A Segmenting Dilemma (for this novice segmenter)

[Glen Blanchard]

I am working on my first segmented piece - more of a partially closed form than a hollow form. In the past I have thought of the advantages that building a segmented piece (bowl or hollow form) up ring by ring would present over beginning with a blank as I have in the past. The benefits and ease of shaping and sanding the interior every few rings sounded nice. However, now that I am there (I have my first 5 of 7 rings glued together and on the lathe) I am kind of stumped and I have to assume that I am not the first one to try to figure this out. Here's my dilemma.....

In order to sand the interior of my first five rings, obviously I have to have the finished interior shape. But I don't have the final exterior form yet and I don't see how I can get it until all the rings are in place, and can view the piece as a whole. I don't want the inside to limit what I can do on the outside and I want to achieve a uniform wall thickness. I am concerned that attempting to totally finish the inside might make those goals difficult to achieve. At the same time, I'd like to be able to take advantage of the ease that not having all the rings in place offers. So I am rather stumped. How do others handle this?

[Justin Stephen]

You can turn the inside and turn most of the outside, leaving most of the outermost ring intact so as to give yourself the maximum gluing surface. You can easily visualize the line even through the last unturned ring that way and just work your way up in stages.

[Michelle Rich]

it is tricky the first time out..you must have "vision" and what the piece will look like at completion..you must also have given yourself enough fudge factor in your ring thicknesses to give yourself room to err. Did you draw this out on paper /computer? that also helps with the "vision" part. I think, for a first, you are learning, learning & learning more & more at each ring..a couple more under your belt and it will be MUCH easier. When I started segmenting (the middle ages) I think for my first few, I just got the inside round..then got the outside shaped ..kinda backwards, but I learned a ton..

[Glen Blanchard]

Thanks Michelle. I used software to map it out. If memory serves, the software defaults to a 1/2" overlap between rings but as this is my first attempt, I increased it to 3/4" to give me greater room for error.

[Sig Mekosky]

I make my taller pieces in two pieces. The bottom half glued to a glue block mounted to a faceplate. The top half glued to a glue block also mounted to a faceplate. I true up the two mating surfaces next. I mount the bottom to the headstock and the top mounted to the tail stock on a live center. Then I join the two halves together by pushing the tail stock towards the headstock until the two halves meet, friction fit only. I then fully shape the exterior of the form. Now I separate the two halves finish the interior of the bottom. Then mount the top half on the headstock and finish the inside of the top half. Sand and finish the interior as needed. Next glue the two halves together. Remove the glue block from the top half. Sand and finish as needed. Then remove the glue block from the bottom. Reverse mount the form to finish the bottom. Done. Good luck.

[Jim Daughtridge]

Thanks Michelle. I used software to map it out. If memory serves, the software defaults to a 1/2" overlap between rings but as this is my first attempt, I increased it to 3/4" to give me greater room for error.

Glen..What software program are you using and where did you get it?
Thank you,
Jim

[Justin Stephen]

Glen..What software program are you using and where did you get it?
Thank you,
Jim

Here is one option at least:

http://www.segmentedturning.com/software.htm

[Glen Blanchard]

Jim - I am using 'Segmented Project Planner' (SPP). Google it and you'll find it easily. You can download a 30 trial copy.

[Tim Boger]

I simply don't sweat the uniform wall thickness issue, I shoot for 3/8 and if I'm within a 1/4" at any 2 points then I consider that a success. To me, it's not rocket science.
Tim