Frame/panel Door VS Solid Drawer Bottom--Why?

[Dennis McDonaugh]

A solid door panel and drawer bottom are essentially the same thing right? Why is it okay to use a frame on four sides of the door, but you always see the solid drawer bottom protrude through the back of the drawer to allow for wood movement?

[Chris Fite]

a. So you can assemble the sides of the drawer box, then insert the bottom.

[Scott Loven]

You can make doors out of a solid board/plywood/MDF, people do it all of the time. The problem as I see it is that those kind of doors are more prone to warping, and don't look as nice. Drawer bottoms don't show, so people don't want to put the effort into them that they would for something that shows like a door. A drawer bottom is held in a dado on three sides so warping should not be an issue.
Scott

[Jamie Buxton]

Your point is that the door panel is captured in a dado around all four sides, while the traditional drawer bottom is captured around three sides. I think the answer might be that the drawer back is generally not very thick. If the maker made a dado in it deep enough to handle all the movement he expects, the dado might go all the way through the back. Well, it might not go all the way through, but it would be deep enough that the bottom edge of the back might break off. In contrast, the door's frame can handle a much deep dado without structural worries.

Another difference is that drawer bottoms may be as much as 25" in the expansion direction. Door panels are rarely that wide. They're generally broken into smaller panels -- partly to make the expansion in each panel smaller. That is, the drawer bottom is going to have larger expansion than the door bottom, which requires a deeper mortise.

[Dennis McDonaugh]

Another difference is that drawer bottoms may be as much as 25" in the expansion direction. Door panels are rarely that wide. They're generally broken into smaller panels -- partly to make the expansion in each panel smaller. That is, the drawer bottom is going to have larger expansion than the door bottom, which requires a deeper mortise.

Jamie, That sounds like the most plausable reason. Most door frames are 2" wide or so and a drawer side is less than 3/4" so you don't have as much room for the dado. I guess I'll do it that way too.

Thanks

[Dennis McDonaugh]

You can make doors out of a solid board/plywood/MDF, people do it all of the time. The problem as I see it is that those kind of doors are more prone to warping, and don't look as nice. Drawer bottoms don't show, so people don't want to put the effort into them that they would for something that shows like a door. A drawer bottom is held in a dado on three sides so warping should not be an issue.
Scott

Scott. I'm not worried about warping, but expansion.

[Dan Gill]

I suspect the simplest reason is that the back of a drawer is hidden from view and there's a little room in the case. Thus you CAN leave a drawer bottom free to expand and you cannot leave one edge of the door off for expansion.

[Lee DeRaud]

Ok, time for my daily quota of one dumb question: assuming a solid wood drawer bottom, what is the "correct" grain direction and is the answer independent of drawer proportions? I.e. if you have a 12"x20" drawer does the grain run the same way regardless of whether the 12" side or the 20" side is the back?

(Followup question: did that first dumb question really only count as one dumb question?)

[Tim Sproul]

JMost door frames are 2" wide or so and a drawer side is less than 3/4" so you don't have as much room for the dado.


It is the drawer front and back thickness that matters for enclosing a solid wood bottom, not the sides so much.

I'm with Jamie's thinking. Thinner front and back compared to frame width and wider panel compared to frame and panel.

Also, I normally partially insert the solid wood bottom before sliding the back into the grooves. I did it once without putting the bottom in first and then had the back slide down on me a wee bit during clamping....well, the bottom of the back needed a little in-place trimming. So now...attach sides to front. Slide bottom in. Slide back in. Clamp. Remove bottom. Let glue cure. Slide bottom in. Fasten to underside of back. Try to fit drawer in case. Curse a lot - I can never seem to get my drawers to fit right from the get-go.... :) .

[Jamie Buxton]

Ok, time for my daily quota of one dumb question: assuming a solid wood drawer bottom, what is the "correct" grain direction and is the answer independent of drawer proportions? I.e. if you have a 12"x20" drawer does the grain run the same way regardless of whether the 12" side or the 20" side is the back?


Lee, if you make the grain direction run the short dimension of the bottom, the bottom is stiffer. That is, there will be less sagging under load. However, you'll have to deal with more expansion if you do it that way, so there's a choice to make. (Of course, you can always make the bottom thicker to get less sagging, so that's another way to skin the cat.)

[Lee DeRaud]

Lee, if you make the grain direction run the short dimension of the bottom, the bottom is stiffer. That is, there will be less sagging under load. However, you'll have to deal with more expansion if you do it that way, so there's a choice to make. (Of course, you can always make the bottom thicker to get less sagging, so that's another way to skin the cat.)I'm starting to understand why plywood drawer bottoms are so popular.:p

[Dennis McDonaugh]

Lee, if you make the grain direction run the short dimension of the bottom, the bottom is stiffer. That is, there will be less sagging under load. However, you'll have to deal with more expansion if you do it that way, so there's a choice to make. (Of course, you can always make the bottom thicker to get less sagging, so that's another way to skin the cat.)

Jamie, Which way is the drawer going to expand the most? Across the grain or with the grain?

[Jamie Buxton]

Jamie, Which way is the drawer going to expand the most? Across the grain or with the grain?

For all practical purposes, solid lumber does not expand or contract along the grain. It does move in the cross-grain direction. (Plywood, because it has grain layers running both directions, does not move in either direction.)

[Jamie Buxton]

I'm starting to understand why plywood drawer bottoms are so popular.:p

Not only is a plywood bottom easier, it has big structural benefits. Because it doesn't move, you can glue it in. Glued in, it is a great big gusset holding the corner joinery together. Also, it holds the sides straight, and it holds the whole drawer square.