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 :

https://www.youtube.com/watch?v=GMuZujQ5_8s

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 littlemachineshop.com.
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

24


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.