Bandsaw Circle Jigs
Collated from newsgroup postings.
Can anyone recommend a source for instructions on making a circle cutting jig for bowl blanks
how about a nail through a piece of plywood. Impale the bowl blank on the nail and turn it.
I think you will be happier drawing a a circle with a compass and sawing on the line. You can make the rough circle round with the lathe in a couple minutes.
If you need to draw a big circle, put a nail through a stick and drill a hole for a pencil.
I had a circle cutting jig for awhile. It was more trouble than it was worth. I found that it was just as well to draw a circle with a compass and freehand cut on the line. I have a large compass that will draw a 12 to14 inch circle and a set of tramel points that will draw as large as you may ever want. A 3/8" or 1/2" bandsaw will easily follow the line on larger bowl blanks, say 8" and up.
I don't remember where I saw it, but one fellow I met used cardboard disks to cut his blanks from 1/2 log pieces. He used a short nail (or tack) to hold the disk in place on the log section, put the flat side of the piece onto the table, and cut around the cardboard disk. Seemed to work real well. He had an assortment of different sizes to fit his needs.
I have tried jigs which have the timber spin on a pivot point. For thin pieces of timber they work. For thick pieces such as you would use for a bowl, the blade changes its tracking angle as the timber turns. The track angle varies due to changes in grain direction and thickness. The changing angle requires constant adjustment to the angle you have to present the timber to the blade in order to cut along the line you want to follow.
I now use a set of discs on heavy paper. With the proper size disc fixed to the top of the timber, I cut along the edge of the disc. The resulting blank takes less effort and looks better than the blanks I tried to cut using a pivot.
cut a circle of plywood or stout cardboard to the size you need, with a hole for a nail in the centre. Place the circle on the piece of wood for your blank making sure you choose the best area for your purpose. Nail it in place. If the wood is uneven (for a natural top bowl ?) keep the circle of ply wood level as you band saw round it and the blank.
I have a set of circles I cut out of cardboard in varying diameters. I tack them to the bark of the piece with two small nails and cut around them. It works well enough to not bother with anything time consuming. By the way, the second nail prevents the template from turning when it gets nicked with the saw blade. No big deal but less annoying.
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