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Plywood bottom for chest of drawers

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Forum topic by Sawdust2012 posted 10-09-2016 11:28 PM 336 views 0 times favorited 5 replies Add to Favorites Watch
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Sawdust2012

93 posts in 1174 days


10-09-2016 11:28 PM

I am making a chest of drawers from hard maple. I have glued up panels for the top, sides and back. The end grain is on the top and bottom of the side panels. Considering wood movement, can I attach a plywood panel to the bottom? How do I need to accommodate the wood movement? The panel would mount inside the span, with the end grain exposed, but resting on the base. I would be using pocket hole joinery unless someone suggests something superior, but please no more dovetails in this wood grained cast iron they sell as hard maple. I’m hoping to avoid another panel glue up, but will do it if I have to. Thanks for your help!


5 replies so far

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JBrow

818 posts in 382 days


#1 posted 10-10-2016 01:33 AM

Sawdust2012,

If I understand your post, you are asking 1) how to incorporate a bottom in your drawers and 2) how to fasten the sides to the front and back to form the drawer box without using dovetails.

My personal preference is to float the drawer bottom in grooves, or in your case dados, in the front, back and sides. However the drawer bottom could be floated in dados in the front and the sides. By reducing the height of the back, the plywood bottom could be screwed to the lower edge of the bottom through oversized holes in the bottom. Dados cut deep enough should accommodate all but the most extremes of wood movement. The oversized holes in the plywood bottom would all the back to expand and contract. I like plywood for the bottom because it is strong, stable, and saves a glue-up.

Screwing the plywood bottom with oversized holes to the bottom edges of the draw box is something I would avoid. My belief is that the drawer bottom would eventually detach from the box and/or sag between the bottom-attaching screws.

Joinery to attach the sides to the front and back could be locking rabbet joints or simple butt joints. The butt joints would be pretty strong with just wood glue, since this would be a long grain to long grain glue joint (as I understand, you plan end gran to run along the top and bottom edges of the drawer box on the sides and the front and back). Since this is a drawer, I would probably reinforce the joints with some dowels. I am sure pocket screws would work, but I prefer the look from more traditional wood to wood joinery.

Potential problems I foresee is as a result of the end grain up orientation of the sides, front and back are that as the front and back expand, the drawer dimensions will change relative to the drawer openings of the chest. This could lead to sticking drawers in the summer and drawers that run cockeyed in the winter, making them harder to close.

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Sawdust2012

93 posts in 1174 days


#2 posted 10-10-2016 01:44 AM

Hi JBrow,
Thanks for your input, and while I’m certain I’ll need help with the drawers also, I was asking, however unclearly, about the carcass. It sounds like you have a good bit of knowledge in this subject. Any input?

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jumbojack

1667 posts in 2086 days


#3 posted 10-10-2016 04:44 AM

I would glue up another panel. That way everything moves together. Drawers are a snap as.long as everything you have built so far is SQUARE.

-- Made in America, with American made tools....Shopsmith

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jdh122

879 posts in 2279 days


#4 posted 10-10-2016 05:38 AM

It’s not necessary to have a solid panel for the bottom. You can instead use 2-3 boards at about 3 inches wide and attach them. I generally use one wide half-blind dovetail for each board, but since you want to avoid dovetails you could use pocket screws. If you’re committed to having a solid bottom, I think that you’d be best gluing up a panel. You might be safe with plywood, but you might not, I wouldn’t take the risk.
On the other hand, plywood will be perfect for the back of the chest, since there will be no wood movement in either direction. If you want to use wood instead you’ll need tongue-and-groove or shiplap.

-- Jeremy, in the Acadian forests

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JBrow

818 posts in 382 days


#5 posted 10-10-2016 01:46 PM

Sawdust2012,

Wow, I was in a dense mind-fog when I wrote my initial reply. I guess I saw drawers and dovetails and maple (typical in drawer construction), assumed drawers and off I went. Sorry.

Unfortunately the mind-fog has not completely lifted. I am confused by your thought of using plywood for the bottom together with the statement

The panel would mount inside the span, with the end grain exposed, but resting on the base.

If the sides of the chest side rest atop the bottom and the edges of the bottom would thus be visible, plywood could possibly be used. It would largely depend on the design of the base, whether the front edge of the bottom is concealed by the bottom front rails of the chest or whether the front rail also rests on the bottom, and the design where the chest meets the base. But without understanding the design a little better, I can offer no suggestions.

But then if the design of this chest is similar at the base as the Chest for American Girl doll posted in your projects, then the method described below could be used. If the sides of the chest are a little shorter than the front, this gap could be incorporated into and accommodated by the base. By the way, nice job on the Doll Chest!

If the edges of the bottom would be concealed by the front and sides of the chest, plywood would be an alternative for the bottom. A stopped-groove in the front assembly and dados in the sides could accept mating tongues in the plywood. The plywood could be glued to the front assembly and left to float in the dados in the side, although about 3” of glue in the dados in the sides at the front only could also be applied. The plywood could be square cut at the back and sized front-to-back so that if the sides contract across their width, the back edge of plywood bottom would not extend beyond the grooves in the back (that would house the back).

You mentioned gluing up a panel for the back. If the front of chest features top, bottom and/or drawer dividing rails whose grain will run parallel to the floor, the grain of the back panel should also run parallel to the floor. If the grain of the wood in the front of the chest is perpendicular to grain of the back, as the back expands and contracts, it could weaken or crack the joints holding the sides to the front to the chest.

I really hope is this reply is more responsive than my first reply.

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