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Forum topic by Chris1939 posted 02-21-2011 05:47 PM 4874 views 0 times favorited 8 replies Add to Favorites Watch
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Chris1939

1 post in 2114 days


02-21-2011 05:47 PM

I have a large family that I can’t seat at my dining room table. I was wondering if I could use MDF or plywood to make a temporary table top to place on top of may table on the days they come over. It would extend 20 inches on each end beyond the existing table top. It would only be needed for meal time when they come, not all the time. Would the 3/4” MDF or 3/4” plywood be strong enough without being supported?

Chris


8 replies so far

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chrisstef

15665 posts in 2469 days


#1 posted 02-21-2011 06:02 PM

I think at 20” either would be good enough to withstand the elbows and leaning on the table. You may want to think about the rubbing that will occur which may scratch the existing tabletop. You may want to fasten it down as well to keep it from shifting and sliding around.

-- rock, chalk, jayhawk

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Jonathan

2608 posts in 2513 days


#2 posted 02-21-2011 06:10 PM

You could also build a frame underneath around the outside to help strengthen/stiffen it, as well as to secure it in place around the table to keep it from shifting. Might want to consider adding some sort of backing material such as cork/rubber/etc. to keep it from sliding around and ruining the underlying table.

I’d go with the MDF over the plywood, as the plywood may tend to splinter. The MDF could crumble a bit, but that’s better than splintering. Might also want to roundover the edge with a router, then apply a few coats of sealer to help hold the edge together. Rounding over the edge will also help with elbow bumps.

-- Jonathan, Denver, CO "Constructive criticism is welcome and valued as it gives me new perspectives and helps me to advance as a woodworker."

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Sawkerf

1730 posts in 2531 days


#3 posted 02-21-2011 06:17 PM

I wouldn’t use MDF. That 20” overhang is way too much for it to handle. It will almost certainly break sooner or later.

The 3/4” ply would work better, but probably needs to be “framed” with something to prevent it from sagging. Unless you have plenty of storage space, you might also want to hinge it so it can be folded for storage.

If I were building this, I would put a “frame” on the bottom the size of the table top and use some non-skid padding to protect the table.

You’re raising the hieght of your table by 3/4” and folks will notice. – lol

-- Adversity doesn't build character...................it reveals it.

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Jonathan

2608 posts in 2513 days


#4 posted 02-21-2011 06:26 PM

Guess I didn’t clarify that the frame was supposed to be underneath the MDF to support it. Sort of like a torsion box, only not that much framing.

-- Jonathan, Denver, CO "Constructive criticism is welcome and valued as it gives me new perspectives and helps me to advance as a woodworker."

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Sawkerf

1730 posts in 2531 days


#5 posted 02-21-2011 06:30 PM

I would still go with the ply. It’s lighter than the MDF.

-- Adversity doesn't build character...................it reveals it.

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Jonathan

2608 posts in 2513 days


#6 posted 02-21-2011 06:59 PM

If you go with the ply, put the outer frame perpendicular to the edge of the ply, creating a lip, creating a flush surface along the top lip. That will strengthen the ply and give you an edge to roundover. You could simply glue or screw a square backing block or cleat and that’ll allow you to use the router on the edge, compared to something like pockethole screws where the screws will be in the path of the router bit.

Do you want something lighter that is easier to move? If so, go with the plywood as Sawkerf said, or if you want something more solid and heavier, go with the MDF. You could also put edge banding around the MDF to keep it from bowing.

Why do I end up overengineering things all the time? :-)

-- Jonathan, Denver, CO "Constructive criticism is welcome and valued as it gives me new perspectives and helps me to advance as a woodworker."

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ddockstader

151 posts in 2724 days


#7 posted 02-21-2011 09:15 PM

Some simple rules:
1. Unless you are serving “Rock” lobster, “Stone” crab, or have family members who weigh 300+ and insist on sitting on the end of the dining table, a 48×96 plywood will work fine without any additional framework – it certainly does for my family at Thanksgiving.
2. Use the plywood – it’s a lot lighter to carry out after dinner than the MDF.
3. ROUND THE CORNERS – have a dedicated piece with rounded corners. I used a 2 inch radius. Those corners, camouflaged by a table cloth, leave some nasty bruises when everyone is jockeying for chairs.

DAMHIKT

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Domer

252 posts in 2829 days


#8 posted 02-23-2011 12:28 AM

I agree that plywood is a lot lighter. I would put the frame underneath the plywood to keep it from moving around during use. I would also put a pad underneath the plywood to keep from scratching your table top.

If you are concerned about storing the plywood, you could cut it in half and hinge it. Easier to move around and store. but will leave the hinges in the way when you use it.

Domer

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