Screws for plywood?

[woodmats]

I often use screws as clamps to hold plywood cabinets together until the glue dries, especially in non-visible and hard to clamp places. My go-to type screw has been coarse thread pocket hole screws because of the flat head but they don't work too well holding plywood end grain. Maybe they're not beefy enough? Is there a better choice?

Mats

[FS7]

I often use screws as clamps to hold plywood cabinets together until the glue dries, especially in non-visible and hard to clamp places. My go-to type screw has been coarse thread pocket hole screws because of the flat head but they don't work too well holding plywood end grain. Maybe they're not beefy enough? Is there a better choice?

Mats

Plywood doesn't really have much of an "end grain," but you could potentially get bulging when screwing into the edge. Pre-drill and use coarse thread screws. 

Why won't the pocket screws work? I have used those before with no problems.

[photobug]

I often use screws as clamps to hold plywood cabinets together until the glue dries, especially in non-visible and hard to clamp places. My go-to type screw has been coarse thread pocket hole screws because of the flat head but they don't work too well holding plywood end grain. Maybe they're not beefy enough? Is there a better choice?

Mats

I agree with FS7

No end grain on plywood, coarse thread screws should work. 

Are you using pockets for your pocket screws?  If not you are using too much screw.  If screwing and gluing 3/4" plywood to make a but joint I would use 1 5/8 to 2" screws predrilled and counter sunk to hold the joint together.  If your screws aren't holding I can think one of two problems.

Not using appropriate pre-drill size or screws not big enough.

Are you pulling the joint tight with a clamp before screwing it?  If not the screws may strip trying to pull tight a too loose joint.

[woodmats]

In this case I'm building a chest of drawers that is 70" long, 21" wide and 25" tall. It has 2 dividers to make 3 sections of drawers so I want to secure the dividers in dado's  after I've applied the glue. I haven't been too successful applying clamps during the glue up for this type of assembly so I use screws to assist holding the dividers when the glue dries. I typically use 1-5/8  pocket screws and in this case, I only drill holes in the top and the bottom and let the pocket hole screws drill into the "end grain" of the dividers. My experience is that with this approach, the plywood (11 layer pine plywood from HD) doesn't hold the screws too well. Would it work better if I pre-drilled the dividers?

Mats

[mad_planter]

I often use screws as clamps to hold plywood cabinets together until the glue dries, especially in non-visible and hard to clamp places. My go-to type screw has been coarse thread pocket hole screws because of the flat head but they don't work too well holding plywood end grain. Maybe they're not beefy enough? Is there a better choice?

Mats

go the other direction.  use pockets to go from the "end grain" to the other piece of plywood.  Avoids a whole host of problems with screwing into the edges of plywood.

[woodmats]

go the other direction.  use pockets to go from the "end grain" to the other piece of plywood.  Avoids a whole host of problems with screwing into the edges of plywood.

That's a good idea except in this case, I only have 3/8" of material left because of the dado if I go from the divider towards the top/bottom.

[Aram]

I often use screws as clamps to hold plywood cabinets together until the glue dries, especially in non-visible and hard to clamp places. My go-to type screw has been coarse thread pocket hole screws because of the flat head but they don't work too well holding plywood end grain. Maybe they're not beefy enough? Is there a better choice?

Mats

Spax. Pilot holes.

[woodmats]

Spax. Pilot holes.

Aram,

I have never used SPAX. I think I will try including drilling the pilot hole like you suggested

[Bill Holt]

Pre-drilling was time consuming...I thought.  But after splitting a nice piece of hardwood more times than I care to admit, pre-drilling became a habit, a very good habit.  Screwing into the plywood edge without pre-drilling is asking for failure, IMHO.

[Stwood_]

3/4 to 3/4 ply.....predrill with a tapered bit with countersink head, and I use 2" #8 screws.