Bridgeport quill to head clearance?

Question

I'm fixing up a Bridgeport head to replace the Millport head on my CNC knee mill. Or trying to see if this head is worth fixing up to replace the Millport head. What sort of clearance should I have between the quill and head? Near as I can measure, I've got about .001 give or take a few tenths. Dry, that's enough to cause some finish chatter I'm sure, but with oil in there, might that be OK?

Reason for the swap is downtime, can't afford it. Got the BP head cheap enough to sit on it for a year before Millport head noises prompted me to get moving on this.

Thanks,

Jon

Ned Simmons · Accepted Answer

The clearance is enough that I wouldn't spend too much time on that head without actually trying it out. I've seen the number for the proper clearance and it's very small-a few tenths perhaps?

Ned Simmons

Jon Anderson · Answer

That sounds more like it. I decided to invest a bit of time and bolted the casting to my mill table, set a mag base on the casting and the indicator on the quill. Using a 2' long AL bar, I could move the quill that .001 fore and aft. I had a full oil film, so it wouldn't just pop over .001, but it would move. Sigh...

Thanks,

Jon

R. O'Brian · Answer

You could have the head rebuilt or trade it in.

See

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They fix your problem by hard chroming the quill and then grind back to size. I have had one of their rebuilt mills for 10 years and it was like new when received.

Randy

Jon Anderson · Answer

Randy,Thanks for that, I emailed and asked for quote on refitting the quill only.Jon

Bridgeport quill to head clearance?

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