My expanding 1/4" plywood

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Forum topic by mtnjak posted 05-26-2016 04:53 PM 665 views 0 times favorited 3 replies Add to Favorites Watch
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52 posts in 3227 days

05-26-2016 04:53 PM

Topic tags/keywords: 14 drawer bottoms drawer dado drawer bottoms drawers problems with drawers wood movement and drawers shop humidity

Recently I picked up some plywood from Menards for building some drawers for one of my shop workbenches. I cut the sheets down last night and prepared to do a dry fit for one drawer. I’m using 1/2” ply for the drawer sides with a 1/4” ply drawer bottom. I ran all the sides through my router table using a 1/4” straight bit for the drawer bottom dado groove. When I went to assemble everything I could not insert the drawer bottom into the grooves. I grabbed my calipers and the groove checked out at 0.25” but when I checked the drawer bottom it checked out around 0.265-ish. I’ve heard of plywood being undersized but I’ve never heard of it being oversized. The plywood I’m using is not oak. However it is rated better than standard plywood with no voids and sanded both sides. (Note: I went with this material because it’s an older 2×4 workbench. I didn’t feel the need to go with more expensive oak due to the nature of retro fitting drawers to an old bench).

The only other thing I can think of is the atmospheric changes in my shop in the last day or two. I live in Illinois and my shop is unfinished. I have a magnetic digital thermometer/humidity gauge stuck to the back side of my bandsaw. I have one in the kitchen and basement as well. Two days ago relative humidity in the shop was 24%; warm and dry, like the desert Southwest. Last night when I tried doing my fit up it was 60% humidity (probably due to the incoming storm front). Could the humidity change be the culprit or do I have some bad 1/4” stock—that I cannot return now since I’ve cut for my drawer bottoms. I moved my drawer parts to the basement where it was (as of last night) 40% humidity (where I run a dehumidifier). I’ll check them again in the next day or so to see if that makes a difference.

Has anyone else experienced an issue like this one? Thoughts?

3 replies so far

View conifur's profile


955 posts in 1327 days

#1 posted 05-26-2016 05:07 PM

I have used Menards 1/4” sanded ply you did and never had a problem and my shop was in my garage and live in humid WI. I made a work bench with drawers 2 summers ago and did not have a problem.

-- Knowledge and experience equals Wisdom, Michael Frankowski

View MadMark's profile


979 posts in 1628 days

#2 posted 05-26-2016 11:01 PM

Sand the edges slightly and use it.

Ply goods are all edges and expand in three directions at once (vs wood which grows 20x in width vs length) so it’s normal to get big changes esp in thinner stock with rapid transpiration.


-- Madmark -

View mtnjak's profile


52 posts in 3227 days

#3 posted 05-27-2016 03:32 AM

I checked it again this afternoon and portions of it read 0.27. I’ll just sand it. Besides that gave me an excuse to buy a new palm sander since my 20 year old Ryobi died recently. While I was picking up the sander at Lowes tonight I had grabbed my calipers to check their sheet stock which came in at 0.22 to 0.25. Lucky me my first time building drawers and I get crappy stock!

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