stannp368
Hot Rolled
- Joined
- Jan 24, 2003
- Location
- Philadelphia, PA USA
A shortcut to chasing the tough ones not on the QC gearbox especially the 9" SB lathe. EX-required to chase 38 TPI. Try the formula--
req pitch for 38 tpi/trial pitch for 36 tpi=.0263/.0278=.946
multiply this by N teeth on stud/N teeth on screw which is 20/56
.946x20/56=.3379 which is close to 20/60 (our new ratio)
NOW-set the QC gearbox to 36 tpi & place a 60 tooth gear as the screw gear
this will give you 38 tpi with just a few thou error per inch
This has worked in the past & is very useful when chasing thds which are not shown on the QC gearbox
req pitch for 38 tpi/trial pitch for 36 tpi=.0263/.0278=.946
multiply this by N teeth on stud/N teeth on screw which is 20/56
.946x20/56=.3379 which is close to 20/60 (our new ratio)
NOW-set the QC gearbox to 36 tpi & place a 60 tooth gear as the screw gear
this will give you 38 tpi with just a few thou error per inch
This has worked in the past & is very useful when chasing thds which are not shown on the QC gearbox