I have no direct experience with ISO30 anything; mid-purchase of a used S30C spindle and tool holders, reported to have low hours. While inspecting the tool holders, all the tapers include markings- some kind of generally blotchy in bands near top and bottom, some with many longitudinal marks starting at the wide end of the tapper and fading out.
The spindle was used with aluminium pretty much exclusively; the tool holders and machine had fine bits of aluminium glitter most everywhere.
Are these markings normal? Obviously, the concern is runout and possible spindle damage. What do your tool holders look like after ~100 hours use? Images attached.
Wow! That’s a lot of wear/damage. Maybe from low drawbar tension causing slip. Possibly the air blast failed and contaminants(chips) entered during a tool change. Every time those gnarly bits were drawn into the taper, they’d likely be damaging the spindle taper. They should look like new at 100 hours and well beyond.
Replace the holders and closely inspect the spindle taper. You could be up for repairs. Does the rest of the machine look like low hours?
I applied a soft chemise and denatured alcohol to the holders- see attached images for the results on the two holders previously pictured. The chemise came away with lots of (presumably) aluminium glitter; a finger nail ran over the surface can detect some of the marks, most with effort.
That is what happens over time when you get chips stuck between the tool holder and the spindle. My machine is setup to blow off the taper every tool change. The tools are also covered until the machine goes to change a tool. Here is one of mine after 2 years of use (probably somewhere around 1000-1500 hours):
Christopher. I work in the CNC metalworking field for my dayjob mostly centered around toolholder dynamics. Those tool holders would not go into our spindles. Anything you can feel with your fingernail on the toolholder taper is going to end up as a witness mark on your spindle taper. Take each toolholder (with its own unique fretting or galling) and multiply that times the number of toolholder you intend to introduce to your spindle, and you can see how quickly you could really mess up a nice spindle taper. I realize we are mostly referring to hobby level machines, (and therefore these issues aren’t seen as drastic) but if your like me, you like to keep you nice things…well, nice. To make matter worse, once your have a transferred witness mark on your spindle from a crappy toolholder, then the next ‘nice, clean’ toolholder you put into the spindle with receive the same witness mark from the spindle. Some of this could be caused by pushing the machine too hard in the cut. Harmonics are a leading cause of fretting, even more so than debris. And the metal fines you cleaned off might have been a combination of your spindle wall and your tool taper.
Exactly my reckoning- I just needed to hear experienced voices say as much. Some have suggested a light application of abrasive to knock down upset metal- but that would only invite the liabilities of imbalance and diminished tolerances, with all the prospects of success of buffing out scratches on a vinyl record.
You really can clean them up, but you’ll need a precision flat ground stone (google it). Robin Renzetti has some good videos on using them for this purpose. Cleaning the inside of the spindle is considerably harder though. That may need to be reground to clean it up. If you have the equipment, it could be done in the machine.
If you have a second spindle and can mount a dressed stone in it, you can use the CNC function of the router to interpolate the correct path of the machine spindle against the second spindle with the stone in it to basically regrind the taper in place.
