Originally Posted by rscott5028
Mark - Congrats! Glad you solved the mystery. It's soooo much better to load it straight than to straighten it after bending.
Gary - I just learned something new. I didn't realize you could have a negative TIR.
here's the deal on all this TIR crap shoot. I do not like to adjust an indicator once it's set, but some guys do. On my Interrapids I can move the dial without disturbing the location much. I rarely use one of the long travel dial indicators due to their excessive built in lag (most have 10% backlash). So I use wand type indicators 95% of the time. I don't like using one tenth indicators much even though I own many of them. Use a .0005" one or a .00025" one most of the time.
Back to the slop in the ram quotation I made (we call that lag by the way). Every ram will have clearence built into it, or you couldn't move it. The rule of the thumb is that if by chance you had .001" clearence in the ram (and guide rods if it comes with them); you'd be hard pressed to load anything less than .002" TIR. In machinery (and a press is a machine) you soon learn this. This is why I brought up the question of built in lag with the press. (looks like he's got about .002" maybe) Now we take all the pieces we are using to size and reload a certain round. I'd bet the farm that there is no perfectly machined piece in that pile of stuff; no matter who made it. You add the die an pick up another five tenths, and a tenth from the shell holder alone. Error in a die is not usually as critcal as the shell holder due to the way the triangle figures out. The longer the case the higher the multiplier is at the base. I personally don't trust any of them.
Measuring case runout is also a crap shoot when you set down and look at it. I use three different gauges. A NECO, and two home brew affairs. Each one works much differently than the others, and each one will show you errors that the others won't. The NECO uses a vee block affair, and I'm not in love with area contact for precision measurments. But it's still a very good unit. One of my others works off of pins, and it's pretty good at picking up the slightest banana. The other uses a series of balls that have minimum area contact. The only moving part is the indicator wand. (in OTW zero lag built into it) Still it will not do everything I want. I'm also a big proponet of the use of multiple indicators on a gauge. Makes it easier to spot runout as it builds up, plus easier to find the high spots and low spot. Still after awhile you end up whipping a dead horse due to other problems.
As for the O.P., I'm glad he got his back down to earth. He now needs to start tweeking a tenth or two out of his setup here and there. A burr here and a hicky there will make up another thousandth.