|Forum topic by daviddoria||posted 05-23-2014 11:59 AM||4059 views||1 time favorited||17 replies|
05-23-2014 11:59 AM
I am trying to make a “bowl from a board”, where concentric rings are cut from a board with an angled blade, then “reverse-stacked” to make the rough shape of a bowl, then finally turned on a lathe. One technique involves cutting the board in half, cutting out “half-rings”, gluing back the cut half-rings back into full rings, then stacking the rings into the bowl blank by gluing up the stacked rings.
Here are some pre-pictures of this half ring setup:
I have seen (and built) a band saw circle cutting jig that require the workpiece to have a dowel/pin of some sort attached to/inserted in the center so that the workpiece can pivot around its center while the blade automatically makes a nice circular cut. However, in the case of half-rings, half of the “center” of the workpiece seems to be missing, so there is no way to insert/attach a pin. I saw one method that glued an auxillary piece (the pine in the pictures) of the same thickness onto the edge of the workpiece so that the center “reappeared”. Then the circle cutting operation is performed, and the auxillary piece removed (how? as now since you have a semicircle you will not have a parallel edge to run against a table saw fence, or a perpendular edge to hold against a miter gauge to sand off the piece, etc.)
Postponing that problem until later, I went ahead and epoxied a 1/2” dowel onto the “center” of my workpiece+glued auxillary piece. I cut a ring, and it worked perfectly! Then I cut a second ring, and the dowel broke off (and since I was holding it against the table, I didn’t realize what had happened until I ruined the workpiece, grrr).
Finally, to my question :) .... is there a trick that I am missing to this method? To anyone who uses it – how do you attach the dowel/pin to the half-workpieces? I had not recessed the dowel, as I didn’t want to damage the workpiece by drilling holes in it, but maybe this is required and then you have to remove enough material to remove the hole later in the process?
Thanks for any tips!