Chiff and Fipple Forums

Lately I have been making flutes out of furniture grade PVC. In the recent past I always turned my nose up at PVC flutes. However in terms of trying to find materials such as good elder, reeds, and bamboos, PVC has been really great to work with. The biggest challenge is drilling sound holes. Currently, I am using twist bits, and I have to start with the smallest bit and work my way up to the desired size hole, but it often leaves an ugly hole that I usually have to file into a better shape. I am wondering if it would be better to use brad pointed bits or forstner bits. Will they make a clean hole? Thank you.

I would put a wooden dowel (same diameter as the inside diameter of the PVC pipe) into the pipe for support and to help give a cleaner cut. Then I would drill a pilot hole (1/8"?) and use the right sized Forstner bit needed for that hole. A pilot hole will keep the Forstner bit from wandering on the curved surface.

A guy I used to work with often had to drill PVC pipes to make frames for theatrical props, and also make entire props out of PVC that were later painted up to resemble something else.

He always used cone bits, and if it needed to be a neat hole, he'd use a cone bit with the maximum diameter the same size as the desired hole. He even had a number of bits he'd adapted for the purpose, grinding down the surplus flare on an oversized cone if he couldn't find one the right size.

Might not be useful, since it's only worth investing time and effort in something you have to do often, but he produced very neat work.

I use these burrs for drilling holes on both wooden and epoxy flutes (which are probably similar to PVC in the way they drill) with a Dremel: https://www.amazon.co.uk/Hakkin-Woodwor ... B09Q8LKZ1C - I use a sharp pointed one for making the initial hole after making a small dent for it in the right location using the tip of a sharp knife which I rotate a few times. The burr jumps inwards suddenly once it's gone through the wall, so you need to put something into the tube to stop it marking the opposite side of the bore. I then switch to a cylindrical burr to widen the hole and work in circles while also tuning the hole. My holes rarely end up completely circular, but their edges are neat. If you want perfect circles you could rig up a system to put the shaft of the burr through a template to confine its range of movement with the flute and template clamped firmly in place. I stopped using normal drill bits because they made a mess of things too many times, and I personally don't mind not having perfect circles as I like the hand-crafted look.

The burrs are still overly aggressive, so it would be good to have something a bit less so. If I had more money to fling at tools, I'd try these https://www.amazon.co.uk/Grinding-Diamo ... B09MDBYWB5 - they're likely still more aggressive that would be ideal, but without being more so when rotating one way than the other. If the Dremel could run backwards the set of burrs that I have would be perfect.