Mandrel saver trouble

[Charles Webster]

I'm new to the wood lathe and pen turning (about 4 months ) and self-learning. I thought I would give Pen Turning a try and really enjoy it.
I read and watched videos that a mandrel saver will keep from bending the mandrel shaft and all the pressure would be on the bushings and blanks instead of the mandrel shaft itself. Well, I purchased a mandrel saver and have had nothing but trouble. I have gone through 2 shafts wabbling and turning out bad pens with a mandrel saver. I don't believe I over tightened the mandrel saver.
Without a mandrel saver using a live center, all my pens came out great (about 29 out of 30 pens). With mandrel saver, I have had none to be proud of. Ever since I started using the mandrel saver all my pens seem to be less than desirable and appear that the mandrel shaft starts to wabble. I don't use a lot of pressure. I figure I will go back to using the live center for my pen turning. Has anyone else had this trouble?
P.S. as this is my 1st post I hope I am posting in the right place. If not please let me know.
Thanks
Charlie

[John K Jordan]

Hello Charles! Hard to tell what the problem is without looking at it. I've used the mandrel saver type of live center on someone's lathe and it worked ok. I didn't put any pressure on it at all, just let the mandrel run loosely in the hole.

Some things I'd check for:

- Does the mandrel saver fit snugly in the tailstock MT (with no wobble)?

- Is the end of the shaft that fits into the mandrel saver clean with no distortion or scratches?

- Is the tailstock properly aligned with the headstock? Put a point in both headstock spindle and tailstock MT2 and bring them up close to see if they align exactly. If not, it's usually pretty easy to fix.

- If you put the mandrel saver in the headstock spindle MT and maybe keep it from spinning with some tape, does it spin true? If not, is there a burr or some junk on the MT? I occasionally clean the Morse tapers on both the headstock and tailstock with this: https://www.woodturnerscatalog.com/p...-Taper-Cleaner

- Is the mandrel perfectly straight? You can usually tell by rolling it on a flat surface such as a table saw bed or bandsaw table. Or hold it against a good straight edge and and turn it to check at different places along the circumference.

JKJ

[Charles Webster]

It's possible that I got a bad mandrel saver. It seems to run true and smooth, but being new to the hobby I might not be seeing the trouble. I just turned a pen (slimline) using a new mandrel shaft and new bushings. I used the live center instead of the mandrel saver and it came out just fine. So, it must be something I am doing wrong with the mandrel saver or it's the mandrel saver itself. Or it could be a loose nut at the lathe (me).

[david privett]

is the morse taper # you are using correct to your lathe?

[Clint Bach]

Hmmm.... Are you using the nut on the tailstock end of the mandrel to hold the bushings and blanks in place? If so remove that nut and use only the mandrel saver and tailstock pressure to hold everything in place.

Just guessing on this one... I can't tell from the previous posts.

c

[Dane Riley]

Some things I'd check for:

- Is the tailstock properly aligned with the headstock? Put a point in both headstock spindle and tailstock MT2 and bring them up close to see if they align exactly. If not, it's usually pretty easy to fix.


JKJ

One thing I've wondered about is if the alignment is off is it because the tailstock is cocked(skewed) or offset? It could line up perfectly if the two errors were opposite. One way to check for this would be to check alignment with a short point and a long Morse taper drill bit. If they both lined up you don't have this problem.

A mandrel saver might be more sensitive to bore-sight error than anything else. Might also take some thought to figure out how to correct this if you have it.

[Peter Christensen]

There is a pen turning forum that goes by the name of International Association of Penturners, IAP for short. Every conceivable method, problem and solutions with mandrels has been discussed quite regularly. There were bearing problems with Mandrel Savers when they first came out. Personally I ditched mandrels ages ago in favour of turning between 60 degree live and dead centres. The dead centre in the headstock and the live in the tailstock. There are special bushings you can buy for use with centres but using the standard ones until very close to finish size, then removing the bushings and completing the pen between the centres only, ensures they are concentric. The disadvantage is you can only do one barrel at a time.