Sunday, February 12, 2017

Calculating Taper Offset Using Tailstock Method

I am interested in a die holder attachment that fits into the tailstock on the lathe.  I was watching a few different episodes on youtube, and found Halligan142's method to be enlightening.  It looks like a good, solid tool :

Common Taper Sizes for South Bend Lathes
TaperMajor DiaMinor DiaLengthTaper/Foot
#00.35610.25202.00 0.6246
#10.4750 0.3690 2.13 0.5986
#20.7000 0.5720 2.56 0.5994
#30.9380 0.7780 3.19 0.6024
For larger taper sizes, visit
In it, he mentions that you can use the tailstock offset to cut your morse tapers.  This works very well, so I thought I'd post his formula :

Taiolstock_Offset=part_len * Taper_Per_Foot


On my South Bend, I should be able to obtain 0.200" offset on the tail stock.  That is about a 0.5" swing from side to side.  So, to cut a taper for my tailstock (a #2 taper), my taper-per-foot is 0.5994.  If I use a 4.5" piece of steel for this, I will get (4.5 * 0.5994) / 24, which comes out to 0.11238750 ".   That means, I can use a 3/4" piece of round bar about 5" long to cut a taper with about 1.5" extra inches to put a flange on.  I only have to offset the tail stock about an eighth of an inch to do it, and I'd have the spindle for the die holder to run on.