How to enlarge grommets

Question

I've installed a telescoping curtain rod that's 1-1/2" in diameter, and bought curtains with grommets that turned out to be only 1.6" in diameter (outer diameter 2.7").

Unsurprisingly, the grommets don't slide easily at all, especially over the two joint between the telescoping portions of the rod. A curtain wand wouldn't help because if I climb on a ladder and pull exactly where the wand would, the grommets still turn at an angle against the rod and block.

Is there some hack I haven't thought of, or another solution other than getting new curtains (expensive and hard to find - I need 100" W x 95"L blackout panels) or returning and replacing the rod (the brackets were a pain to mount)?

The must be a machine that could file the grommets from the inside, but I don't know the name for it. Essentially, a cone-shaped grinding stone/bit that spins around its axis, so I could lower the grommets and shave off a few millimeters from the inner diameter to reach the recommended 1/4" difference between grommet inner diameter and rod outer diameter.

Answer 1

Grommets are typically thin wall tubing with the ends peened over to form the flange you see in the photo. Any tool used to grind away at the inside diameter will remove most or all of the thin wall tubing composing the grommet.

The primary option you have is to remove the existing grommets and purchase a grommet installation kit for the size you need. It's an anvil smaller than a hockey puck and a driving tool. The grommet half is placed through the hole, then set on the anvil with the other grommet half on top of the fabric. The driving tool has a recess and a point to match the inside and outside curves of the grommet. A solid strike with the hammer provides the bending and bonding force.

There are other types of grommet installation tools resembling mechanical presses with much higher prices. For the occasional or hobbyist use, the hammer method is more cost effective, with the slight penalty of inconsistent results.

Answer 2

You can get conical grinders that fit into an electric drill:

Amazon.com search for "cone grinder"

You might be able to get one the correct size.

Assuming you can then clamping the curtain and carefully applying the cone to the inside of the grommets might work. I'd try it on a spare one first though. Though these things are usually made from very thin metal so it's highly likely that any grinding will remove the grommet completely. That coupled with the difficulty in clamping the grommet so it can be ground would make this the option of last resort.

A better (and indeed simpler) solution is to what fred-dot-u suggests in their answer and replace the grommets with ones the correct size.