I'm trying to figure out why I'm getting 0.012" (!) runout on my adjustable pen mandrel. The mandrel (Craft Supplies) is the one with a collet on a (#2) morse taper that allows the pen mandrel to slide in and out. Truly great idea! But I cannot get it to work with my Jet mini. I first noticed that the morse taper was not fitting snugly, but it seemed OK, so I ignored it. My first pen didn't look too good, though. :-/
After measuring 0.012" runout on the mandrel where it enters the collet, I pulled the mandrel out and rolled it on my bandsaw table -- no problem. Then I put the mandrel in my Jacobs chuck (with morse taper) in the lathe, there was zero runout. My technique with the tailstock is to advance the live center with the lathe running, until it just comes into contact with the mandrel and starts spinning. No undue force.
I contacted CS and talked to technical support. They sent out another one, and it's the same problem. I called back today, and they said they had checked out my return, and it seems fine to them on their lathe. So it must be the combination of the mandrel's MT and that of my Jet mini.
Now I'm wondering if the machining marks (ridges) on either the mandrel or my Jet (or both) are too large. I'm pretty sure its these oversize ridges that keep it from seating. The MT for my Jacobs chuck is much smoother, and snugs up very well. CS tech support concurs that their mandrel's MT has the ridges, and says my Jet mini MT should be smooth.
Any Jet mini owners out there that can shed some light? Any MT experts? Anyone else with this mandrel? I think I'm gonna take it to Woodcraft and compare it to their mandrel (is it the same mfr?) and in their lathes.
If this is just how it is, it's definitely a no-go for me.
Thanks, Tom