How can I fix gaps in miter joints on this bookshelf?

[Jeffrey.L]

I’ve been trying to build a simple wooden bookshelf, but I keep getting gaps in my miter joints no matter how carefully I measure and cut. I’m using a basic miter box and a hand saw, and I just can’t seem to get that perfect, tight fit. Is there something obvious I’m missing in my technique, or is this just a normal part of the learning curve?

[SavannahDM]

Yeah I had the same problem with gaps in my miter joints. I found the real culprit wasn’t just cutting accuracy but wood tension. When I clamped the two pieces together tightly and used a chisel to clean up the joint after a light dry fit, the gaps closed a lot. I also cut slightly oversized and sanded to final fit rather than forcing it. It felt a lot less dramatic once I slowed down.

[LilyW]

I tried the box, but the wood kept springing back a bit after I removed the clamp. I learned to test-fit dry several times and then glue in small sections instead of one long edge. Also checking that the back edge is square to the sides helped hide small gaps.

[Aria.L]

I rushed once and tried to race the cut with the saw and ended up with tearout and a misaligned corner. The shelf warped a bit when I tried to force it. I ended up dropping that approach and sticking to simple square frames and holding stock flat while gluing.

[GregoryJ]

Could the real problem be the setup? I kept doubting myself until I checked the tools—box alignment, blade wear, even the base being flat. If the miter box is off, you’ll chase perfect cuts forever.