Some of you may recall that we thought we had a broken king pin mount this past summer when we went to Nashville for the eclipse. DW and I stripped off the plastic under the 5th wheel area, inspected and reinstalled. Most of the weight of this plastic is held by right angle brackets on the sides about 1/2" x 1/2". Screws go from below into the plywood behind the fibreglass outer wall - in other words into the layers of plywood not through the layers.Well, when I got there to Mesa, I noticed that the bracket is pulling away. Obviously the screws didn't bite and hold in the plywood. Probably shouldn't have put them back in the same holes. Duh.Anyway, is it worth pre-drilling new holes and coating the screws with epoxy before setting them. Or is there a better technique?As a last resort, I could put SS screws into the side of the bracket and go into the wall cross-grain. That's only going to be 1/4" from the end of the plywood - can't imagine that will hold well.

This is the bracket I want to secure.If I have to, I'll put screws into the steel subframe.

What I'd do is head to a lumber store and get a length of hardwood dowel twice the diameter of the screw I intended to use. Drill a tight fit hole for the dowel(s) in the same holes that were used before, slather it with plenty of carpenters glue, tap the dowel(s) into the hole(s), cut them off flush. Give the glue 24 hours to dry. Then use a drill bit almost the same size as the new SS screws I was going to use to pre-drill the holes for use by the screws. Then use plastic washers maybe if the plastic sheet got damaged and the holes were torn a bit. This all depends on how thick the plywood edge you're drilling into is. You do want some plywood on either side of the dowels of course. It's the glue that will do the work of holding things together in the wood.Some measurements and a picture or three of your situation would really help get more answers. (The image above is blank).

Jim@HiTek wrote:What I'd do is head to a lumber store and get a length of hardwood dowel twice the diameter of the screw I intended to use. This all depends on how thick the plywood edge you're drilling into is. This was my first thought. But the epoxy may be worth trying, especially if you can use longer screws.(I can see the image, it's a cow standing in a field. :))

Regarding the title to your post, by definition plywood has grains crossed ply by ply. How can one not go cross grain in plywood?

gbopp wrote:Jim@HiTek wrote:What I'd do is head to a lumber store and get a length of hardwood dowel twice the diameter of the screw I intended to use. This all depends on how thick the plywood edge you're drilling into is. This was my first thought. But the epoxy may be worth trying, especially if you can use longer screws.(I can see the image, it's a cow standing in a field. :))It's a white cow, standing in a field, in a snow storm.

How to secure screws in plywood going with grain??

35 Replies

Jim
Explorer
Dec 14, 2017
gbopp wrote:
Jim@HiTek wrote:
What I'd do is head to a lumber store and get a length of hardwood dowel twice the diameter of the screw I intended to use.
This all depends on how thick the plywood edge you're drilling into is.

This was my first thought. But the epoxy may be worth trying, especially if you can use longer screws.
(I can see the image, it's a cow standing in a field. :))

It's a white cow, standing in a field, in a snow storm.
Lwiddis
Explorer II
Dec 14, 2017
Regarding the title to your post, by definition plywood has grains crossed ply by ply. How can one not go cross grain in plywood?
gbopp
Explorer
Dec 14, 2017
Jim@HiTek wrote:
What I'd do is head to a lumber store and get a length of hardwood dowel twice the diameter of the screw I intended to use.
This all depends on how thick the plywood edge you're drilling into is.

This was my first thought. But the epoxy may be worth trying, especially if you can use longer screws.
(I can see the image, it's a cow standing in a field. :))
Jim
Explorer
Dec 14, 2017
What I'd do is head to a lumber store and get a length of hardwood dowel twice the diameter of the screw I intended to use. Drill a tight fit hole for the dowel(s) in the same holes that were used before, slather it with plenty of carpenters glue, tap the dowel(s) into the hole(s), cut them off flush. Give the glue 24 hours to dry. Then use a drill bit almost the same size as the new SS screws I was going to use to pre-drill the holes for use by the screws. Then use plastic washers maybe if the plastic sheet got damaged and the holes were torn a bit.

This all depends on how thick the plywood edge you're drilling into is. You do want some plywood on either side of the dowels of course. It's the glue that will do the work of holding things together in the wood.

Some measurements and a picture or three of your situation would really help get more answers. (The image above is blank).
joebedford
Nomad II
Dec 14, 2017

This is the bracket I want to secure.

If I have to, I'll put screws into the steel subframe.

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How to secure screws in plywood going with grain??

35 Replies

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