I have attached a picture of the thread chart on my Seneca Fall lathe (circa 1903). Also attached is a computer created file in PDF format of the data so it is more readable.
I have all (11) gears that are needed, but I am struggling to understand the chart. I have been successful setting up the gears to cut a 12 TPI thread. This works great. I thought excellent I'm on the way!!
12 TPI is setup using a 48 tooth gear on the stud and 32 tooth gear on the screw. The compound on the banjo gets both a 60 and a 40 tooth gear.
I tried setting up for 13 TPI with a 48 on the stud and a 52 on the screw as the chart show. Gears don't even get close to meshing. I tried adding the 60/40 on the banjo. Does not work either.
I can't figure out why the chart has so many spaces for the compound that are blank.
I will be eternally grateful if someone can straighten me out.
Thanks
I have all (11) gears that are needed, but I am struggling to understand the chart. I have been successful setting up the gears to cut a 12 TPI thread. This works great. I thought excellent I'm on the way!!
12 TPI is setup using a 48 tooth gear on the stud and 32 tooth gear on the screw. The compound on the banjo gets both a 60 and a 40 tooth gear.
I tried setting up for 13 TPI with a 48 on the stud and a 52 on the screw as the chart show. Gears don't even get close to meshing. I tried adding the 60/40 on the banjo. Does not work either.
I can't figure out why the chart has so many spaces for the compound that are blank.
I will be eternally grateful if someone can straighten me out.
Thanks