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.
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?
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...