Look in alt.binaries.pictures. woodworking for "Arc calculator - Arc height calculation.sxc".
It's a spreadsheet I did for the freeware Open Office suite's Calc spreadsheet program. You can download that Sun Corporation freebie ( a direct alternative to Microsoft Office, it also reads their files, with some exceptions due to different formatting and so on) here if you like:
formatting link
'll do one in Excel if someone requests it. Spreadsheets are not usually compatible, so it will have to be redone. This is a fairly simple one, and I hope it will be of use. just ignore the math in the formulas if you want, but it's not protected if you feel the urge ot look into it.I divided the half chord into ten parts, but can also redo that if more are needed. This does the calculation knowing the chord half-length, and the height from chord to arc at its center. Calculations are for other heights along the chord to get points on the arc. Just the half is needed for a template, or to transfer directly.
Enjoy!
Bill.