Darryl Keil Last Activity 2025-09-09 11:09 AM
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Gary H Phillips

Posts: 46

Joined: 2007-05-06
Location: Seekonk, MA

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Subject : Hi to you all! And...a question or two...
Posted : 2007-05-13 9:04 AM
Post #33816
Greetings!


First of all, I'd like say how nice this site is. Not only does this forum come highly recommended, but so does the company. I can see why, in both instances.

I have been reserching for some time into building a vacuum table. Since I am in the pipe organ business some/most of the things we do are big. My permanent table will be 120" x 60". The top is being fabricated already, it is 1-1/4" moisture resistant MDF covered in shiny white formica with a regrind on the underside. The table will be made rather heavy and will not be movable but it will come apart as it will be bolted together. I will also make a nice Homosote cover for this table so it can be used for other gluing and assembling.

I won't be doing much in the way of veneering, per se, but more like laminating 2 sheets of Europly together to make an odd or thick size such as 1-1/2 (HEAVY!) or 7/8" for example. A question, would a top caul be necessary if it's, lets say, two sheets of 3/4 or 3/8 and 1/2"?

I guess the best glue for this is the 2 part glue everyone talks about here (cannot remember the name at this second)? Is titebond III ok? I've been using it when I needed to glue things now, but I want the best bond.

I'm very much looking forward to having this built and running. Not only will it allow me to build things like tables (pipe organ chest tops...lots of holes, all must line up, usually 3 plys of some type of wood) but I will be able to laminate for special projects and of course make up my frabrications for my custom reservoir work.

I look forward to reading most of the past posts here over the next few weeks...and of course, the new ones too!



Cheers

Gary H Phillips
GHP Associates
36 Maple Avenue
Seekonk, MA 02771





 
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Darryl Keil

Posts: 1455

Joined: 2003-05-22
Location: Maine

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Subject : RE: Hi to you all! And...a question or two...
Posted : 2007-05-13 6:11 PM
Post #33818 - In reply to #33816
Gary,

Cauls are really only needed for veneer work so you don't need them when gluing sheets of plywood together.

Regular yellow glue will do a good job in your situation but if you want the most rigid glue line you can get then I would use the urea resin glue.

I don't know if you were saying this in your post but laying up different thickness sheets to one another can cause warping unless it is balanced. Example, 3/4" to 1/2" would warp, but 1/2" to 3/4" with another 1/2" on the other side would be balanced

Sincerely
Darryl Keil


 
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Gary H Phillips

Posts: 46

Joined: 2007-05-06
Location: Seekonk, MA

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Subject : RE: Hi to you all! And...a question or two...
Posted : 2007-05-13 8:13 PM
Post #33819 - In reply to #33818
Yes, I generally try to glue sheets together evenly, but sometimes it doesn't work out. We made up 7/8" by using a 3/8 and 1/2 and it was fine, but I think the next time I would use 2, 1/4" and one 3/8" sheets. Once we had 1/2 and 3/4 glued up once to make 1-1/4" and it warped slightly.

I'm not really up on glues that are used these days. I will have to do more reading.

Thanks for your input!



Cheers

Gary



 
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Don Stephan

Posts: 825

Joined: 2003-07-18
Location: Cincinnati, Ohio

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Subject : RE: Hi to you all! And...a question or two...
Posted : 2007-05-13 8:48 PM
Post #33820 - In reply to #33819
I'm nost sure if you're planning to have a grooved bottom platen in the bag and/or a top caul. Without either, there is a chance the lamination will not be flat.

When pressing say two sheets of plywood by themselves that are extremely convex in length, if they are placed with the convex curves in the same direction, the vacuum probably will not force the lamination flat.

If they are pressed with a VERY rigid grooved bottom platen, the lamination probably will be forced flat. If using a flaxible glue, however, like PVA, there might be some spring back after the lamination is removed from the bag. A rigid glue will minimize the chances of springback.

If they two sheets are placed with the convex curves opposing each other on a VERY strong platen, the lamination is more likely to be flat.

When pressing veneer onto a single sheet of plywood or MDF, this is not such an issue because the result, even if the substrate was 3/4" thick, will have at least a slight amount of flex if needed to fit into a frame. In your case with such thick laminations it likely will be very difficult to flex the lamination after the glue cures. That's the only reason I mention the above.


 
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Gary H Phillips

Posts: 46

Joined: 2007-05-06
Location: Seekonk, MA

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Subject : RE: Hi to you all! And...a question or two...
Posted : 2007-05-14 7:09 AM
Post #33821 - In reply to #33820
I want to thank you for your points. I have learned so much from this Forum.

This is an interesting point. The first vacuum table I saw, was exactly that, a table with a cross grooved into it and a hole throught the center to draw the air out through. This table was made back in the 70's. They would use rolled rubber roofing. It would be taped around and when sealed, they'd turn the pump on and the rest is pretty much what happens with the bag system, excepting the vacuum would make the component dead flat, or as flat as the table is.

The point you raise is what I said right from the first, how to make things flat *and* have the pressure to make it glue together.

When I make a 1-1/2 Europly glue up to make a reservoir top frame, it needs to be pretty much dead flat. Cover stock (7/8" for instance) they can have a bit of a crown to them, but not much.

I know this forum is owned by a company that makes bags and other associated stuff, but do any of you use the sheet of rubber or plastic taped to the table top method?


Cheers,

Gary


 
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ckurak

Posts: 107

Joined: 2006-10-28
Location: Florida

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Subject : RE: Hi to you all! And...a question or two...
Posted : 2007-05-14 3:08 PM
Post #33822 - In reply to #33821
Gary,

Welcome.

A note about "flat" tables. I also have a 5x10 table. I built it with 2x6's as per Vacupress' table plans for the flip-top press. It works extremely well.

One caveat though, especially for the type of work you do, be sure the table really is FLAT. I put a straight edge across the top and found that the center sagged. This may not be an issue for gluing veneer to both sides of a substrate. However, I was laminating two pieces of 3/4" plywood together for additional structural integrity on a project. It was very critical that the resulting 1.5" assembly be perfectly flat.

All that I had to do to fix it was add two more legs, one each at the mid-point of the long sides. Problem solved.

One more tip: You talk about having a very heavy table that cannot be moved. Try adding 4 trailer jacks (can be found at Harbor Freight) to the corner legs. Simply crank the jack handle on each corner, roll the table to its new location, and lower again. You could even get fancy and add an adjustable foot under each leg. Crank the table up with the trailer jack, adjust the foot, and lower again.

Just some thoughts...

Charles


 
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Gary H Phillips

Posts: 46

Joined: 2007-05-06
Location: Seekonk, MA

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Subject : RE: Hi to you all! And...a question or two...
Posted : 2007-05-15 6:59 AM
Post #33823 - In reply to #33822
Charles, thanks for the welcome

I understand what you are talking about when you say it must be flat. When I say this table will be heavy, I mean heavy. Not to put down anyones plans or ways of doing things, but I would never use framing lumber for building a table. I have a bunch of quartered White Oak that I bought years ago. I will use that for the support rails that will be 9' long. The cross members will be Poplar. I plan on doing honeycomb-like floor joist supports in the field, this should keep it flat. If need be, I too would add a center leg or two.

My first plan had iron wheels on the four legs and I was going to mount hydrolic (sp) bottle jacks on the four corners to level. I don't think I'm going to do that now.

I will have a leveling system I will not go into here, but it involves very heavy bolts threaded into the leg posts...something like a 1-1/2" x 6" bolt.

With the bag system though, I still have a funny feeling in my gut that things might not be flat as the vacuum only pulls the parts together and not down flat, unless you suck to the table...



Cheers,

Gary



 
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Don Stephan

Posts: 825

Joined: 2003-07-18
Location: Cincinnati, Ohio

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Subject : RE: Hi to you all! And...a question or two...
Posted : 2007-05-16 6:39 PM
Post #33824 - In reply to #33823
Gary:

If you are making a flip top system, the vacuum will tightly compress whatever is being pressed flat against the surface, at about 12 PSI or so if you're near sea level. If the surface of your flip top frame is sufficiently rigid (and your materials certainly would be sufficiently rigid) it will not give so your laminations should be as flat as your surface.

If you're planning on using a platen and caul in a vacuum bag, you could make a torsion box platen using perhaps 1" honeycomb. Such a torsion box platen hopefully would be more rigid than the materials being pressed, and so again the laminations should be as flat as the surface (of the platen). The only catch would be to make the torsion box platen as flat as necessary. After making it, you could use winding sticks and planes/belt sanders/... to make sufficiently flat. An alternative would be to look for a large commercial woodworking shop with a wide belt sander sufficiently large to flatten it for you.
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