You can buy dowel rod at your average Home Depot inexpensively. Dowels are a great way to easily make strong joints between two pieces of wood. Unfortunately, most big box store dowel rod isn’t actually round. The pictured piece was supposed to be 3/8″ (0.375″), but it’s actually a hundredth of an inch larger than that in places.
This may seem insignificant, but it makes the dowel basically worthless. If the dowel is slightly too small, the gap can be filled with glue. However, if it’s too big like this, it will not fit in a 3/8″ hole. Fortunately, there’s an easy fix for cheap dowel rod like this. It only requires a hand drill, a piece of sandpaper, and some utility gloves for safety.
The procedure is simple. First, chuck the dowel rod in the drill as though it were a bit.
I use gloves when I actually do this, because the dowel rod will get quite hot. I’m using my bare hand in the picture to keep the glove from obscuring things. The idea is to hold the sandpaper in place with your palm, while also keeping the dowel spinning in place. The dowel will want to walk to the right as it spins, but if you let it spin against your hand, it will sand itself down on the sandpaper. Depending on how fast you turn the drill, this can build up heat pretty quickly.
This will pretty quickly crank out sawdust. I move the dowel along the sandpaper to try to evenly sand the whole thing. Then, I chuck the other end of the dowel into the drill to get the other side. It doesn’t take long to take that extra hundredth of material off.
This isn’t going to make perfect dowels like a well-calibrated jig, but it does make the $2 Home Depot stuff usable. I overshot 3/8″ just slightly here, but the extra thousandth of an inch will just make room for glue. It’s still not going to be perfectly round, but this is an easy fix for cheap dowel rod to allow it to be used for dowel joinery, without having to build any complicated jigs.