I have been working on a vacuum veneering blog that I thought may be interesting to anyone getting into laminating. I made a number of tutorials that try to show the many uses of using vacuum. The blog will be updated frequently. Any comments would be great.
Ted
Replies
You should check out the forum on http://www.vacupress.com
I have added 3 new tutorials to the blog that may be worth looking at.
Ted
Just a quick note. For anyone that wants to experiment with vacuum laminating, Rockler has a relatively inexpensive ($60 ?) tool for smallish projects such as a skateboard. The vacuum is achieved by a small hand pump. In fact, the photo in the catalog looks basically like
1) an oversized heavy-duty Ziploc bag (the kind I've seen recently on commercials, for holding clothing, etc. for storage), with
2) the grey rubber "one-way-valve" stopper from a Vacu-Vin kit ($8.95 from most wine shops or the 'net) poked through one side of the bag, off in a corner so it's out of the way, and sealed with a good-quality flexible silicone or something (stoppers are neoprene I believe)
3) the white hand-pump from the same Vacu-Vin kit (kit comes with 2-3 stoppers, extras are a couple bucks for a pair)
I can vouch that the Vacu-Vin stoppers hold a vacuum (or at least very low pressure) in a wine bottle - I've used them for years and even after weeks in the fridge the stoppers go "hsssssst" when I pinch them to release the pressure. The first time I chose a project that needs vac-lamination I plan to try something like the Rocker device. If anyone has actually tried the Rocker device (or something like it), pls post here if it did indeed work well.
Your blog looks interesting, however even with reading glasses and a 19" monitor I can't read the font you chose.
nicobie
The text size is the canned size that the blog uses. I will look at it and see if there is a way of making the letters larger. There is a quick fix at your end if you are using Explorer. Click on VIEW at the top of the window, then on TEXT SIZE. You can increase the text on any page you view with this function.
Thanks
Ted
Edited 5/19/2006 2:58 pm ET by Ted Hunter
Thanks Ted,
I didn't know that.
Nicobie, with some operating systems and, if you have a wheel mouse, adjusting text size in a window can be done by left clicking in the window somewhere handy, then hold down the control key followed by spinning the mouse wheel. It works for me in MS Windows XP. I'm not sure if it works in earlier Windows operating systems and I can't say if it works in Mac systems. Slainte.Richard Jones Furniture
Hi Ted,
Thin Air Press - a good site with good information.
Coincidently, just before reading your post here and on that website during my lunch, I finished one of my usual plywood molds for some fair size cabinet doors - see attachments. It's 32-inches wide by 40-inches high. I've always built them sturdy enough to withstand implosions, but the cost is high. The big one in the photo took about four hours time, and a sheet of plywood, which means its cost is about $450. Curved work does have its price. The doors will be of three layers of bending poplar (plywood) and two of 1/4-inch VGDF plywood.
I never thought of using styrofoam for a mold. I might try it next time. I'm guessing it doesn't compress at all, but I wonder how accurate it can be cut using the method you show photos of. Have you tried using a hot wire to cut foam? How would you cut a piece as large as my wooden mold in the photo?
Here's another question: Do you have a method for predicting springback? Depending on the number and thickness of lamina, I've just guessed and tightened the curve a bit. But winging it like that isn't always accurate enough when the resulting bent part is 2-inches thick and has to mate to a convex curved part.I've been bending wood with steam and clamps for almost 35 years, and vaccuum pressed a boat's cabintop about 25 years ago. Ed McClave, a fellow wooden boatbuilder, wrote a piece on springback, but it's another one of those things I can't find.
By the way, I graduated from industrial vaccuum cleaners to a Mercury Vaccuum Press (MVP-50) about 12 years ago. I use a compressor driven device that rapidly gets the air out of the big bag, but that thing is pretty noisy. My first project with the MVP was an entry door laminated with W.E.S.T. epoxy and 289 parts, including a plywood core, 2-in-thick rift oak rails and stiles, and many parts of 3/8-inch black walnut and 1/2-inch rift oak to give the field a woven look. I'll have to look for photos of that one - it's just now being re-finished after 12 good years.
Gary W
gwwoodworking.com
Edited 5/19/2006 4:43 pm by GaryW
Edited 5/19/2006 4:53 pm by GaryW
Hi Gary
WOW! nice molds. I have built a few similar molds in the past. Mostly for student work at the University I teach at. They are expensive and time consuming but great if you are doing multiple pressings and you want it right every time.
At school I have had students make up 8 foot long by 3' wide molds. These were done for one off projects for a furniture design class. They were very successful but were meant to pull only one or 2 forms from the mold. The other thing they used, instead of solid veneers was wiggle board (wobble board, snakeboard) for the interior laminations. These helped build thickness quickly and was much cheaper than solid veneer.
I think if you were accurate and built a foam mold with a plywood bottom that you would be happy with the results. You may want to put a plywood edge at the two ends of your mold for the veneers to rest on. The mass of the foam should have no problem holding the shape. Hope this makes sense.
Your problems calculating springback I have no answers for. There are I think too many variables to change a formulated result. You probably know more about eyeballing springback than most from your experience in making thick multiple forms.
Hope this helps.
Ted
Just to let people know and I appologize for not letting people know before:
I am a teacher/artist in Canada. My wife and I invented the Thin Air Press kit while teaching kids skateboard deckmaking. My postings on this Fine Woodworking forum are intended to be educational and not promotional. Please let me know if I've overstepped my bounds with any comments I post here.
Edited 5/20/2006 4:22 pm ET by Ted Hunter
Thanks for your response, Ted.
Your suggestion to use plywood ends, or basically to "fill" a plywood box with foam makes sense. It seems that only the edges of the mold would be in jeopardy and that the field of the foam would maintain its shape.
If I learn more re: springback predictions, I'll forward it to you.
Do two of the bent forms in the class12 photo make up the piece in the class12 photo? If so, how did you join them?
Lastly, where and what do you teach? I've done a little and would enjoy doing more again - especially as I get older.Gary W
gwwoodworking.com
Hi Gary
Sorry for not promtly answering your previous questions.
The two forms were joined together using biscuits. She had a tough time aligning the two pieces to match. A better way may have been a half lap joint along the length of the ends. Most of the larger projects at school are done at the end of term where students are under a lot of pressure to get things done. Because of this, the easy method was choosen for joining the two pieces together.
The school I teach at is called the Ontario College of Art and Design. It is Canada's oldest art college.
Over the last 19 years I have taught a number of different classes at OCAD. The ones at the college, related to woodworking have been everything from intro to advanced classes. Most of these classes are in design with second and 3rd year students. I also teach, at the college, first year Form and Structure classes (3D) where the fundamentals of building form relating to design are taught.
With Roarockit I have taught classes over the last 5 years in Maui Hawaii at an artist center called the HuiNoea and a private school called Seabury. These classes are all about young people laminating their own skateboard decks and have been very successful. This is where we perfected the system we now sell to woodworkers. We figured if the kit worked well for young people, a bunch of woodworkers might also be able to have some fun with it.
Ted
Gary, If you have not ever tried taking the form out of the bag, you need to give it a try. It looks to me that you are making life a lot harder than it needs to be.For that slight bend, I would not expect any spring-back. When I finish the vac process, and take it out of the bag, I always place the part back on the form t see how they fit, often to pick some indexing marks off to transfer to the part, and I just don't see any spring-back with that much thickness.If I were making a form to handle a shallow bend like that, using epoxy for the glue, I would expect the parts to virtually sag down to the form from its own weight. Once the vacuum is drawn, you should be able to take the bag of parts off and set it aside if you wanted to use the same form for multiple parts.Finally, If you don't have to build the form to withstand the compression of being inside the bag, it only needs to be strong enough to hold the weight of the parts plus the force necessary to bend the bundle of parts to the shape. So for that form you could have used about four 1/4" MDF cross members with the arc cut in them fitted into a dado on the ends with maybe another run down the middle to keep them upright. A form like this can be knocked together in minutes, and discarded when you are finished.
Hi Keith,
I don't know what you mean by "taking the form out of the bag," unless it is to make the curved panels without a vacuum press or external clamps and cauls. I used that mold for a couple of 13/16-in-thick doors, which I laminated with 1/4-inch VGDF veneered MDF panels on each side with a core of four layers of Italian bending poplar. Those panels hardly would "virtually sag down to the form from its own weight." MDF is fairly stiff, and if I'd not cheated and used veneer over an 8-layer bending poplar core, the poplar would not have sagged over the form. Vacuum bagging any curved lay-up is the only practical way to insure solid and void free results. I use it for veneering flat work too, to avoid voids.
As to springback: I made that mold with a radius a few inches smaller than the desired 80-inch inside radius, and springback was nil. My question to Ted Hunter really applies to tighter bends than this one (I've seen some useful formulas, but can't remember where).
I've used literally barrels of W.E.S.T. epoxy to lay up curved, vacuum bagged and clamped pieces. It's a pain in a vacuum bag, because the set time is so much longer than TiteBond, which is my preferred glue. I use epoxy only when necessary, like for pieces that'll end up outside in the weather.Gary W
gwwoodworking.com
Gary, I didn't read anything about MDF in your first post, and I must have misunderstood what the Italian bending poplar is. I assumed that it was something comparable to the 1/4 and 3/8" bending-ply that I use. It is so limber that when I pick it up in the middle, it will fold over with both ends pointing at the floor.When I put the stack of laminates in a bag, and then lay the bag of glued up parts on top of the form, they would sag to that form from their own weight, or with only a slight push along the edges. When the vacuum is drawn, it is stiff enough to pick up off of the form even while the glue is still liquid.If you have not thrown away the form in your photo, you should give it a try. Just take some of your scrap, spread some glue on it, seal it in a bag, lay it over that form, and draw a vacuum, then pick it up and see how stiff it is.
I used the veneered MDF because I wanted the veneer to match the sequenced panels adjascent and above the curved doors. Italian bending poplar is about 3/32-inch thick of two surface veneers and an opposing direction core veneer. I've never used bending plywood (sometimes called "wacky wood"), as you describe it, in the vacuum press. I use that stuff infrequently, and only when forming a curve that doesn't need to be free of defects - like fixed panels over a curved top and bottom carcase edge.
And now I see what you mean, to "take the form out of the bag." No, I haven't tried it, and don't think I will, because my material is too stiff to count on it conforming to the curve of the form without the help of the vacuum bag press.Gary W
gwwoodworking.com
Very nice site. I added the link to my favorites. Thanks.
Hilmar
Thanks for pointing out the slip.
Ted
A really cool, and mindblowing, concept is that if one takes say a 6" cube of MDF, places it in a bag and draws a vacuum to say 12 PSI, there is 6*6*12=432 pounds of force on EACH of the six sides of the cube, including the bottom, but it still is light enough to support with one hand.
Metod,
I have no glue what are You telling me and why!
Hilmar
Edited 5/28/2006 9:40 pm ET by h12721
I run 29 in. of vacuum and have not had any glue boil yet.
My understanding of vacuum is that any water based material will boil at a lower temperature. The higher the vacuum the lower the temperature needed for this to occur. Physics is physics!
The vacuum seems not to effect the glues I have been working with. I mostly use Titebond III but have done lots of pressing using regular white glue and never had a problem. I do see bubbling in excess glue once in a while.
Here is a chart that shows vacuum/boiling point of water info:
CHART
Ted
I'm a big fan of physics and was merely making the observation that at 29" of mercury vacuum I have not had a problem with glue boiling. I consider the outgassing of entrapped air one of the benefits of glueing under vacuum.
Since the house is on fire let us warm ourselves. ~Italian Proverb
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