How difficult is it to manufacture a movement bridge accurately?

Depends what you mean by 'accurately.' Holding a tolerance of a few microns on hole centers is a different game than making a bridge that just looks skeletonized. The visual skeletob part is easier than people think; the functional geometry is where it gets ugly.

Small independents do it, but usually with a lot of outsourcing or very old manual machines. CNC helps, but the setup and fixturing for a one-off bridge can eat You alive.

I tried to make one in my garage once. Let's just say the bridge now holds up a shelf. Accuracy is hard.

The hardest part for me is always the jewel holes and the pivots liniNg up. You can mill a beautiful bridge shape and then ruin it by being 0.02mm off on a hole.

It's not just the machining. Heat treatment and stress relief matter too. A bridge that warps after finishing is a nightmare.

I've seen some microbrand skeletons where the bridges look like they were cut with a Dremel. Then again, I've seen cheap Chinese ones that are surprisingly clean., So maybe the bar isn't as high as we think for just looking okay.

Clean-looking and accurate are not the same. A bridge can look fine and still have sloppy tolerances that cause poor amplitude or premature wear.

This thread makes me appreciate my watchmaker. He makes it look easy, but I know it's not.

OP, if you're thinking thinking of trying it, start with a brass or aluminum practice piece. Don't touch a real movement until you can hit hole positions consistently. And get a good rotary table or a jig borer if you can.

Jig borer is the old-school way for a reason. CNC is great but the learning curve for CAM and workholding is steep for one-offs

Also, don't underestimate the finishing. Anglage, polishing, and graining are where a lot of the perceived quality comes from. A functionally accurate bridge can still look cheap if the finishing is bad.

I think that's why some skeleton watches cost so much. The bridge is basically a piece of jewelry that also has to be a precision part part. Two skill sets in one.

So the consensus is: hard, but not impossible. Got it. I'll stik to buying them for now.

One more thing: if you're doing skeletonization, you have to think about rigidity. Removing material can make the bridge flex, which throws off the gear mesh. So it's not just about hitting the holes; it's about keeping the structure stiff enough.