A few days ago, I started torquing my ER20 collet nuts to 39 ft/lbs per recommendations. I ensured that each tool had the proper collet size. Some of the collets now have obviously uneven gaps. From what I know, this is less than ideal. I tried redoing the trouble makers several times, no change.
I don’t know is it indicated that the individual collet or tool holder is just bad?? Or, should each tool be “custom torqued”, regardless of tool size, till the gaps are uneven, then back off 5 ft/lbs??
I’ve also been measuring tools with a granite plate and tool height gauge. when I face a part with a 1/2" endmill for example, it seems to take off too much. Ex: I tell it to take off 0.010", it actually takes off 0.012" to 0.014". Adding a couple thou to the measured length seems to fix this. I got an Edge Tech. analog tool setter to measure in the spindle, because I had heard that the TTS collars flex a little. today I did an experiment measuring the same tools using both methods. Some were the same, some were up to 0.004" different, and none were exactly the same as the one’s I “corrected” based on facing cuts.
Ex: 1/2" endmill granite plate = 3.2465" Edge Tech. = 3.2476" “corrected” = 3.2493"
Technically, I could correct square endmills based on facing cuts, other tool geometries, not so much.
I’m not sure what the root cause is. I know my axis scale and backlash are pretty dead on. Any advice on how I can measure the “functional” length of tools without experimenting, and/or suggestions for a root cause, would be greatly appreciated.
Thanks,
Joe