How to align tailstock with mandrel?

[Jerry Ingraham]

I've been turning pens for a few weeks now and have continually fought an out of round issue. I have checked the bushings on the mandrel and they're a pretty snug fit (it occurs with all my bushing kits). I have quit over-tightening the mandrel nut. I have quit overtightening my tailstock quill. That all being said, I do know that my tailstock doesn't line up with the mandrel pocket, it is off by 1/16". I slipped a .025" feeler gauge under the tailstock base on the backside and it was enough to bring everything into alignment. Unfortunately, I am out of pen kits so I haven't been able to see if it corrects my dilemna. If it does, how do I go about correcting this condition? It can't be good for any turning, let alone pens. Tonite, I'll check it against the spur drive as well. My lathe is a Rikon mini. Any thoughts?
Jerry

[Jason Boushard]

check and make sure your base is level that could be throwing it off I am redoing my base today.

[Mike Vickery]

For the sake of arguement even though you say you are not over tightening the nut. Try unscrewing the nut and check allignment. You would be suprised how little preasure by the nut can knock it off alignment. After that I would make sure the mandrel is not bent and your tailstock and headstock line up.

[Jerry Ingraham]

Mike,
This evening I'm going to check the alignment of the live center with the spur drive. I suspect that it is off. As to the overtightening, I may still be doing so. I'll probably inch up on the minimum pressure needed to turn the blanks without them spinning on the mandrel.

Jason,
What do you mean by levelling the base?

[Ellen Benkin]

What brand of mandrel are you using? I found that problem with the PSI mandrel because it didn't have an indent for my tailstock center and I couldn't get it to set in completely correctly. I bought a mandrel from Rockler, which does have an indent, the tailstock center fit right into it, and everything is very round.

[Grant Wilkinson]

I think that you have the right approach. Before going any further with the mandrel/tail stock alignment, make sure the tail and head stocks align.
If they do, you may want to make sure that the mandrel isn't bent. If, before you started loosening things up, you want a bit too far, you may have bent it.

[Jerry Ingraham]

Ellen,
My mandrel is from CSUSA. It, too, has the indent for the tailstock which I use. Yesterday, I tried turning a cigar pen and ended up with way too much eccentricity which made me start to look for the problem. Prior to this, I had been simply turning slimlines which I could sand out the out of round condition. The cigar pen however, is all but ruined (in my eyes). I am ordering a 60 degree live center today and will be checking the live center to headstock alignment tonight. I also will be checking to see if I have bent my mandrel. I'll get to the bottom of this one way or the other!
Jerry

[Joe Melton]

When you check alignment, I suspect you are simply moving the tailstock in next to the headstock and observing whether the points on the spur drive and live center meet. This really isn't the way to check alignment.
What you want is that an imaginary center line through the headstock spindle meets the live center tip when the head- and tailstocks are separated by the distance of a pen mandrel.
You can check this by first finding a "perfectly" straight mandrel. You really should have a dial indicator, but you can get by doing this:
1. With the mandrel held in your headstock, and unsupported at the tailstock end, turn the handwheel slowly and observe the turning end of the mandrel. If the end describes a circle instead of a point, then something is out of alignment. You can check this closer by moving one end of the tool rest to it is very close to the mandrel end. Then turn the handwheel and closely observe the space between the rest and the mandrel. With the high place on top, mark on your handwheel or exposed threads of your spindle. Now move the mandrel around and recheck. You can tell in this way if the morse taper is not machined "parallel" to the spindle center line or if the problem is in your mandrel. Hope this makes sense.
2. Keep in mind that if the end of the mandrel describes a circle, and if the mandrel is straight, then bending the mandrel in an attempt to make the end describe a point will only worsen your problem.
3. If the mandrel end describes a point, and this point is not aligned with your live center tip, you have a problem with the alignment of the headstock (assuming the tailstock cannot be adjusted). You can try to adjust out this misalignment by shimming the headstock or by moving it around (by loosening its hold-down bolts). This adjusting will result in the single point at the end of the mandrel being moved to another position, hopefully closer to the live center tip.
4. The end of the mandrel will almost certainly describe a circle. This is because the mandrel itself is not perfectly straight, and/or the method of holding it is imperfect. Bear in mind you are dealing with cheaply made machined parts, not precision parts. You cannot pay six dollars for a mandrel and expect it to be perfect. The same applies to the method of holding it, whether it is with a morse taper or a Beall collet chuck, or otherwise. Furthermore, once you use a mandrel, the pressure you exert on it by turning a pen blank will bend the mandrel. This is worse if you use the smaller "A" mandrels. (I always remind myself that mandrels are expendables, like bushings, and need be replaced every 50 pens or so.)
5. Now tighten the live center to the mandrel. I generally do this by moving the tailstock close enough so the live center contacts the mandrel. Then I turn the lathe on. Then I move the live center away, so it stops spinning. Then I move it toward the mandrel, to the point where it starts spinning, and lock the tailstock. This is putting the minimum pressure on the mandrel, helping to prevent bending it.
6. If you have a dial indicator, you should check the end of the mandrel now, with the live center engaged. If the dimple in the end of the mandrel is not centered, the mandrel will now burn excentrically. Bad bearings in your live center will cause eratic measurements, too.
6. Penturners live with this alignment problem and make adjustments for it. If you can take out some of the misalignment by shimming the headstock, do it. If your live center bearings are bad, replace them or the center.
Personally, when making a pen, I rotate my bushings (holding the blanks steady) 180 degrees between sanding grits, which is, in my opinion, good enough. Some people mount and turn one blank at a time, because the further you turn from the headstock, the more the out-of-roundness problem becomes.
Hope this helps.
Joe