The shock from schaeffer's hammer always has the same damage range, it is independent of dps, the only stats that affect it, in my experience are critical hit chance (which make the shock crit more) and critical hit damage (which make those crits do more damage).
Critical hit chance and damage are not important for thorns damage itself, they don't trigger it.
The Jim Brown (a form of bulldozer, what my barb has right now I think) is nearly attack speed independent this type of build allows you to use your ias slot on equipment for thorns and allows for the high crit chance/crit damage.
Here are some approximate maximums per gear slot:
shoulder: ~3500 (deathwatch mantle)
this maxes you out at about 24000 thorns damage
I would recommend using an SOJ so you'll want to reduce it to ~22500 thorns...
This is then obviously multiplied by tough as nails if you choose to go that way
This can be a substantial boost to TDPS as attacks received per second*thorns damage is your boost.
As mentioned before, minimize your dex, you should have 0 dex from gear if possible.
Andariel's Visage: 5%(lowest you can find) fire damage taken, 40% (highest you can find) chance to nova, str, max thorns
Death Watch Mantle: 35% chance to explode, Str, Thorns as secondary rolls. The knives from death watch mantle have 100% proc chance, or close to it, it is very powerful.
Cindercoat: Str, 3 sockets, 5000 thorns max thorns damage, plus just generally really strong stats make for a gret armor
Schaeffer's Hammer: High damage 25% lightning Skills, 50% chance to be protected, 200% crit damage
Revenge is an important skill here as you will be getting hit often.
You can get a lot of items with thorns damage at a discount because most people (in general rightly so) think that thorns suck
a quick for instance, you can get a pair of IK gloves with 170+ str, 10 crit chance 48 crit damage and ~600 thorns for like 20 milion