Bowl and platter turning is so much faster and easier when starting from a round blank. Now, all those of you who buy their blanks in the round, you can safely skip this page. I, however, get most of my wood as slabs or rounds off trees, and then cut them myself with a chainsaw into blanks, which usually are square or odd shapes.
There are folks out there who have made themselves elaborate jigs for their bandsaws. No doubt these work fine, but this doesn’t work for me. For starters, my bandsaw is too small and doesn’t have such a heavy duty table (I have one of these fold down bandsaws that are actually made for metal cutting, but it cuts wood just fine). The next thing is that these jigs all require a centre hole, which these folks then use for their screw chuck. I don’t have a screw chuck either (although I may well buy or make one at some point), I either work with a faceplate or a drive centre.
So here’s a simple solution to the problem:
This is a piece of pine roughly 25mm x 8mm, but any wood will do. It’s about 300mm long, the length essentially determines the bigtgest circle you can scribe. At one end drill a hole through the small face, just slightly smaller than a 2″ nail that is then pushed into it (should not need any glue, but you don’t want the wood to split, either, hence the hole)
Now use a clamp to hold your pen of choice at the radius you want, and hey presto, there’s your circle scriber. Infinitely adjustable. Dead simple to use, and works perfectly.
To scribe a circle, simply push the nail slightly into the centre, so that it can rotate there (this means: do NOT hammer it in, just make a mark). And now pull round. With a bit of guidance this will go over uneven surfaces (e.g. bark or chain saw marks).
Finding the centre of a blank is also easy. Set the pen at a distance slightly larger than your desired circle. Now place the nail at the centre of each side of the blank, right at the edge, and draw a small segment in the middle. This will create a figure of 4 curved lines with a small area enclosed in it. The centre of that area is your blank centre.