On 25 Oct, 18:16, Rod wrote:

Want to attach a piece of M10 threaded rod between two pieces of timber.
One end I shall simply drill a hole right through and put washer/nut on
the end. But the other end needs to be secure without making a hole
right through (for aesthetic reasons).

Hard to say definitely, without knowing more about it.

Can you make a hole, so long as nothing protrudes afterwards?

Can you make a hole and plug it?

Where are the forces acting? Tension in the rod? Shear? As you're
using M10, presumably there's a significant force involved and any
"attachment plate" would itself have to be well attached.

I suspect I'd be looking at a mortice into the end of the timber and
the rod screwing through a nut & washer dropped down this mortice.
However that also reduces the thickness of the timber that's taking
the load by a significant amount. There's also the risk of rain
collecting in there and rot.

I guess I'd probably end up drilling a counterbore and having a hole
visible, but without the protrusion. A totally hidden fixing would be
either too awkward, or too inefficient in terms of timber thickness /
load.