Headstock Alignment

P

parshal

Member
I've got a Precision Matthews 1340GT which allows the headstock to be aligned. I'll spare the long story but the other day I releveled the lathe with a Starrett 98-8 level, dialed in a test bar with the set-tru chuck and cut a dumbell test bar protruding about 10" from the chuck. It was off .002". So, I used an MT test bar (12-15" long, I think) directly in the spindle. My bar obviously isn't ground perfectly so I used the Rollie method to align the headstock. I then did a cut with my test bar and it was within .0005".

I have a Wilson neck die blank that I'm cutting for my 6.5 SS to use for resetting necks on pulled bullet cases during my load development. The through hole is .350" near the top. It's then .328" at the end. Their instructions are to align, center drill, twist drill and ream. I used a long stem Mitutoyo 513 long stem indicator in the bore to adjust the chuck. I reached in the die and used the .350" hold to align. When I had that set I checked the .328" hole and it was out a couple thou. I ran the indicator in using the carriage to see if the hole was concentric and it's out by about a thou. Making the assumption that Wilson ran a straight hole I would think the headstock should be moved to 'straighten' the die in the chuck. However, the test cuts show it to be straight.

I assume I should trust the test cuts more than the Wilson die being cut straight. But, to get a true straight 'chamber' I would think it would be best to align the headstock. This may be more academic and my 'runout' probably won't make a huge difference once reamed.

What say the experts?
 
No expert here

BUT there is the reamer and how it is directed to be considered I think. we only talking a couple of inches here. One can never really trust anything commercially made, from my experiences.

Pete
 
You can trust that the Wilson die blanks are NOT straight. Best to set them up in a way that allows you to get them running true to the reamed bore, pre bore, then ream the chamber.
 
I've never liked Wilson dies

SGS said:
You can trust that the Wilson die blanks are NOT straight. Best to set them up in a way that allows you to get them running true to the reamed bore, pre bore, then ream the chamber.
Click to expand...

I have some of them but never use them. I graduated to a turret press years ago for my loading. Just my taste I know but my Harrell die is straight as is my Forster Micrometer Seater. I felt it was a huge upgrade. Had nothing to do with straightness but irregular OAL's when seating. I want every round as perfect as I can make it and couldn't get that out of hand dies..


Pete
 
These aren't my go-to dies. I use them a bit at the range when I don't want to drag the Co-Ax along. I'm doing this one so I can reset the neck tension after pulling bullets during load development.
 
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