I need to drill a hole in a bowl I’m turning (making a yarn bowl). I’m looking to see if anyone has any “tricks” for doing this. I was planning on turning the bowl and then making a curved backer block on the bandsaw to prevent tearout on the inside of the bowl. I don’t want to drill the hole before turning the bowl because I’m concerned about a catch when the bowl gouge goes over the hole.
Any advice is appreciated.
Replies
location and bit choice
As Swenson suggests, the location of the hole can be a critical element in your decision of how to approach the drilling operation. So is bit choice. If the bowl can be solidly supported and clamped on a drill press, a Forstner bit might also be a good option, combined with the drilling from both sides approach. Making a very small pilot hole (1/16" or so) through the bowl can also give either a brad point or Forstner center spur a guide.
Catches
I don't want to give you advice and have you tear out a bowl, but I don't think a small pre drilled hole will cause a tool catch.
Pre-drilled hole and catches
The final hole will be about 3/8", and I'm already terrible at turning the insides of bowls without catching which is why I'm concerned.
A couple of thoughts
1. After drilling the hole you could then press a plug into the hole (no glue just a snug fit ). Turn the bowl then carefully press the plug out.
2. If you happen to have access to a metal lathe, I do, then you can turn that part of the bowl on the metal lathe which has a stout , extremely stable and controllable, cross slide to hold the cutter that will not allow a catch to happen. This is called an interrupted cut and is a routine operation on a metal lathe.
PS: I have done wood turning only on my metal lathe but from some of the frail, full of holes bowls I have seen that wood turners have cut it should be doable on your wood lathe once you learn how.
In this video advance it some to skip the introduction if it doesn't interest you.
http://www.youtube.com/watch?v=nkZQ-_0my6M
Once you've shaped the outside, drill the hole and fill with wax. Keep your tool rest close to the bowl and ride the bevel. Work inward from the outside, get the edge the right thickness and then leave it alone as you go deeper. In larger bowls, the outer edge will flex if you turn thin.
Two ideas come to mind. 1. Use a brad point bit to drill and when the tip just starts to penetrate the inside of the bowl stop and then drill from the inside. This of course assumes that the axis of the hole doesn't interfere with the rim on the opposite side of the bowl. 2. Put some blue tape on the inside of the bowl where the hole will be and if it makes you feel even better squirt some hot glue on the tape to create your solid backing. Drill away.
Not sure what kind of wood you are using, but I would imagine that any minor chip out wouldn't be an issue because I would imagine that you're going to want to sand a nice smooth radius on all the edges of the hole and slot since you don't want the yarn getting hung up on it.
Good luck,
Doug
My instinct is that you aren't going to want perfectly square edges on the sides of your hole, anyway, so a little bit of tear out is ok. Sanding and sculpting the edges of the hole to create softer corners might look and feel better on an already soft, round bowl shape.
Plus, if you drill directly into the side grain (as opposed to the end grain part of the bowl) from the outside, the curved shape of the bowl means there will be fibers behind the ones you're cutting through to either side of the hole, theoretically protecting you from really big blow out. The effect is better on smaller diameter bowls. Having a sharp bit helps, too, of course.
The other option is drilling directly into the endgrain, which should have virtually no tearout, but which would make the thin, swirly part of the cutout (if you're doing that) really weak.
Regardless, doing a test bowl first wouldn't hurt!
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