Table top Equalizer slides and wood movement?

[Sam Murdoch]

I will soon be attaching some Osborne Equalizer slides to a table top that I am building - so here is a question

How does one accommodate wood movement with these things?

It is a 54" diameter cherry table - so 2- 27" x 1" thick halves with the grain running perpendicular to the slides. Each 1/2 will be made up of 3 boards. There will be 4 screws holding the slides to each half (so 8 screws per half). If I elongate the holes through the slides to allow for some modest wood movement I expect that over time and repeated opening and closing of this pretty heavy table top that the position of the slides will change due to sloppy holes. That could - and very likely - effect the proper closing/alignment of the 2 halves.

What to do? 1) Screw them down tight and expect that the top will be OK? 2) Leave them loose and expect a call back or a Howler letter from an irate client in a year or 2? Is there an 3rd option?

Please help if you have an idea on the subject. Thanks.

[Jim Neeley]

Sam,

Running the grain perpendicular to the slide direction of motion is you friend and the answer is not #1 or #2 but #1.5. You'll want to allow for movement, especially across the grain but that does not mean every slot must be elongated, just enough to provide for the movement.

I would take the screws nearest the joint tight in fixed holes and elongate the rest enough to permit the full expansion / contraction. This will keep the joint working well in the long-term while allowing for expansion and contraction cross-grain.

Jim

[Lee Schierer]

Off hand, I would make the screws closest to the center tight with no hole slop. Let the outer edges move with seasonal changes. Since Osborne is appears to be a quality company, I would suggest that you contact them for suggestions.

[Sam Murdoch]

Excellent - making the near edge hole(s) tight and leaving a bit of play in the others is completely obvious (now ).
Sometimes my "trained professional" hat falls over my eyes . So option 1.5 it will be.

And yes, Lee, Osborne has been great to work with. Good product and service and they have been more than willing to answer any questions. Just thought to ask you guys first on this one.

Thanks for the help.

[Jim Neeley]

Sam,

Depending upon the amount of expected movemet, I've seen the use of an oversized washer under a pan-head screw to permit the screw to have metal-on-metal sliding rather than trying to slide on wood, where it might bite. This permits to to tighten the sliding screws tighter since the metal-metal friction is less, which reduces wiggle in the top.

Jim