Re: PC Turn 50 Headstock Alignment
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To test spindle runout remove the chuck and using a Dial Indicator place the tip in the taper and gently turn by hand on the back of the spindle. Mount the indicator on the bed, its the most rigid part of the machine. This will give you the runout of the spindle, place the tip on the face and also check the face runout. these should be way under .001 runout
To test the runout of the chuck do as above. I am assuming that you have the precision 3 jaw chuck that has the square chuck key. The other cheaper chuck used a Jacobs drill key, I had one of these and it runout quite a bit. The precision 3 jaw I have now is less than .001 runout. The standard is usually measured at 1 inch from the chuck.
If you have part taper then your tailstock may also be out of alignment. You can buy a ground steel Lathe mandrel that has a center on each end. I have one of these, bought years ago from ENCO, you must use a center in the spindle and one in the tailstock. Chucks do wear with use. The jaws can also have taper. Has the lathe been crashed? That could also be a problem.
Sometimes gunk gets trapped under the tailstock, I would remove it and check the bottom for gunk. At that time I would also polish the bed. Are there any dings on the ways?, if so use a fine stone to remove them.
My PCturn50 typically has less than .0005 on parts that are 6 inches long, I use a live center to support the part. If you have bench centers you can also use indicators to check the roundness of your parts, if you have roundness issues it will show.
I worked at a precision shop where the 18 inch swing Mori-Seiki Manual lathe had bearing issues and ran out .002, the lathe had seen heavy use and was removed for rebuilding.
On Sunday, June 7, 2020, 11:14:26 AM EDT, rcflyer <sclcl082@...> wrote:
There are many variables which can cause taper in a turned part. To test spindle runout, chuck drill rod or similar and indicate from the tool post.
On Sat, Jun 6, 2020 at 11:56 PM David Rabenius via groups.io <firstname.lastname@example.org> wrote: