Replies

1. 
   HowardAcheson | Jun 14, 2002 05:52pm | #1

   First, to know how much expansion you will have to deal with, go to http://www.woodbin.com and click on the "Shrinkulator". Inputs are species, width, relative humidity or moisture content change and the output is the amount of expansion/contraction.

   Next, for slots, I would rather use a round head or binder head screw. You can tighten them much more without the having the taper of the conical head trying to wedge open the hole or slot and perhaps, splitting the wood.

   I would make the screw body clearance slot first then route a counterbore slot to allow the head of the screw to be below the surface of the cleats. On a picnic table, I would use stainless steel screws.

1. 
   JohnKrist | Jun 15, 2002 03:47am | #2

   Thanks for the input. What's a "binder head". Good comments on the wedging forces of the screws. My bias is to draw up the cleats just enough to be tight and hold; I have a hunch that it would not be too hard to put alot stress into the system on each cleat with the 8 to 10 screws per cleat.

   Thanks again,

   JK

1. 
   HowardAcheson | Jun 16, 2002 07:17pm | #4

   A "binder" head screw is a round head that has been flattened. Generally, it will have a slightly larger diameter head also.

2. 
   geoffmurray | Jun 16, 2002 07:52am | #3

   I've had success using oversize holes and finishing washers, in stead of elongated holes/slots. They are easier to make for one. A hole twice as big as the diameter of the screw gives lots of room to move in either direction and the finishing washer alleviates the need to countersink. This worked on a large oak trestle table and cedar picnic table.

3. 
   Hempstalk | Jun 16, 2002 10:07pm | #5

   Check Lee Valley Tools.  They sell special slotted washers indended for this use.  You simply route or drill for the washer and it takes care of movement.