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What would be considered acceptable runout for the spindle on a verticle mill?

One horsepower or less?

Or fifty horsepower and greater?

If you mean BirdPort/ BeePee class, not Swiss watch / optical industry nor marine Diesel maker drive-thru size just say "Bridgeport"

At which point... just check their specifications ....

Or those for any OTHER "comparable" machine if you cannot find the specs on your OWN one.

Done.

:D
 
What would be considered acceptable runout for the spindle on a verticle mill?

A popular type of cutting tool on vertical mills is a flycutter. It has one cutting edge, so any runout on the spindle is irrelevant unless the spindle speed is so fast that the imbalance is an issue. Even then, the flycutter is so unbalanced that the spindle runout will not matter.

Boring and facing is also done with single point cutters, so runout does not matter for those either.

Drilling is a different matter.

Or, to put in more scientific terms, it depends...

Larry
 
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Runout on small endmills is pretty immaterial too,unless its like .003" ,cause just about every hobby mill the cutter holding collets are not all that accurate,and cheap steel endmills just cut on one flute if runout is excessive.....this even s up next time the endmill is used ,so not of any great concern......keyways may be a bit loose,but the cheap cutter may be undersize anyway,so it all evens out.
 
I wouldn't call runout immaterial - maybe inconsequential for a hobby guy - no way in hell it's immaterial in a shop that does machining for money. Excess runout can cause a serious problem with tool wear, accuracy, can limit feedrate and all sorts of other issues.

If you're checking the I.D. spindle taper, I'd expect to see not more than a few tenths runout - ideally less than that. At the O.D. of a cutting tool, preferably less than . 001" runout. In reality, on something like a Bridgeport that's been used hard and put away wet this may not be the case - especially if someone has had the spindle apart and not reassembled it *just so* to minimize runout.
 
I have a small Clausing but do fiddly work on it and had about 4 tenths in the spindle that translated to a couple thou. 1" out. Was finding it hard to do accurate work.

Re-ground the spindle, installed new bearings and shimmed to top bearing in the bore (it was a 1/2 thou loose) and ended up with virtually no runout.

Accurate work is much easier now. So I guess it depends what you're doing...


 
I assume op is referring to his new purchase here, for those intersted:
Questions about a Van Norman #2 duplex milling machine

Van Norman's can be capable of better work than their operators ordinarily need.

"CAN be."

But "weary" is weary. New is not forever.

See Terry's post on basic refurb back to OEM spec.. or better.

How true is table travel? What about flex?

IOW .. how much goodness do yah need?

How much time and money is it worth?

Flex is harder to deal with. Ergo my "main" mill masses 5205 Avoir, has under 7 1/2 thou of table sag in 48 inches accumulated over 60 or so years.

Good enough with a skosh of compensating to JF "run what I got."
 
Runout is more likely due to tooling than the spindle, itself. Indicate the spindle taper to see if it's the actual spindle running out. If a VN is running out, it's the bearings. They were very well made machines when new, and on a #2, there is no way to bend the spindle, given how the taper actually sits partially in the lower bearing.

If you are getting runout on an endmill or other tooling in the spindle, it could be compounding errors. If you have a NMTB 40 taper, with a MT 3 adapter and a drill chuck set up, you could have .0004 on the MT adapter and .0015 on the drill chuck (or easily more). Extend that out 4" on a drill point and it may be making a very obvious circle instead of spinning true.
 








 
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