Airtight Drawer Problem

[Mike M]

I know that one of the tests of a good drawer is for it to trap a cushion of air behind it when it closes -- but --

I built a chest and dresser for our bedroom. The backs are a tight fit to the back of the drawer guides and the dust shields are 1/4" BB plywood set in 1/2" deep dados that fit snugly. The drawers are fairly well isolated, but not perfectly sealed.

I find that when I close the drawer any faster than very gently, there is an obvious piston effect -- a good thing. The problem is that closing one drawer at normal speed causes the adjacent drawers to open a bit (~1/8"). I then have to go back and close them -- a nuisance.

One solution would be to cut a hole in the back behind each drawer to let the air out. The downside is that each time the drawer is opened, any dust behind the chest will get sucked into the drawer compartment and eventually into the drawer.

Another solution would be to caulk any small gaps in the dust panel dados and between the drawer guide and back. This would still leave a small opening at the expansion joint in the back corners of the guide frame. I could caulk this joint too as long as the joint can still move as the solid cabinet sides expand and contract. This should cure the problem, but it seems like a bit of overkill.

Any other suggestions?

Mike

[Beechwood Chip]

One solution would be to cut a hole in the back behind each drawer to let the air out. The downside is that each time the drawer is opened, any dust behind the chest will get sucked into the drawer compartment and eventually into the drawer.

Cut the holes, but cover them with either a bit of cloth to keep dust from coming in, or with a flap so that air can leave when you close the drawer, but can't enter (bringing dust) when you open the drawer.

[Ben H]

Cut the holes, but cover them with either a bit of cloth to keep dust from coming in, or with a flap so that air can leave when you close the drawer, but can't enter (bringing dust) when you open the drawer.

Thats the first thing that came to mind, a one-way valve. Kinda like a respirator or snorkel.

[Mike M]

Good Idea ! ! ! Sounds like the hole saw is going to get a workout.

One of my buddies also suggested an exhaust fan that turned on when the drawer was open. It would create a suction that would counteract the pressure and also make the drawers self closing. Friend wife didn't appreciate the humor or the idea.

[Pete Bennett]

The correct way to make drawers is to have the back of the drawer a little less high than the sides and front for exactly this reason. As you open the drawer air from outside the carcass will flow in and over the drawer back to compensate. The same will happen when you close them except in reverse. The air will be forced out over the back and out through the carcass front. Sounds as though you've made some very well fitting drawers for all that. Well done.

Pete

[adamking]

Pete's right. The back of the drawer should always be made 1/16" narrower than the front and sit lower than the front as well. This makes a slightly trapazodial shaped drawer. Also, keep in mind a piston fit is nice, but what about in the middle of the summer humidity? Good luck prying that open! A proper drawer fit isn't about how tight or how much air it traps. It's about fitting the opening and in a way that allows it to function properly and smoothly all year long.

Don't cut holes in the back of your piece. Take the drawer out and lightly plane the back sides so the back goes in to the opening loose. Also plane the top of the back down a bit from the top of the sides.

Try that. Let us know if it helps.

[Mike M]

I didn't mention the size of the drawers. They are 8" high and 25" wide and 19" deep.

I made the drawers with bottoms that slide in after they were glued so there is already 5/16" underneath the drawer plus another 1/4" to the dust panel on all but the bottom drawer. I also made the back slightly lower than the sides as Pete suggests.

Until the last inch, as the drawer front enters the cabinet, the piston effect just blows air out under the drawer. The last inch is when the other drawer pops out.

As far as wood movement is concerned, I built these pieces over the summer in my basement shop (air conditioned). Unless I put them in a room with no A/C I shouldn't have a problem with the drawers binding up.

Mike

[jHop]

Don't cut holes in the back of your piece. Take the drawer out and lightly plane the back sides so the back goes in to the opening loose. Also plane the top of the back down a bit from the top of the sides.

Try that. Let us know if it helps.

What about using a chisel to "notch" out a small area of the back? Say, 1/16" deep? and maybe 1/2" wide? or would it need to be wider? Yes, I know the "correct" way is to do as you suggested, but I'm trying to think of a quick fix to a completed project that doesn't require disassembling the drawers to get them lower than the sides.

[adamking]

What about using a chisel to "notch" out a small area of the back? Say, 1/16" deep? and maybe 1/2" wide? or would it need to be wider? Yes, I know the "correct" way is to do as you suggested, but I'm trying to think of a quick fix to a completed project that doesn't require disassembling the drawers to get them lower than the sides.

All you need is a shoulder plane or even a sharp chisel to slowly and carefully pare the top of the back down. It doesn't take much. Also a low angle block plane can reduce the back ends in thickness a bit. Again, you're not going to need to remove much.

Keep in mind, this isn't about trapped air. It's about the drawer fitting the opening too tightly.

I would hate to see anyone put holes in the back of a beautiful piece you labored for hours on.

[adamking]

I didn't mention the size of the drawers. They are 8" high and 25" wide and 19" deep.

I made the drawers with bottoms that slide in after they were glued so there is already 5/16" underneath the drawer plus another 1/4" to the dust panel on all but the bottom drawer. I also made the back slightly lower than the sides as Pete suggests.

Until the last inch, as the drawer front enters the cabinet, the piston effect just blows air out under the drawer. The last inch is when the other drawer pops out.

As far as wood movement is concerned, I built these pieces over the summer in my basement shop (air conditioned). Unless I put them in a room with no A/C I shouldn't have a problem with the drawers binding up.

Mike

A/C won't stop any wood movement, even though it's regulating air temperature. Sounds like you built these drawers very well. If you're getting too much of a piston effect (like other drawers popping out) then just get your smoothing plane, or low angle block plane, and plane the sides of the drawer at an extremely light setting. Take one or two passes each side, and check the fit until it stops pushing the other drawers out. Or you could lightly sand the sides instead of planing them, but you actually risk taking too much off that way.

[flairwoodworks]

Mike,

Will the weight of the contents keep the drawers closed?

[kesac]

I know that one of the tests of a good drawer is for it to trap a cushion of air behind it when it closes -- but --

I built a chest and dresser for our bedroom. The backs are a tight fit to the back of the drawer guides and the dust shields are 1/4" BB plywood set in 1/2" deep dados that fit snugly. The drawers are fairly well isolated, but not perfectly sealed.

I find that when I close the drawer any faster than very gently, there is an obvious piston effect -- a good thing. The problem is that closing one drawer at normal speed causes the adjacent drawers to open a bit (~1/8"). I then have to go back and close them -- a nuisance.

One solution would be to cut a hole in the back behind each drawer to let the air out. The downside is that each time the drawer is opened, any dust behind the chest will get sucked into the drawer compartment and eventually into the drawer.

Another solution would be to caulk any small gaps in the dust panel dados and between the drawer guide and back. This would still leave a small opening at the expansion joint in the back corners of the guide frame. I could caulk this joint too as long as the joint can still move as the solid cabinet sides expand and contract. This should cure the problem, but it seems like a bit of overkill.

Any other suggestions?

Mike

Yes. Quit making your drawers so tight. That is only good for showing off to yourself. No one else will care. The drawer will not last any longer for being that tight, and you will have unnecesary problems with sticky drawers when the weather changes.

[nateswoodworks]

I did the same thing when I was getting started, minimal tolerances just seemed to scream quality to me at that time. The problem came when I seriously couldn't get the drawer open for about 6 months! It seemed to take a few drawer projects for me to get the right feel for smooth and no slop and good for all seasons, and this is going to vary on where you call home. No matter what it sounds like you excelled at fitting your drawers-good job.

Nate

[Mike M]

First of all, the drawers are not fit too tight. When I built the chest in August I left a gap between the drawer face and frame of .040" on the top and sides (I use formica samples as a gauge). The bottom is a little less. Since I built it at the most humid time of year, I didn't leave extra clearance since the wood shrinks when the heat is on. Now that the heat is on, the gap is a bit bigger.

As I said above, the problem occurs in the last 3/4" of closing - as the drawer front enters the cabinet. If you look at the numbers, the drawer front is 8" x 25". During the last 3/4" of closing there is a piston of 8 x 25" or 200 square inches compressing the air The perimeter of the front is 66 inches, so with a gap of .040" this leaves a relief port of 2.6 square inches. The velocity of the air escaping around the drawer front must move at 200/2.6 = 76 times as fast as the drawer is closing. This is what is creating the back pressure which is forcing some air into the adjacent drawer's compartment.

The only way to alter the drawer to solve the problem is to make the gaps larger. Now that the heat is on, the gap along the top has increased a bit and the problem is less. I kind of like the smaller gaps and prefer that the drawers not look like a sloppy fit, so I'll live with the problem and close the drawers slowly so the air can escape.

Thanks for all the suggestions, they got me thinking about the problem.

Mike

[nateswoodworks]

Are your drawers sliding on runners or full dust frames, you mentioned it before but I just wanted to make sure. If they are riding on full dust frames I would think that it would work to bore a hole or a few holes in all the dustframes at the very back of the drawer compartment allowing the air to funnel out through the drawer cavity down into the one lower and if need be all the way through the bottom, and best of all nobody would ever see it. It is your project and your baby you have to do it the way you want, I am just saying that I would personally take a little off the back of the drawer thus allowing the air to travel into the drawer itself, I would also taper the sides of the drawer to match the back to it is all even but that's just me. If you look at older furniture a lot of the drawers sides were tapered making them wider at the front 3/4" to make a nice tight reveal but just enough of a gap for season movement and to probably help with your problem as well. To make it so the drawer still travels smooth there is a runner fitted to slide against the inside of the drawer under the drawer bottom and is attached to the dustframe. This is the way I do my furniture so that I can have small gaps around the drawer fronts and they travel smooth as glass with no slop. Like I said this is just the way I do it and this is your baby. Please let us know how you turn out.

Nate