How much gap for a 10" drawer?

[David Coburn]

Well the title pretty much sums it up... I have some solid walnut drawer faces that are 10, 9, 8, and 6 inches tall. I'm trying to decide what gap to leave around the face for expansion and contraction. Unit has been built in a garage shop over the past several months. Location is Dallas Texas and it was the hottest summer on record. Customer location is also Dallas but they could possibly move to Chicago in a year or two. Obviously it will be in a climate controlled space.

Thanks,david

[Steve Baumgartner]

The answer varies with the species of wood, the grain orientation, the type of finish, and the annual humidity range where the piece will be, so there are no guarantees. I was taught to allow for .5-1% width change seasonally. That works out to about 1/16-1/8 inch per foot of width, so a bit less than that for your 10 inch drawer. It also depends on how the drawer is suspended. For a typical drawer sliding on runners at the bottom, all the movement is at the top of the opening. The gap at the bottom doesn't change, but sometimes I plane some off the bottom edge of the drawer front because I think it looks better with a gap similar to the top. If the drawer is hung from the center of the sides, you need to leave half the clearance at the top and half at the bottom.

[Lee Schierer]

First off, I would apply equal amounts of finish to all sides of the drawer front. Then I would leave a gap of 1/16-3/32" per side or about the thickness of a penny after finishing (which means you might want a gap of 1/8" per side to start before you apply the finish).

[David Coburn]

Sooo.... from the two answers above it seems that roughly a 1/16" gap all the way around is a good place to start... yes? My initial thinking was this or just a bit more...

thanks,
david

[Brian Tymchak]

If I make an assumption that the relative humidity in your garage is higher than what is going to be found in a climate controlled room (~30-35%) then the drawer front should (maybe "could" is the better word) actually shrink a bit across it's width, yielding a larger gap.

I personally don't know how to calculate that movement, but I resort to the Shrinkulator on Wood Web. For the following results I assumed a starting Relative Humidity of 60% in your shop and a final RH of 35% in the piece's final resting spot. The Tangential Final Dimension is what you are interested in. The dimension is 10" (the largest of the front drawers). You can play around with the shrinkulator to adjust as you see fit. Might be good to actually monitor the RH in your shop. It will change day to day depending on the weather.

Edit #2: Going back to Lee's note, these results assume unfinished wood. I don't know how factor in using a finish, other than knowing it will slow the rate of shrinkage. Don't know if finish will make a difference in the final dimension after full acclimation.

HTH, Brian


Edit: The results didn't paste properly. I'm recreating them here by hand.


Shrinkulator Summary Table

Species=Black Walnut
Initial MC = 11.0
Final MC = 6.9
Initial Dim = 10 (inches)
Final Dim Radial = 9.92
Final Dim Tangent. = 9.88
Change Radial = -0.08
Change Tangent = -0.12

MC = Moisture Content

Walnut, Black	11.0	6.9	10	9.92	9.88	-0.08	-0.12

[David Coburn]

Thanks to everyone ....

seems that the answers are all in the same basic range.. The "shrinkulator" kind of pegs it for me though... I figure I'll try to get as close to 1/32" all the way around for now...

thanks again,
david

[Zach Callum]

It can get pretty humid in the Chicago area in the summer....

[Frank Drew]

It can get pretty humid in the Chicago area in the summer....

I think the original poster mentioned that the piece would be living in climate control.

[Peter Quinn]

If you leave a 1/32" gap either the client should move to the mohave dessert or you will be getting a call back eventually to fix the drawers. Round my way most ole timers don't bother with shrinkulators, calculators, or even rulers when hanging doors and drawer fronts that are inset. They use nickels or a dimes. A dime if building in the summer, because it will shrink in the winter, and a nickel if building in the winter, because in the summer, it will grow. Now being that the Northeast is where most of this American fine furniture tradition began, there may be some shred of traditional yankee wisdom in this logic? Either way, pick a SOLID GAPPING SHIM, like a feeler gauge of sorts, and set all the drawers and doors in your piece consistently with what ever size gap you choose. It has to look consistent when you deliver it when it will face the most scrutiny of its service life! FYI, if you are going on the tight side, those little formica samples available in the counter top department of most home centers are pretty much a perfect .055" last I checked, and make excellent gauges for gapping doors, in summer round here.

Having put calipers to a good amount of pocket change, I've found your average dime is around .055", and your average nickel is around .080'-090". So between 1/16" to 3/32" works pretty well. Problem with the nickel and dime method is most wood workers I know these days don't have two nickels to rub together let alone two dimes, so pennies may be a better option? Pennies are just a little bit fatter than dimes.

I haven't got as much faith in "Climate control" as some, because that is rarely defined very clearly. I have worked in houses where it was literal; lots of money had been paid for central steam generators, whole house dehumidifiers, air purifiers, air handlers, air exchangers, tight building envelopes, etc, and the "climate" could genuinely be maintained within a very tight range of RH and temperature regardless of exterior conditions. But these are rare and generally for the very rich luxury homes. Most basic HVAC systems provide somewhere between OK and SUCKS level of actual climate control. Its more like climate "mitigation" than any measure of actual control. The air conditioner cuts the RH to around 55% in the pit of summer when the outside is hovering around 90%, and it bumps it up to around 30% in winter with one of those little gerbil wheel with sponge type humidifiers. If the RH swing is going to be 25-30% seasonally, the gap had better accommodate that. In my old completely uncontrolled bungalow, I back bevel the knob side to keep things from sticking in sticky months without leaving a monster gap showing in the winter.

[David Coburn]

"two nickles to rub together" .... a woodworker and a poet and quite a bit of truth to boot...

Again, sounds like good advice..

thank you,
david