Pillar Drill Accuracy/Runout issues?

[Dissolve]

Hi,

My Fobco Star pillar drill has new bearings and with the quill locked into place the spindle measures 0-1 thou of runout, but with the lock off it measures something like 3-4 thou..

With the original Jacbos chuck (unknown history) a chucked smooth rod measures 7-8 thou runout (Quill locked)
and with the new Axminster Super Precision chuck I purchased I can get 6-7 thou runout (Quill locked)

I know having that 3-4 thou play in the quill isn't ideal, but if the spindle measures 0-1 thou when it's locked surely I should be able to get the chucked accuracy better than 6 thou with the quill locked?

Anyone have any ideas? I don't think I can resolve the play in the quill as it's likely just wear and tear, but any ideas/opinions would be appreciated!

 

[tool-me-up]

its more than likely part of the attachments for the chucks to the quill. If its a morse taper It could be a simple gouge or rust patch pushing the chuck to one side slightly.
I would try and get the dial indicator on the inside of the quill and see if that reveals anything ( tricky i know)

 

[Spindle]

Hi

Tool-me-up is correct, the run out is most likely to be induced by a poor match of either the Morse or Jacobs tapers. Are you changing over the chucks and tapers or just the chucks?

If chucks and tapers - check the quill taper for corrosion or dirt

If just the chucks - check the Jacobs taper and the Morse taper for corrosion and dirt

The other possibility if you are changing just chucks is that you may have a distorted mandrel - remove the chuck and clock the run out on the Jacobs taper to check.

Regards Mick

 

[custard]

Good thread.

When a superb drill like a Fobco gives up to 8 thou of run out in practise, imagine what some of the cheap and cheerful Chinese drills are delivering?

 

[RogerP]

My cheapo Chinese Ryobi pillar drill

Fitted with a cheapo Axminster 1-16mm chuck and arbor

.. . gives a total 4mm run-out measured on the shank of a new 13mm Dormer drill.

That's good enough for me.

 

[Dissolve]

Thanks for the input guys! The fobco has a JT6 on the end of the spindle directly, so no arbor is necessary, and the spindle has been dressed smooth and measures within 1 thou when the quill is locked.. I'm ignoring the quill movement at the moment simply because if the spindle measures so accurately.

The new axminster chuck is obviously not rusted and I've tried cleaning and re-fitting both chucks with no difference!

Looks like I might have to spend a bit more and buy a new Jacobs if I want any improvement..

 

[tool-me-up]

If you have some thing perfectly round with no known run-out you can lock that into the chuck jaws and use it as a pivot point to measure the taper for run out. It can be a bit of a faff on making something to hold it still mind - Last time I did something similar I made a set of V blocks to support the rod and tack welded a big chunk of steel block to the end of the test rod so it had enough weight to balance the chuck on the blocks