[scott216]

I'm looking for suggestions on measuring runout on new toolholders that I buy. There are several source of runout. You have the spindle, TTS holder, the ER collet, the ER nut and the end mill. I know the ultimate test is measure the runout of the end mill in the holder and in the spindle. But I'm looking to judge the quality of the TTS holders and collets when I first buy them to see how good they are. I don't know of any way to tell how good the ER nuts are and I don't know how important they are to run-out. I do have a tenths indicator.

One idea I had to measure the TTS holder is to put it in a 4-jaw chuck in my lathe, dial in the shank then measure the ER taper. I could also buy a high quality ER collet and nut (and assume it has negligible runout) and put a gauge pin in as my end mill, them measure the runout on the gauge pin. I'd like a simpler setup. Maybe use a v-block instead of mounting in a lathe. That would probably work with a precision collet and gauge pin, but it might be hard to just measure the taper. A tiny amount of axial movement would mess up the reading.

[deadlykitten]

hy to trully check a toolholder, you have to apply kind of a similar quality check procedure as the toolholder producer does

a faster way, to target only er chuck runnout, in respect to taper, is to simply clamp the toolholder, gently, on the flange, because taper, flange diameter and flange frontals are all machined during same operation; flange frontal and er chuck frontal may not be paralel

once clamped, simply put the dial on flange diameter, flange face, and inside er chuck; is not needed to tap/center the toolholder diameters to target 0 tir, is enough to simply adjust flange face tir, then compare diameters runnout : for example, if 2 different diameters have a runnout of cca1mm, with peeks at same spindle phase, and 0 face tir, then that part is coaxial ... thus, on other words, diameters are coaxial if their tir is identical, and phases are matched

instead of a chuck, you can also use your cnc mill spindle, as long as it delivers consistent clamping position

thus, there are tricks to check runout, without necessarily dialing the part,towards 0, but by using a comparison

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besides runout, taper surfaces need checking also the angle : for the outside taper, use a toolholder as reference, and calibrate on it 2 dials, as far as possible one from the the other; they will load more on less in respect to contact point height, but the diff between them should be consistent : again this is a relative measure, not absolute, but pretty fast and easy to replicate

for the inside taper, is a bit more tricky, because it is small, but you can jog a dial inside it, and look for similar values at similar travels, thus, how i like to call it, similar drops; is not needed for the dial palpator to be exactly on the plane of simetry of the toolhilder, but more important is to achieve consistent clamping for all measuring all toolholders; again, if mill spindle delivers consistent mounting, use it, and create a nice low feed program to create contact between dial and toolholder

such relative measurements don't say that a group of parts are good or bad, but that they are identical within the deviation that you found during measuring / kindly