开云体育

Hi Thomas,

If you want to replace a metric lead screw by an imperial one, the pinion sets, as per the threading table of your lathe, will need to be modified. This is mandatory because there are no common divider in between millimeters and inches. So,

- either you recompute each pinion set for each pitch with the existing pinions, making the compromise to have some close approximations,
- or you'll have to buy pinions compatible with the imperial pitches you intend to make. In your case, the existing pinions are more likely metric in diameter and module. Imperial pinions are imperial?(!), their teeth are measured in inches, and the metric 'module' is expressed in terms of 'diametral pitch' that is a different unit. The module is equal to the primitive diameter in mm divided by the number of teeth hence a module of 1 corresponds to a tooth-to-tooth distance of 3.14mm measured on the primitive diameter. The diametral pitch is equal to the number of teeth divided by the primitive diameter in inches. Both Module and Diametral Pitch have no unit.

Equivalence table (the circular pitch corresponds to the distance between 2 teeth, measured on the primitive diameter, here in mm. No practical use, just an indication) :

Of course, metric gears are not compatible with imperial pinions, even with the same tooth number or same diameter.

In addition, make sure? before ordering that you have room to mount the pinions on the existing bracket.

Just a remark: It seems that you didn't make threading for 5 years, otherwise you had already discovered the issue, do you absolutely need to make the transition to imperial ? The character of this transition does only apply to threading, unless you have specific accessories TBD on your lathe. In consequence, if you don't thread on the lathe and if the lead screw and/or half nuts aren't damaged, keep the current configuration !

Regards