When soldering the shader groups on the shader bars, you can use the same needle bar jig, just switch bar heads for shader groups. The rules are the same, with the loop of the bar facing to the right and the bar riding under the needle group. Remember to use the flat needle bars for shaders.
The final touch on the shaders will be the spreading of the needles. This process will also apply to four needle flat shaders. It is a known fact that spread or forked shader needles (whichever you prefer to call them) will put ink in the skin faster and better than a set of needles that are not spread. Also, spreading of the needles takes up the slack in the tube tip and does away with any side motion of the needles which could cause splattering or possibly cutting of the skin. When spreading the needles with a thin bladed knife, be very careful not to snap the outside needle. If you do, you can always trim the needle off, likewise the other side and use it for a four needle shader. Do not overspread the needles or they will bind inside the tube tip and the results will be that there is such a drag of two metals rubbing together, your machine will not function properly. Refer to needle spreading diagrams.
Take your time when practicing. Check all needles with an eve loupe in all phases of needle making. Extreme care should be used when handling needles in needle making or very few indeed will make it to the sterilization. With practice, your needles will be something to be proud of, perfect in uniformity and professional in their usage as a tattoo instrument.