I am using figure 8 fasteners to attach a veneered 3/4" MDF tabletop to the apron. Two questions... Are there any special screws that I should be using? I was thinking of 8x5/8" wood screw. Do I predrill a "regular" pilot hole in MDF?
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For MDF, the coarser the thread, the better.
Drill the pilot hole slightly larger than you would for solid wood. Also, with MDF you'll often (virtually always) get a little raised "donut" around the hole, which should be pared off with a sharp chisel. Of course with veneer covering the MDF itself, this won't be an issue with this particular project.
Use a light touch to drive the screws ... very easy to strip out MDF.Larry -
I've had good luck with sheet metal screws with a flat head. Like Larry said, don't over tighten in the mdf.
WayneWayne JComment
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Larry,Originally posted by LarryG
By slightly larger, do you mean longer or wider?Comment
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I meant wider (diameter), but now that you mention it ... be sure to drill deep enough, too. I usually drill the pilot hole about 1/16" shy of the screw length.Originally posted by jarhead
Like Wayne, I've found that sheet metal screws work very well, if the head doesn't create a clearance problem.LarryComment
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I've always used coarse thread drywall screws. I also countersink the hole to eliminate the raised donunt effect.David
The chief cause of failure in this life is giving up what you want most for what you want at the moment.Comment
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you might want to look at #8 x 1 1/4" particle board screws - they seem to work pretty good. i got them at a local hardware store here - i've never even looked at hd to see if they have them or what they call them though.Originally posted by jarheadComment
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I'd be worried about drilling any fastener into the back of a single-thickness piece of MDF -- especially if I had a nice piece of veneer on front. Could you face-glue small mdf blocks to the backside, and put your fasteners into that?
Just thinking out loud...hate to see you punch through, or even dimple a nice top.
Regards,
TomComment
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Tom,Originally posted by Tom Miller
I can't picture what you're suggesting. Here's how I am attaching the tabletop to the apron.Comment
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My suggestion may not work very well with this type of fastener -- I've certainly never done it. But, in this case, you'd drill the hole for the fastener in the apron 1/2" deeper, and face glue a piece of 1/2" mdf to the underside of the table top. This way, instead of <1/8" tolerance in your drill depth for the screw into the table top, you have >1/2" tolerance.Originally posted by jarhead
I just try to limit my chances of screwing up when I can clearly see them -- there's plenty that I don't see. You're probably more careful than me, in which case you'll be fine.
Regards,
TomComment
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Tom raises a good point. When drilling pilot holes in a piece only 3/4" thick, there's little margin for error.
And here, maybe, is another: since your top's substrate is MDF, why the figure-eights in the first place? Do you want the top to be removable? If not, MDF is sufficiently stable that movement is not of concern. You could just glue the top to the aprons ...LarryComment
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Brian
Welcome to the school of life
Where corporal punishment is alive and well.Comment
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Larry,Originally posted by LarryG
I like your and Tom's ideas. The reason for figure 8's is because the knucklehead that I am, I was following the plans (even thought the plans call for plywood as a substrate). I don't want the top to be removable, but I may have a problem with gluing the top... when I place the tabletop on the apron, I see some gaps. I think the bent apron is not perfectly flat.Comment
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As long as you're open to trying something different, you could glue the mdf block to the bottom, and then just screw down an oversized (fender) washer that sticks into a groove in the apron, like so:
Note the (exaggerated) vertical placement of the groove so the washer pulls the top down tight.
Regards,
TomComment
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