Hi guys
I have a problem, I need to make a 1.5 inch long "slot" down the center of a piece of round bar. But it is alway a little off centre, I will describe my process, please advise where im going wrong, im still a newbie so be gentle
i machine the round bar in my lathe to the desired diamter. I then move to my cnc Taig mill.
I have a milling vice with a V running down it's length that I use to hold round objects. Im not too sure how well the mill aligned, basially I have the bolts going into the T-slots, and then pull in it and tighten, I guess if the slots that the bolts go into are no precise, then neither is my alignment, but the problem is not withthe slot running down it's length, so can't be that bad, the problem is with it not being dead center horizontally, as in the cutter is not touching the highest part when it starts, it's not out by much, but enough to mess things up at 30,000 rpm (im making a spring loaded engraving tool).
Now then, one it's in the vice horizontally, I put the jog rate right down, put a 0.125 dia round bit (perfectly round, no teeth) in the collet, and slowly move it upto the side of the bar until i cannot see any light between where they touch, I zero the axis, move up the Z and move towards the center by half the diamter of the bit, I then move further to the center half the diamter of the workpiece. Now in theory i should be dead center, but im not, any ideas?
Im using a verner calliper to measure diamters which does not feel that accurate.
Also, un-related question, how the hell do I re-align a peice of round stock in my lathe chuck after taking it out and putting it back in, do i need to use a dial test indicator and turn it by hand until it moves, then tap with a small hammer/mallet?
Any advice appreciated.
DJH