Bonding Ply


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If both panels are slightly oversized you can glue them together with a little offset . One panel would have 2 adjacent edges with a perfect 90 degree corner exposed, then you can use those edges to trim the opposite edges, spin,it around and trim the other 2

This yields 4 flush edges and a square panel . 1/8"offset is plenty, but make the panels about 1/2" oversized just in case .

Too much clamping pressure around the edges and not enough in the middle can cause problems. Do a dry run of your clamping before you get out the glue.

A stack of weights and a few clamps should work.

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The issue with using sandbags could be getting enough psi to properly press the panel... and what to do with them when you're done... I don’t have experience with low-pressure pressing to comment on the sand approach… But I suspect you'd need a lot of sand...

 

If we take vacuum pressing as a benchmark: A 30x30 panel is 900sqin w/ vacuum press at just shy of 14.7lb/sqin. So the panel in a vacuum press would receive around 13Klbs total. 13Klbs in 50lb bags = 265 bags… That’s a lot of sand :)

 

I just don't know how much psi you actually need to a 30x30 panel... and what that translates into sand... Don't get me wrong, it may work just fine... I simply raise the point because screw presses apply even more pressure than vacuum presses --- and if you could press panels using just a 200lbs of sand, I'm not sure the vacuum guys would be in business...

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If we take vacuum pressing as a benchmark: A 30x30 panel is 900sqin w/ vacuum press at just shy of 14.7lb/sqin. So the panel in a vacuum press would receive around 13Klbs total. 13Klbs in 50lb bags = 265 bags… That’s a lot of sand :)

So what you're saying is he needs some kind of platten that he can park his car on...

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==>needs some kind of platten that he can park his car on...

We'll at 13Klbs, maybe a box truck?  That's certainly one solution :)

 

Actually, just discovered that a lower-end Mack semi-truck is a little over 13Klbs, but at $140K, it's not the value option... :)

 

 

Of course, you can gin-up a DIY vacuum press for a couple hundred: http://www.joewoodworker.com/veneering/welcome.htm

 

 

And if you look at the used market, a screw press for considerably less…

 

 

But I suppose you could rent a box truck for a day for what -- $90? :)

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If we take vacuum pressing as a benchmark: A 30x30 panel is 900sqin w/ vacuum press at just shy of 14.7lb/sqin. So the panel in a vacuum press would receive around 13Klbs total. 13Klbs in 50lb bags = 265 bags… That’s a lot of sand :)

 

 

 

does a vacuum press really tet that close to a perfect vacuum? don't get me wrong, even if it only drew the pressure to 7psi that is awesome force available.  i have never used one so i just find it impressive

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==>does a vacuum press really tet that close to a perfect vacuum?

Excellent catch...

 

I'm not sure what Joe's V2 Venturi setup can draw, but yea, it's not 29.92Hg... I did notice that he's lowered the price to $164... For the occasional veneer job, that price is kind of hard to ignore: http://www.veneersupplies.com/products/Project-V2-Auto-Cycling-Venturi-Vacuum-Press-Kit.html

 

 

I just looked at my setup, and it draws to 27Hg -- so that would be 12Klbs on a 30x30 panel -- so we're down to 239 bags of sand... Much better! :)

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==>just from an engineering and production experience i want to build one

I haden't thought of getting one for quite some time -- didn't realize just how useful one could be... Now that I've got shop vac, it's hard to think of how I got along without it... I use vacuum clamps frequently... They are great for final sanding, face planing, really anything where you don't want clamps in the way... I've also used vac for of DIY jobs... Great addition to any shop...

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==>does a vacuum press really tet that close to a perfect vacuum?

Excellent catch...

 

I'm not sure what Joe's V2 Venturi setup can draw, but yea, it's not 29.92Hg... I did notice that he's lowered the price to $164... For the occasional veneer job, that price is kind of hard to ignore: http://www.veneersupplies.com/products/Project-V2-Auto-Cycling-Venturi-Vacuum-Press-Kit.html

 

 

I just looked at my setup, and it draws to 27Hg -- so that would be 12Klbs on a 30x30 panel -- so we're down to 239 bags of sand... Much better! :)

 

Mine is at 29Hg. For the most part 20 is plenty but a little extra power is nice so that you don't have to over work the pump.

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==>frame press 7x12

Nice, but lot of floor space if you're not doing lots of veneer jobs...

 

Run it closer to 23-25 and leave the rest as headroom?  Drawing 29 all the time would be hard on the seals... You're in the Pacific North West, right?  Does the high %RH cause maintenance problems on the pump?... I seem to remember my setup having lots of disclaimers on ambient humidity...

 

 

@OP, sorry we're onto to pumps -- we'll get around to solving your problems in a while :)

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==>frame press 7x12

Nice, but lot of floor space if you're not doing lots of veneer jobs...

Run it closer to 23-25 and leave the rest as headroom? Drawing 29 all the time would be hard on the seals... You're in the Pacific North West, right? Does the high %RH cause maintenance problems on the pump?... I seem to remember my setup having lots of disclaimers on ambient humidity...

@OP, sorry we're onto to pumps -- we'll get around to solving your problems in a while :)

Don't really know. It's about 15 years old and has made a few thousand doors. It still works well will probably outlast me.

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I'd suggest making two or three or four cauls with a gentle curve on one side, maybe 1/8" less than in the middle on each end. Put your wood glue on, put the 3/4" panel on top of the 1/2" panel, then put the calls, curved side down across the panels. Clamp each end of the caul. As you put pressure on the ends, the center of the caul will put good pressure down in the middle of your panel. If you want you can put clamps between the cauls, but it's probably overkill. As suggested above, make your panels a little oversize and cut to final size after glue up. That should work, and you don't need big vacuum bags.

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