Turned blank not centered on tube

[MacG]

Greetings All,

In the picture you will see that the turned wood is not centered on the tube. This is the nib end of a Cigar pen and it was turned on a 7 mm mandrel, #2 morse taper in head stock and a mandrel saver in the tail stock. I should mention also that both halves of the cigar pen were on the mandrel.

Any idears?

 

[WriteON]

I'm gonna take wild shot..
Slightly bent mandrel
Head and tail stock not centered.
Off center bushings
Too much pressure sanding

 

[ed4copies]

IF both tubes were on the mandrel simultaneously, is the other one the same?

If yes, the mandrel is likely bent
If no, the bushing used for the one shown has an off-center hole.

 

[jttheclockman]

Hello Mac and welcome to the site.

so many things can produce that effect and it will be hard for us to pin point it for you. But as mentioned we can help with suggestions.

Lets start at the beginning. Is this the first time you have noticed this??? Is this the first time you used this kit with these bushings?? Is there any firsts at all with making this pen and let us know. We go from there.


I do not believe it is a bent mandrel because you are using a mandrel saver. Or at least I should say it is not from over tightening. The rod could very well be bent but i will reserve my opinions when we hear from you on my first questions.

 

[MacG]

I'm gonna take wild shot..
Slightly bent mandrel
Head and tail stock not centered.
Off center bushings
Too much pressure sanding

Wow three replies fast!

So many options, now I wish I posted this when I turned it a couple of weeks ago

Well, the pic shows the rough turned blank which was on the thin side down to the bushing but not down to the bushing on the thick side. I thought that was the odd thing.

I measured the bushings for off center bore and overbore for where the shaft goes through. but what I did not measure was the step of the bushing from the tube ID to the finished pen barrel for center meaning is the shoulder the same all the way around.

Well I remounted on the mandrel and slowly with a skew was able to bring it to round. I think you are right about the tailstock being out of alignment. Both the 1014 jet and the Nova Midi have some slop and it was the tailstock end of the pen which went out of round not the head stock. It would also explain a bit of how after I moved the tailstock unmounting and remounting I was able to get it back into shape.

I was asking to avoid repeating the error and not go to far and wreck a good blank as I lucked out on this one.

Have you tried the B sized mandrels (thicker shaft) over at Arizona Shilouette?

 

[MacG]

Hello Mac and welcome to the site.

so many things can produce that effect and it will be hard for us to pin point it for you. But as mentioned we can help with suggestions.

Lets start at the beginning. Is this the first time you have noticed this??? Is this the first time you used this kit with these bushings?? Is there any firsts at all with making this pen and let us know. We go from there.

Not the first time using these bushings on a cigar/big ben kit.

I do not believe it is a bent mandrel because you are using a mandrel saver. Or at least I should say it is not from over tightening. The rod could very well be bent but i will reserve my opinions when we hear from you on my first questions.

Using the mandrel saver I thought the mandrel was almost irrelevant, almost. But as I mentioned above I think the tailstock out of alignment. This is a new Nova midi. There is a bit of play at the back of the tailstock tenon in the ways while the front seems nearly slop free so it could have been twisted a bit resulting in an eccentric rotation. As mentioned above after remounting and careful skew work I got it round again. Don't want to have to that again

I was also wondering if the tube ID was larger on this one tub allowing an offset of the bushing pushed to one side but I could not verify that.

Thanks to All for helping with this.

 

[jttheclockman]

I do not believe it is tailstock alignment. All lathes have the tailstock movement as you put it. If you believe there is a problem then you need to look into that. If the lathe is new look into warrenty work. You can not have those problems. Make sure your lathe sits flat and level on a table or bench and is not racked.

You did not answer if this was the first time you seen this happen on any pen??? How many pens have you made??? If you have 2 lathes and they both have tailstock problems I would look deeper into this. Not adding up in my mind.

 

[Hawkdave]

Hi Eric and welcome to IAP.

You mention you used a mandrel saver. Is the pen mandrel threaded on the end that enters the mandrel saver?

If it is, there is a tendency for the thread to wear down with repeated use. This will cause the shaft to be sloppy in the mandrel saver.
I also experienced something similar and after finding out what was causing the issue, I got my mate to make me a shaft minus the threaded end. That fix my problem straight away.

Dave.

 

[thewishman]

To lessen the out-of-round problem, stop the lathe when you get close to the finished size of the barrel and rotate the bushings on each end. I turn each bushing about 1/3 of the diameter in opposite directions, without moving the barrel. Just before sanding, I rotate again. That should help reduce the problem.

Two things I did to further reduce the problem:

Shorten the mandrel and turn only one barrel at a time, this helped a lot.

Get rid of the mandrel and use bushings made to fit 60 degree centers in the tailstock and headstock (they are called TBC - turning between center bushings) - this made things even better.

 

[MacG]

I do not believe it is tailstock alignment. All lathes have the tailstock movement as you put it. If you believe there is a problem then you need to look into that. If the lathe is new look into warrenty work. You can not have those problems. Make sure your lathe sits flat and level on a table or bench and is not racked.

You did not answer if this was the first time you seen this happen on any pen??? How many pens have you made??? If you have 2 lathes and they both have tailstock problems I would look deeper into this. Not adding up in my mind.

So a little slop in the ways is ok.

Yes I have seen it on other pens and I guess I'll have to keep a log of what I was doing at the time .eg. both halves on a mandrel, TBC etc.

I have seen some spiraling that requires a deeper cut to get under it and clean it off. Depending how close to finished size I may sand the high spots off.

Made about 4-5 dozen pens. My wife probably has a dozen to herself

I am going to analyze the tail stock issue a little closer. You say it normal to have some play (some at least to slide it back and fourth) but should I be able to feel it by twisting the released tail stock in the ways enough to hear or feel it hit/click?

 

[MacG]

To lessen the out-of-round problem, stop the lathe when you get close to the finished size of the barrel and rotate the bushings on each end. I turn each bushing about 1/3 of the diameter in opposite directions, without moving the barrel. Just before sanding, I rotate again. That should help reduce the problem.

Two things I did to further reduce the problem:

Shorten the mandrel and turn only one barrel at a time, this helped a lot.

Get rid of the mandrel and use bushings made to fit 60 degree centers in the tailstock and headstock (they are called TBC - turning between center bushings) - this made things even better.

Thanks for the tips. I have turned between centers with just the standard bushings but specific bushing for this may work better. Do you know if they have higher tolerances than the standard Penn State type bushings?

 

[Joey-Nieves]

Hello Mac and welcome to the site.

so many things can produce that effect and it will be hard for us to pin point it for you. But as mentioned we can help with suggestions.

Lets start at the beginning. Is this the first time you have noticed this??? Is this the first time you used this kit with these bushings?? Is there any firsts at all with making this pen and let us know. We go from there.


I do not believe it is a bent mandrel because you are using a mandrel saver. Or at least I should say it is not from over tightening. The rod could very well be bent but i will reserve my opinions when we hear from you on my first questions.

John, over tightening the tail stock will cause the mandrel to bou even with the saver.

 

[thewishman]

To lessen the out-of-round problem, stop the lathe when you get close to the finished size of the barrel and rotate the bushings on each end. I turn each bushing about 1/3 of the diameter in opposite directions, without moving the barrel. Just before sanding, I rotate again. That should help reduce the problem.

Two things I did to further reduce the problem:

Shorten the mandrel and turn only one barrel at a time, this helped a lot.

Get rid of the mandrel and use bushings made to fit 60 degree centers in the tailstock and headstock (they are called TBC - turning between center bushings) - this made things even better.

Thanks for the tips. I have turned between centers with just the standard bushings but specific bushing for this may work better. Do you know if they have higher tolerances than the standard Penn State type bushings?

They are usually spot on. I have a couple of bushings that I like to be bigger than the regular ones - keyrings and Sierra Vista top. I have bushings from three different makers and they have all been good.

Nikitas - http://www.penturners.org/forum/member.php?u=9301 - does a great job and can make about any bushing you want.

 

[jttheclockman]

Hello Mac and welcome to the site.

so many things can produce that effect and it will be hard for us to pin point it for you. But as mentioned we can help with suggestions.

Lets start at the beginning. Is this the first time you have noticed this??? Is this the first time you used this kit with these bushings?? Is there any firsts at all with making this pen and let us know. We go from there.


I do not believe it is a bent mandrel because you are using a mandrel saver. Or at least I should say it is not from over tightening. The rod could very well be bent but i will reserve my opinions when we hear from you on my first questions.

John, over tightening the tail stock will cause the mandrel to bou even with the saver.

Have to take your word for it. I do not own one and have never used one. But from what I have seen you are basically tightening against the bushings. You basically are pushing against a solid piece of wood.

Maybe that is the problem but from what I am reading we will never know.

 

[Charlie_W]

I have also seen many turners leave the tailstock quill lock loose as they say it slows them down having to loosen and tighten each time you make an adjustment to the quill. Both of my lathes have slop in the quill and not locking it down could account for things not lining up properly and or moving as pressure is applied to the blank while turning.
My take on the quill lock is that it was determined decades ago that it was needed. If not, manufacturers would have done away with it as a cost cutting measure. It has a purpose so I use it.

Don't know if this your problem but just one more thing to check.

You could have several things combining to cause your issue. A little play between the bushing and the mandrel, bushing loose in the tube, bent mandrel, play between the mandrel and the mandrel saver, quill slop, head stock/tail stock alignment, tailstock to bed play, ends of blanks not being square, etc.....just a little off on several of these in conjunction can add up.

Needing to rotate the bushings confirms that something is not running true.

I only use between center bushings whenever I can. Even turning your blank close to the bushing and then going totally between centers for the last few thousandths, is another method to have concentric blanks. You just need a caliper to measure your blanks in comparison with the pen hardware. Remember to allow for sanding and also for finish.

Good luck!

 

[MacG]

I have also seen many turners leave the tailstock quill lock loose as they say it slows them down having to loosen and tighten each time you make an adjustment to the quill. Both of my lathes have slop in the quill and not locking it down could account for things not lining up properly and or moving as pressure is applied to the blank while turning.
My take on the quill lock is that it was determined decades ago that it was needed. If not, manufacturers would have done away with it as a cost cutting measure. It has a purpose so I use it.

Don't know if this your problem but just one more thing to check.

You could have several things combining to cause your issue. A little play between the bushing and the mandrel, bushing loose in the tube, bent mandrel, play between the mandrel and the mandrel saver, quill slop, head stock/tail stock alignment, tailstock to bed play, ends of blanks not being square, etc.....just a little off on several of these in conjunction can add up.

Needing to rotate the bushings confirms that something is not running true.

I only use between center bushings whenever I can. Even turning your blank close to the bushing and then going totally between centers for the last few thousandths, is another method to have concentric blanks. You just need a caliper to measure your blanks in comparison with the pen hardware. Remember to allow for sanding and also for finish.

Good luck!

Ah loose quill...I have noticed at times mine has backed nearly all the way out. Randomly enough to not make that connection. I will pay more attention to this.

Thanks all for your input and resources.

 

[Charlie_W]

I have also seen many turners leave the tailstock quill lock loose as they say it slows them down having to loosen and tighten each time you make an adjustment to the quill. Both of my lathes have slop in the quill and not locking it down could account for things not lining up properly and or moving as pressure is applied to the blank while turning.
My take on the quill lock is that it was determined decades ago that it was needed. If not, manufacturers would have done away with it as a cost cutting measure. It has a purpose so I use it.

Don't know if this your problem but just one more thing to check.

You could have several things combining to cause your issue. A little play between the bushing and the mandrel, bushing loose in the tube, bent mandrel, play between the mandrel and the mandrel saver, quill slop, head stock/tail stock alignment, tailstock to bed play, ends of blanks not being square, etc.....just a little off on several of these in conjunction can add up.

Needing to rotate the bushings confirms that something is not running true.

I only use between center bushings whenever I can. Even turning your blank close to the bushing and then going totally between centers for the last few thousandths, is another method to have concentric blanks. You just need a caliper to measure your blanks in comparison with the pen hardware. Remember to allow for sanding and also for finish.

Good luck!

Ah loose quill...I have noticed at times mine has backed nearly all the way out. Randomly enough to not make that connection. I will pay more attention to this.

Thanks all for your input and resources.

Try to keep your quill as close to the tailstock as possible. If anything tailstock/quill related is off, it will be magnified with the quill extended a ways.

Good luck!

 

[More4dan]

An out of aligned tail stock would only result in a taper cut on a metal lathe where the cutting tool is fixed to the axis of rotation. Oval cut can only occur with the bushing moving on the mandril rod due to an oval hole through the bushing Smith wear or an off center hole. Wear on the mandril rod making it oval counlod also do it.