problem with spliting plywood

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problem with spliting plywood

Postby sxjames » Thu Jul 13, 2017 6:11 pm

Greetings

I've noticed that when driving a #8 x 1-5/8" construction screw into the end grain of a 3/4" Baltic birch plywood panel, the plywood has a tendency to split. While I've drilled a small pilot hole/countersink in the piece I'm attaching to the plywood end, I haven't actually drilled a pilot hole into the plywood end itself -- these screws are supposed to be self tapping. I thought that perhaps I should just grab my trusty #8 pilot/countersink bit and drill a pilot into the end grain. So...has anyone else had this problem when driving large diameter (#8 or larger) screws into the end of plywood? If so, how did you solve it?

Thanks,
Stephen
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Re: problem with spliting plywood

Postby EZDog » Thu Jul 13, 2017 6:18 pm

Pocket Screws


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Re: problem with spliting plywood

Postby pchast » Thu Jul 13, 2017 8:08 pm

Insert a cross dowel and drill a pilot hole.
Its super strong but more work....
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Re: problem with spliting plywood

Postby HMK » Thu Jul 13, 2017 8:35 pm

The end of plywood is not a good place to put a fastener.
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Re: problem with spliting plywood

Postby EZDog » Fri Jul 14, 2017 4:20 pm

HMK wrote:The end of plywood is not a good place to put a fastener.


Which is why I think Pocket Screws would work there.

Give the screw a little "Meat" to grab onto!
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Re: problem with spliting plywood

Postby troubleScottie » Fri Jul 14, 2017 6:11 pm

When using pocket screw (well any screws) you should be putting the screw into the framing. Yes you might go through some plywood. But your intention/desire is to have most of the screw in the solid wood. Pocket screws improve the amount of wood that is incorporated into the joint and use less of the end grain.

More to the point, plywood end grain is not particularly strong. I would imagine MDO might have more grab than some -- but still poor. Even screwing into the end grain of wood is not the best plan. That is why there are all those wood working techniques eg dovetailing and metal gadgets eg IKEA-like fasteners out there. Push comes to shove, brads/staples and glue might work.
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Re: problem with spliting plywood

Postby QueticoBill » Fri Jul 14, 2017 7:40 pm

Biscuits and glue will work.
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Re: problem with spliting plywood

Postby EZDog » Sat Jul 15, 2017 4:45 am

troubleScottie wrote:When using pocket screw (well any screws) you should be putting the screw into the framing. Yes you might go through some plywood. But your intention/desire is to have most of the screw in the solid wood. Pocket screws improve the amount of wood that is incorporated into the joint and use less of the end grain.

More to the point, plywood end grain is not particularly strong. I would imagine MDO might have more grab than some -- but still poor. Even screwing into the end grain of wood is not the best plan. That is why there are all those wood working techniques eg dovetailing and metal gadgets eg IKEA-like fasteners out there. Push comes to shove, brads/staples and glue might work.

I use pocket screws into plywood all the time.
It works well and for items that get abused and stressed too.
Maybe not ideal from a design standpoint but great in practice for me.
I usually am joining 1/2" or 3/4" Birch void free ply which is much more dense than typical ply but for benches and boxes it will work well.
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Re: problem with spliting plywood

Postby elcam84 » Sat Jul 15, 2017 10:39 pm

Yup like said screwing into the edge of plywood is not going to hold much. If you really have to then use a dowel nut like mentioned. Its a common knock down furniture fastener. Or if using a bolt use a square nut inserted in the same fashion.
Another method is to drill and tap the hole then squeeze super glue in the hole and then clean out with the tap afterwards.

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