Lamination Press

[Mike OMelia]

Anybody ever built a lamination press? Perhaps using hydraulic car jacks? I saw a homemade jig on CL some guy built for pressing bearings. Seems it could be used for laminations (not talking veneer here).

Mike

[Jamie Buxton]

What that thing does is apply pressure in one point. With more jacks, it could apply pressure at more points. A downside to it is that the thing is big. It takes lots of space to store. A better tool for lamination is a vacuum bag. It applies pressure everyplace, which is good. It applies lots of pressure -- a ton per square foot -- so that's good. And it takes very little room to store. And a vacuum bag is probably less expensive than that press, too.

[Mike OMelia]

So, you are saying that if I have, say, 3 boards that are 3" wide, by .75" thick by 3' long, I can laminate them into a stack using a vacuum bag that will do as good a job as a press? That works out to ~14 psi (one ton/ft2). Right? So 3"*36" is 108 in2 times 14 psi means I will have the equivalent of 1512 pounds of force squeezing them together??

If this is correct, then I have underestimated the power of vacuum clamping! I have a couple of pumps, all I need to do is build up a joe woodworker setup, no?

Mike

[Jamie Buxton]

Yup, 14 psi is what you get. If you already have a vacuum pump, all you need is a bag. You can build one for $20-$50, depending on size. I make mine from 20 mil sheet vinyl I get at a local plastics place. It comes on a 54"-wide roll, and they sell it for $5 or so per yard. I've also seen sheet vinyl at fabric stores. Vinyl cement comes from the plastics place, or Home Depot. Vinyl tubing comes from HD.

[Mike OMelia]

I am just having a hard time believing that the vacuum bag will do what it takes maybe 10 clamps to do, and even then I don't get complete closure!

Mike

[Mike Henderson]

For straight laminations, like the example you gave, a vacuum bag should work fine. But so should a bunch of clamps. If you're going to bend those laminations you've got a more serious problem.

Also, there's two problems with building your own bag. The first is that it's difficult to get all the seams airtight. The second thing is that the seam is bulky so you have to do special closures for the bag. If you buy a commercial bag the seams will be fused and flat. You can then use the lightweight "C" style closures which are much easier to use.

Mike

[Jamie Buxton]

... there's two problems with building your own bag. The first is that it's difficult to get all the seams airtight. The second thing is that the seam is bulky so you have to do special closures for the bag....

That's not my experience. I've been making my own bags for a couple decades. I use them until the plasticizer evaporates out of the sheet vinyl and it gets so brittle it cracks. Then I make a new one. I've never had a seam leak. And I use a homebrew C closure I made from two pieces of PVC water pipe.

[Mike Henderson]

That's not my experience. I've been making my own bags for a couple decades. I use them until the plasticizer evaporates out of the sheet vinyl and it gets so brittle it cracks. Then I make a new one. I've never had a seam leak. And I use a homebrew C closure I made from two pieces of PVC water pipe.
Perhaps you can start a thread and give some pointers for shop made bags. When I tried, I had the problems I mentioned. I eventually went to commercial bags. Given the amount of money I spent on the materials and the time I put in, the commercial bag was less expensive. But maybe I just didn't do things right when I tried to make my own.

Mike

[Mike OMelia]

Perhaps you can start a thread and give some pointers for shop made bags. When I tried, I had the problems I mentioned. I eventually went to commercial bags. Given the amount of money I spent on the materials and the time I put in, the commercial bag was less expensive. But maybe I just didn't do things right when I tried to make my own.

Mike

I'm with Mike on this. I would love to know how you do it. Also, what is a C closure?

Mike

[Mike Henderson]

I'm with Mike on this. I would love to know how you do it. Also, what is a C closure?

Mike
I'll see if I can take a picture since it's hard to describe in words. Later today.

It's two pieces of pvc used for closing a vacuum bag. It's easy to use and lightweight. Lightweight is good because sometimes you have your bag on a table and the edge hangs over. If you use a heavy closure, say two pieces of wood with clamps, it's difficult to get the bag closed and the weight of the closure can pull the bag off the table if you only have a light project in the bag. They're the best method I know of to a close vacuum bag. But to use them, the bag needs to be flat - that is, the seams need to just be pressed together and not doubled.

[Added note: Also a C closure is fast. When working with veneer, you usually want to get the work into press as fast as possible, before the veneer absorbs water (from the glue) and starts making like a potato chip.]

Mike

[Jamie Buxton]

..Perhaps you can start a thread and give some pointers for shop made bags..

I'll do that. One of my bags is about due for replacement. I'll make a new one, and photograph it as I go. This weekend, I think.

[Jeff Duncan]

Another vote for using vacuum clamping. Presses are old school technology that very few people use anymore. The biggest problem being that your limited to the size press you buy/build. With a vacuum press there is practically no limit. you need to press something bigger, just buy a bigger bag. You can laminate a bunch of solid wood that's 4" wide by 8' long and then swap bags and do a 4 x 8' sheet of veneer.

You specifically question using it on hardwoods and I can tell you from experience it will give you a very good clean joint. I use mine to do door stiles and glue up 3 layers of stock to make them. The parts I just did last week were actually 5-1/4"w x 86"L and it worked just fine. Unlike using manual clamps the glue line is just about perfect as the pressure is evenly applied to every square inch. A press would likely glue up just as well, but again, your limited in terms of size.

As far as making bags I have not tried it personally, but my understanding is that it is not complicated at all. I've read of shops that do a lot of narrow curved work buying rolls of poly (think of a trash bag with no end) and just cut to length and seal the ends for disposable vac bags. There is a lot of info out there to get you going.

good luck,
JeffD

[Mike OMelia]

Thanks Jamie, looking forward to it. Mike, thanks. Jeff, I bet thats how they are made at Joe Woodworkers...

Mike

[Larry Edgerton]

I have one 18' long for laminating Azek. I used 14" LVL's, with threaded rod 1 foot on center running down both sides. It opens to 12" for laminating columns, and will go down to zero. I made a 1' long socket by welding two OHC spark plug sockets together and use an air wrench to tighten it up. You have to be fast with big Azek laminations and clamps were just to slow and cumbersome. I made it in one piece, but have since cut it in half to make it easier to move. When I need long stock I just slide them back together. I made it for Azek, but it works well with wood as well.

Larry

[Mike Henderson]

Here's some pictures of the C-closure. It consists of two pieces of PVC, one a regular piece of pipe and one that is cut so that if you look at it from the end, it looks like the letter "C".
195295
195292

To close a bag, you lay the regular piece of PVC on top of the end of the bag, then fold the bag over the piece of PVC.
195296
195294

Finally, you take the C shaped piece of PVC and snap it over the bag and other piece of PVC. This closes the bag quick and tight, and the whole thing is lightweight.
195293

Mike

[Mike OMelia]

Mike, are both pipes the same diameter? Not sure why one is blue, the other white

Mike

[Mike Henderson]

Mike, are both pipes the same diameter? Not sure why one is blue, the other white

Mike
The C pipe is a bit larger diameter than the plain pipe. It needs to be larger to fit over the other pipe with the bag in between them. It has a lot of spring in it so it will open to fit.

The color doesn't mean anything. I have another closure where the C pipe if black. I think they make them different colors so you don't grab the wrong one when you're scrambling to get the bag closed and the work under press.

You can buy C closures from Joe Woodworker. You choose the length to suite your bag. BTW, if you buy a commercial bag, they're measured on the capacity and not the actual measurements of the bag. So a bag that's 4'x8' will press a (thin, maybe 3/4") panel 4'x8'. The bag is larger than 4'x8'. Remember that most people think veneer when dealing with vacuum bags.

Mike

[Jamie Buxton]

I use a C closure on my bags. I made mine before Joe Woodworker existed. He may now be the easier way to go. At any rate, my inner pipe is 1/2" schedule 40 PVC water pipe. It has an OD of .84". My outer pipe is something I think is called class 200. It is used for lawn sprinklers, and has a thinner wall than the schedule 40 stuff. This is called 3/4" pipe. It has an ID of .88", and a wall thickness of .06". The thin wall means that it bends fairly easily to snap over the bag as it wraps around the inner tube. I tried using schedule 40 for the outer tube, but the thicker wall is too thick to snap over the bag. You can rip the class 200 on the table saw to turn it into the C shape, but do it with two passes. If you attempt to do it with one pass, the blade will be exiting the tube in an area where the tube is not touching the table, so the tube will attempt to rotate. Bad things then happen rapidly. DAMHIKT.

[Larry Edgerton]

I am just having a hard time believing that the vacuum bag will do what it takes maybe 10 clamps to do, and even then I don't get complete closure!

Mike

I made the press I mentioned earlier because the vacuum system would collapse the Azek columns. They have to be hollow for steel in the center. My kids used to find all kinds of stuff to put in the bags to see what it would crush. Lots of nice even power there.

[John TenEyck]

I also make my own vacuum bags, using a pretty simple approach. I buy 20 mil clear vinyl sheet from McMaster Carr. I fold the sheet back on itself to form one end. The two open sides are glued with regular PVC pipe cement. I found it's best not to use cleaner first. I apply a inch wide band of glue on one edge, lay the other edge on top, put a wooden caul on top and clamp it down to my workbench for a couple of hours. The most important thing here is to get plenty of glue at the end of the bag, where it's folded back on itself, and put a clamp directly over the fold so that it flattens out and bonds.

The bag penetration for the vacuum hose is just two pieces of 1/2" PVC sheet. The outer piece is drilled and threaded for a hose barb fitting to connect to the vacuum hose. The inner piece has a 1/4" deep dado routed in it in an X pattern so that even when the bag is evacuated there is an open air path. Cut out a small hole in the bag near the closed end and glue the two pieces of PVC to the bag both inside and out to make a sandwich. Here's a picture of the bag penetration:



195404Never had an edge or penetration leak yet in over 10 years.

The open end of the bag is closed by just winding it around a piece of rectangular stock. No clamps, nothing. The bag folding back on itself under the vacuum forms a good seal, at least for me. No trouble holding 22" Hg or so, which is about all my pump seems to pull. Here's a pic of the bag in use, from the closure end:

195405

Hope you find this helpful.

John

[Chris Fournier]

I wouldn't bother using a vacuum system to edge glue boards, way too cumbersome and slow. Edge glueing? Use clamps. Vacuum bagging is great but not at all the answer to every glue up.

As for mechanical/hydraulic press technology being the has been old school approach, this is untrue. Mechanical presses can generate way more clamping force than a vacuum bagging set up and in many cases - bent laminations, this extra force is required. Also think about the bonus of heated platens in mechanical presses. Of course few small shop can afford to have a 4'X8' mecahanical press on the floor!

All of this talk of 14 psi is theoretical when it comes to your vacuum press. Can your pump pull 28" of water? Are you at sea level? Likely not in most instances. Hey the foces are still terrific for a small shop and the flexibility of the vacuum set up is unbeatable! Storage is a treat.

As for making your own bags, nothing could be easier. Take care laying it out and the rest just falls into place. There are plenty of great adhesive options out there.

Vinyl is cheap and easy to use when making your own bags (which I do when I know that the glue up is gonna be a prickly one and the bag may be a one shot wonder) Polyurethane is really a superior bag material although more expensive. I've had the same 30 mil poly bag for about 15 years now so the higher cost is really a good value given the durability of the material compared to vinyl.

[Frank Drew]

I wouldn't bother using a vacuum system to edge glue boards, way too cumbersome and slow.

Agree, trying to edge glue in a vacuum bag would be nuts, but I think the OP is asking about laminating (face gluing) boards.

I'm with the low-tech-is-fine approach to vacuum pressing. I was lucky to find a used laboratory grade vacuum pump for $75 that really did pull close to 29 in/Hg, and made my own bag from sheet vinyl, found some scrap 1/4" hose, etc.

But If I simply had to laminate three pieces of 1" x 4" x 3' I'd probably just slather the glue on and use hand screws.

[Jeff Duncan]

I made the press I mentioned earlier because the vacuum system would collapse the Azek columns. They have to be hollow for steel in the center. My kids used to find all kinds of stuff to put in the bags to see what it would crush. Lots of nice even power there.

Larry, not sure what kind of system you have but you should be able to drop the pressure (vacuum) down to create just enough force for your application. I vary mine depending on what I'm gluing up.

good luck,
JeffD

[Craig Feuerzeig]

Wow... a question about gluing a couple pieces of 1 bye 3 together... and 2 pages about vacuum pumps... :eek: :(

Curved cauls and a clamp on each end. ;)

[Larry Edgerton]

Larry, not sure what kind of system you have but you should be able to drop the pressure (vacuum) down to create just enough force for your application. I vary mine depending on what I'm gluing up.

good luck,
JeffD

I just bought a industrial vacuum regulator on fleabay, and am looking forward to using it. My pump is a fairly large pump made for medical use, and I did not have a good way to control it. Still in this circumstance vacuum in not the answer.

I would still use my press for the columns. They are usually over ten feet tall, 5/4 Azek, splined joints on opposing sides, and the glue sets really fast especially in warm weather. Once I start glueing them together I only have a very short time before the first joint glued is setting, so I have to do all four joints and have it clamped in 3-4 minutes. I assemble on a long table that is lined up with the clamp, slide it into the clamp, and it takes me about 30 seconds to have pressure on it when in the clamp. These things are very heavy, and trying to manuver them into a bag quickly without damage would be too difficult, and too slow. The cost of the material demands no failures. Azek is not very ridgid, and the press works to make sure they are straight in both directions when the glue sets. The columns must be in clamps for twentyfour hours.

[Mike OMelia]

Yes, I was talking about face glueing, not edge glueing. At this point, I am dubious about whether this will work... but the numbers seem to indicate it will. So I will try it. My guitar work can benefit from this as well (brace work, bonding top and backs to sides, etc).

Thanks!

Mike

[Chris Fournier]

This press is pretty useless for both of these operations. If you were stack laminating bowl blanks then I'd say the press would be helpful - but just so. This press will be of little to no use for a neck blank glue up as you are likely attempting. You will need a good caul to distribute the single point pressure of the bottle jack along the 3' of your blank. This will be a total waste of time and not yield results superior to using the clamps that you likely already own.

Using this press for guitar work is like cracking walnuts with a pile driver. Not applicable unless you are forming metal parts.

If you are a serious mechanic or machinist type then this press will be a great addition to your shop; if you are a guitar maker there are far better ways to spend your tooling/equipment budget.