This jig is ideal for finding the inside bottom of a bowl relative to the outside. It aids in getting the correct wall thickness near the bottom. This is easy to build, cheap, easy to use, and very effective.
I start out making the base and vertical member. The base was made from a piece of 8"x8" plywood. The vertical member is made from a 20" long 2"x2" piece of maple. The height of the jig depends on the swing of your lathe. My lathe has a 20" swing. If you have a smaller lathe, a smaller jig can be made.
The two holes seen in the picture below are needed for dowels. The hole in the middle of the vertical piece is centered to your spindle. I use a 1/4" wooden dowel in this hole. The hole near the top will be the support arm for the pen laser. For added strength, I used a 3/8" steel dowel for the added weight of the laser and laser support.
I added set screws to the vertical members to secure the dowels in place. Thumb screws would work just as well. This allows for adjustment of the dowels when aligning the laser.
After hollowing out the interior of your bowl to an approximate depth, place the base of the jig onto the ways of your lathe. Adjust the laser so that the red light shines on the tip of the bottom dowel.
Slide the entire jig towards the bowl until the bottom dowel is touching the interior bottom of your bowl. Find where the laser light meets the exterior of your bowl. This is the interior bottom of your bowel.
Other uses of these handy lasers:
The same principles described above can be added to other woodturning tools in your shop. I have made simular adjustable laser arms for:
Bowl coring tools
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