Darryl Keil Last Activity 2024-10-10 3:42 PM
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DLoretto

Posts: 4

Joined: 2011-08-05
Location: Eden, NY

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Subject : Caul deflection, amount allowed
Posted : 2011-08-05 12:21 PM
Post #36443
Hi,
I found no discussion on the amount of allowable caul deflection. I am about to press a entire kitchen cabinet door array and want to use 1/2 Melamine cauls without cutting new ones for each different size. I tested one pair of door panels on 1/4 MDF core, with the face and backer cut from the same flitch (1/32 each). I used waste core material around the overhanging edges, in between the cauls, so the deflection would have been 1/16. The panels seem OK. I ran them through the drum sander and they seem fine. What do you think?
Thanks in advance,
Don


 
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Don Stephan

Posts: 825

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

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Subject : RE: Caul deflection, amount allowed
Posted : 2011-08-05 6:43 PM
Post #36444 - In reply to #36443
When faced with this situation I simply work from the largest to the smallest doors, trimming the top caul as the next door gets smaller. I don't worry if the bottom caul is oversize, as it is firmly supported by the grooved platen. Just my two cents.


 
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Darryl Keil

Posts: 1453

Joined: 2003-05-22
Location: Maine

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Subject : RE: Caul deflection, amount allowed
Posted : 2011-08-05 9:48 PM
Post #36445 - In reply to #36443
Don,

I try to make my support blocking, (when I use them) the same thickness as the panel being pressed. I'm quite surprised you did not have problems with a full 1/16" thickness variation. How about putting scrap pieces of veneer underneath the spacer pieces to achieve the same thickness.

I actually do the same thing Don does when pressing a bunch of panels, start with the biggest one's and work down. For simple flat panel pressing where the veneer is reasonably flat I use 1/8" melamine cauls which are quite cheap.

Darryl Keil


 
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DLoretto

Posts: 4

Joined: 2011-08-05
Location: Eden, NY

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Subject : RE: Caul deflection, amount allowed
Posted : 2011-08-06 7:31 AM
Post #36446 - In reply to #36445
Darryl,


Thanks, I will press the scrap veneer and core along with the first good panel and strive to keep the deflection to zero. Seems so obvious, I feel silly to have asked.
Thanks to everyone who replied,
Don


 
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Darryl Keil

Posts: 1453

Joined: 2003-05-22
Location: Maine

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Subject : RE: Caul deflection, amount allowed
Posted : 2011-08-07 9:15 AM
Post #36447 - In reply to #36446
Don,

No question is too silly. Always better to ask.

See, what happens is this. When a caul goes off the panel into open space, even if its only a 1/32" space, the vacuum bag tries to push the caul downward into this area. This downward pressure ends up using the edge of the panel as a fulcrum point which in turn attempts to lift the caul upwards, off the panel. Obviously it cant, but it does lessen the vacuum pressure a few inches inward along the edge of the panel. In this reduced pressure area you do risk low bonding of the veneer and possible failure.

Hope this explanation made sense.

Darryl Keil
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