Question on Mandrels???

[Jonathon Spafford]

Gotta question on my pen mandrel... I have been noticing that my pen tubes are off center. I checked to see if it is something recently gone wrong, but my older pens are the same way. I was just so proud to make my first pen that I didn't notice. :D
Anyway, now that I am a little more detailed oriented I am trying to figure out the problem. I am imagining the mandrel is somehow bowed. I don't overtighten the talk stock so I don't imagine that is the problem. It is a Penn State and those seem to be on the cheaper side. Anyway, how would you get the bow out of a mandrel???

[Ken Fitzgerald]

Jonathon.......I've noticed that too on mine. A couple of things could cause it...1) the mandrel isn't straight....2) Putting too much pressure on the mandrel with the tailstock live center......

I'm afraid I don't know how you'd straighten a mandrel......

[Lisa Gilbert]

I have the exact same problem, and we splurged on the expensive, sturdier "professional" (hah!) mandrel. I'm anxious to hear some answers.

[Gary DeWitt]

I'd check the "straightness" of the mandrel by rolling the shaft on a piece of glass or marble or any known flat surface. If your mandrel has a MT at the end, let it hang off the edge.
Once you're sure it's straight when it's not turning, you need to find out what happens when you turn with it. When you bring the tailstock up to it, does it move or bend a bit to fit into the live center? Are you absolutely sure you only put enough pressure on the ts to contact the mandrel? Do you get any sounds or other evidence of vibration while turning, such as from too much bevel pressure on the wood? Are the mandrel shaft and the pen tubes a pretty close fit, just slide together?
Some stuff you can check, otherwise, you got me...

[john blanchard]

Do you have a 60 degree live center drove myself crazy with the same problem until i figured out mine was not.

[Wayne Bitting]

I had the same problem with the mandrel when I was turning on the ShopSmith. The new lathe I switched to PSI's maxi mandrel which allows you to adjust the length of the shaft to meet your pen size and not have to use spacers. Did 8 pens since I got it this weekend and they are all true.

[David Walser]

Here's the best explanation I've ever found on how to get your mandrel running true: http://www.woodturnerruss.com/Pen12a.html.

It's from Russ Fairfield's website. Russ has a ton of information on pen turning and it's a good place to go even if you are an experienced pen turner. For a newbie, it's all but a must.

Oh, he has some videos on pen turning available. I've not seen them and would appreciate a review of them if any of you have seen them.

[Ron Raymond]

Well, David beat me to posting Russ's website...he's right about it being a terrific site. I had emailed Russ asking permission to post a link to his website, and in his response he added this:

"You might also note that the biggest cause of out of round pens is not the mandrel, but over aggressive sanding. The wood density is not the same all the way around a pen barrel because of the grain orientation, and the softer wood sands away faster than the harder wood. Flat grain sands away faster then the edge grain orientation."

[David Walser]

"You might also note that the biggest cause of out of round pens is not the mandrel, but over aggressive sanding. The wood density is not the same all the way around a pen barrel because of the grain orientation, and the softer wood sands away faster than the harder wood. Flat grain sands away faster then the edge grain orientation."

Great! One more thing to worry about...

[Dario Octaviano]

Things I do:

1. Try turning one piece at a time (need an adjustable mandrel or collet chuck for this)
2. Use 60 degree live center
3. Do not over tighten tailstock
4. Light cuts (do not push)
5. Stabilize wood with thin CA after final cuts (also before if wood is funky/soft)
6. Avoid using "dull" sandpaper.
7. Make sure the ends are "milled" properly and are perfectly perpendicular to the tube (very important!!!)
8. Mandrel is clean (a tiny drop of CA is enough to cause problems)
9. Bushings are clean.
10. MT2 driver (hole at headstock) and MT2 of mandrel are clean...again a small dirt here will be magnified the further you are from the head stock.
11. Engage tailstock first before tightening the mandrel knob.

Check all these and hopefully you will have a better fitting pen.

[John Hart]

My first thought was the perpendicularity of the ends. How are you squaring up your blanks after tube insertion? Just the slightest bit of angle will cause the condition you are describing. Along with all the other suggestions of course...but that's the first thing I thought of.

[Bernie Weishapl]

One thing I was told and can't remember if it was Russ or another pen turner. I took a scrap piece of walnut about 1 1/2" wide and ran it across the jointer for a flat surface. The wrap my sandpaper around the piece of walnut. It will give you a very flat surface when sanding and not have a tendency to make uneven surfaces. Has changed and helped me a lot.