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+-- Thread: Crazy Clamping Requirements? (/showthread.php?tid=7138311)
Crazy Clamping Requirements? - Sullivan - 11-07-2015
So I am gluing up some veneer using Titebond Cold Press for Veneer glue. The bottle specifies that I "press the substrates together at 100-250 psi."
So for a 1 foot square (144 square inches) I would need to apply 14,400-36,000 pounds of weight. How is that possible in a home shop?
A vacuum press only applies 14.7 psi, 1/10 what they specify.
Re: Crazy Clamping Requirements? - JGrout - 11-07-2015
It is the weight of the atmosphere pressing downward or enveloping that applies the pressure to laminate with the closer to sea level the more the weight Once you get around 10000+ ft of elevation the vacuum is no longer adequate
so if you are between 0 and 9500ft the vacuum press will supply more than adequate pressure to laminate successfully
Re: Crazy Clamping Requirements? - Dullblade - 11-07-2015
It is per square inch not times per square inch. So the square inch in the bottom left corner would receive 100 psi as well as the adjacent corner receiving 100 psi and all square inches in between.
Re: Crazy Clamping Requirements? - iclark - 11-08-2015
It sounds like Titebond does not consider that line of their product to be adequate in a vacuum press.
It sounds like you need a veneer press (screw or hydraulic) in order to use that glue according to directions.
Re: Crazy Clamping Requirements? - jteneyck - 11-08-2015
You are right, 100 psi would require 14,400 lbs of force on a 1 ft^2 area. You are also right, there's no way that is going to happen in a home workshop, nor many others for that matter. Luckily, cold press veneers work just fine for us flat landers with a vacuum press which, you are right again, can only apply a max. of 14.7 psi. They state that the product is for use "with hydraulic or vacuum press", so it's curious how Titebond came up with that recommendation. It sounds pretty similar to what they recommend for their other glue products that would be used for normal cabinet/furniture construction where mechanical clamping on typically small cross sections can get you to 200+ psi.
Glue away. Use a vacuum bag if you have it or lots of clamps if you don't. It will work.
John
Re: Crazy Clamping Requirements? - Sullivan - 11-08-2015
I used my vacuum press and it came out just fine, as I knew it would. I was just curious about the pressures specified by the manufacturer as they seemed very high and unachievable in a home shop, especially as the size of the work piece increases.
I may contact the manufacturer just to see what they say.
Re: Crazy Clamping Requirements? - bandsaw - 11-08-2015
I think Titebond has a typo - I suspect 100 - 250 pounds per square FOOT. About the only way to get that much pressure would be in a roller press at the nip point between two very large rollers.
Re: Crazy Clamping Requirements? - loosetoe - 11-08-2015
About two years ago I noticed this. I called franklin-titebond to ask if this clamping requirement was indeed true. They informed me that this glue is not appropriate to use in a vacuum bag, but was rather formulated for hydraulic presses. Because of their advice, I do not use this glue.