Dining/Game Table - #11 Inner Rail & Structural Support Assembly

With the MDF securely screwed down I could flip the assembly over and drill the previously started pilot holes for the #8 X 2 ½” screws that will lock this assembly to the inner rails.  This is what I end up with.  There is still work to do on this pilot hole but that will come later.

In Progress Pilot Hole

One of the problems I had was with how to grip the playing surface and lock the structural support to the inner rail.  At first it seemed like I had two mutually exclusive choices:

1. Have the playing surface and pad gripped enough to hold it in place but not enough to cause it to pucker or wrinkle.  Unfortunately, this left the structural support connection to the inner rail wiggly and not at all solid or secure. 
2. Mash the pad into oblivion which caused the surface to pucker and wrinkle but did lock the structural support to the inner rail.

After some thought and experimentation I found a way to accomplish both goals, lightly gripping the pad and locking the structural support to the inner rail.  I added small flat head screws to act as spacers between the MDF and the inner rail.  These small screws are located on either side of the large #8 X 2½” screws used to lock the structural support to the inner rail.  By varying the height these small screws are exposed above the MDF allows me to control the amount of compression applied to the playing surface and pad.  It also provides a solid bearing surface between the structural assembly and the inner rail once the large screws are tightened allowing everything to be locked solidly together. 

Here I have temporarily clamped the rough cut inner rail pieces together to form a corner and set them on the small screw spacers.  The large #8 X 2 ½” screws will come up between the small screws.  The gap between the inner rail and the MDF in the photo is 1/8” or half the overall thickness of the pad that probably will be used.  The final gap will be set after I get a sample of the pad and do some testing.

Clamping Gap for Playing Surface

With the locations set and the small screws test fit I took them all out so I could work on the inner rails.  I retrieved the four roughed out pieces, checked them to see if they were all straight, flat and true which they were.  I had run them through the thickness sander using a coarse 120 grit paper so now picked the show face then using 220 grit paper ran them through the sander.  Next was to rip them down to about 1/8” over final width.  Final width will be determined once I have the pad gap set.

Inner Rail Location

Cutting to final length was next.  The inside face of these pieces have a plywood alignment guide fastened to them so they and the playing structural supports are aligned.  When I checked the thickness of the inner rails pieces I found that they were about 1/64” thinner than the structural support pieces.  That’s due to taking the cup out of the original board with the thickness sander. 

What this means is the cross-pieces need to be 1/32” longer than the structural pieces so the inner faces of the inner rail and structural support will align.  The long side inner rails will not change they are the same length as the structural ones.  It also means the effort I had made to make sure and not change the stop I had used on my chop saw to cut the structural cross-pieces to length did me no good.  Oh well, it could have been worse I could have cut the cross-pieces 1/32” too short attached the plywood alignment guides then found that the inner rail assembly was too small. 

With the inner rails cut to length I clamped them in place and screwed them together using #6 x 1½” screws.

Assembling Inner Rail

Once all four corners were screwed together I could work on drilling the final stage of the pilot holes for the large #8 X 2½” screws.  This brings to light the reason I removed the small spacer screws.  The bit I have is just long enough to go through the structural support and the MDF and mark the inner rail.  As shown here it’s not long enough to drill a full depth pilot hole.   Now with the pilot hole locations marked I could take the clamps off, take the inner rail frame apart and using the drill press finish the last bit of the pilot holes. 

Drill & Screw Lengths 

I want the large #8 X 2½” screws to spin freely in the structural support and the MDF so all the clamping force is generated in the inner rail.  This means I need to go back and enlarge holes in the structural support and MDF before attaching the inner rail.  This drawing shows a before and after of this last bit of drilling.  Note how the pilot hole steps down as it goes into the inner rail.

After reassembling the inner rail, I clamped it in place and at long last I was ready to run the long #8 X 2½” screws in place or nearly so.  Because the small spacer screws are not in place I will hold off screwing them all the way in.  Once I had that done I could take all the #8 X 2½” screws out, remove the inner rail frame, take it apart, notch the ends of the long inner rails to clear the upper screws holding the outer rails to the legs and set the structural assembly back into the table where it goes.  As a safe place to keep them out of harm’s way I just set the inner rails in place where they will go. 

Inner Rail Assembly Set In Place

Once I get the pad and playing surface sample I will do some testing with it to determine the final small spacer screw height and use that to get my final width of the inner rails.

Next Up – Roughing Out Alignment Guide, Test Fit Playing Surface/Pad, Drilling & Assembling Spacer/Inner Rail