[cabinetman]

Tenons and created dowels that are of a close fit make for good mating when glued. If you notice that the prefabricated dowels that are sold have a very slight chamfer on the ends, and could have flutes, or spiral grooves.

If you cut a dowel from dowel rod, and leave the ends just cut with a sharp edge, and drill a matching hole, when inserted, will scrape the sidewalls of glue and push it to the bottom of the hole. In addition to that, if the fit is that tight, that action can be compressive, in that it not only pushes the glue (which is like a hydraulic compression), it compresses the air. In this instance, you may experience the dowel not wanting to move into the hole, and if it does, will be forced upward out of the hole. This can make clamping ineffective to impossible.

The slight chamfer on the ends provides for a 'feeder' lead, allowing a smooth insertion, and minimizing getting caught on any grain, and reduces the 'scraping' of the walls. The flutes and spirals allow for glue and air to escape allowing the dowel to go into the hole without having a glue amount to collect towards the end of the dowel.

When applying glue the first third to half of the hole will be scraped, pushing the glue to the balance of the hole and what is excess will collect at the bottom. So, not much glue is needed on the bottom third of the hole, except for a light coating. Having the depth of the hole slightly deeper than the reach of the dowel will allow for what gets collected at the bottom.

Likewise for tenons, I got into the habit of a very slight chamfer on the lead edge, and some 'escape' grooves on the face of the tenons for glue and air. Looking at this tenon from another thread, you can see how sharp the leading edge is. If the mortise for that tenon is a very close fit, the tenon can have the ability to be restrictive and react as a smooth dowel would do with respect to compressing glue and air when mating up.

.

 

[cabinetman]

Good walk through Cabinetman, when cutting dowels from a rod depending on the diameter of the rod a pencil sharpener will put a small chamfer on the end of the dowel.

I've done that with dowels that were about ¼" in diameter. But, generally speaking it only takes a few seconds to hand turn a dowel end on some sandpaper.

Also the toothed hole on a set of pliers will crimp the flutes in the side of the dowel and allow the air and glue a way out.

I've done that too, using the jaws on a large slip joint pliers, and pounding the dowel in it's length from one end to the other. I use a machinists vise, and set the pliers with the jaws flat on top of the vise, and pound the dowel down through the open jaws. I leave the dowel long and cut off any peening of the ends, and then apply a slight chamfer.

.