Install a large shaft adapter
Small adapter fits Ge0600 & GDO600
Large adapter fits GD 0800C
Start with a stock die grinder GD 0800C, Shaft adapter & wrenches 
Remove Stock Nut & Collet 
Insert Threaded shaft 
TIghten the nut, but do not over tighten or you risk cracking the shaft 
What a cracked shaft looks like. This was tightened too much. 
Finished assembly
We carry shaft adapters in 2 sizes-
Small adapter fits Ge0600 & GDO600
Large adapter fits GD 0800C