Warning , this is most controversial , The 2 steamer magazines had all the Luddite machinists goin ballistic . I knew they were wrong when they said "
The book says to true a lathe head ....
Printer platten bar about 5/8" Dia , DTI on top ,near then about 8 inches away from head . Bar bend will effect accuracy .
If head is pointing up , the DTI will range different , near the head vs 8 inches away from head .
Say you rotate chuck and DTI swings
center DTI face , split the difference till the swing in one rotation is equal + and - . +6 mils then -6 mils . This is the chuck of spindle or whatever , forget it , not important now ...
Then read at 8 " .
- 8 and -4 . The head is pointing up 2 mils . If it read +6 and -6 it woul be perfect .
Now without the numbers .... It dont matter if the spindle is off , only that it and the chuck be tite , no play , no slop .
A very round rod in a lathe spindle thats not gyrating too much can transfer a perfect reading of the head alignment , out to a Dial-Test-Indicator , Rod bend will void the accuracy .....
I have done a lathe spindle reading in less than 30 seconds .
Cutting a test piece to read a lathes taper is Luddite , expensive unproductive , embarrassing .... did i miss anyone ....
I love precision measure .... Im figuring cheap ways to clock stuff on a granite surface plate .
Maybe i can use a Digi-mike w/ .00005 readout to fast do transfers to my glued together 1-2-3 blocks ....
I hate using Gage blocks , for the scratching that
magically appears on their perfectly polished faces .... I wring one end , then as you slide it around , all the air gets out . If ya wring starting centered , ya leave a bit of air in the center.
Cut off the dead end of an expensive Dig-Mike and mount it as a ht gage ..... !!!
Almost as good simply using a DTI ( 0.0001 hash marks ) , but it only ranges over about .001 ! For the arc it travels .... So hand me a hack saw and a Mitutoyo ..... Any complaints ?