QC 30 Spindle Nut causing runout, part number/where to find?

[Sparky_NY]

I am not positive about the bridgeport spindle but many have their angular contact bearings with chevron markings (etched arrows) on the outer races. This is pretty standard for abec 7 matched pairs. Those marks are to be aligned which gives minimum runout.

Did you try and blue up a toolholder and see what the taper contact pattern is in the new spindle? Maybe, with luck, there is a tiny fault.

Alright, tried the new spindle lock nut and to no avail, same runout. I think it's a problem with the taper itself and is in need of a professional regrind.

Luckily I had the extra spindle here I bought to throw in.

Threw that in and I'm getting .0005 or less inside the tool holders now, so I'm pretty happy. I wish it was less, but I'm not sure if I could ask for more.

What does everyone else have in their toolholders?

I had some measuring .0005 and the best one was around .0004 or so. This is measuring the inside of it.

I didn't have time to throw a tool in and measure the runout on the tool itself yet.

Can you really get better than .0005 on a bridgeport without having it professionally reground? By that I mean from the factory were they any better than that even?

[shiver-91vr4]

I thought there was something marked on the outer races, but when I asked the guy who sold it to me he said there shouldn't be any. I'll have to look on the one I pulled out to see if there are. If so, I'll pull it out and try to align my new one.

I blue'd up the taper and it's absolutely mint. This spindle was rarely used, compared to my old one it's in perfect shape. There wasn't anything near the bearings etc, they were perfect with a light film of oil. On my old one, they were covered in black cruddy grease/oil.

What was the original spec on runout on the bridgeports?

[shiver-91vr4]

Thanks so much! You did everything but make the screw and install it for me!

I'm curious, you mention the other hole is for a different position when steeing it up, what is that all about?

If you need to make the grip tighter/looser you can remove the longer screw and twist the housing until the next outside hole aligns with the inner groove stop.

This effectively loosens or tightens how tight the 1/4 turn makes the tool. You'll find that one position will be too tight and the tool holders cannot even be started to tighten, and the one right below that is perfect, but go too far and it wont tighten down at all.