Using workshop press to laminate timber?

[Albert Lee]

Has anyone done this before? by using workshop press to laminate timber?

glue area is 2400mm x 150mm, (95 inch x 6 inch)

According to Titebond, gluing pressure should be 150psi, thats about 36 ton of force required for that area. it is doable with a lot of clamps but just takes a lot longer than 2 x 20 ton hydraulics press, obviously the distribution of the force needs to be considered but is this an viable option?

any comments appreciated.

[Jamie Buxton]

Here we go again. Conventional wood glue does not require pressure to cure. You can make a perfectly sound glued joint with a wiped joint -- that is, with zero clamping pressure. Clamping does two things for gluing. First, if the gluing surfaces are not flat, the clamps deform the wood to make the two pieces close. Second, the clamps squeeze out any excess glue. In practice, if you apply enough pressure to get squeeze-out, you're good to go. 150 psi is way overkill unless you're doing something wrong preparing your wood for the gluing operation. You don't need 36 tons for your job.

All of that said, if you're clamping those long boards with a single-point clamp, you're going to have an almost-impossible job to distribute force out to the ends of the boards. You'd be better off using a vacuum veneer press. It puts pressure everywhere -- that's one of its big virtues. There's no issue of building crazy cauls to distribute the force.

[Albert Lee]

thanks Jamie. I am glueing anywhere between 20-30 pieces each time, its nearly impossible to get them all straight, I am running a small production shop. I will be using 2-3 press as well.

[Mark Bolton]

I would disagree with Jamie's response and there are 1000s of posts in the archives here and elsewhere on the subject so no need to revisit. Is you can search out an article in fww many years back about PVA and clamp pressure you'll find clear information.

The shop arbor press issue comes up often but to me the issue is that hydraulic presses unless they are dynamically powered to maintain a set pressure all leak off over time. So depending on how fast your presses leak off you may lose clamping force before the glue cures.

[Mark Bolton]

https://www.finewoodworking.com/2010...ets-to-success

[Wayne Lomman]

Hydraulics don't leak unless they are faulty. The more common reason for the appearance of hydraulic pressure loss is actually shrinkage as the glue cures. It's most noticeable when there are multiple glue joints. Use presses with a decent heavy steel channel or whatever on either side of the timber and you will get a good result. Heavy steel is important so that it all stays straight. Cheers

[Mark Bolton]

You'll have to tell that to every heavy equipment operator, consumer level arbor press owner, auto mechanic, and hydraulic cylinder rebuilder.

All bottle jacks, hydraulic cylinders, valves, and so on, wear very quickly and have internal leakage by the piston in the cylinder. It's why home movers and people who raise homes use cribbing after jacking to support the structure overnight. Because the hydraulic jacks leak off. Most all floor jacks in your garage leaks off when you jack up your car. Some slowly, some more quickly.

Its of course an issue of wear but even on a piece of heavy equipment it will be apparent far far before you ever are at a point remotely close to rebuild. Go to basically any excavator, backhoe, end loader, whatever, raise the stick or bucket up in the air and stand there. You here it creaking down. Hook a tape measure to the stick or the bucket and you'll watch it leaking down. Put a nice big scoop of material in the bucket and it will be even faster.

Large industrial presses that need to maintain specific pressures for long periods maintain preset hydraulic pressure dynamically. Any consumer to modest level arbor press with a little bit of time on it that has a pressure gauge reading tons of force will show it clearly. Put a block of steel in, pump it up to the max force, and lock the cock on the cylinder. Come back in a half hour and it'll have gone down. There is no shrinkage. Its internal leakage in the cylinder.

I've rebuilt the cylinders on my endloader and backhoe as well as when they get bad and they are great for a while but it's just a part of the game.

[Doug Hepler]

Mark

You are a gentleman and a scholar. You saved me the effort of looking up the article you cited. Actually what Jamie wrote is not wrong, but it might mislead some people. Of course PVA will cure without pressure, but that is not the issue. And yes, some un-clamped joints will be strong enough for some applications. Who knows how much pressure is exerted on tenon cheeks in a well-fitting M&T joint? However, for a lamination job I would (and do) get as much clamp pressure as I reasonably can. It is probably not as high as Rabiej would recommend. I say, definitely clamp joints when possible to get maximum joint strength.

Doug

[Mark Bolton]

And yes, some un-clamped joints will be strong enough for some applications

I wouldnt disagree with that statement in the least. Extremely precise joinery and impeccable attention to detail, on a piece that is going to be treated like it should be, sure, an abysmal glue joint would likely be strong enough. Many of those pieces would likely stay together without any glue at all.

Unfortunately thats not the world most things live, or are produced, in. And its not even what any glue manufacturer calls out. The only common commercial adhesive that calls out reduced clamping pressure are those that require a thick glue line like epoxy.

It takes some scouring but there are numerous posts on several forums both hobby and professional where people have done the real world testing (like Franklin hasnt?!? lol). There is no common shop that can exert too much clamping force on a long grain PVA glue up. Going bananas with clamping force to make up for poor fit isnt the point but a precisely jointed part with perfectly tight fit simply will never be overclamped in an average shop.

We put the clamps to everything and we reef them down as hard as we can and space them super close.

[fRED mCnEILL]

"Go to basically any excavator, backhoe, end loader, whatever, raise the stick or bucket up in the air and stand there. You here it creaking down. Hook a tape measure to the stick or the bucket and you'll watch it leaking down. Put a nice big scoop of material in the bucket and it will be even faster."
Not that it probably matters to this discussion but I have a 1973 JD tractor with a bucket.The damn tractor is nearly worn out and I sure haven't done any repairs on the bucket.But I can load it up and let it sit for weeks with no measurable movement. On the other hand I have a floor jack that is much newer and with infinitely less use that does bleed down.

[Mark Bolton]

The damn tractor is nearly worn out and I sure haven't done any repairs on the bucket.But I can load it up and let it sit for weeks with no measurable movement

I remember several old timers carrying on when they would get a farm tractor that they could spear a round bale of hay and hold it as high as the 3pt hitch will go and have it never leak off all night long. Definitely happens. But Ive never been on, or around, a piece of hydraulic equipment whether it be in a shop or in the field that the hydraulics didnt leak off a bit (or a lot) and you'd be broke rebuilding cylinders on a monthly basis if you were going to re-pack them every time you started to see some drift.

Whenever I have thought of using a shop arbor style press for clamping glue ups Ive always thought if your press doesnt maintain pressure dynamically you'd want to apply your clamping force with the hydraulics then back it up with a screw jack of some sort to hold the clamping pressure. Id almsot guarantee you you'd come back in the morning to the pressure gauge on the press WAY down.

[Albert Lee]

massive thanks to you Mark, I was going to invest some serious money into 2 Compac press. but I am putting the purchase on hold after reading this thread and your response... very informative.

[Wayne Lomman]

Pardon me for working in an environment with reliable hydraulics. Sure we have one forklift that will sink if you leave it in the air and one CNC where the spindle drops overnight. We know about those and the maintenance is scheduled. The other 30-odd forklifts and CNCs are 100% reliable. They have to be. A workshop is not an earthmoving machine with a severe environment. A hydraulic press will maintain pressure for the time required for the glue to cure and will improve productivity. We were using hydraulic presses in 1985 for furniture making in a production shop. It wasn't a new idea. If anyone is still worried, have a quick read about how many hours you need to clamp a good PVA glue. Cheers

[Mark Bolton]

Pardon me for working in an environment with reliable hydraulics. Sure we have one forklift that will sink if you leave it in the air and one CNC where the spindle drops overnight. We know about those and the maintenance is scheduled. The other 30-odd forklifts and CNCs are 100% reliable. They have to be. A workshop is not an earthmoving machine with a severe environment. A hydraulic press will maintain pressure for the time required for the glue to cure and will improve productivity. We were using hydraulic presses in 1985 for furniture making in a production shop. It wasn't a new idea. If anyone is still worried, have a quick read about how many hours you need to clamp a good PVA glue. Cheers

I shoot for 30-45 minutes in the clamps. But a big critical glue up that has a lot of time and material involved I'd leave it go a while longer. Depending on the press I'd still be concerned itd be leaking off from the second I left the press.

Agreed, good equipment is important Unfortunately you just dont know til you know.

[Joe Calhoon]

Our skid steer bleeds off pretty quickly but hydraulic presses are common in the woodworking industry. We have a Italpress frame clamp that holds pressure. Doors and windows are cycled quickly through this but sometimes we face glue scantlings in this where they are pressed for 4 hours or sometimes overnight with no loss of pressure. I also used a Barth hand hydraulic press in a shop we were setting up and it held fine.
a couple local shops here had shop built stile presses made with steel beams and hydraulic cylinders that the owners said worked well.
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