EPAIII
Diamond
- Joined
- Nov 23, 2003
- Location
- Beaumont, TX, USA
I haven't visited here in a while.
Some time ago, when I was selling metric conversion gears for the SB-9C, I created an Excel workbook to show all the possible threads I could produce with the the gears and compounds that I possessed. I have a number of additional change gears that were not in the original SB set and also three compounds. The spreadsheet also shows all the possible metric threads with that set of gears. The approach I took was to calculate the thread pitch produced by every possible combination of the gears on a two arm banjo. So, hopefully, none were left out. A summary sheet was then created with only the thread pitches, inch and metric, that would seem to be of any practical use. All the really odd ones were not copied to that sheet.
A caveat: this spreadsheet only calculates the threads that are mathematically possible with the gears. It does not check to see if they can be physically arranged in the necessary configuration on the lathe. Some of the combinations of gears may not be possible to assemble without special brackets. Nor does it address additional compound combinations of the basic change gears that can be created with a keyed bushing. That would increase the total number of possible threads by well over a factor of 100X.
Caveat 2: The metric conversion gear that I was selling consisted of individual 100 tooth and 127 tooth gears that could be used separately or assembled into a compound. I did it that way because using the 127 tooth gear as a single, separate gear allowed cutting some metric threads that the use of the 100::127 compound did not.
I was asked for a copy of this Excel workbook on another board and that request lead me to upload the Excel file and an instruction file to my DropBox. If anyone would like them, here is the link:
Some time ago, when I was selling metric conversion gears for the SB-9C, I created an Excel workbook to show all the possible threads I could produce with the the gears and compounds that I possessed. I have a number of additional change gears that were not in the original SB set and also three compounds. The spreadsheet also shows all the possible metric threads with that set of gears. The approach I took was to calculate the thread pitch produced by every possible combination of the gears on a two arm banjo. So, hopefully, none were left out. A summary sheet was then created with only the thread pitches, inch and metric, that would seem to be of any practical use. All the really odd ones were not copied to that sheet.
A caveat: this spreadsheet only calculates the threads that are mathematically possible with the gears. It does not check to see if they can be physically arranged in the necessary configuration on the lathe. Some of the combinations of gears may not be possible to assemble without special brackets. Nor does it address additional compound combinations of the basic change gears that can be created with a keyed bushing. That would increase the total number of possible threads by well over a factor of 100X.
Caveat 2: The metric conversion gear that I was selling consisted of individual 100 tooth and 127 tooth gears that could be used separately or assembled into a compound. I did it that way because using the 127 tooth gear as a single, separate gear allowed cutting some metric threads that the use of the 100::127 compound did not.
I was asked for a copy of this Excel workbook on another board and that request lead me to upload the Excel file and an instruction file to my DropBox. If anyone would like them, here is the link:
