What’s the best way to fix gaps in miter joints on a wooden side table?

[SavannahPB]

I’ve been trying to build a simple wooden side table, but my miter joints keep coming out with tiny gaps no matter how carefully I measure and cut. I’m using a basic miter saw and I’ve checked that the blade is at a perfect 45-degree angle, so I’m not sure what I’m missing. Is there a specific technique for clamping or trimming that helps close those seams before gluing?

[Scarlett.L]

I had those tiny gaps too on miter joints. It was not just the cut angle the clamp pressure and how the pieces met mattered. I tried corner clamps and a couple of spring clamps so the seam stayed tight while the glue set. If there was a small mismatch I slipped in a thin shim behind the seam and then trimmed it after it dried.

[WilliamG]

I kept thinking the blade was perfect but the cut could still drift a hair when the saw wheel warmed up or the fence flexed. I started dry fitting first and rechecking the actual angle on the piece after I cut and I noticed the joint opened a bit when I pressed it together with a clamp.

[Jonathan53]

For me the bigger problem was not the angle but the rest of the frame not being square. I built the base and the top would not sit flush even with perfect joints so I would trim a touch here and there with a block plane after glue. It felt like chasing the seam instead of the whole rectangle.

[Anthony.D]

Maybe it is the wood moving as it dries or the glue pulling the corners inward once the clamps are removed. Do you think the real issue is moisture or something else?