Shelving Unit Construction Question

[Mike Goetzke]

I'm building two shelving units for the sides of our fireplace. They were designed with 5 fixed shelves and a top. I dadoed the sides (oak ply) 1/4" deep for the shelves. I've used this construction technique several times in the past. The first cabinet glued up great and the face frame laid on it perfectly. The face frame on the second one was way off. The frame was nice and square but the cabinet was off by almost 1"! The width across all the shelves was spot on (all shelves seated in dados). But looking down the length on the sides they look wavey. I used the same clamping, tools, etc.. for the two units. I have never seen ply be wavey like this before. I did manage to get it lined up pretty good but not without stressing the parts. When I unclamp it tomorrow we'll see if it's acceptable.

Any clues what happened?


Thanks,

Mike

[william watts]

wavy plywood is no fun, but it's possible that your shelves are racked forming a parallelogram shape. The shelves will fit fine, but the cabinet will lean left or right. Did you use a back on the cabinets? The back will keep it square. Measure the diagonals they should be equal.

[Mike Goetzke]

Thanks for the reply Bill but the sides look wavy.

Posting this caused me to think of something I did for the first time on these cabinets that may have caused this. I used painters tape on both sides of the dados to prevent glue on the wood. When I removed the tape I discovered some was difficult to remove. Now wondering if some could have gotten pulled into the dados and caused the side to bow? Although, I had the same issue the tape on both units and the other was perfectly square.

Mike

[John TenEyck]

Are you sure you cut all the shelves to the same length? Stranger things have happened - I know from experience.

John

[Mike Goetzke]

I measured across where every shelf is and they all are within less than 1/16" variance.


Mike



Are you sure you cut all the shelves to the same length? Stranger things have happened - I know from experience.


John

[Roy Harding]

Are you sure you cut all the shelves to the same length? Stranger things have happened - I know from experience.

John

Conversly, are the dados all consistent in depth? If you have a 1/16" variance in shelf length, and a 1/16" variance in dado depth ...