# How much does an embouchure's shape affects the ability to produce a note on a flute?

I've already asked a bunch of (more theoretical) questions about the subject, but I'm trying to build a flute — a chromatic flute to be more precise. I don't play the flute or any other woodwind currently.

The aim eventually is to build it from bamboo. Because I'll need to buy more "exotic" bamboo for the final product, I wanted to test the viability of an online tone hole calculator on a plastic tube first. I found only one calculator which allows you to plan holes for an entirely chromatic flute, but it doesn't let you insert (or tell you even) the length of the flute, but rather just the base note ("bell"). So I figured I'll just start with no hole other than the embouchure, see what note it produces, adjust length to an accurate note, and then calculate from that note.

The plastic is way too rigid and thus drilling the embouchure was very difficult. The drill I used is only 5mm, and while at first I thought I'd use sandpaper to increase the diameter to ~10mm, the sandpaper barely takes away material. So I tried to work it around with the drill head, but obviously the final shape became pretty rough.

Anyway, I could barely produce any notes from it. I looked at tutorials about correct air blowing into the embouchure, and the sounds I managed to produce from it were 90% note-less air, 9% screeching overtones (they seemed too high to be the fundamental for this flute's length), and 1% which might have managed to ring out the fundamental.

Is it likely this is mostly because the embouchure didn't follow a correct shape? I tried to find out what the shape should be like, and it seems it might need to have sharp, knife-like edges (the inside edges of the embouchure sanded thinly) so it slices the air in two. Is this correct? Perhaps it doesn't matter THAT much and something else with this beginning-of-a-flute doesn't work?

Depending on the diameter of the tube the optimum embouchure diameter should be about 10-15 mm. The hole can either be circular or slightly oval (with the long axis along the tube) or more of a 'rectagular' oval. The exact shape is not critical as long as it's symmetrical, but the edges need to be really clean and sharp and the sides should be parallel (or nearly so: some flute-makers undercut the hole a bit).
The size of the hole affects the tuning: a smaller hole will make the instrument flatter.