Member postings for Ron Zitron

Hi

I am overwhelmed by the number of responses. Thank you. I will be performing several more tests in the next week or so. Unfortunately the necessity of earning a living prevents me from spending more time in my workshop.

To try and answer some of the comments:

AAy1 and Russell: I have already taken the tailstock off to check if there is any junk at the interface with the ways. It is clean and smooth. I still have to dismantle the tailstock completely.

John: What is a Morse taper test bar? I also don't quite follow your suggestion of mounting a dial gauge in the spindle/chuck and clocking the tailstock bore. Couldn't any discrepancy also be caused by problems with the headstock or my ability/inability to correctly mount the dial gauge?

Martin: I didn't think of dirt where that headstock contacts the bed. I'll check it out. Regarding your suggestion of machining an unsupported piece of steel - couldn't any discrepancies be caused by poor mounting in the chuck? I've only got a 3 jaw chuck and have yet to acquire the 4 jaw.

Harold: I will follow your suggestion re repeating the test with the tailstock spindle fully extended and not extended.

Gray: What is the significance of doing a test between dead centres? I would have thought that the tests done demonstrate that the dead and live centres are concentric throughout?

Many thanks

Ron

Hi,

I recently purchased an EMCO Compact 5 lathe from a deceased estate. I've always enjoyed using my hands although that is not how I earn a living. Hopefully this addition to my garage, which already has more hardware in it that meets with the approval of someone else residing at the same
address, will keep me occupied and out of mischief for many happy hours.

I believe that I got the lathe at a good price as the previous owner had
purchased it in 1984 but had never used it. It was still in the original
packaging! The date of manufacture was in October 1982.

When I machine a length of steel mounted between a dead and a live centre, I get a few thou difference in the diameters near the headstock and near the tailstock.

I conducted the following test:

1. Put a dead centre in the headstock.
2. Put a live centre in the tailstock spindle.
3. Brought the tailstock close to the headstock and locked it.
4. Brought the points of the two centres together by using the tailstock handle while holding a 6" steel rule between centres.
5. When the rule was clamped between the centres it remained perfectly vertical, but was twisted, indicating an apparent misalignment of the headstock and tailstock in the horizontal direction.
6. I repeated the above while
a. Rotating the spindle,
b. While rotating the dead centre within the spindle,
c. While rotating the live centre point, and
d. While rotating the entire live centre within the tailstock.

The steel rule always indicated the same misalignment throughout each of the above tests.

I don't think that the bed is twisted and that shimming will help. To try and check for this I conducted another test:

Turned a piece of steel about about seven inches long held between a dead centre in the headstock and a live centre in the tailstock. The diameter measured at the tailstock was 11 thou (yes, that much) less than that about 0.5" from the headstock end. I couldn't turn all the way to the headstock end as the last half inch was occupied by the lathe dog.

I then repeated the above but with a piece of steel about 2 inches long. The discrepancy was again 11 thou'.

This would seem to indicate that bed is not twisted and the tailstock was too far forward (or the heastock too far back) by 5.5 thou'.

This seems inconceivably excessive. Does anyone have any ideas/suggestions? I’m reluctant to start filing anything or doing anything that cannot be undone.

Thanks

Ron