only ...(please advise if this is wrong) but to my way of thinking , if i glue both, the veneers would curl up before i could get my wood and glue and caul sandwhich in the bag.

    3. from what i have read so far, the pump is supposed to be running the whole time , my main question is how long do i let the sandwhich cure , or press to get a good bond ??

    4 can i use packing tape to wrap my platten and caul boards so they dont stick to the project instead of wax paper . these two pieces will be used over and over so, i think its worth the time spent taping them up.

    5. and lastly this is my first time doing this , so if i have forgotten anything please let me know, or anything you think of that might help before i do a booo booo

    oops almost forgot , the shop temperature is about 55 to 60 degrees and will remain that way all night . any problem with that ??

    thanks alot in advance
    grizzly
    what are you building today ??

    GRIZZLY

  2. #2
    Join Date
    Feb 2007
    Location
    oswego county , upstate n.y.
    Posts
    280
    hi all

    ok dinner is done, i've got a full belly and a sinking energy level.....been up for 29 hrs and fading out fast, i dont belong in the same space as any power tools soooooo i am going to bed and will start fresh in the morning

    have a good night all , i will check back in the morning and see what kind of things i forgot

    have a great night
    what are you building today ??

    GRIZZLY

  3. #3
    Steve Clardy Guest
    Tod gets back on board and He can help you out Jim.

    I've never done vac bagging.

  4. #4
    Join Date
    Nov 2006
    Location
    Villa Park, CA
    Posts
    1,407
    See answers in the quote.

    Mike

    Quote Originally Posted by jim capozzi View Post
    hi all

    ok so heres the scoop. i pulled the trigger yesterday and bought a vacuum press setup from rockler WW in maine . (its all joan's fault )

    ok so i got it home and have already made my platten board with the cross cut groove grid, and a matching top platten or caul the same size. both are about 30x30 with corners and edges rounded over with an 1/8th inch bit .

    after dinner i would like to try it out . and i have a few questions .........

    1. is it better to use MDF or baltic birch ply for a substrate ?

    A. Either will work, but MDF is usually less expensive.

    2. i will be using cold press veneer glue on the substrate only ...(please advise if this is wrong) but to my way of thinking , if i glue both, the veneers would curl up before i could get my wood and glue and caul sandwhich in the bag.

    A. Yes, you normally only put glue on the substrate. Another reason is because too much glue can come through the veneer and ruin the job. After you put the veneer on both faces, use some packing tape to hold it in place - run the packing tape from one face to the other and make sure it also sticks to the side of the substrate. Even then, the veneer will probably move a little bit during the press.

    3. from what i have read so far, the pump is supposed to be running the whole time , my main question is how long do i let the sandwhich cure , or press to get a good bond ??

    A. Depends upon the type of pump - some are intermittent and detect the amount of vacuum, shutting off when there's enough and turning on when the level of vacuum is less than some level. If this doesn't make sense to you, then most likely your pump should run continuously. To tell when the glue is cured, you can put some on a piece of wood outside the bag and test it to see when it's cured. Your glue will have guidelines as to how long it takes to cure. If you exceed the guidelines, you'll be safe.

    4 can i use packing tape to wrap my platten and caul boards so they dont stick to the project instead of wax paper . these two pieces will be used over and over so, i think its worth the time spent taping them up.

    A. Humm, I never thought of that. I use a piece of 20mil plastic on both sides of the work (against the veneer) to prevent the work from sticking to the platen and caul. The only problem with the packing tape idea is that sometimes you need to put a piece of duck cloth under the caul to accomodate different thicknesses of veneer - you want something between the veneer and the duck cloth to keep the duck cloth from sticking to the veneer. If you're only using one kind of veneer on a face you don't need the duck cloth.

    5. and lastly this is my first time doing this , so if i have forgotten anything please let me know, or anything you think of that might help before i do a booo booo

    A. Do a practice (or test) piece before you do your actual work. You need to experience what's going to happen in each step. Round over the top edges of your caul so you don't have sharp edges against the bag. You're going to have to hold the caul in place as the vacuum pulls down so it doesn't get out of place. Don't make the caul too big or the sides will pull down and you won't get a full press in the center of your work. If you're using multiple kinds of veneer on a face, use a piece of duck cloth between the plastic sheeting and the caul or platen to accomodate the differences in thickness - otherwise, the thin pieces of veneer might not glue down properly. A "sky hook" to hold the top of the bag opening really helps if you're putting the work in by yourself. I'm sure I'm forgetting something. Practice, practice, practice before doing the real work. Make SURE you're comfortable with EACH step before you put the real work in the bag.

    oops almost forgot , the shop temperature is about 55 to 60 degrees and will remain that way all night . any problem with that ??

    A. Depends on the glue. Make sure the glue will cure at that temp. Run a test before you do the real work.

    thanks alot in advance
    grizzly
    Last edited by Mike Henderson; 03-25-2007 at 05:22 AM.
    Ancora imparo
    Go into the world and do well. But more importantly, go into the world and do good.

  5. #5
    Join Date
    Oct 2006
    Location
    ozarks
    Posts
    4,992
    jim, mike`s answered your questions well, the only things i`d add are that i wax my plattens instead of using wax paper and i`ve found that a doubled layer of nylon window screen will facilitate vacuum travel just fine...no need to kerf a plate as long as you use the screen...one more thing...on glues, some glues take substantially longer to set in a vacuum so be sure to err on the side of caution......good luck! tod
    [SIZE="1"] associated with several importers and manufacturers.[/SIZE]

  6. #6
    Join Date
    Feb 2007
    Location
    oswego county , upstate n.y.
    Posts
    280
    thank you mike

    i am going to do a first attempt now that i am a member of the living again man those long days are tougher than they used to be ..... ok so its off to the shop we go , i will take pictures of the results and the process to post later on .
    thanks for the help , talk to ya'll later
    what are you building today ??

    GRIZZLY

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