OK, so you have a Logan Lathe with that wonderful 8-pitch Lead Screw, and your buddy (or boss, or customer) wants you to make him a metric thread. How to do it? More importantly, CAN you do it?
The answer is Yes, but you need to make some modifications. First of all, you will need a set of Metric Transposing Gears. Most all manufacturers, including Logan Engineering, use a 127 tooth gear somewhere in the gear train to accommodate the difference between inch pitch and metric. This even applies to Lathes with metric lead screws. The original Logan set-up used a 100 and 127 tooth gear combination. The difficulty with this is that they won't fit inside the change gear guard cover. They are also expensive!
For this reason we can now supply a 37 and 47 tooth gear set which will be accurate to within 2/100 of 1%. For those who need greater accuracy, we can still provide the 100 and 127 tooth as well.
Now you need to set up your lathe for the particular pitch. Here you will find a "PDF" file containing diagrams and instructions. Download metric_threading.pdf and decompress on your system. Hopefully everything will be self explanatory, but if not, contact us as noted in the file.
Sample Metric Threading Charts
If you have suggestions for tips, let us know!