5C collet Alignment in a Mill

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Nyala

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When I first received my PM-25 mill, 5C collets were inserted until it followed the alignment "pin" and the drawbar drew it in nicely. Just like I expected it to work.

Over time I had trouble locating the alignment pin but the collets still went in a could still be tightened with the drawbar. Seemingly, no ill effects.

The one day I was milling something and a small socket set screw fell onto the table. I knew what it was immediately but wondered why everything worked without it and whether or not I needed to put it back in.

So, my newbie question is, do I need to put it back in?

Thank you.
 
I think you have your collets mixed up, Most mills use R-8 collets.
 
Your spindle is R8, not 5C, and no, you shouldn’t need the set screw.
 
Those pins/screws are a POA at best, they will make it easier to tighten the collet sometimes, but are easily sheared off, if using end mill holders they are un necessary, as the body of the holder can be grasped while tightening the drawbar.
 
You're lucky it fell out, no need to remove it.
 
Sorry, you are right about R8 vs 5C. I was just looking at purchasing a couple 5C collets and had 5C on my mind as I typed. In any case, the R8 collet seems to worked even without the alignment pin.

Thanks for the responses.
 
My alignment pin fell out or sheared off. I don't miss it. I'm using a power drawbar and everything works fine. In the beginning, the pin was actually too proud and I had to reduce its protrusion, as I recall.
 
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