Does anyone know what size screw fits the stock door handle?
Welcome the forum. I took one out of my P1 and near as I can tell it is a 2mm screw but the pitch was weird. It was non standard and would not fit a M2x0.4. Manual measurement using a caliper got a measurement of 0.61 and I had to eyeball that using a Loupe. So I’m guessing its more likely 0.6mm pitch.
Sorry for the crappy photo. Click to zoom.
I compared it against the Screw Kit that I purchased off the Bambu Store and it’s definitely not one of the screws in that kit. Screws Kit - X1 Series/P1 Series and AMS | Bambu Lab USA Store
However, I will say this: if you lost the original screw, don’t agonize over it. I dropped my glass lid about a year ago, and fortunately the only damage was the handle, which snapped the screw cleanly. Because they are plastic, a self-tapping screw did the trick. Later, I ended up printing a replacement knob that I thought looked better and was more functional. There are plenty of P1 knobs on on Printables for the P1 and X1. Once again, a self-tapping screw did the trick. I tend to keep a lot of the Amazon screw kits on hand for exactly this kind of use—when making 3D printed items that I want to fasten but don’t necessarily need to use heated brass inserts.
Here’s a link for the right search term. They come in all sizes and threads. Amazon.com : self tapping m2 screws
If your preference is to keep the same hex “Socket Cap” head for appearances sake, then take a look at this one.
